Patent Description:
Owing to such advantages as high energy density, high power density, multiple cycles and long storage time, lithium-ion batteries and the like have been widely used in electric vehicles.

However, the extension of the service life of batteries of an electric vehicle has always been a problem in the industry. <CIT> describes a battery capping device. <CIT> mentions a battery-filling opening. <CIT> relates to a battery vent cap includes a cylindrical body having an upper portion and a lower portion. <CIT> states a lithium-ion battery, comprising a cover plate. <CIT> relates to a top cover for a lithium-ion secondary battery.

An object of the present application is to provide a lithium-ion battery with improved performances. The invention is defined by the appended claim set.

According to a first aspect of the present application, an end cover assembly is provided, including:.

In some embodiments, the cover body further includes a main body part which covers at least part of the sealing element, and the limiting part is connected to the main body part and extends along a radial direction of the through hole.

In some embodiments, there are a plurality of limiting parts, and the plurality of limiting parts are arranged at intervals along a circumferential direction of the main body part.

In some embodiments, the end cover further includes a guiding part communicated with the accommodating part, and the limiting part is configured to enter the accommodating part via the guiding part, or be detachable from the end cover via the guiding part.

In some embodiments, the cross section of the accommodating part is C-shaped or V-shaped.

In some embodiments, the accommodating part includes a first limiting wall, a second limiting wall arranged opposite to the first limiting wall, and a side wall which connects the first limiting wall and the second limiting wall.

In some embodiments, when the cover body rotates to the first position, the first limiting wall abuts against the limiting part to limit separation of the cover body from the end cover.

In some embodiments, at least one of the limiting part, the first limiting wall and the second limiting wall is provided with an inclined surface, and the inclined surface is configured to guide the limiting part to enter the accommodating part.

In some embodiments, a first groove is arranged on a surface, far away from the shell, of the main body of end cover, and the installation part is fixed in the first groove.

In some embodiments, the accommodating part is formed on an inner side of the installation part, the cover body includes a main body part which covers at least part of the sealing element, and the main body part is arranged in an opening , which is formed in the installation part and surrounds the through hole, the opening is communicated with the accommodating part, and the limiting part is connected to an outer side of the main body part and extends along a radial direction of the through hole.

In some embodiments, the accommodating part is formed on the outer side of the installation part, the cover body includes a main body part which covers at least part of the sealing element, the main body part is sleeved outside the installation part, and the limiting part is connected to an inner side of the main body part and extends along a radial direction of the through hole.

In some embodiments, the end cover is provided with an opening which surrounds the through hole, and the opening is arrangeable on a side, far away from the shell, of the through hole, the accommodating part is formed on a side of the opening, the cover body includes a main body part which covers at least part of the sealing element, and the main body part is arranged in the opening, and the limiting part is connected to the outer side of the main body part and extends along a radial direction of the through hole.

In some embodiments, a stopping part is arranged in the accommodating part to limit maximum rotation stroke of the limiting part.

In some embodiments, a limiting structure is arranged between the limiting part and the accommodating part, and the limiting structure is configured to limit misplacement and separation between the cover body and the accommodating part when the cover body is arranged in the first position.

In some embodiments, the limiting structure includes:.

In some embodiments, along an axial projection of the through hole, a maximum diameter of the sealing element is greater than a minimum diameter of the through hole.

In some embodiments, the sealing element includes a sealing column and a thrust table connected to one end of the sealing column, the thrust table is arranged radially, the sealing column is inserted into the through hole, and the thrust table abuts against the end cover.

In some embodiments, a rotation angle of the cover body from the first position to the second position is less than <NUM>°.

In some embodiments, the cover body is in contact with the sealing element, a friction coefficient of a contact surface between the sealing element and the cover body is less than a friction coefficient of a contact surface between the sealing element and the end cover.

In some embodiments, in an axial direction of the through hole, a protruding part is arranged on a surface at which at least one of the cover body and the end cover is in contact with the sealing element, and the cover body abuts against the sealing element, such that the sealing element abuts against the protruding part.

According to a second aspect of the present application, a housing assembly for a secondary battery is provided and includes:.

According to a third aspect of the present application, a secondary battery is provided, including: a shell and an end cover assembly in the above embodiments, wherein the end cover assembly covers an opening of the shell to form a housing assembly of the secondary battery; or
the housing assembly in the above embodiments.

According to a fourth aspect of the present application, a battery pack is provided, and the battery pack includes a plurality of secondary batteries in the above embodiments.

According to a fifth aspect of the present application, a device using the battery is provided, and includes the secondary battery in the above embodiments, wherein the secondary battery is configured to provide electric energy.

In a non-claimed aspect, a liquid injection method of a secondary battery is provided, including:.

In non-claimed embodiments, before the cover body is placed on the housing, the liquid injection method further includes:
installing the sealing element on the housing or the cover body.

In non-claimed embodiments, the liquid injection method further including:.

In non-claimed embodiments, after the cover body is separated from the housing, the liquid injection method further includes:
removing the sealing element from the housing or the cover body.

In a non-claimed aspect, a liquid injection device for the secondary battery is provided and includes:.

In non-claimed embodiments, the liquid injection device further including:
a sealing element disassembly and assembly mechanism, configured to install the sealing element on the housing or the cover body, or remove the sealing element from the housing or the cover body.

In non-claimed embodiments, the cover body disassembly and assembly mechanism is configured to rotate the cover body from the first position to the second position, such that the limiting part and the accommodating part are misplaced along the circumferential direction of the through hole, to separate the cover body from the housing.

In non-claimed embodiments, a sealing element disassembly and assembly mechanism is configured to remove the sealing element from the housing or the cover body when the cover body is separated from the housing.

As to the end cover assembly of the embodiment of the present application, separation of the cover body from the end cover can be realized through rotating the cover body, to realize secondary liquid injection. Through convenient secondary liquid injection, in the present application, the degree of reduction in capacity of a cell can be effectively slowed down, and the service life of the battery can be prolonged.

Drawings illustrated herein are used for providing further understanding of the present application and form part of the present application, and illustrative embodiments of the present application and description thereof are intended for explaining instead of improperly limiting the present application. In the drawings:.

The present application will be described in detail below. In the following paragraphs, different aspects of the embodiments are defined in more details. Each aspect defined in this way can be combined with any other one aspect or a plurality of aspects, unless explicitly stated that no combination is allowed. Especially, any characteristic deemed to be preferable or advantageous can be combined with any one or more characteristics which are deemed to be preferable or advantageous.

The terms "first" and "second" used in the present application are merely used for convenience of description, to distinguish different components with the same name, rather than implying precedence or primary and secondary relationship.

In addition, when the element is called to be "on" the other element, the element can be directly arranged on the other element, or can be indirectly arranged on the other element, and one or more intermediate elements are inserted therebetween. In addition, when an element is called to "be connected to" the other element, the element can be directly connected to the other element, or can be indirectly connected to the other element, and one or more intermediate elements are inserted therebetween. In the following text, the same reference numeral represents the same element.

The "a plurality of' used in the present application means more than two (including two), similarly, "a plurality of groups" refers to more than two groups (including two groups).

To clearly describe each orientation in the following embodiments, for example, each orientation of the battery is defined by the coordinate system in <FIG>, x direction represents a length direction of the secondary battery <NUM>; y direction is vertical to x direction in the horizontal plane, and represents a width direction of the secondary battery <NUM>; z direction is vertical to the plane formed by x direction and y direction, and represents a height direction of the secondary battery <NUM>. Based on such definition of orientations, the orientation or positional relationship indicated by such terms as "up", "down", "top", "bottom", "front", "rear", "inner" and "outer" are merely for the convenience of description of the present application, rather than indicating or implying that the device referred to must be located in a certain orientation or must be constructed or operated in a certain orientation, therefore, the terms cannot be understood as a limitation to the protection scope of the present application.

Many problems may lead to a shortened service life of the lithium-ion batteries, those skilled in the art have tried to solve the problem from many different angles over the years, however, no anticipated effect has been achieved.

As a part of the invention-creation process of the present application, after numerous tests and verifications, the inventor found that one of the reasons leading to shortened service life of the battery is as follows: in the using process, the battery is subjected to charge and discharge cycles for a plurality of times, the electrolyte inside the battery will be inevitably subjected to irreversible reaction consumption, and the capacity of the battery will be decreased accordingly. Therefore, the inventor found that, if the electrolyte inside the battery can be supplemented in the using process of the battery, the degree by which the capacity of the battery decreases will be effectively slowed down, and the service life of the battery is prolonged.

The lithium-ion battery is mainly composed of positive electrode materials, negative electrode materials, electrolyte and a diaphragm, wherein the electrolyte is an ionic conductor which plays a role of conduction between the positive electrode and the negative electrode of the battery, and is generally composed of electrolyte lithium salt and organic solvent. To prevent extravasation of electrolyte in the using process which may pollute surrounding air and environment, or prevent entrance of water vapor or metal particles into the inside the battery which may cause short circuit of the positive electrode and the negative electrode, the battery proposes a high requirement on the sealing performance of the structure. In the related technology known to the inventor, infusion of electrolyte of a battery is generally performed in the production stage, after infusion of electrolyte is finished, to ensure airtightness of the battery, the liquid injection hole is generally closed through a laser welding manner.

As to this type of battery, liquid supplement is difficult in the using process, if liquid needs to be supplemented, the laser welding structure also needs to be destroyed, and resealing is difficult, moreover, the structure of the battery will be destroyed irreversibly, and the using performance of the battery is influenced.

In view of this, the present application tends to provide a secondary battery which can realize repeated disassembly and assembly of the liquid injection component, to conveniently disassemble the liquid injection component to supplement liquid, and after liquid supplement is finished, the liquid injection hole can be closed reliably. However, in combination with the structural characteristics and performance requirements of the lithium-ion batteries, when the battery with dismountable liquid injection component is designed, numerous problems need to be solved simultaneously.

For example, <NUM>, as compared with a lead-acid battery, the overall size of the lithium battery is small, correspondingly, the size of the liquid injection hole is also small, and the design of a dismountable structure is difficult; <NUM>, the liquid injection component should be disassembled conveniently and rapidly, to facilitate operation and reduce maintenance time; <NUM>, in the disassembly process of the liquid injection component, short circuit of the positive electrode and the negative electrode of the electrode assembly, caused when external impurities or metal scraps squeezed from the battery fall into the shell, should be prevented; and <NUM>, when the battery is used in a vehicle, the vehicle will vibrate in an operating process, when the battery is used for a long time or the battery is disassembled and assembled for a plurality of times, since the size of the liquid injection component is small, the structural strength of the liquid injection component when the liquid injection component closes the liquid injection hole should be ensured, to ensure reliability and service life of the battery during operation.

