Patent Description:
For energy-storage apparatuses such as lithium batteries or sodium batteries, after end cover assemblies are assembled, electrolytes are filled through liquid-injection holes of the end cover assemblies, and after filling the electrolytes, sealing caps need to be welded to the liquid-injection hole to seal the liquid-injection hole. However, for the existing energy-storage apparatuses, poor welding often occurs after welding the sealing cap, resulting in low product yield. The EP patent <CIT> relates to the following. Provided is a secondary battery (<NUM>) including a cap assembly (<NUM>). The cap assembly (<NUM>) includes a cap plate (<NUM>) including an electrolyte injection hole (<NUM>), the electrolyte injection hole (<NUM>) includes an upper tapered portion, and the tapered portion has a surface roughness. The secondary battery (<NUM>) further includes a sealing member located in the electrolyte injection hole (<NUM>) to seal the electrolyte injection hole. The sealing member includes a cap and a resin coated on an outer circumference of the cap. Thus, a secondary battery (<NUM>) including an electrolyte injection hole (<NUM>) having a very excellent sealing characteristic can be provided. Also, productivity of a fabrication process can be improved by removing need for a cap welding process.

In view of the above-mentioned problem, an end cover assembly that can improve the yield is provided in embodiments of the present disclosure.

In a first aspect of the present disclosure, an end cover assembly for an energy-storage apparatus is provided. The end cover assembly includes a top cover. The top cover has a first surface and further defines a liquid-injection hole extending through the first surface. The first surface includes a first sub-surface and a second sub-surface connected to the first sub-surface. The first sub-surface is around the liquid-injection hole. The second sub-surface is around a periphery of the first sub-surface. Roughness of the first sub-surface is greater than roughness of the second sub-surface.

Further, the roughness Ra of the first sub-surface is in a range of <NUM> ≤ Ra ≤ <NUM>.

Further, the first sub-surface is annular. The first sub-surface has a linewidth L1 in a range of <NUM> ≤ L1 ≤ <NUM>.

Further, the first sub-surface is annular, the liquid-injection hole is circular. A ratio of an outer radius R1 of the first sub-surface to a radius R2 of the liquid-injection hole is in a range of <NUM> ≤ R1/R2 ≤ <NUM>.

Further, the end cover assembly further includes a sealing cap and an annular welding portion located at a junction between the sealing cap and the top cover. The sealing cap seals the liquid-injection hole and is connected to the top cover. The top cover is further provided with a first welding mark at the first sub-surface. The first welding mark includes a first end portion and a second end portion opposite to the first end portion. The first end portion is connected to the welding portion. The second end portion is located at a periphery of the welding portion and is spaced apart from the welding portion.

Further, a ratio of an outer radius R4 of the welding portion (<NUM>) to a length L2 of the first welding mark (<NUM>) is in a range of <NUM> ≤ R4/L2 ≤ <NUM>.

Further, the first welding mark (<NUM>) is straight, and an angle α between a line connecting a center of the sealing cap (<NUM>) and the first end portion (<NUM>) and the first welding mark (<NUM>) is in a range of <NUM>° ≤ α ≤ <NUM>°.

Further, the first sub-surface is annular. The sealing cap is circular. A ratio of an outer radius R1 of the first sub-surface to a radius R3 of the sealing cap is in a range of <NUM> ≤ R1/R3 ≤ <NUM>.

Further, the top cover is further provided with a second welding mark at the first sub-surface. The second welding mark includes a third end portion and a fourth end portion arranged opposite to the third end portion. The third end portion is connected to the welding portion. The fourth end portion is located at the periphery of the welding portion and is spaced apart from the welding portion. The first end portion is spaced apart from or overlapped with the third end portion. The second end portion and the fourth end portion are respectively arranged at opposite sides of a line connecting the first end portion and a center of the liquid-injection hole.

Further, the welding portion is annular, the first welding mark has a length L2 satisfying <NUM> <MAT>. The second welding mark has a length L3 satisfying <NUM> ≤ L3 ≤ <MAT>. R1 is the outer radius of the first sub-surface. R4 is an outer radius of the welding portion.

Further, the length L2 of the first welding mark is in a range of <NUM> ≤ L2 ≤ <NUM>. The length L3 of the second welding mark is in a range of <NUM> ≤ L3 ≤ <NUM>.

Further, a ratio of an outer radius R4 of the welding portion (<NUM>) to the length L3 of the second welding mark (<NUM>) is in a range of <NUM> ≤ R4/L3 ≤ <NUM>.

Further, the second welding mark (<NUM>) is straight. An angle β between a line connecting a center of the sealing cap (<NUM>) and the third end portion (<NUM>) and the second welding mark (<NUM>) is in a range of <NUM>° ≤ β ≤ <NUM>°.

Further, the welding portion is annular. The first welding mark and the second welding mark are straight. The first welding mark and the second welding mark are both tangent to the welding portion.

Further, the welding portion is annular. The second welding mark is arc. The second welding mark is tangent to the welding portion.

Further, the top cover further has a second surface away from the first surface. The liquid-injection hole further extends through the second surface. The second surface includes a third sub-surface and a fourth sub-surface connected to the third sub-surface. The third sub-surface is around a periphery of the liquid-injection hole. The fourth sub-surface is around a periphery of the third sub-surface. The third sub-surface exceeds the fourth sub-surface to form a protrusion.