On the basis of a comprehensive consideration of the above technical problems, the present application provides an end cover assembly, a secondary battery, a battery pack and a device using the battery, to facilitate secondary liquid injection of the battery. That is, through reserving a liquid injection hole, the process of injecting electrolyte into the inside of the battery according to a required amount includes primary liquid injection and secondary liquid injection. Secondary liquid injection can further be called supplemented liquid injection and further liquid injection, etc. Secondary liquid injection means to supplement or replace electrolyte of the battery, or add or supplement any solid, liquid or gas to the battery. Through convenient secondary liquid injection, the present application can effectively slow down the degree of decrease in the capacity of the cell, and prolong the service life of the battery.

The device using the battery includes a secondary battery <NUM> configured to provide electric energy for the device, as shown in <FIG>, the device using the battery can be a vehicle <NUM>, for example, a new energy vehicle, and the new energy vehicle can be a battery electric vehicle, a hybrid electric vehicle or an extended range vehicle, etc., or the device using the battery can also be an unmanned aerial vehicle or a ship, etc. The secondary battery <NUM> which can realize secondary liquid injection can enable the device to reduce the frequency of battery replacement, save cost, and improve reliability and power performance of the device during operation.

To enable the battery to have a higher power to satisfy use demands, as shown in <FIG>, a battery pack <NUM> can be arranged in the device using the battery. In some embodiments, the battery pack <NUM> includes a first shell <NUM>, a second shell <NUM> and a plurality of battery modules <NUM>, wherein the first shell <NUM> is buckled with the second shell <NUM>, and the plurality of battery modules <NUM> are distributed in a space enclosed by the first shell <NUM> and the second shell <NUM>.

As shown in <FIG>, the battery module <NUM> includes a plurality of secondary batteries <NUM>, and the plurality of secondary batteries <NUM> can be connected in series, in parallel or in series and parallel to realize a large capacity or power. For example, as shown in <FIG>, the secondary battery <NUM> can be placed vertically, the height direction of the secondary battery <NUM> is consistent with the vertical direction, and a plurality of secondary batteries <NUM> are arranged side by side along a width direction; or the secondary battery <NUM> can be placed horizontally, the width direction of the secondary battery <NUM> is consistent with the vertical direction, a plurality of secondary batteries <NUM> can be stacked for at least one layer along a width direction, and each layer includes a plurality of secondary batteries <NUM> arranged at intervals along a length direction.

To enable those skilled in the art to clearly understand improved points of the present application, the overall structure of the secondary battery <NUM> is firstly illustrated.

As shown in <FIG>, the secondary battery <NUM> includes a shell <NUM>, an electrode assembly <NUM> and an end cover assembly <NUM>, wherein the end cover assembly <NUM> includes an end cover <NUM>', the end cover <NUM>' is connected with the shell <NUM> to form a housing of the secondary battery <NUM>, the electrode assembly <NUM> is arranged inside the shell <NUM>, and the shell <NUM> is internally filled with electrolyte. The secondary battery <NUM> can be square, cylindrical or of other shapes.

According to actual use demands, a single or a plurality of electrode assemblies <NUM> can be arranged. As shown in <FIG>, at least two electrode assemblies <NUM> which are wound independently can also be arranged inside the battery. The electrode assembly <NUM> can form a main body part through winding or stacking a first pole piece, a second pole piece and a diaphragm arranged between the first pole piece and the second pole piece, wherein the diaphragm is an insulator arranged between the first pole piece and the second pole piece. The main body part has two opposite end faces. In the present embodiment, the first pole piece being a positive pole piece and the second pole piece being a negative pole piece is taken as an example for illustration. A positive active substance is coated on a coating area of the positive pole piece, while a negative active substance is coated on the coating area of the negative pole piece. A plurality of uncoated areas extending from the coating area of the main body part are stacked to serve as a tab. The electrode assembly includes two tabs <NUM>, that is, a positive tab and a negative tab. The positive tab extends from the coated area of the positive pole piece, while the negative tab extends from the coated area of the negative pole piece.

The end cover assembly <NUM> is arranged on the top of the electrode assembly <NUM>, as shown in <FIG> and <FIG>, the end cover assembly <NUM> includes an end cover <NUM>' and two terminals <NUM>, the two terminals <NUM> are respectively a positive electrode terminal and a negative electrode terminal, each terminal <NUM> is correspondingly provided with an connector <NUM>, and the connector <NUM> is arranged between the end cover <NUM>' and the electrode assembly <NUM>. As shown in <FIG>, an installation hole <NUM> is arranged at the part, corresponding to the terminal <NUM>, on the end cover <NUM>', the terminal <NUM> is fixed in the installation hole <NUM>, and a sealing ring <NUM> is arranged between the terminal <NUM> and the installation hole <NUM>. For example, the tab <NUM> of the electrode assembly <NUM> in <FIG> is arranged at the top part, the positive tab is connected with the positive terminal through one connector <NUM>, and the negative tab is connected with the negative terminal through another connector <NUM>. Optionally, the secondary battery <NUM> can include two terminal assemblies <NUM> which are respectively arranged at two ends of the shell <NUM>, and each end cover assembly <NUM> is provided with a terminal <NUM>.

The end cover <NUM>' can further be provided with an anti-explosion component, and when too much gas exists inside the secondary battery <NUM>, gas inside the secondary battery <NUM> is released timely, to avoid explosion. The end cover <NUM>' is provided with a vent hole <NUM>, the vent hole <NUM> can be arranged in the middle position, along the length direction, of the end cover <NUM>', and the through hole <NUM> can be arranged between the installation hole <NUM> and the vent hole <NUM>. The anti-explosion component includes an anti-explosion valve <NUM>, and the anti-explosion valve <NUM> is arranged on the vent hole <NUM>. Under a normal state, the anti-explosion valve <NUM> is installed in the vent hole <NUM> in a sealed manner, when the battery expands and air pressure inside the housing rises to exceed a preset value, the anti-explosion valve <NUM> is open, and gas is released outwards through the anti-explosion valve <NUM>.

In some embodiments, as shown in <FIG>, the end cover <NUM>' is provided with a through hole <NUM> configured to inject electrolyte into the secondary battery <NUM>, the through hole <NUM> can adopt a circular hole, an oval hole, a polygonal hole or a hole of other shapes, and can extend along a height direction of the end cover <NUM>'. The end cover <NUM>' is provided with a liquid injection component configured to close the through hole <NUM>.

After the overall structure and the application of the secondary battery <NUM> are described, the liquid injection component of the present application will be elaborated in detail below. Firstly the liquid injection component being arranged on the end cover <NUM>' is taken as example, based on the structure, the present application provides a plurality of embodiments, and the common points of each embodiment are firstly given below.

As shown in <FIG> to <FIG>, the present application provides an end cover assembly <NUM> for a secondary battery <NUM>. In some embodiments, the end cover assembly <NUM> includes: an end cover <NUM>', a sealing element <NUM> and a cover body <NUM>.

The end cover <NUM>' is provided with a through hole <NUM> for injection of electrolyte and an accommodating part <NUM>, with the secondary battery <NUM> as a basis, the through hole <NUM> can be arranged along a height direction of the secondary battery <NUM>, that is, arranged along a thickness direction of the end cover <NUM>', or can be arranged in an inclined manner. The accommodating part <NUM> is arranged on a side, far away from the shell <NUM>, of the end cover <NUM>' and is arranged along a circumferential direction of the through hole <NUM>, and the accommodating part <NUM> can be a cavity extending along the partial circumferential direction of the through hole <NUM>. A preset distance exists between the accommodating part <NUM> and the surface, adjacent to the inside of the shell <NUM>, of the end cover <NUM>' and the size of the preset distance is not defined, for example, the accommodating part <NUM> can be arranged in the upper area, middle area or lower area of the end cover <NUM>', such that at least part of the end cover <NUM>' is arranged between the accommodating part <NUM> and the electrode assembly <NUM>, rather than directly setting the accommodating part <NUM> on the bottom surface of the end cover <NUM>'.

The sealing element <NUM> is configured to seal the through hole <NUM>, and the cover body <NUM> is configured to cover at least part of the sealing element <NUM>, to prevent separation of the sealing element <NUM> from the end cover <NUM>'.

The cover body <NUM> can press the sealing element <NUM>, such that the sealing element <NUM> can deform and improve the sealing effect, or the cover body <NUM> is only in contact with the sealing element <NUM> to limit the degree of freedom along a height direction; when the sealing element <NUM> is closely matched with the through hole <NUM> and can independently close the through hole <NUM>, the cover body <NUM> and the sealing element <NUM> can also be arranged at intervals in the height direction. The cover body <NUM> can completely cover the sealing element <NUM>, to exert a pressure onto the sealing element <NUM>, limit the position or prevent external impurities from entering the battery; when the sealing element <NUM> is closely matched with the through hole <NUM> and can independently close the through hole <NUM>, the cover body <NUM> can also partially cover the sealing element <NUM>.

The cover body <NUM> is configured to be rotatable, for example, the cover body <NUM> can rotate within the plane vertical to the height direction, and the rotation axis can be an axis of the through hole <NUM>. As shown in <FIG>, the cover body <NUM> includes a limiting part <NUM>, and the limiting part <NUM> can extend along the partial circumferential direction of the through hole <NUM>.

A clamping structure is formed between the limiting part <NUM> and the accommodating part <NUM>, wherein when the cover body <NUM> rotates to a first position, part or all of the limiting part <NUM> is located inside the accommodating part <NUM> to limit separation of the cover body <NUM> from the end cover <NUM>', to close the through hole <NUM>; when the cover body <NUM> rotates to a second position along a clockwise direction or an anti-clockwise direction, the limiting part <NUM> and the accommodating part <NUM> are misplaced along the circumferential direction of the through hole <NUM>, and the limiting part <NUM> is completely separated from the accommodating part <NUM>, to realize separation of the cover body <NUM> from the end cover <NUM>', and under the state, electrolyte can be injected.

In the present application, the cover body <NUM> can be separated from the end cover <NUM>' through rotating the cover body <NUM>, to realize secondary liquid injection. Through convenient secondary liquid injection, in the present application, the degree of reduction in capacity of the secondary battery <NUM> can be effectively slowed down, and the service life of the battery can be prolonged. Further, after the liquid injection component is disassembled, the air inside and outside the shell <NUM> is communicated through the through hole <NUM>, to discharge gas inside the shell <NUM> or bubbles between the pole pieces. Through discharging bubbles between the pole pieces, the gap between the pole pieces is shortened, thereby improving the cycling performance of the secondary battery <NUM>, and further prolonging the service life of the secondary battery <NUM>. Through discharging gas inside the shell of the secondary battery <NUM>, in the present application, pressure inside the shell <NUM> can be released, to reduce continuous pressure exerted by the gas inside the shell onto the anti-explosion valve <NUM>, lower the risk of liquid leakage of the secondary battery <NUM> due to creep rupture of the anti-explosion valve <NUM> or the risk of shortened service life due to entrance of water vapor, to further prolong service life of the cell, meanwhile, the acting force exerted onto other structures due to expansion of the secondary battery <NUM> when the gas inside the secondary battery <NUM> is large can be reduced, thereby avoiding structural damage of other structures due to overlarge expansive force of the secondary battery <NUM>, and prolonging service life of the battery pack. The cover body <NUM> is limited or separated from the accommodating part <NUM> through rotating, in the rotating process, the limiting part <NUM> may be in friction with the inner wall of the accommodating part <NUM>, to produce metal particles. Since in the present application, the accommodating part <NUM> is arranged on a side, far away from the shell <NUM>, of the end cover <NUM>', metal particles produced in the rotating process will not directly fall into the shell <NUM> and cause short circuit of the secondary battery <NUM>, thereby further improving safety of the secondary battery <NUM>.

An extending length of the limiting part <NUM> along the circumferential direction of the through hole <NUM> and an extending width along the radial direction of the through hole <NUM> ensure strength of the clamping structure. When disassembly and assembly are performed for a plurality of times, the clamping structure can also be prevented from damage. Moreover, when the secondary battery <NUM> is applied to the vehicle <NUM>, since the vehicle <NUM> will vibrate in the operating process, in the present application, through enhancing the clamping strength of the limiting part <NUM> and the accommodating part <NUM>, damage caused when the limiting part <NUM> and the accommodating part <NUM> are vibrated for a long time can be prevented, thereby ensuring reliability and service life of the secondary battery <NUM> during operation.

In the present application, the through hole <NUM> is opened and closed through rotation of the cover body <NUM>, such that a detachable structure is formed between the cover body <NUM> and the end cover <NUM>'. The liquid injection structure will not be damaged when the cover body <NUM> is opened, after secondary liquid injection is finished, the through hole <NUM> can also be closed reliably, to ensure operating reliability of the battery after secondary liquid injection. Therefore, the appearance of the secondary battery <NUM> is kept consistent with the appearance of the secondary battery <NUM> before liquid injection, and use after secondary liquid injection is not influenced. Further, the through hole <NUM> is closed through directly rotating the cover body <NUM>, therefore, sealing of the through hole <NUM> can be realized with no need of laser welding, thereby reducing cleaning step on the through hole <NUM> before laser welding, and improving production efficiency of the battery.

In the present application, the limiting part <NUM> is matched with or separated from the accommodating part <NUM> through rotation of the cover body <NUM>, the structure is simple, the requirement on match precision is low, and repeated use is allowed; in the aspect of processing, the cover body <NUM> is provided with a limiting part <NUM>, the end cover <NUM>' is provided with an accommodating part <NUM> and they are both easy to process and are suitable for lithium-ion batteries with a small overall size; in the aspect of disassembly and maintenance, the disassembly and assembly of the cover body <NUM> are easy to operate, then the assembly efficiency of the battery can be improved during production, and the maintenance time can be shortened during secondary liquid injection.

<FIG> are structural schematic diagrams of an end cover assembly <NUM>-<NUM> of a first embodiment of the present application. Wherein <FIG> shows a sectional view of a first embodiment of the present application; <FIG> are respectively a top view and a sectional view of the cover body <NUM> in <FIG>; and <FIG> are respectively structural schematic diagrams of a front side and a back side of an installation part <NUM> in <FIG>.

As shown in <FIG>, the cover body <NUM> further includes a main body part <NUM> configured to cover at least part of the sealing element <NUM>, for example, the main body part <NUM> can be disk-shaped or ring-shaped, etc. The limiting part <NUM> is connected to the main body part <NUM> and extends along the radial direction of the through hole <NUM>, according to the matching manner of the end cover <NUM> and the end cover <NUM>', the limiting part <NUM> can extend inwards or outwards along the radial direction. For example, the limiting part <NUM> can be a boss which extends along a circumferential direction of the main body part <NUM>, and the shape of the cross section of the boss is compatible with the accommodating part <NUM>.

As shown in <FIG>, a plurality of limiting parts <NUM> are arranged, the plurality of limiting parts <NUM> are arranged at intervals along the circumferential direction of the main body part <NUM>, correspondingly, a plurality of accommodating parts <NUM> are also available, and the plurality of limiting parts <NUM> and the plurality of accommodating parts <NUM> are set to be in one-to-one correspondence. Two limiting parts <NUM> are arranged in <FIG>, and the two limiting parts <NUM> are arranged oppositely relative to the center of the main body part <NUM>.

In the present embodiment, through setting a plurality of limiting parts <NUM>, the cover body <NUM> has a plurality of limiting supports in the first position, can be clamped stably by the accommodating part <NUM>, and can reduce the clamping force exerted onto the limiting part <NUM>, to ensure strength of the limiting part <NUM>. For example, the plurality of limiting parts <NUM> can be distributed along the circumferential direction of the main body part <NUM>, can realize more balanced distribution of pressure exerted onto the cover body <NUM> along the whole circumferential direction, and can prevent the cover body <NUM> from tilting, thereby being beneficial for smoothly rotating the cover body <NUM> from the first position to the second position during secondary liquid injection, and also preventing the limiting part <NUM> from scratching the sealing element <NUM> during rotation as to the structure, pressing the sealing element <NUM>, of the cover body <NUM>.

As shown in <FIG>, the end cover <NUM>' further includes a guiding part <NUM> which is communicated with the accommodating part <NUM>, and the limiting part <NUM> is configured to enter the accommodating part <NUM> through the guiding part <NUM>, or to be separated from the end cover <NUM>' through the guiding part <NUM>, and the guiding part <NUM> forms a channel for the accommodating part <NUM> to be communicated with the outside of the end cover <NUM>'. For example, a plurality of accommodating parts <NUM> are arranged along the circumferential direction, the guiding part <NUM> is an opening area formed between adjacent accommodating parts <NUM>, when the cover body <NUM> is arranged in the second position, the limiting part <NUM> and the accommodating part <NUM> are misplaced circumferentially, and are arranged in the guiding part <NUM>. Or only one accommodating part <NUM> is arranged along the circumferential direction, and the guiding part <NUM> is the opening area, except the accommodating part <NUM>, on the circumferential direction.

A circumferential length of the guiding part <NUM> can be greater than that of the limiting part <NUM>, and does not exceed the circumferential length of the accommodating part <NUM>, to possibly increase the clamping length of the limiting part <NUM> and the accommodating part <NUM>, and improve the limiting stability, and the circumferential length of the guiding part <NUM> should make the limiting part <NUM> smoothly enter the guiding part <NUM>.

As shown in <FIG>, the accommodating part <NUM> includes a first limiting wall 12A, a second limiting wall 12B arranged opposite to the first limiting wall 12A, and a side wall 12C configured to connect the first limiting wall 12A and the second limiting wall 12B.

As shown in <FIG>, when the cover body <NUM> rotates to the first position, the first limiting wall 12A is abutted against the limiting part <NUM>, the first limiting part 12A is a top wall, and can limit the degree of freedom of upward movement of the cover body <NUM> along a height direction, to limit separation of the cover body <NUM> from the end cover <NUM>'. The second limiting wall 12B is a bottom wall, and a preset distance exists between the second limiting wall 12B and the surface, adjacent to the shell, of the end cover <NUM>'. To reduce resistance during rotation of the cover body <NUM>, a gap can exist between the second limiting wall 12B and the limiting part <NUM>; optionally, the second limiting wall 12B can also be abutted against the limiting part <NUM>. Similarly, to reduce resistance during rotation of the cover body <NUM>, a gap can also exist between the side wall12C and the limiting part <NUM>; and optionally, the side 12C can also be in contact with the limiting part <NUM>.

When the cover body <NUM> needs to be installed, a downward acting force is exerted onto the cover body <NUM>, a gap can be formed between the limiting part <NUM> and the first limiting wall 12A through deformation of the sealing element <NUM>, at this time, the cover body <NUM> is rotated to make the limiting part <NUM> smoothly enter the accommodating part <NUM>, after the first position is reached, the cover body <NUM> is loosened, the cover body <NUM> moves upwards under the elastic effect of the sealing element <NUM>, until the top surface of the limiting part <NUM> is abutted against the first limiting wall 12A, at this time, a gap may exist between the bottom surface of the limiting part <NUM> and the second limiting wall 12B.

When the cover body <NUM> needs to be disassembled, a downward acting force is exerted onto the cover body <NUM>, a gap is formed between the limiting part <NUM> and the first limiting wall 12A through deformation of the sealing element <NUM>, at this time, the cover body <NUM> is rotated, such that the limiting part <NUM> and the accommodating part <NUM> are smoothly misplaced circumferentially, and are arranged in the guiding part <NUM> as a whole. At this time, the second position is reached, and the cover body <NUM> is taken off for liquid injection.

As shown in <FIG>, the accommodating part <NUM> extends along the circumferential direction of the through hole <NUM>, and the cross section is C-shaped, C shape merely illustratively shows the shape of the accommodating part <NUM>, and the first limiting wall 12A, the second limiting wall 12B and the side wall 12C can be planes or cambered surfaces. Such type of accommodating part <NUM> has a higher clamping strength when the accommodating part <NUM> is matched with the limiting part <NUM>. Moreover, when the first limiting wall 12A is a plane and the top surface of the limiting part <NUM> is also a plane, an abutted area between the first limiting wall 12A and the limiting part <NUM> can be increased, the clamping stability is improved, frictional force between the first limiting wall 12A and the limiting part <NUM> can also be increased, and the difficulty of circumferential rotation of the cover body <NUM> under a clamping state relative to the end cover <NUM>' is increased.

In some embodiments, a limiting structure is arranged between the limiting part <NUM> and the accommodating part <NUM>, and is configured to limit misplacement and separation of the cover body <NUM> from the accommodating part <NUM> when the cover body <NUM> is in the first position. If the device using the secondary battery <NUM> produces great vibration or shock in the operating process, the limiting structure can make the limiting part <NUM> and the accommodating part <NUM> be reliably clamped in the first position, thereby preventing the limiting part <NUM> from circumferential rotation and separation from the accommodating part <NUM>, making connection between the cover body <NUM> and the end cover <NUM>' more reliable, improving sealing performance to the electrolyte, and ensuring reliability of the battery during operation.

As shown in <FIG> and <FIG>, the limiting structure includes: a limiting opening <NUM> and a first convex part <NUM>. Wherein the limiting opening <NUM> is arranged on one of the limiting part <NUM> and the accommodating part <NUM>, for example, the limiting opening <NUM> can be a hole or a groove, etc., the first convex part <NUM> is clamped with the limiting opening <NUM>, and is arranged on the other of the limiting part <NUM> and the accommodating part <NUM>. When the cover body <NUM> is arranged in the first position, under the elastic effect of the sealing element <NUM>, the limiting opening <NUM> is tightly clamped with the first convex part <NUM>, such that the limiting part <NUM> and the accommodating part <NUM> will not rotate and loosen due to such external forces as vibration and shock; or, the cover body <NUM> realizes clamping through interference fit between the limiting opening <NUM> and the first convex part <NUM>.