Further, the second surface further includes a fifth sub-surface. The fifth sub-surface is around a periphery of the fourth sub-surface and is connected to the fourth sub-surface. The fifth sub-surface exceeds the fourth sub-surface. The third sub-surface exceeds the fifth sub-surface. The third sub-surface, the fourth sub-surface, and the fifth sub-surface cooperatively define a groove around the protrusion.

Further, the protrusion has a linewidth S1 in a range of <NUM> ≤ S1 ≤ <NUM>. The groove has a linewidth S2 in a range of <NUM> ≤ S2 ≤ <NUM>.

Further, the energy-storage apparatus further includes an electrode assembly. The top cover further has a second surface away from the first surface. The liquid-injection hole further extends through the second surface. The top cover further defines a first accommodating recess from the second surface. A second accommodating recess recessed from a bottom wall of the first accommodating recess. A first through hole extending through both a bottom wall of the second accommodating recess and the first surface. The first accommodating recess, the second accommodating recess, and the first through hole are in communication with one another. The first through hole is spaced apart from the liquid-injection hole. The end cover assembly further includes a lower plastic member and a pole. The lower plastic member is disposed on the second surface of the top cover. The lower plastic member includes a body portion, a first abutting portion protruding from a surface of the body portion facing the top cover, and a second abutting portion protruding from the surface of the first abutting portion facing the top cover. The first abutting portion is located in the first accommodating recess and abuts against the bottom wall and a side wall of the first accommodating recess. The second abutting portion is located in the second accommodating recess and abuts against the bottom wall portion and a side wall of the second accommodating recess. The lower plastic member further defines a second through hole that sequentially extends through the body portion, the first abutting portion, and the second abutting portion. The second through hole is defined corresponding to the first through hole. The pole has one part located at a side of the lower plastic member away from the top cover, and the other part sequentially extending through the second through hole and the first through hole and insulated from the top cover. The pole is configured to be electrically connected to the electrode assembly.

Further, the end cover assembly further includes a lower plastic member disposed on a side of the top cover away from the first surface. The lower plastic member includes a first plastic sub-member, a second plastic sub-member, a third plastic sub-member, and a fourth plastic sub-member. The first plastic sub-member and the second plastic sub-member are arranged at an interval in a first direction on a surface of the top cover away from the first surface. The first plastic sub-member defines a leakage hole at a position of the first plastic sub-member close to the second plastic sub-member. The leakage hole is in communication with the liquid-injection hole. The first plastic sub-member has a first peripheral side wall and a second peripheral side wall that are connected end-to-end and define the leakage hole. The first peripheral side wall is a cambered surface. The second peripheral side wall is a flat surface. The second peripheral side wall is closer to the second plastic sub-member than the first peripheral side wall. The third plastic sub-member and the fourth plastic sub-member are arranged at an interval in a second direction. The third plastic sub-member is connected to both the first plastic sub-member and the second plastic sub-member in a snap-fit manner. The fourth plastic sub-member is connected to both the first plastic sub-member and the second plastic sub-member in a snap-fit manner. The third plastic sub-member and the fourth plastic sub-member are both partially located between the first plastic sub-member and the second plastic sub-member. The first direction is perpendicular to the second direction.

Further, the top cover further has a second surface away from the first surface, and defines an explosion-proof hole extending through the first surface and the second surface. The explosion-proof hole is spaced apart from the liquid-injection hole. The end cover assembly further includes an explosion-proof sheet sealing the explosion-proof hole and connected to the top cover. The first plastic sub-member further defines a vent channel in communication with the leakage hole. The vent channel extends through both a surface of the first plastic sub-member facing the second plastic sub-member and a surface of the first plastic sub-member facing the top cover, and the vent channel is in communication with a side of the explosion-proof sheet facing the first plastic sub-member.

In a second aspect of the present disclosure, an energy-storage apparatus is provided. The energy-storage apparatus includes the end cover assembly described in the embodiments of the present disclosure, an adapter sheet, and an electrode assembly. The adapter sheet is disposed at a side of the top cover away from the first surface and has one end electrically connected to the end cover assembly. The electrode assembly is disposed at a side of the adapter sheet away from the end cover assembly. The electrode assembly is electrically connected to one end of the adapter sheet away from the end cover assembly.

In a third aspect of the present disclosure, an electricity-consumption device is provided. The electricity-consumption device includes an electricity-consumption device body and the energy-storage apparatus described in the embodiments of the present disclosure. The energy-storage apparatus supplies power to the electricity-consumption device body.

The end cover assembly according to the embodiments of the present disclosure includes the top cover. The top cover has the first surface and further defines the liquid-injection hole extending through the first surface. The first surface includes the first sub-surface and the second sub-surface connected to the first sub-surface. The first sub-surface is around the liquid-injection hole, the second sub-surface is around the periphery of the first sub-surface. The roughness of the first sub-surface is greater than the roughness of the second sub-surface. Since the roughness of the first sub-surface is greater than the roughness of the second sub-surface, when the sealing cap is subsequently welded to seal the liquid-injection hole, the reflection of laser by the top cover can be reduced, so as to reduce the laser absorptivity of the welding material of the top cover, avoiding the problem that the temperature cannot reach a welding temperature caused by the reduced laser absorptivity of the welding material due to the reflection of laser by the top cover. In addition, since the roughness of the first sub-surface is greater than the roughness of the second sub-surface, when a top patch is attached to the first surface of the top cover, gas between the top patch and the first sub-surface of the top cover can be discharged through a rough micro-gap of the first sub-surface to avoid formation of local bubbles, which can increase the binding force (i.e., the adhesive force) between the top patch and the first sub-surface, improving the sealing effect on the liquid-injection hole. Furthermore, during the process of filling the electrolyte into the energy-storage apparatus through the liquid-injection hole at high speed, a small amount of electrolyte will splash around the liquid-injection hole. However, the subsequent laser welding of the sealing cap requires high cleanliness of the metal surface. If there are impurities, such as the electrolyte or dust, remaining on the metal surface, when the laser beam scans to the impurities (e.g., the fine particles of electrolyte), the impurities will vaporize to explode instantly, which is likely to cause defects such as pores or splashes at the welded part.

To describe technical solutions in the present disclosure more clearly, the following briefly introduces the accompanying drawings required for describing implementations. Apparently, the accompanying drawings in the following description show merely some implementations of the present disclosure, and a person of ordinary skill in the art may still derive other drawings from these accompanying drawings without creative efforts.

<NUM> - electricity-consumption device, <NUM> - electricity-consumption device body, <NUM> - energy-storage apparatus, <NUM> - electrode assembly, <NUM> - positive-electrode tab, <NUM> - negative-electrode tab, <NUM> - adapter sheet, <NUM> - positive-electrode adapter sheet, <NUM> - negative-electrode adapter sheet, <NUM> - housing, <NUM> - end cover assembly, <NUM> - top cover, <NUM> - first surface, <NUM> - first sub-surface, <NUM> - second sub-surface, <NUM> - abutting sub-surface, <NUM> - liquid-injection hole, <NUM> - second surface, <NUM> - third sub-surface, <NUM> - fourth sub-surface, <NUM> - fifth sub-surface, <NUM> - protrusion, <NUM> - groove, <NUM> - first accommodating recess, <NUM> - second accommodating recess, <NUM> - first through hole, <NUM> - explosion-proof hole, <NUM> - explosion-proof sheet, <NUM> - protective sheet, <NUM> - sealing cap, <NUM> - welding portion, <NUM> - first welding mark, <NUM> - first end portion, <NUM> - second end portion, <NUM> - second welding mark, <NUM> - third end portion, <NUM> - fourth end portion, <NUM> - positive-electrode metal pressing block, <NUM> - negative-electrode metal pressing block, <NUM> - lower plastic member, <NUM> - body portion, <NUM> - first abutting portion, <NUM> - second abutting portion, <NUM> - second through hole, <NUM> - first plastic sub-member, <NUM> - leakage hole, <NUM> - first peripheral side wall, <NUM> - second peripheral side wall, <NUM> - vent channel, <NUM> - second plastic sub-member, <NUM> - third plastic sub-member, <NUM> - fourth plastic sub-member, <NUM> - positive-electrode upper plastic member, <NUM> - negative-electrode upper plastic member, <NUM> - pole, <NUM> - positive pole, <NUM> - negative pole, <NUM> - sealing ring, <NUM> - sealing pin.

To enable those skilled in the art to better understand the solutions of the present disclosure, the technical solutions in embodiments of the present disclosure will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present disclosure. Apparently, the described embodiments are merely some of, rather than all, the embodiments of the present disclosure. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present disclosure without any creative effort shall fall within the scope of protection of the present disclosure.

The terms such as "first" and "second" in the specification and the claims of the present application and in the accompanying drawings are intended to distinguish different objects, rather than to describe a specific order. In addition, the terms of "include" and "have" and any variations thereof are intended to cover the non-exclusive inclusion. For example, the process, method, system, product or device, which includes a series of steps or units, is not limited to the listed steps or units, but optionally further includes unlisted steps or units, or optionally further includes other steps or units inherent to the process, method, product or device.

The technical solutions in the embodiments of the present disclosure will be described below with reference to the accompanying drawings.

It may be noted that, for ease of description, in the embodiments of the present disclosure, the same reference numerals denote the same components, and for the sake of brevity, the detailed description of the same components is omitted in different embodiments.

Referring to <FIG>, an electricity-consumption device <NUM> is provided in embodiments of the present disclosure. The electricity-consumption device <NUM> includes an electricity-consumption device body <NUM> and an energy-storage apparatus <NUM>. The energy-storage apparatus <NUM> supplies power to the electricity-consumption device body <NUM>.

The electricity-consumption device <NUM> in the embodiments of the present disclosure may be, but not limited to, a portable electronic device, such as a mobile phone, a tablet computer, a laptop, a desktop computer, a smart bracelet, a smart watch, an e-book reader, and a game console. The electricity-consumption device <NUM> may also be transportation means such as an automobile, a truck, a car, a van, a bullet train, a high-speed train, and an electric bicycle. In addition, the electricity-consumption device <NUM> may also be various household appliances, etc. It can be understood that the electricity-consumption device <NUM> illustrated in the drawings of the present disclosure is only one of the forms of the electricity-consumption device <NUM>, and may not be construed as a limitation on the electricity-consumption device <NUM> provided in the present disclosure.

Referring to <FIG> and <FIG>, an energy-storage apparatus <NUM> is provided in embodiments of the present disclosure. The energy-storage apparatus <NUM> includes an electrode assembly <NUM>, an adapter sheet <NUM>, and an end cover assembly <NUM>. The adapter sheet <NUM> is electrically connected to the electrode assembly <NUM>. The end cover assembly <NUM> is disposed at a side of the adapter sheet <NUM> away from the electrode assembly <NUM> and is electrically connected to the adapter sheet <NUM>.