As shown in <FIG>, the first convex part <NUM> is arranged on the first limiting wall 12A of the accommodating part <NUM>, and the first convex part <NUM> is a cylinder; as shown in <FIG>, the top surface of the limiting part <NUM> is formed with a limiting opening <NUM>, the limiting opening <NUM> is a circular hole, when the cover body <NUM> is in the first position, the cylinder is embedded into the circular hole, to limit rotation of the cover body <NUM>.

As shown in <FIG>, along an axial projection of the through hole <NUM>, a largest diameter of the sealing element <NUM> is greater than a minimum diameter of the through hole <NUM>. The structure can prevent the sealing element <NUM> from entering the shell <NUM> through the through hole <NUM> in the assembly or secondary liquid injection process.

As shown in <FIG> and <FIG>, the sealing element <NUM> includes a sealing column <NUM> and a thrust table <NUM> connected to one end of the sealing column <NUM>. The sealing column <NUM> is inserted into the through hole <NUM>, for example, the sealing column <NUM> is closely matched with the through hole <NUM>, to improve the sealing effect to the electrolyte. The thrust table <NUM> is arranged radially, and is abutted against the end cover <NUM>'. To make the sealing column <NUM> be inserted into the through hole <NUM>, a first chamfer <NUM> is arranged at the end, far away from the thrust table <NUM>, of the sealing column <NUM>. To well seal the connecting part between the sealing column <NUM> and the thrust table <NUM>, a transition part <NUM> is arranged at a connecting part between the sealing column <NUM> and the thrust table <NUM>, and the transition part <NUM> can be a fillet angle or an oblique angle.

The sealing element <NUM> can separately close the through hole <NUM>, when secondary liquid injection is required, after the cover body <NUM> is disassembled, the through hole <NUM> is still closed by the sealing element <NUM>, and finally electrolyte can be injected after the sealing element <NUM> is disassembled; when the cover body <NUM> is installed, the through hole <NUM> is firstly closed through the sealing element <NUM>, and then the cover body <NUM> is installed. In this way, in the disassembly and assembly processes of the cover body <NUM>, the through hole <NUM> is in a closed state, thereby further preventing short circuit of the positive electrode and the negative electrode of the electrode assembly <NUM> caused when metal scraps, produced from friction between the cover body <NUM> and the accommodating part <NUM> during rotation of the cover body <NUM>, fall into the shell <NUM>, and ensuring operating performance of the battery.

The sealing element <NUM> and the cover body <NUM> can be set to be of an integrated structure, but also can be set to be of a split structure.

As shown in <FIG> and <FIG>, when the cover body <NUM> rotates from the first position to the second position, a rotating angle is less than <NUM>°. Through such a setting form, the cover body <NUM> can be clamped with the accommodating part <NUM> only by rotating for a small angle, thereby improving convenience and efficiency in assembly. Optionally, when the cover body <NUM> rotates from the first position to the second position, the rotating angle can also be greater than or equal to <NUM>°.

As shown in <FIG>, the cover body <NUM> is in contact with the sealing element <NUM>, and a friction coefficient of the contact surface between the sealing element <NUM> and the cover body <NUM> is less than a friction coefficient of the contact surface between the sealing element <NUM> and the end cover <NUM>'. In this way, when the cover body <NUM> is rotated, the rotational frictional force of the cover body <NUM> is small, the cover body <NUM> is easy to assemble, and the abrasion of the sealing element <NUM> can be reduced. To reduce frictional force between the sealing element <NUM> and the cover body <NUM>, lubricating oil can be coated between the sealing element <NUM> and the cover body <NUM> or other manners of arranging other spacing pieces with a small frictional force can be set.

As shown in <FIG>, in the axial direction of the through hole <NUM>, a protruding part <NUM> is arranged on the surface on which at least one of the cover body <NUM> and the end cover <NUM>' is in contact with the sealing element <NUM>, for example, the protruding part <NUM> can be of a ring structure or can be a plurality of protruding columns which are arranged at intervals. The cover body <NUM> abuts against the sealing element <NUM>, such that the sealing element <NUM> abuts against the protruding part <NUM>. Through enhancing the partial pressing force between the cover body <NUM> and the sealing element <NUM>, the structure can prevent failed sealing caused by inconsistent compression amount at each part of the sealing element <NUM>, thereby optimizing the sealing effect to the through hole <NUM>, and preventing electrolyte from leaking outwards.

To facilitate rotation of the cover body <NUM>, the main body part <NUM> of the cover body <NUM> is provided with a clamping part <NUM> which is configured to receive external operation to drive the cover body <NUM> to rotate. The clamping part <NUM> is set to facilitate rotation of the cover body <NUM> through the match between the tooling and the clamping part <NUM>, exertion of an external force is facilitated during disassembly and assembly of the cover body <NUM>, and the rotation angle of the cover body <NUM> is easy to control. The structural form which can be adopted by the clamping part <NUM> will be given below, and the following specific structures can be set separately or can be combined arbitrarily.

As shown in <FIG>, the clamping part <NUM> includes a plurality of holes 211A arranged on the main body part <NUM>, and the plurality of holes 211A can be arranged at the position, adjacent to the periphery, of the main body part <NUM>, for example, three holes 211A can be arranged.

As shown in <FIG>, the end cover <NUM>' includes a main body of end cover <NUM> and an installation part <NUM>, the installation part <NUM> is arranged on the surface of the main body of end cover <NUM>, and is set to surround the through hole <NUM>, for example, the installation part <NUM> can be arranged on the surface, far away from the shell <NUM>, of the end cover body <NUM>, and the accommodating part <NUM> is arranged in the installation part <NUM>, or the accommodating part <NUM> is enclosed by the installation part <NUM> and the main body of end cover <NUM>.

In the present embodiment, the end cover <NUM>' is designed to be of a split structure, since the main body of end cover <NUM> is of a thin plate structure which is complex and difficult to process, the installation part <NUM> is set to facilitate formation of the accommodating part <NUM>, to lower processing difficulty of the main body of end cover <NUM>.

As shown in <FIG>, the accommodating part <NUM> is enclosed by the installation part <NUM> and the end cover body <NUM>. As shown in <FIG> and <FIG>, the installation part <NUM> includes an installation ring <NUM> and a limiting table <NUM>, the limiting table <NUM> is connected to the inner wall of the installation ring <NUM> and extends inwards along a radial direction, the installation ring <NUM> is fixed on the main body of end cover <NUM>, an accommodating part <NUM> is formed between the limiting table <NUM> and the main body of end cover <NUM>, and the bottom surface of the limiting table <NUM> serves as the first limiting wall 12A.

As shown in <FIG> and <FIG>, a surface, far away from the shell <NUM>, of the main body of end cover <NUM> is provided with a first groove <NUM>, the installation part <NUM> is fixed in the first groove <NUM>, the through hole <NUM> is arranged on the bottom wall of the first groove <NUM>. The accommodating part <NUM> is formed on the inner side of the installation part <NUM>.

Such type of structure can reduce the height of the installation part <NUM> relative to the main body of end cover <NUM>, to reduce the height by which the liquid injection component protrudes out of the main body of end cover <NUM>, to reduce the overall height of the battery, and simultaneously reduce possibility of collision between the liquid injection component and other parts in the installation or using process of the secondary battery <NUM>, secondly, when the secondary battery <NUM> is applied to the battery pack, since the height of the installation part <NUM> is lowered, other components are easily installed above the end cover assembly <NUM>, for example, a detection circuit configured to acquire signals of the secondary battery <NUM>.

Specifically, the installation part <NUM> can be fixed in the first groove <NUM> through many manners. For example, close match, bonding, installation or welding of fasteners, etc. For the welding form, a side surface at which the installation part <NUM> is matched with the first groove <NUM> is a conical surface, the radial size of the opening end of the first groove <NUM> is greater than the radial size of the bottom of the first groove <NUM>, and the matching surface between the installation part <NUM> and the first groove <NUM> is welded through laser.

In the structure, the side of the first groove <NUM> is designed to be a conical surface, which can play a guiding effect on placement of the installation part <NUM> into the first groove <NUM>, and when laser welding is adopted, no gap exists in the incidence path of laser, and no explosion points will exist during welding due to gaps, thereby enhancing structural strength of welding.

As shown in <FIG>, the accommodating part <NUM> is formed on the inner side of the installation part <NUM>, the cover body <NUM> further includes a main body part <NUM> configured to cover at least part of the sealing element <NUM>, and the main body part <NUM> is arranged in the opening <NUM> formed when the installation part <NUM> surrounds the through hole <NUM>, the opening <NUM> is communicated with the accommodating part <NUM>, and the limiting part <NUM> is connected to the outer side of the main body part <NUM> and extends along the radial direction of the through hole <NUM>.

In the present embodiment, the cover body <NUM> is arranged in the opening <NUM>, which is beneficial for reducing the height by which the liquid injection component protrudes out of the main body of end cover <NUM>, then not only possibility of collision between the liquid injection component and other parts in the installation or using process of the secondary battery <NUM> can be lowered, in addition, when the secondary battery <NUM> is applied to the battery pack <NUM>, other components are easily installed above the end cover assembly <NUM>, for example, a detection circuit configured to acquire signals of the secondary battery <NUM>.

Specifically, as shown in <FIG>, the installation part <NUM> includes an installation ring <NUM> and a limiting table <NUM>, the limiting table <NUM> is connected to the inner wall of the installation ring <NUM>, the limiting table <NUM> can be arranged at an end, far away from the through hole <NUM>, of the installation ring <NUM>, to reserve space for forming the accommodating part <NUM> on the height direction. The limiting table <NUM> is flush with the surface, far away from the through hole <NUM>, of the installation ring <NUM>, to increase the height of the accommodating part <NUM> to the greatest extent, correspondingly the thickness of the limiting part <NUM> can also be increased, to improve the clamping strength between the limiting part <NUM> and the accommodating part <NUM>. Wherein the inner area enclosed by a plurality of limiting tables <NUM> in the installation part <NUM> forms an opening <NUM>, the main body part <NUM> is arranged in the opening <NUM>, and the opening <NUM> is communicated with the accommodating part <NUM>.

Since the installation part <NUM> is arranged in the first groove <NUM>, the bottom wall of the limiting table <NUM>, the side wall of the installation ring <NUM> and the bottom wall of the first groove <NUM> enclose to form an accommodating part <NUM>, therefore, the bottom wall of the limiting table <NUM> serves as a first limiting wall 12A, the bottom wall of the first groove <NUM> serves as a second limiting wall 12B, and the side wall of the installation ring <NUM> serves as a side wall 12C.

Wherein the limiting table <NUM> can extend inwards along a radial direction from the inner side of the installation ring <NUM>, and the limiting table <NUM> extends along the circumferential direction. For example, a plurality of limiting tables <NUM> are arranged at intervals along the circumferential direction on the installation ring <NUM>, and the plurality of limiting tables <NUM> can be distributed uniformly, a guiding part <NUM> is formed between adjacent limiting tables <NUM>, and the guiding part <NUM> is communicated with the accommodating part <NUM>. As shown in <FIG> and <FIG>, two limiting tables <NUM> are available, the limiting part <NUM> can rotate from the inside of the guiding part <NUM> to the center area along the circumferential direction of the limiting table <NUM> by only rotating for <NUM>°, the center area along the circumferential direction of the limiting table <NUM> is taken as a first position, thereby being capable of reducing possibility of misplacement between the limiting part <NUM> and the accommodating part <NUM> under such external force as vibration and shock.

In some embodiments, at least one of the limiting part <NUM>, the first limiting wall 12A and the second limiting wall 12B is provided with an inclined surface <NUM> which is configured to guide the limiting part <NUM> to enter the accommodating part <NUM>. In this structure, through the setting of an inclined surface <NUM>, the limiting part <NUM> can smoothly enter the accommodating part <NUM>, no alignment is required to adjust the limiting part <NUM> to a designated height, thereby improving assembly efficiency, also preventing collision between the limiting part <NUM> and the opening of the accommodating part <NUM>, prolonging the service life of the liquid injection component, and reducing the production of metal scraps.

Specifically, as shown in <FIG>, the limiting part <NUM> is provided with an inclined surface <NUM> which is configured to guide the limiting part <NUM> to enter the accommodating part <NUM>. In this structure, through the setting of an inclined surface <NUM>, the limiting part <NUM> can smoothly enter the accommodating part <NUM>, no alignment adjustment is required, thereby improving assembly efficiency, also preventing collision between the limiting part <NUM> and the opening of the accommodating part <NUM>, prolonging the service life of the liquid injection component, and reducing the production of metal scraps. Moreover, when the inclined surface <NUM> is arranged on the limiting part <NUM>, processing is facilitated.

Specifically, the inclined surface <NUM> is arranged on a side, along the circumferential direction, of the limiting part <NUM>, and the inclined surface <NUM> is configured to enable the thickness of the side, along the circumferential direction, of the limiting part <NUM>, to be gradually decreased from the inside to the outside. The inclined surface <NUM> can be arranged at one side or two sides of the limiting part <NUM> along the circumferential direction. For example, the inclined surface <NUM> can be a plane or a cambered surface, etc..

As shown in <FIG>, a plurality of limiting parts <NUM> are connected at intervals onto the outer side of the main body part <NUM> along the circumferential direction, the plurality of limiting parts <NUM> can be arranged at intervals uniformly, and the limiting part <NUM> extends outwards along a radial direction from the outer side of the main body part <NUM>. An inclined surface <NUM> is arranged on two side surfaces, along the circumferential direction, of the limiting part <NUM>, such that the limiting part <NUM> enters the accommodating part <NUM> more smoothly.

As shown in <FIG>, the sealing element <NUM> includes a sealing column <NUM> and a thrust table <NUM> connected to one end of the sealing column <NUM>. The sealing column <NUM> is inserted into the through hole <NUM>, the thrust table <NUM> is arranged along a radial direction, and is abutted against the end cover <NUM>'. For example, the sealing element <NUM> adopts electrolyte-resistant high elastic materials, such as rubber or other plastic plastics, etc..

Through adopting the sealing element <NUM>, when secondary liquid injection is required, after the cover body <NUM> is disassembled, the through hole <NUM> is still closed by the sealing element <NUM>, and finally electrolyte can be injected when the sealing element <NUM> is disassembled; when the cover body <NUM> is installed, the through hole <NUM> is closed firstly through the sealing element <NUM>, and then the cover body <NUM> is installed. In this way, in the disassembly and assembly processes of the cover body <NUM>, the through hole <NUM> is in a closed state, thereby preventing short circuit of the positive electrode and the negative electrode of the electrode assembly <NUM> caused when metal scraps, produced from friction between the cover body <NUM> and the accommodating part <NUM> during rotation of the cover body <NUM>, fall into the shell <NUM>.

As shown in <FIG>, a second groove <NUM> is arranged on the surface, adjacent to the through hole <NUM>, of the main body part <NUM>, and the thrust table <NUM> is arranged in the second groove <NUM>. As shown in <FIG>, the bottom wall of the second groove <NUM> can further be provided with a protruding part <NUM>, and the protruding part <NUM> can enhance partial pressing force of the cover body <NUM> onto the sealing element <NUM>, thereby improving the sealing effect.

As shown in <FIG>, when the cover body <NUM> is rotated, to reduce collision between the limiting part <NUM> and the accommodating part <NUM>, a downward acting force can be exerted onto the cover body <NUM>, such that the limiting part <NUM> has a reduced height and can enter the accommodating part <NUM> more smoothly, however, if the acting force is too large, the sealing element <NUM> will be crushed. The second groove <NUM> enables that the bottom surface of the cover body <NUM> is abutted against the end cover body <NUM> when the downward force is too large, the maximum amount of compression of the sealing element <NUM> is the height of the second groove <NUM>, thereby avoiding too large exerted acting force, the amount of compression of the sealing element <NUM> exceeds the capacity of the sealing element <NUM> itself, and the sealing effect will be influenced if the sealing element <NUM> is crushed.

As shown in <FIG>, the top surface of the installation part <NUM> does not exceed the top surface of the main body of end cover <NUM>, for example, the two face are flush. Moreover, at least part of the sealing element <NUM> is arranged in the second groove <NUM>, such that the top surface of the cover body <NUM> does not exceed the top surface of the installation part <NUM>. Therefore, the liquid injection component will not be higher than the top surface of the main body of end cover <NUM>.

Such a structure can reduce the overall height of the secondary battery <NUM>, improve the energy density, and reduce the possibility of collision between the liquid injection component and other parts in the installation or using process of the secondary battery <NUM>; when the secondary battery <NUM> is applied to the battery pack <NUM>, other components can be easily installed above the end cover assembly <NUM>, for example, the detection circuit configured to acquire signals of the secondary battery <NUM>.

To make it easy for the limiting part <NUM> to enter the accommodating part <NUM> through rotation, the height of the accommodating part <NUM> is greater than the limiting part <NUM>. After the limiting part <NUM> enters the accommodating part <NUM>, under the effect of the elastic force of the sealing element <NUM>, the top surface of the limiting part <NUM> will be in contact with the first limiting wall 12A, however, a gap exists between the bottom surface of the limiting part <NUM> and the second limiting wall 12B. Therefore, in order that the top surface of the cover body <NUM> does not exceed the top surface of the installation part <NUM>, the height of the cover body <NUM> is smaller than the height of the installation part <NUM>. Such a structure can not only enable the cover body <NUM> to be rotated smoothly, but also reserve a space for the installation of the sealing element <NUM> while reducing the overall height of the battery.

The assembly process of the secondary battery <NUM> at which the end cover assembly <NUM>-<NUM> is arranged is as follows: firstly, the installation part <NUM> is placed in the first groove <NUM>, and is welded; then electrolyte is injected through the through hole <NUM>, and the sealing element <NUM> is installed after liquid injection is finished; then the cover body <NUM> is placed on the end cover <NUM>', and the cover body <NUM> covers at least part of the sealing element <NUM>, wherein the cover body <NUM> is placed in the second position in which the limiting part <NUM> is misplaced with the accommodating part <NUM> in a circumferential direction; and finally, a special tool is used to clamp three holes 211A, an acting force is applied downwards such that a gap forms between the limiting part <NUM> and the first limiting wall 12A, rotation for <NUM>° is performed such that the cover body <NUM> rotates from the second position to the first position, then the limiting part <NUM> enters the accommodating part <NUM>, to restrict separation of the cover body <NUM> from the housing. After rotation is in place, the cover body <NUM> is released, under the elastic force of the sealing element <NUM>, the cover body <NUM> enables the cover body <NUM> to be abutted against the first limiting wall 12A.

When secondary liquid injection needs to be performed on the secondary battery <NUM>, a special tool is used to clamp the three holes 211A, the cover body <NUM> is rotated in a reversed direction, such that the cover body <NUM> reaches the second position from the first position, the cover body <NUM> is taken off, and the sealing element <NUM> is taken off, after electrolyte is injected, the assembly process is repeated, and maintenance of the battery is finished.

<FIG> is a deformation example of the cover body <NUM> in the end cover assembly <NUM>-<NUM>. Different from <FIG>, in <FIG>, the clamping part <NUM> includes a polygonal groove 211B arranged at the center area of the main body part <NUM>, and can be a triangular, rectangular, pentagonal or hexagonal groove, etc..

<FIG> are deformation embodiments of an installation part <NUM> of a first embodiment.

As shown in <FIG>, an inclined surface <NUM> is arranged on the first limiting wall 12A of the accommodating part <NUM>, along the rotating direction at which the cover body <NUM> reaches the first position from the second position, the inclined surface <NUM> is constructed to have a gradually decreased distance with the second limiting wall 12B. The inclined surface <NUM> can be arranged on one end or two ends, along the circumferential direction, of the accommodating part <NUM>, such that the limiting part <NUM> can smoothly enter the accommodating part <NUM>. For example, the inclined surface <NUM> can be a plane or a cambered surface, etc. Optionally, the inclined surface <NUM> is arranged on the second limiting wall 12B of the accommodating part <NUM>.

The accommodating part <NUM> is internally provided with a stopping part <NUM> which is configured to limit maximum rotation stroke of the limiting part <NUM>. Each accommodating part <NUM> can be provided with a stopping part <NUM>. The stopping part <NUM> can stop rotation of the limiting part <NUM>, and prevent the limiting part <NUM> from directly rotating outwards from the accommodating part <NUM>.

Under the state of reaching the maximum rotation stroke, a side face, along the circumferential direction, of the limiting part <NUM> is completely fit with the stopping part <NUM>. For example, the main body part <NUM> is provided with two limiting parts <NUM> uniformly along the circumferential direction, and two side faces, along the circumferential direction, of the limiting part <NUM> are both in parallel with the central plane of the cover body <NUM>, correspondingly, the stopping parts <NUM> of the two accommodating parts <NUM> are in central symmetry about the central plane of the through hole <NUM>, and the two stopping parts <NUM> are in parallel with each other. Optionally, the side face, along the circumferential direction, of the limiting part <NUM> can also be partially abutted against the stopping part <NUM>.

To prevent circumferential rotation of the installation part <NUM> during installation relative to the first groove <NUM>, as shown in <FIG>, the bottom of the installation part <NUM> can be provided with a second concave part <NUM>, for example, the second concave part <NUM> can be arranged on the bottom of the installation ring <NUM>. Correspondingly, as shown in <FIG>, a second convex part <NUM> is arranged at the position at which the bottom wall of the first groove <NUM> is connected with the side, and the second convex part <NUM> is matched with the second concave part <NUM>, to limit circumferential rotation of the installation part <NUM> relative to the first groove <NUM>.