The energy-storage apparatus <NUM> of the embodiments of the present disclosure may be, but not limited to, a lithium-ion secondary battery, a lithium-ion primary battery, a lithium-sulfur battery, a sodium/lithium-ion battery, a sodium-ion battery or a magnesium-ion battery, an energy-storage battery, and other energy-storage apparatus <NUM>. It can be understood that the energy-storage apparatus <NUM> illustrated in the drawings of the present disclosure is only one of the forms of the energy-storage apparatus <NUM>, and may not be construed as a limitation on the energy-storage apparatus <NUM> provided in the present disclosure.

Optionally, the adapter sheet <NUM> may be, but not limited to, at least one of copper foil and aluminum foil.

Optionally, the adapter sheet <NUM> includes a positive-electrode adapter sheet <NUM> and a negative-electrode adapter sheet <NUM>. The electrode assembly <NUM> includes a positive-electrode sheet (not shown), a separator (not shown) and a negative-electrode sheet (not shown) arranged in sequence. The positive-electrode sheet and the negative-electrode sheet are both electrically connected to the end cover assembly <NUM> by means of the adapter sheet <NUM>. The positive-electrode sheet includes a positive current collector, a positive-electrode tab <NUM> electrically connected to the positive current collector, and a positive active layer disposed on a surface of the positive current collector. The positive-electrode sheet is electrically connected to the positive-electrode adapter sheet <NUM> by means of the positive-electrode tab <NUM>. The negative-electrode sheet includes a negative current collector, a negative-electrode tab <NUM> electrically connected to the negative current collector, and a negative active layer disposed on a surface of the negative current collector. The negative-electrode sheet is electrically connected to the negative-electrode adapter sheet <NUM> by means of the negative-electrode tab <NUM>.

It can be understood that the positive-electrode adapter sheet <NUM> and the negative-electrode adapter sheet <NUM> are different adapter sheets. The adapter sheet <NUM> for electrically connecting the positive-electrode tab <NUM> to the end cover assembly <NUM> is the positive-electrode adapter sheet <NUM>, and the adapter sheet <NUM> for electrically connecting the negative-electrode tab <NUM> to the end cover assembly <NUM> is the negative-electrode adapter sheet <NUM>.

In some embodiments, the energy-storage apparatus <NUM> of the present disclosure further includes a housing <NUM>. The housing <NUM> is connected to the end cover assembly <NUM>, and the housing <NUM> and the end cover assembly <NUM> cooperatively define an accommodating recess. The accommodating recess is used to accommodate the electrode assembly <NUM> and the adapter sheet <NUM>.

In some embodiments, the energy-storage apparatus <NUM> of the present disclosure further includes an electrolyte (not shown). The electrolyte is accommodated in the accommodating recess, and at least part of the positive-electrode sheet and at least part of the negative-electrode sheet are immersed in the electrolyte.

After the components of the energy-storage apparatus are assembled, the electrolyte is filled through a liquid-injection hole of the end cover assembly. After the electrolyte is filled, the liquid-injection hole is plugged with a rubber tack, and a sealing cap made of metal is welded to a top cover by means of laser welding above the liquid-injection hole to achieve secondary sealing for the liquid-injection hole so as to prevent the electrolyte from overflowing.

The top cover is generally made of metal, such as <NUM>-series aluminum alloy. Aluminum alloy is a non-ferrous metal that has strong reflectivity to all kinds of light. Laser, as a high-energy beam, is more likely to reflect on the surface of the aluminum alloy. In other words, aluminum alloy, a non-ferrous metal, has high reflectivity and low absorptivity for laser. In addition, all metals have thermal conductivity, so aluminum alloy also has strong thermal conductivity, and is easy to reflect laser or quickly transfer the heat of laser during laser welding, so that the temperature of the part to-be-welded cannot meet the welding requirements, eventually resulting in welding failure of the sealing cap. Thus, during laser welding of the sealing cap, it is necessary to strictly control the power density of laser and the movement speed during welding to prevent reflection or transfer of laser, and it is desired to weld aluminum alloy with extremely high energy density beam in a very short time, which can prevent the problems such as reflection.

In addition, during welding of the sealing cap, the laser absorption of the welding material depends on some important properties of the material, such as absorptivity, reflectivity, thermal conductivity, melting temperature, and evaporation temperature, in which the absorptivity is most important. The factors that affect the laser beam absorptivity of the material include two aspects. The first is the coefficient of resistance of the material. From the measurement of the absorptivity of the polished surface of the material, it has been found that the absorptivity of the material is directly proportional to the square root of the coefficient of resistance, and the coefficient of resistance varies with the temperature. Secondly, the surface state (or smoothness) of the material has an important influence on the beam absorptivity, and thus significantly influences the welding effect.

Referring to <FIG> and <FIG>, an end cover assembly <NUM> is further provided in embodiments of the present disclosure. The end cover assembly <NUM> is for the energy-storage apparatus <NUM> and includes a top cover <NUM>. The top cover <NUM> has a first surface <NUM>, and the top cover <NUM> further defines a liquid-injection hole <NUM> extending through the first surface <NUM>. The first surface <NUM> includes a first sub-surface <NUM> and a second sub-surface <NUM> connected to the first sub-surface <NUM>, the first sub-surface <NUM> is around the liquid-injection hole <NUM>, the second sub-surface <NUM> is around the periphery of the first sub-surface <NUM>, and the roughness of the first sub-surface <NUM> is greater than the roughness of the second sub-surface <NUM>.