<FIG> are deformation embodiments of the shape of the accommodating part <NUM> in a first embodiment.

In some embodiments, as shown in <FIG>, the cross section of the accommodating part <NUM> is also C-shaped.

As shown in <FIG>, the inner wall of the accommodating part <NUM> is provided with a first concave part <NUM> which extends circumferentially, the limiting part <NUM> includes a limiting table <NUM> and a third convex part <NUM> which is arranged on the limiting table <NUM> and which extends along the circumferential direction, when the cover body <NUM> rotates to the first position, the third convex part <NUM> is abutted against the first concave part <NUM>, to limit separation of the cover body <NUM> from the end cover <NUM>'.

For example, the first concave part <NUM> can be arranged on at least one of the first limiting wall 12A, the second limiting wall 12B and the side 12C. As shown in <FIG>, the first concave part <NUM> is arranged on the first limiting wall 12A, correspondingly, the third convex part <NUM> is arranged on the top surface of the limiting table <NUM>. In addition, the first concave part <NUM> is arranged on the second limiting wall 12B, and the third convex part <NUM> is arranged on the bottom surface of the limiting table <NUM>; the first concave part <NUM> is arranged on the side 12C, and the third convex part <NUM> is arranged on the side face of the limiting table <NUM>.

As shown in <FIG>, the accommodating part <NUM> is arranged on the installation part <NUM>, the accommodating part <NUM> is arranged on the inner side of the installation part <NUM>, and extends along the circumferential direction of the installation part <NUM>. The cross section of the installation part <NUM> is I-shaped. The accommodating part <NUM> is arranged on the installation part <NUM>, to reserve a sufficient space for the sealing element <NUM>, thereby optimizing the sealing effect through increasing thickness of the sealing element <NUM>, and prolonging service life of the sealing element <NUM>.

In some other embodiments, as shown in <FIG>, the accommodating part <NUM> extends along the circumferential direction of the through hole <NUM>, and the cross section is V-shaped, the orientation of the V-shaped opening is not limited, for example, the opening can be upwards, downwards, leftwards, rightwards or towards an inclined direction. Correspondingly, the cross section of the limiting part <NUM> can also be V-shaped.

The accommodating part <NUM> is provided with a first limiting wall 12A and a second limiting wall 12B with one of the sides being connected mutually, when the cover body <NUM> rotates to the first position, the first limiting wall 12A is abutted against the limiting part <NUM>, and the first limiting wall 12A is arranged above the second limiting wall 12B. To reduce resistance during rotation of the cover body <NUM>, a gap may exist between the second limiting wall 12B and the limiting part <NUM>; optionally, the second limiting wall 12B can also be abutted against the limiting part <NUM>. As shown in <FIG>, the first limiting wall 12A is arranged horizontally, and the second limiting wall 12A has a gradually increased radial direction from the bottom to the top.

<FIG> are structural schematic diagrams of an end cover assembly <NUM>-<NUM> of a second embodiment of the present application, the end cover assembly <NUM>-<NUM> differs from the end cover assembly <NUM>-<NUM> mainly in the specific structure of the installation part <NUM>.

As shown in <FIG>, the installation ring <NUM> includes a ring body 41A and a connecting part 41B, the ring body 41A is installed in the first groove <NUM>, the connecting part 41B is connected to the inner wall of the ring body 41A, and extends towards the direction far away from the main body of end cover <NUM> relative to the ring body 41A, for example, the connecting part 41B is set to be vertical or inclined relative to the ring body 41A, a plurality of connecting parts 41B can be arranged at intervals along the circumferential direction on the ring body 41A, and the plurality of connecting parts 41B can be arranged uniformly at intervals. The limiting table <NUM> is connected to one end, far away from the ring body 41A, of the connecting part 41B and extends inwards along a radial direction. An L-shaped structure is formed between the connecting part 41B and the limiting table <NUM>, a guiding part <NUM> is formed between adjacent L-shaped structures, and the area enclosed by a plurality of limiting tables <NUM> forms an opening <NUM>.

In the present embodiment, since adjacent connecting parts 41B are not closed, the cover body <NUM> is in the second position, such that the limiting part <NUM> is arranged in the guiding part <NUM>, at this time, the limiting part <NUM> is exposed from the adjacent connecting part 41B, in the assembly and disassembly processes of the cover body <NUM>, the alignment conditions between the limiting part <NUM> and the accommodating part <NUM> can be observed conveniently, such that the limiting part <NUM> can enter the accommodating part <NUM> more easily. Moreover, to make the cover body <NUM> rotate smoothly, a downward pressure also needs to be exerted onto the cover body <NUM> when the cover body <NUM> rotates, in this way, the resistance during rotation of the cover body <NUM> can be slightly increased, when the limiting part <NUM> enters into and exists from the accommodating part <NUM>, such type of structure makes it easy for the operator to assist manually in toggling the cover body <NUM> to rotate, thereby improving convenience of operation.

As shown in <FIG>, the limiting opening <NUM> is arranged on the first limiting wall 12A of the accommodating part <NUM>, and the limiting opening <NUM> is a cambered groove which extends along a radial direction of the cover body <NUM>. As shown in <FIG>, two sides, along the circumferential direction, of the limiting part <NUM> are both provided with a cambered inclined surface <NUM>, and the two inclined surfaces <NUM> are tangent such that the top surface of the limiting part <NUM> forms an overall cambered surface, to serve as the first convex part <NUM>. When the cover body <NUM> is in the first position, part of the top part of the limiting part <NUM> is embedded into the limiting opening <NUM>, to limit rotation of the cover body <NUM>. When the cover body <NUM> rotates along the clockwise or anticlockwise direction, the limiting part <NUM> can enter the accommodating part <NUM> more smoothly.

As shown in <FIG>, the clamping part <NUM> is a cross groove 211C arranged in the central area of the main body part <NUM>.

As shown in <FIG>, the sealing element <NUM> includes a spacing sheet <NUM> which is arranged towards the surface of the cover body <NUM>. The spacing sheet <NUM> covers at least part of the surface of the thrust table <NUM>, for example, the spacing sheet <NUM> can adopt an aluminum sheet or tetrafluoro plastic sheet, etc. The spacing sheet <NUM> can be fixed onto the thrust table <NUM> through bonding or a fastener, and the friction coefficient of the contact surface between the spacing sheet <NUM> and the cover body <NUM> is smaller than the friction coefficient of the contact surface between the sealing element <NUM> and the end cover <NUM>'. Or, the spacing sheet <NUM> can also be directly placed on the thrust table <NUM>, and the friction coefficient of the contact surface between the spacing sheet <NUM> and the thrust table <NUM> is greater than the friction coefficient of the contact surface between the spacing sheet <NUM> and the cover body <NUM>.

As shown in <FIG>, to save the installation space of the sealing element <NUM>, the top of the main body of end cover <NUM> is provided with a fourth groove <NUM>, and the thrust table <NUM> is arranged in the fourth groove <NUM>. As shown in <FIG>, one end, adjacent to the sealing column <NUM>, of the thrust table <NUM> is provided with a second chamfer <NUM>, such that the thrust part <NUM> can enter the fourth groove <NUM> more smoothly when the sealing element <NUM> is installed.

<FIG> give structural schematic diagrams of the end cover assembly <NUM>-<NUM> of a third embodiment of the present application. In the third embodiment, the cover body <NUM> is also arranged inside the opening <NUM>, and the end cover assembly <NUM>-<NUM> differs from the end cover assemblies <NUM>-<NUM> and <NUM>-<NUM> in that an accommodating part <NUM> is directly formed on the end cover <NUM>'.

Specifically, as shown in <FIG>, the end cover <NUM>' is further provided with an opening <NUM> which surrounds the through hole <NUM>, and the opening <NUM> is arranged on a side, far away from the shell <NUM>, of the through hole <NUM>, the accommodating part <NUM> is formed on the side of the opening <NUM>, the cover body <NUM> further includes a main body part <NUM> which is configured to cover at least part of the sealing element <NUM>, and the main body part <NUM> is arranged in the opening <NUM>, and the limiting part <NUM> is connected to the outer side of the main body part <NUM> and extends along a radial direction of the through hole <NUM>.

The accommodating part <NUM> of the present embodiment can be directly formed on the end cover <NUM>', no installation part <NUM> needs to be set separately, thereby omitting the step of fixing the installation part <NUM> to the main body of end cover <NUM> of the above embodiment. In the long-term use process of the battery, the overall strength of the end cover <NUM>' is higher, the position of the accommodating part <NUM> will not change, and the risk that the cover body <NUM> is separated from the accommodating part <NUM> in the using process of the secondary battery <NUM> can be lowered.

As shown in <FIG>, a third groove <NUM> is formed on the surface, far away from the shell <NUM>, of the end cover <NUM>', the third groove <NUM> is arranged above the accommodating part <NUM>, and the radial size of the third groove <NUM> is greater than the radial size of the opening <NUM>. Correspondingly, as shown in <FIG>, the cover body <NUM> further includes an extending part <NUM>, the extending part <NUM> is connected to an end, far away from the limiting part <NUM>, of the main body part <NUM>, and extends along the whole circumferential direction of the main body part <NUM>. The extending part <NUM> is matched with the third groove <NUM>, to close the accommodating part <NUM>, prevent external impurities from falling off between the cover body <NUM> and the end cover <NUM>', and further improve reliability of the battery during operation.

As shown in <FIG>, the clamping part <NUM> includes a boss 211D with the side being provided with a plane, and the boss 211D can be a long rectangle or a long circle, etc..

<FIG> give structural schematic diagrams of an end cover assembly <NUM>-<NUM> of a fourth embodiment. The fourth embodiment differs from the previous three embodiments in that, the accommodating part <NUM> is formed on the outer side of the installation part <NUM>, the main body part <NUM> of the cover body <NUM> is sleeved outside the installation part <NUM>, and the limiting part <NUM> is connected to the inner side of the main body part <NUM> and extends along the radial direction of the through hole <NUM>.

In the present embodiment, the cover body <NUM> is sleeved outside the installation part <NUM>, making it easy for the operator to directly exert an external force onto the cover body <NUM> to enable the cover body <NUM> to rotate, therefore, operation is easy, no special tooling needs to be designed, the assembly efficiency can be improved, and maintenance is convenient during secondary liquid injection. Moreover, since the cover body <NUM> is sleeved outside the installation part <NUM>, the installation part <NUM> generally needs to protrude out of the surface of the end cover body <NUM>, the accommodating part <NUM> is formed on the side of the installation part <NUM>, thereby improving strength of the main body of end cover <NUM> on the one hand, and being beneficial for reducing thickness of the main body of end cover <NUM> on the other hand.

Specifically, as shown in <FIG>, the installation part <NUM> includes an installation ring <NUM>, the outer side of the installation ring <NUM> is formed with an accommodating part <NUM> which extends along the circumferential direction, for example, a plurality of accommodating parts <NUM> are arranged at intervals uniformly along the circumferential direction, the guiding part <NUM> is formed on the outer side of the accommodating part <NUM>, and the first end of the guiding part <NUM> is communicated with the top part of the installation ring <NUM>, the second end is communicated with the accommodating part <NUM>, specifically, the second end of the guiding part <NUM> is communicated with the first end along the circumferential direction of the accommodating part <NUM>. For example, the guiding part <NUM> can extend along an axial direction of the installation ring <NUM> or extend in an inclined manner, such that the guiding part <NUM> is connected with the installation ring <NUM> to form an L-shaped groove.

As shown in <FIG>, the main body of end cover <NUM> is provided with a first groove <NUM>, and the bottom wall of the first groove <NUM> is provided with a through hole <NUM>. To improve installation stability of the installation part <NUM> in the first groove <NUM>, the installation part <NUM> further includes a base <NUM>, the base <NUM> is connected to the bottom of the installation ring <NUM>, and the base <NUM> is arranged in the first groove <NUM>, and the base <NUM> can be fixed with the first groove <NUM> through such manners as close match, bonding, welding or connection through fasteners. The top surface of the base <NUM> can be no higher than the first groove <NUM>.

As shown in <FIG>, the cover body <NUM> includes a main body part <NUM> and a limiting part <NUM>, the main body part <NUM> is of a ring-shaped structure, the top of the ring-shaped structure can be closed, and can also be provided with an opening, the inner wall of the main body part <NUM> is provided with a plurality of limiting parts <NUM> at intervals along the circumferential direction, for example, three, the three limiting parts <NUM> can be arranged at intervals uniformly, the limiting part <NUM> is arranged on the inner side of the main body part <NUM>, and extends inwards along the radial direction, the limiting part <NUM> can be arranged at the bottom of the main body part <NUM>, correspondingly, the accommodating part <NUM> can also be arranged at the bottom of the installation part <NUM>, for example, the top surface of the base <NUM> serves as the second limiting wall 12B. Such type of matching structure can reduce the height by which the cover body <NUM> protrudes out of the end cover body <NUM>, to reduce overall height of the battery.

As shown in <FIG>, a limiting opening <NUM> is arranged on the first limiting wall 12A of the accommodating part <NUM>, and the limiting opening <NUM> is concave inwards relative to the first limiting wall 12A. The limiting part <NUM> serves as the first convex part <NUM>, and is configured to be embedded into the limiting opening <NUM> when the cover body <NUM> is in the first position. The limiting opening <NUM> is arranged at the first limiting wall 12A of the accommodating part <NUM>, and the limiting opening <NUM> is concave inwards relative to the first limiting wall 12A; and a plurality of accommodating parts <NUM> can be arranged at intervals along the circumferential direction of the through hole <NUM> and are independent, and the limiting opening <NUM> is arranged on the end, far away from the guiding part <NUM> along the circumferential direction, of the accommodating part <NUM>.

As shown in <FIG>, a plurality of accommodating parts <NUM> are arranged at intervals along the circumferential direction of the through hole <NUM>, and the limiting opening <NUM> is arranged at the end, far away from the guiding part <NUM>, of the accommodating part <NUM>.

As shown in <FIG>, the sealing element <NUM> includes a sealing sheet <NUM>, and the sealing sheet <NUM> can be attached onto the inner bottom surface of the cover body <NUM>.

The assembly process of the secondary battery <NUM> at which the end cover assembly <NUM>-<NUM> is arranged is as follows: firstly, the installation part <NUM> is placed in the first groove <NUM> and is welded; then, electrolyte is injected into the through hole <NUM>; then, the sealing sheet <NUM> is attached to the inner bottom part of the cover body <NUM>; and finally, the cover body <NUM> is sleeved outside the installation part <NUM>, in the sleeving process, the limiting part <NUM> enters through the guiding part <NUM>, when the limiting part <NUM> reaches the accommodating part <NUM>, a downward acting force is exerted onto the cover body <NUM>, the cover body <NUM> is rotated such that the limiting part <NUM> moves inside the accommodating part <NUM>, after the limiting part <NUM> reaches the limiting opening <NUM>, the cover body <NUM> is released, the cover body <NUM> is abutted against the top wall of the limiting opening <NUM> under the effect of an elastic force of the sealing element <NUM>, to limit circumferential rotation of the cover body <NUM>, since then assembly is finished.

When secondary liquid injection needs to be performed on the secondary battery <NUM>, the cover body <NUM> is rotated in a reversed direction, such that the cover body <NUM> reaches the second position from the first position, the cover body <NUM> is taken off together with the sealing element <NUM>, after electrolyte is injected, the assembly process is repeated, then maintenance of the battery is finished.

The top cover assembly <NUM>-<NUM> is suitable for a structure with a small circumferential width of the limiting part <NUM>, and a plurality of accommodating parts <NUM> can be designed to be of independent forms. As to the structure with a large circumferential width of the limiting part <NUM>, a plurality of accommodating parts <NUM> can be cut-through along the whole circumferential direction of the installation ring <NUM>, and the second end of the guiding part <NUM> is communicated with the cut-through area of the adjacent accommodating part <NUM>. As to the structure, a limiting opening <NUM> can also be arranged on the first limiting wall 12A, the limiting opening <NUM> is arranged between adjacent guiding parts <NUM>, and the limiting opening <NUM> is concave inwards relative to the first limiting wall 12A, such that the limiting part <NUM> is matched with the limiting opening <NUM> when the cover body <NUM> is arranged in the first position. Such a structure can lower processing difficulty, and since the circumferential width of the limiting part <NUM> is increased, the clamping strength between the limiting part <NUM> and the accommodating part <NUM> can be increased.

<FIG> is a deformation embodiment of the accommodating part <NUM> in a fourth embodiment. <FIG> differs from <FIG> in that, a plurality of accommodating parts <NUM> are arranged at intervals along the circumferential direction of the through hole <NUM> and are cut-through in the circumferential direction, and the guiding part <NUM> is communicated with the cut-through area of the adjacent accommodating part <NUM>. In <FIG>, a limiting opening <NUM> can also be arranged on the first limiting wall 12A of the accommodating part <NUM>, and the limiting opening <NUM> is concave inwards relative to the first limiting wall 12A. As shown in <FIG>, the limiting part <NUM> serves as the first convex part <NUM> and is configured to embed into the limiting opening <NUM> when the cover body <NUM> is arranged in the first position. As shown in <FIG>, the accommodating part <NUM> extends along the whole circumferential direction of the through hole <NUM>, and the limiting opening <NUM> is arranged between adjacent guiding parts <NUM>.

<FIG> show structural schematic diagrams of an end cover assembly <NUM>-<NUM> of a fifth embodiment. The end cover assembly <NUM>-<NUM> differs from the end cover assembly <NUM>-<NUM> of the fourth embodiment in the forming manner of the accommodating part <NUM>. The installation part <NUM> includes an installation ring <NUM> and a limiting table <NUM>, the outer side of the installation ring <NUM> is provided with a plurality of limiting tables <NUM> at intervals along the circumferential direction, the limiting table <NUM> extends outwards along the radial direction, for example, a plurality of accommodating parts <NUM> are arranged at intervals uniformly along the circumferential direction, for example, two or three accommodating parts <NUM> can be available, the main body of end cover <NUM> can be provided with an installation hole, the installation ring <NUM> is inserted into the installation hole for fixation, and the inner hole of the installation ring <NUM> forms a through hole <NUM>. The limiting table <NUM> and the main body of end cover <NUM> together form an accommodating part <NUM>, the bottom wall of the limiting table <NUM> serves as a first limiting wall 12A, the top surface of the main body of end cover <NUM> serves as the second limiting wall 12B, and the outer side of the installation ring <NUM> serves as the side 12C.

The cover body <NUM> includes a ring-shaped main body part <NUM> and a limiting part <NUM>, the top part of the main body part <NUM> can be closed or can be provided with an opening, the limiting part <NUM> is arranged on the inner side of the main body part <NUM> and extends inwards along the radial direction, the limiting part <NUM> can be arranged at the bottom of the main body part <NUM>, to reduce the height of the cover body <NUM> relative to the main body part <NUM>, and a preset interval is formed between the limiting part <NUM> and the inner bottom surface of the cover body <NUM>.

The sealing element <NUM> can adopt a sing ring <NUM>, or adopt a sealing sheet <NUM> or a sealing nail. To save installation space of the sealing element <NUM>, the top of the installation part <NUM> is provided with a fourth groove <NUM>, and the sealing element <NUM> is arranged in the fourth groove <NUM>.

In the present embodiment, after assembly or secondary liquid injection, the cover body <NUM> is sleeved outside the installation part <NUM>, in the sleeving process, the limiting part <NUM> enters through the guiding part <NUM>, after the limiting part <NUM> reaches the accommodating part <NUM>, a downward acting force is exerted onto the cover body <NUM>, the cover body <NUM> is rotated to enable the limiting part <NUM> to move inside the accommodating part <NUM>, after the limiting part <NUM> reaches the limiting opening <NUM>, the cover body <NUM> is released, the cover body <NUM> is abutted against the top wall of the limiting opening <NUM> under the effect of an elastic force of the sealing element <NUM>, to limit rotation of the cover body <NUM> along the circumferential direction, since then the assembly is finished.

Secondly, based on the improvement of the end cover assembly <NUM> in the above embodiment, the present application further provides a housing assembly <NUM> for a secondary battery, in some embodiments, as shown in <FIG>, the housing assembly <NUM> includes: a housing <NUM>', a sealing element <NUM> and a cover body <NUM>. The housing <NUM>' includes a shell <NUM> and an end cover <NUM>' connected with the shell <NUM>, and the end cover <NUM>' closes the opening end of the shell <NUM>. The side of the housing <NUM>' is provided with a through hole <NUM> for injection of electrolyte and an accommodating part <NUM>, the accommodating part <NUM> is arranged on a side, far away from the shell <NUM>', of the housing <NUM>' and is arranged along the circumferential direction of the through hole <NUM>; and the sealing element <NUM> is configured to seal the through hole <NUM>.

The cover body <NUM> is configured to cover at least part of the sealing element <NUM>, the cover body <NUM> is configured to be rotatable, and includes a limiting part <NUM>. Wherein when the cover body <NUM> rotates to the first position, the limiting part <NUM> is located inside the accommodating part <NUM> to limit separation of the cover body <NUM> from the housing <NUM>'; when the cover body <NUM> rotates to the second position, the limiting part <NUM> and the accommodating part <NUM> are misplaced along the circumferential direction of the through hole <NUM>, to realize separation of the cover body <NUM> from the housing <NUM>'.