It may be noted that when the end cover assembly <NUM> is mounted to the energy-storage apparatus <NUM>, the top cover <NUM> is connected to the housing <NUM> to define the accommodating recess.

Optionally, the top cover <NUM> may be made of, but not limited to, aluminum or an aluminum alloy, etc. The end cover assembly <NUM> of the embodiments of the present disclosure includes the top cover <NUM>. The top cover <NUM> has a first surface <NUM>, and the top cover <NUM> further defines the liquid-injection hole <NUM> extending through the first surface <NUM>. The first surface <NUM> includes a first sub-surface <NUM> and a second sub-surface <NUM> connected to each other, the first sub-surface <NUM> is around the liquid-injection hole <NUM>, the second sub-surface <NUM> is around the periphery of the first sub-surface <NUM>, and the roughness of the first sub-surface <NUM> is greater than the roughness of the second sub-surface <NUM>. Since the roughness of the first sub-surface <NUM> is greater than the roughness of the second sub-surface <NUM>, when the sealing cap is subsequently welded to seal the liquid-injection hole <NUM>, the reflection of laser by the top cover <NUM> can be reduced, so as to reduce the laser absorptivity of the welding material of the top cover <NUM>, avoiding the problem that the temperature cannot reach a welding temperature caused by the reduced laser absorptivity of the welding material due to the reflection of laser by the top cover <NUM>. In addition, since the roughness of the first sub-surface <NUM> is greater than the roughness of the second sub-surface <NUM>, when a top patch is attached to the first surface <NUM> of the top cover <NUM>, gas between the top patch and the first sub-surface <NUM> of the top cover <NUM> can be discharged through a rough micro-gap of the first sub-surface <NUM> to avoid formation of local bubbles, which can increase the binding force (i.e., the adhesive force) between the top patch and the first sub-surface <NUM>, improving the sealing effect on the liquid-injection hole <NUM>. Furthermore, during the process of filling the electrolyte into the energy-storage apparatus <NUM> through the liquid-injection hole <NUM> at high speed, a small amount of electrolyte will splash around the liquid-injection hole <NUM>. However, the subsequent laser welding of the sealing cap <NUM> requires high cleanliness of the metal surface. If there are impurities, such as the electrolyte or dust, remaining on the metal surface, when the laser beam scans to the impurities (e.g., the fine particles of electrolyte), the impurities will vaporize to explode instantly, which is likely to cause defects such as pores or splashes at the welded part.

Optionally, the first sub-surface <NUM> is formed by means of low-power laser scanning that removes impurities such as the electrolyte or dust remaining around the liquid-injection hole by ablation while forming the rough surface (i.e., the first sub-surface <NUM>), so that the welding surface is cleaned in advance for the subsequent high-power laser welding process of the sealing cap <NUM> to improve the uniformity and sealing performance of welding, thereby prolonging the service life of the energy-storage apparatus <NUM>.

Optionally, the sealing cap may be made of, but not limited to, aluminum or an aluminum alloy, etc..

Optionally, the roughness Ra of the first sub-surface <NUM> is in a range of <NUM> ≤ Ra ≤ <NUM>. Specifically, the roughness Ra of the first sub-surface <NUM> may be, but not limited to, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, etc. If the roughness of the first sub-surface <NUM> is too small, the laser reflectivity of the first sub-surface <NUM> is excessively large, affecting the laser absorptivity of the laser welding material, so that during welding of the sealing cap to the top cover <NUM>, the temperature cannot reach the welding temperature, affecting the sealing effect of the sealing cap on the liquid-injection hole <NUM>. If the roughness of the first sub-surface <NUM> is too large, when the top patch is attached to the first surface <NUM>, an adhesive layer for attaching the top patch is insufficient to extend into the bottom of a trench (i.e., the gap of the first sub-surface <NUM>) for attachment, reducing the sealing performance of the liquid-injection hole <NUM>. It can be seen that in the present disclosure, the roughness is short for surface roughness, which can be regarded as the quality of a surface of not being smooth. In addition, the surface roughness is a component of surface finish (surface texture). In an embodiment of the present disclosure, the roughness refers to arithmetical mean roughness, represented by Ra, which means the value obtained by the following formula and expressed in micrometer (µm) when sampling only the reference length Q from the roughness curve in the direction of the mean line, taking X-axis in the direction of mean line and Y-axis in the direction of longitudinal magnification of this sampled part and the roughness curve is expressed by <MAT>.

In a specific embodiment, the first sub-surface <NUM> is a rough surface, and the second sub-surface <NUM> is a smooth surface (i.e., the surface that is smooth).

Referring to <FIG>, in some embodiments, the first sub-surface <NUM> is annular, and the first sub-surface <NUM> has a linewidth L1 in a range of <NUM> ≤ L1 ≤ <NUM>. Specifically, the linewidth L1 of the first sub-surface <NUM> may be, but not limited to, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, etc. If the linewidth of the first sub-surface <NUM> is too small, the impurities such as the electrolyte are likely to splash out of the first sub-surface <NUM> during filling. The larger the linewidth of the first sub-surface <NUM> is, the more it can ensure that the error of the laser beam is within the range of the first sub-surface <NUM> during welding of the sealing cap to the liquid-injection hole <NUM>, so as to avoid the problem that the temperature cannot reach a standard welding temperature caused by the reduced laser absorptivity of the welding material due to the reflection by the second sub-surface <NUM> (a clean surface). The excessively large linewidth of the first sub-surface <NUM> will cause the waste of laser scanning energy and also prolong the machining time, thus increasing the machining cost of the energy-storage apparatus <NUM>.

Optionally, the first sub-surface <NUM> is annular, the liquid-injection hole <NUM> is circular, and the ratio of an outer radius R1 of the first sub-surface <NUM> to the radius R2 of the liquid-injection hole <NUM> is in a range of <NUM> = R1/R2 ≤ <NUM>. Specifically, the ratio of the outer radius R1 of the first sub-surface <NUM> to the radius R2 of the liquid-injection hole <NUM> may be, but not limited to, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, etc. The larger the diameter of the liquid-injection hole <NUM> is, the more electrolyte passing through per unit time, and the further the electrolyte splashed outwards. If R1/R2 is too small, the electrolyte is likely to splash out of the first sub-surface <NUM> during filling. The excessively large R1/R2 will cause the waste of laser canning energy and also prolong the machining time, thus increasing the cost of the energy-storage apparatus <NUM>.

Referring to <FIG>, in some embodiments, the end cover assembly <NUM> further includes a sealing cap <NUM> and an annular welding portion <NUM> located at the junction between the sealing cap <NUM> and the top cover <NUM>. The sealing cap <NUM> seals the liquid-injection hole <NUM> and is connected to the top cover <NUM>. The top cover <NUM> is further provided with a first welding mark <NUM> located at the first sub-surface <NUM>. The first welding mark <NUM> includes a first end portion <NUM> and a second end portion <NUM> opposite to the first end portion <NUM>. The first end portion <NUM> is connected to the welding portion <NUM>, and the second end portion <NUM> is located at the periphery of the welding portion <NUM> and is spaced apart from the welding portion <NUM>.

It may be noted that the welding portion <NUM> and the first welding mark <NUM> are both formed during welding of the sealing cap <NUM> and the top cover <NUM>. During welding of the sealing cap <NUM> to the top cover <NUM>, the welding material is welded a circle around the periphery of the sealing cap <NUM> to form the annular welding portion <NUM>, and after the annular welding portion <NUM> is formed, welding is continued on the top cover <NUM> to form the first welding mark <NUM>. It can be understood that the first welding mark <NUM> is the ending point of laser welding.

During laser welding of the sealing cap <NUM> to the top cover <NUM>, there is a large shrinkage force before the welding material is completely solidified, so that at the end of welding, the relatively large temperature difference at the end is likely to cause end cracks. The arrangement of the first welding mark <NUM> at a position away from the annular welding portion <NUM> (there is no need for welding two materials together) can allow the whole annular welding portion <NUM> to be uniform, improving the sealing performance of the liquid-injection hole <NUM>. The arrangement of the starting and ending points of welding on the first sub-surface <NUM> outside the welding portion <NUM> can better prevent the risk of sealing failure due to fine cracks caused by the concentration of stress of the welding portion <NUM> on the part-to-be welded.

Optionally, the second end portion <NUM> is located within the range of the first sub-surface <NUM>. This can better prevent the second sub-surface <NUM> from reflecting laser after the welding is outside the range of the first sub-surface <NUM> (i.e., the welding reaching the second sub-surface <NUM>).

Optionally, before the sealing cap <NUM> is welded, the surface of the top cover <NUM> is cleaned. The aluminum alloy is active and is easy to be oxidized, and a large amount of dust, moisture, etc. are likely to adhere to its surface, so that during welding, if it is not prepared well, the matters adhered to the surface will easily remain on the surface of the aluminum alloy along with the rapid laser welding, thus affecting the quality and welding effect of the aluminum alloy. Therefore, before welding of the aluminum alloy, it is necessary to clean the surface of the aluminum alloy to remove oil stains and the like on the surface. Also, in order to prevent safety threats, such as explosion, caused by oxidation during welding, it is also necessary to thoroughly clean the metal surface to completely remove the oxide film.

In some embodiments, the first sub-surface <NUM> is annular, the sealing cap <NUM> is circular, and the ratio of the outer radius R1 of the first sub-surface <NUM> to the radius R3 of the sealing cap <NUM> is in a range of <NUM> ≤ R1/R3 ≤ <NUM>. Specifically, the ratio of the outer radius R1 of the first sub-surface <NUM> to the radius R3 of the sealing cap <NUM> may be, but not limited to, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, etc. If the ratio of the outer radius R1 of the first sub-surface <NUM> to the radius R3 of the sealing cap <NUM> is too small, the linewidth of the first sub-surface <NUM> is insufficient for close attachment of the top patch to the first sub-surface <NUM> during attachment of the top patch. If the ratio of the outer radius R1 of the first sub-surface <NUM> to the radius R3 of the sealing cap <NUM> is large, the linewidth of the first sub-surface <NUM> is too large, so that when the top patch is attached, the gas between the top patch and the first sub-surface <NUM> of the top cover <NUM> cannot be completely discharged through the rough micro-gap of the first sub-surface <NUM>, which is likely to form local bubbles, reducing the sealing effect on the liquid-injection hole <NUM>. When the ratio of the outer radius R1 of the first sub-surface <NUM> to the radius R3 of the sealing cap <NUM> is <NUM> to <NUM>, it is possible to ensure that the linewidth is sufficient to enhance the close attachment of the top patch to the first sub-surface <NUM>, and also avoid excessively large linewidth of the first sub-surface <NUM> that will reduce the sealing effect on the liquid-injection hole <NUM> due to formation of local bubbles caused by the gas between the top patch and the first sub-surface <NUM> of the top cover <NUM> being unable to be completely discharged through the rough micro-gap of the first sub-surface <NUM> during attachment of the top patch.