In the present embodiment, the through hole <NUM> can be arranged on any wall surface of the housing <NUM>', for example, the through hole <NUM> can be arranged on the end cover <NUM>', or arranged on the wall surface, except the end cover <NUM>', on the housing <NUM>', such that the setting position of the through hole <NUM> can be more flexible. As shown in <FIG>, since the size of the lithium battery is small, and the end cover <NUM>' is provided with a terminal <NUM> and an anti-explosion component <NUM> installed on the vent hole <NUM>, or an end cover temperature collection structure will also be set in some other structures, the remaining area on the end cover assembly <NUM> is small, if the through hole <NUM> is arranged on the other surfaces of the housing <NUM>', then the size of the liquid injection component is allowed to be increased, to further enhance structural strength, the reliability in closing electrolyte is improved in a vibrating operating environment, and a big operating space is available when the liquid injection component is disassembled and assembled.

As shown in <FIG>, the through hole <NUM> is arranged on the wall surface, adjacent to the end cover <NUM>', on the housing <NUM>', such that the secondary battery <NUM> can be stably placed with the end cover <NUM>' being upwards. For example, the through hole <NUM> is arranged on the wall surface, adjacent to the largest side surface, on the housing <NUM>', in this way, when the plurality of secondary batteries <NUM> are placed horizontally or vertically to form a battery module <NUM>, the contact of the maximum side faces of adjacent secondary batteries <NUM> can still be kept, such that the structure of the battery module <NUM> is more stable, and the size can be reduced. The liquid injection component in <FIG> can select any embodiment described in the part of the cover body assembly <NUM>.

The housing assembly <NUM> of the present embodiment can flexibly and conveniently realize repeated disassembly and assembly of the liquid injection component, such that when the electrolyte is not sufficient or the performance of the electrolyte is lowered, the liquid injection component can be conveniently disassembled for secondary liquid injection, and gas in the battery is discharged, after secondary liquid injection is finished, the liquid injection hole can also be closed reliably, to ensure operating reliability of the battery after secondary liquid injection, and enable the appearance of the battery to be consistent with the appearance before liquid injection.

For the embodiments in which a liquid injection component is arranged on other faces of the shell, please refer to each above embodiment in which the end cover <NUM>' is provided with a liquid injection component, which will not be repeated redundantly herein.

Secondly, the present application further provides a liquid injection method of the secondary battery <NUM>, based on the secondary battery <NUM> of the above embodiments, in some embodiments, as shown in the flow diagram of <FIG>, the liquid injection method includes:.

Step S101, injecting electrolyte through the through hole <NUM> on the housing <NUM>' of the secondary battery <NUM>;.

Step S102, placing the cover body <NUM> on the housing <NUM>', covering, by the cover body <NUM>, at least part of the sealing element <NUM>, wherein the cover body <NUM> is placed in the second position, and the limiting part <NUM> of the cover body <NUM> and the accommodating part <NUM> on one side, far away from the inside of the housing <NUM>', of the housing are misplaced along the circumferential direction of the through hole <NUM>; and.

Step S103, rotating the cover body <NUM> from the second position to the first position, such that the limiting part <NUM> enters the accommodating part <NUM>, to limit separation of the cover body <NUM> from the housing <NUM>'.

Compared with the traditional manner in which the liquid injection hole is closed through laser welding, in the present application, not only the welding process is avoided, but also a plurality of processes of subsequent cleaning of welding slags and drying of liquid residual from cleaning caused by welding are avoided. Therefore, in the present application, the production efficiency of the battery is improved. In the present application, the match between the limiting part <NUM> and the accommodating part <NUM> is realized through rotation of the cover body <NUM>, the assembly is simple and rapid, in the assembly process of the battery, the assembly efficiency of the liquid injection component can be improved, thereby further improving production efficiency of the battery.

Further, as shown in <FIG>, before the cover body <NUM> is placed on the housing <NUM>' in step <NUM>, the liquid injection method further includes:.

Step S102A, installing the sealing element <NUM> on the housing <NUM>' or the cover body <NUM>.

In the present embodiment, the sealing element <NUM> is installed on the housing <NUM>' or the cover body <NUM>, the sealing element <NUM> can be directly covered after the cover body <NUM> is installed, or a pressing force can be produced to the sealing element <NUM>, to play a better sealing effect on the through hole <NUM>. For example, for the end cover assemblies <NUM>-<NUM>, <NUM>-<NUM>, <NUM>-<NUM> and <NUM>-<NUM>, the sealing element <NUM> can be installed on the end cover <NUM>'; as to the end cover assembly <NUM>-<NUM>, the sealing element <NUM> includes a sealing sheet <NUM>, the cover body <NUM> is of a cap cover structure, and the sealing sheet <NUM> is attached onto the inner bottom surface of the cover body <NUM> in advance.

In some other embodiments, as shown in <FIG>, the liquid injection method of the present application further includes:.

Step S104, rotating the cover body <NUM> from the first position to the second position, such that the limiting part <NUM> and the accommodated part <NUM> are misplaced along the circumferential direction of the through hole <NUM>; and.

Step S105, separating the cover body <NUM> from the housing <NUM>', to further inject electrolyte.

In the traditional manner of closing the liquid injection hole through laser welding, secondary liquid injection of the battery is not allowed. In the present application, disassembly of the cover body <NUM> can be realized flexibly and conveniently through steps S104-S105, such that when the electrolyte is not sufficient or the performance of the electrolyte is lowered, the liquid injection component can be conveniently disassembled for secondary liquid injection, and gas in the battery is discharged. After liquid injection is finished, the installation of the cover body <NUM> is finished through steps S101-S103, to close the through hole <NUM>. The service life of the battery is improved through secondary liquid injection.

Through the liquid injection method, repeated disassembly and assembly of the liquid injection component can be realized flexibly and conveniently, after secondary liquid injection is finished, the liquid injection hole can be closed reliably, to ensure operating reliability of the battery after secondary liquid injection, and enable the appearance of the battery to be kept consistent with the appearance before liquid injection; moreover, the maintenance time can be shortened during secondary liquid injection, liquid can be supplemented timely when the performance of the battery is lowered, to ensure operating performance of the battery.

Further, as shown in <FIG>, after the cover body <NUM> is separated from the housing in step S105, the liquid injection method further includes:.

step S106, removing the sealing element <NUM> from the housing <NUM>' or the cover body <NUM>.

In the present embodiment, after the sealing element <NUM> is removed from the housing <NUM>' or the cover body <NUM>, electrolyte inside the housing <NUM>' can be poured out conveniently, to prevent the electrolyte from flowing onto the sealing element <NUM>, enable the sealing element <NUM> to keep clean, and prolong the service life.

Finally, the present application further provides a liquid injection device <NUM> configured to inject liquid into the secondary battery <NUM>, to realize the above liquid injection method. As shown in <FIG>, in some embodiments, the liquid injection device <NUM> includes: a liquid injection device <NUM> configured to inject electrolyte into the housing through the through hole <NUM> arranged on the housing <NUM>'; and a cover body disassembly and assembly mechanism <NUM>, configured to rotate the cover body <NUM> from the second position to the first position when the cover body <NUM> is placed on the housing <NUM>' and is in the second position, such that the limiting part <NUM> of the cover body <NUM> enters the accommodating part <NUM> on one side, far away from the inside of the housing <NUM>', of the housing <NUM>', and separation of the cover body <NUM> and the housing <NUM>' is limited; wherein in the second position, the limiting part <NUM> and the accommodating part <NUM> are misplaced along the circumferential direction of the through hole <NUM>.

Compared with the traditional manner in which the liquid injection hole is closed through laser welding, in the present application, not only the welding process is avoided, but also the plurality of processes of cleaning of welding slags and drying of liquid residual from cleaning caused by welding are avoided. The device can simply and efficiently manufacture batteries, and further improve assembly efficiency of the battery.

In some embodiments, the liquid injection device <NUM> further includes: a sealing element disassembly and assembly mechanism <NUM>, configured to install the sealing element <NUM> on the housing <NUM>' or the cover body <NUM>, or remove the sealing element <NUM> from the housing <NUM>' or the cover body <NUM>.

Through the embodiment, the sealing element <NUM> can be conveniently disassembled and assembled in the processes of battery assembly and secondary liquid injection, to improve the disassembly and assembly efficiency, reduce pollution to the sealing element <NUM>, and prolong service life of the sealing element <NUM>.

In some embodiments, the cover body disassembly and assembly mechanism <NUM> is configured to rotate the cover body <NUM> from the first position to the second position, such that the limiting part <NUM> is misplaced from the accommodating part <NUM> along the circumferential direction of the through hole <NUM>, to separate the cover body <NUM> from the housing <NUM>'.

The device can flexibly and conveniently assist in disassembly and assembly of the cover body <NUM> in the production and assembly of the battery and secondary liquid injection processes, the operation is simple, so as to improve assembly efficiency of the battery, and shorten maintenance time required during secondary liquid injection of the battery, and when the performance of the battery is lowered, liquid can be supplemented timely, to ensure operating performance of the battery.

In some embodiments, the sealing element disassembly and assembly mechanism <NUM> is further configured to remove the sealing element <NUM> from the housing or the cover body <NUM> after the cover body <NUM> is separated from the housing <NUM>'.

In the present embodiment, the sealing element <NUM> can be conveniently removed from the housing <NUM>' or the cover body <NUM>, to conveniently pour out electrolyte inside the housing <NUM>', for fear that electrolyte flows onto the sealing element <NUM>, then the sealing element <NUM> can be kept clean, and the service life is prolonged.

Protection subjects and features in each embodiment in the above application can be used for reference with each other, when the structure allows, those skilled in the art can also flexibly combine technical features in different embodiments, to form more embodiments.

Claim 1:
An end cover assembly (<NUM>) for a secondary battery (<NUM>), comprising:
an end cover (<NUM>'), provided with a through hole (<NUM>) for injection of electrolyte and an accommodating part (<NUM>), wherein the accommodating part (<NUM>) is arrangeable on a side, far away from a shell (<NUM>), of the end cover (<NUM>') and is arranged along a circumferential direction of the through hole (<NUM>);
a sealing element (<NUM>), sealing the through hole (<NUM>); and
a cover body (<NUM>), covering at least part of the sealing element (<NUM>), wherein the cover body (<NUM>) is rotatable and comprises a limiting part (<NUM>);
wherein when the cover body (<NUM>) rotates to a first position, the limiting part (<NUM>) is located inside the accommodating part (<NUM>) to limit separation of the cover body (<NUM>) from the end cover (<NUM>'); when the cover body (<NUM>) rotates to a second position, the limiting part (<NUM>) and the accommodating part (<NUM>) are misplaced along the circumferential direction of the through hole (<NUM>), to realize separation of the cover body (<NUM>) from the end cover (<NUM>');
wherein the end cover (<NUM>') comprises a main body of end cover (<NUM>) and an installation part (<NUM>), wherein the installation part (<NUM>) is arranged on a surface of the main body of end cover (<NUM>), and is arranged to surround the through hole (<NUM>), and the accommodating part (<NUM>) is arranged in the installation part (<NUM>) or enclosed by the installation part (<NUM>) and the main body of end cover (<NUM>).