Referring to <FIG>, in some embodiments, the top cover <NUM> is further provided with a second welding mark <NUM> located at the first sub-surface <NUM>. The second welding mark <NUM> includes a third end portion <NUM> and a fourth end portion <NUM> opposite to the fourth end portion <NUM>, the third end portion <NUM> is connected to the welding portion <NUM>, and the fourth end portion <NUM> is located at the periphery of the welding portion <NUM> and is spaced apart from the welding portion <NUM>. The first end portion <NUM> is spaced apart from or overlapped with the third end portion <NUM>, and the second end portion <NUM> and the fourth end portion <NUM> are respectively arranged at two opposite sides of a line connecting the first end portion <NUM> and the center of the liquid-injection hole <NUM>.

It may be noted that, in this embodiment, the welding portion <NUM>, the first welding mark <NUM>, and the second welding mark <NUM> are each formed when the sealing cap <NUM> is welded to the top cover <NUM>. When the sealing cap <NUM> is welded to the top cover <NUM>, the second welding mark <NUM> is firstly formed at the side of the first sub-surface <NUM> of the top cover <NUM> away from the sealing cap <NUM>, the annular welding portion <NUM> is then formed between the sealing cap <NUM> and the top cover <NUM>, and the first welding mark <NUM> is finally formed at the side of the first sub-surface <NUM> of the top cover <NUM> away from the annular welding portion <NUM>. The first welding mark <NUM> and the second welding mark <NUM> are approximate to line segments of a straight line that each are roughly tangent to the annular welding portion <NUM>. It can be understood that the first welding mark <NUM> is the ending point of laser welding, and the second welding mark <NUM> is a starting point of laser welding.

During welding of the sealing cap <NUM>, when laser welding is performed at the starting position, the temperature of the welding material is not enough, so that the material to be welded cannot reach a molten state desired for good welding, reducing the sealing performance of the liquid-injection hole <NUM>. The arrangement of the second welding mark <NUM> can allow welding to be performed at a high welding temperature when the welding portion <NUM> is formed, so that the sealing cap <NUM> can be better welded to the top cover <NUM> to better seal the liquid-injection hole <NUM>. Also, in order to also shorten the welding process time (i.e., it is unexpected to prolong the movement time of a laser head during initial welding), the starting point of welding is also set on the outside of the annular welding portion <NUM>, so as to minimize the welding stroke while ensuring the sufficient temperature during forming of the welding portion <NUM> by welding, thereby improving the welding efficiency.

In other embodiments, the problem of insufficient initial welding temperature can be solved by means of reducing the movement speed of the laser head or welding a circle from the initial position and then surrounding and covering a small section of the initial welded part to achieve uniform welding, and it is not necessary to space the starting point away.

Optionally, the welding portion <NUM> is annular, the length L2 of the first welding mark <NUM> <MAT>, andthe length L3 of the second welding mark <NUM> satisfies <NUM> <MAT>, where R1 is the outer radius of the first sub-surface <NUM>, and R4 is the outer radius of the welding portion <NUM>. In this way, when the welding portion <NUM> is formed by welding, the temperature is sufficient, so that the sealing cap <NUM> can be better welded to the top cover <NUM> to better seal the liquid-injection hole <NUM>, and the first welding mark <NUM> and the second welding mark <NUM> can also be controlled within the range of the first sub-surface <NUM>, avoiding the problem of light reflection during welding due to the marks being beyond the range of the first sub-surface <NUM>.

Optionally, the length L2 of the first welding mark <NUM> is in a range of <NUM> ≤ L2 ≤ <NUM>; and specifically, the length L2 of the first welding mark <NUM> may be, but not limited to, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, etc. If the first welding mark <NUM> is too short, it is likely to cause end cracks, affecting welding of the sealing cap <NUM> to the top cover <NUM>, thus affecting the sealing effect. If the first welding mark <NUM> is too long and is out of the range of the first sub-surface <NUM>, it is likely to cause the problem of light reflection during welding.

Optionally, the length L3 of the second welding mark <NUM> is in a range of <NUM> ≤ L3 ≤ <NUM>. Specifically, the length L3 of the second welding mark <NUM> may be, but not limited to, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, etc. If the second welding mark <NUM> is too short, the temperature of the welding material is insufficient during forming of the welding portion <NUM> by welding, which affects welding of the sealing cap <NUM> to the top cover <NUM>, thus affecting the sealing effect. If the second welding mark <NUM> is too long and is out of the range of the second sub-surface <NUM>, it is likely to cause the problem of light reflection during welding.

In a specific embodiment, the welding portion <NUM> is annular, the first welding mark <NUM> and the second welding mark <NUM> are straight, and the first welding mark <NUM> and the second welding mark <NUM> are both tangent to the welding portion <NUM>. The first welding mark <NUM> and the second welding mark <NUM> are straight, and the straight welding marks can shorten the movement path of the laser welding head, improving the welding efficiency.

In another specific embodiment, the welding portion <NUM> is annular, and the first welding mark <NUM> is straight and is tangent to the welding portion <NUM>; and the second welding mark <NUM> is arc, and the second welding mark <NUM> is tangent to the welding portion <NUM>. When the sealing cap <NUM> is welded to the top cover <NUM> for laser welding, it is not necessary to align the starting position to a specific position, and the position tangent to the sealing cap <NUM> may be adjusted by means of an arc, so that the welding operation is more convenient, and the requirement for the accuracy of the starting position is low.

Referring to <FIG> and <FIG>, in some embodiments, the ratio of an outer radius R4 of the welding portion <NUM> to the length L2 of the first welding mark <NUM> is in a range of <NUM> ≤ R4/L2 ≤ <NUM>. Specifically, the ratio of the outer radius R4 of the welding portion <NUM> to the length L2 of the first welding mark <NUM> may be, but not limited to, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, etc. If the ratio of the outer radius R4 of the welding portion <NUM> to the length L2 of the first welding mark <NUM> is too large, the first welding mark <NUM> is too short, which is likely to cause end cracks, affecting welding of the sealing cap <NUM> on the top cover <NUM>, thus affecting the sealing effect. If the ratio of the outer radius R4 of the welding portion <NUM> to the length L2 of the first welding mark <NUM> is too small, the first welding mark <NUM> is too long and is out of the range of the first sub-surface <NUM>, it is likely to cause the problem of light reflection during welding. When the ratio of the outer radius R4 of the welding portion <NUM> to the length L2 of the first welding mark <NUM> is <NUM> to <NUM>, during forming of the welding portion <NUM> by welding, the temperature is sufficient, so that the sealing cap <NUM> can be better welded to the top cover <NUM> to better seal the liquid-injection hole <NUM>, and the first welding mark <NUM> can also be controlled within the range of the first sub-surface <NUM>, avoiding the problem of light reflection during welding due to the marks being beyond the range of the first sub-surface <NUM>.

Optionally, in some embodiments, the first welding mark <NUM> is straight, and an angle α between a line connecting the center of the sealing cap <NUM> and the first end portion <NUM> and the first welding mark <NUM> is in a range of <NUM>° ≤ α ≤ <NUM>°. Specifically, the angle α between the line connecting the center of the sealing cap <NUM> and the first end portion <NUM> and the first welding mark <NUM> may be, but not limited to, <NUM>°, <NUM>°, <NUM>°, <NUM>°, <NUM>°, <NUM>°, <NUM>°, <NUM>°, <NUM>°, <NUM>°, <NUM>°, etc. In this angle range, the path of laser welding is smoother, so as to avoid reduction of the overall welding uniformity and reduction of the sealing performance of welding caused by the accumulation of molten metal at the welded part due to a relatively large turning angle.

In some embodiments, the ratio of the outer radius R4 of the welding portion <NUM> to the length L3 of the second welding mark <NUM> is in a range of <NUM> ≤ R4/L3 ≤ <NUM>. Specifically, the ratio of the outer radius R4 of the welding portion <NUM> to the length L3 of the second welding mark <NUM> may be, but not limited to, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, etc. If the ratio of the outer radius R4 of the welding portion <NUM> to the length L2 of the second welding mark <NUM> is too large, the second welding mark <NUM> is too short, which is likely to cause end cracks, affecting welding of the sealing cap <NUM> to the top cover <NUM>, thus affecting the sealing effect. If the ratio of the outer radius R4 of the welding portion <NUM> to the length L2 of the second welding mark <NUM> is too small, the second welding mark <NUM> is too long and is out of the range of the first sub-surface <NUM>, which is likely to cause the problem of light reflection during welding. When the ratio of the outer radius R4 of the welding portion <NUM> to the length L2 of the second welding mark <NUM> is <NUM> to <NUM>, during forming of the welding portion <NUM> by welding, the temperature is sufficient, so that the sealing cap <NUM> can be better welded to the top cover <NUM> to better seal the liquid-injection hole <NUM>, and the second welding mark <NUM> can also be controlled within the range of the first sub-surface <NUM>, avoiding the problem of light reflection during welding due to the marks being beyond the range of the first sub-surface <NUM>.

Optionally, the second welding mark <NUM> is straight, and an angle β between a line connecting the center of the sealing cap <NUM> and the third end portion <NUM> and the second welding mark <NUM> is in a range of <NUM>° ≤ β ≤ <NUM>°. Specifically, the angle β between the line connecting the center of the sealing cap <NUM> and the third end portion <NUM> and the second welding mark <NUM> may be, but not limited to, <NUM>°, <NUM>°, <NUM>°, <NUM>°, <NUM>°, <NUM>°, <NUM>°, <NUM>°, <NUM>°, <NUM>°, <NUM>°, etc. In this angle range, the path of laser welding is smoother, so as to avoid reduction of the overall welding uniformity and reduction of the sealing performance of welding caused by the accumulation of molten metal at the welded part due to a relatively large turning angle.

Referring to <FIG> again, optionally, the first surface <NUM> further includes an abutting sub-surface <NUM>. The abutting sub-surface <NUM> is around the periphery of the liquid-injection hole <NUM>, the first sub-surface <NUM> is around the periphery of the abutting sub-surface <NUM> and is connected to the abutting sub-surface <NUM>, and when the sealing cap <NUM> is arranged on the first surface <NUM>, the sealing cap <NUM> abuts against the abutting sub-surface <NUM>. By means of providing the abutting sub-surface <NUM>, the sealing cap <NUM> abuts against the abutting sub-surface <NUM>, such that the liquid-injection hole <NUM> can be better sealed.

Optionally, the abutting sub-surface <NUM> is recessed from the first sub-surface <NUM>, the sealing cap <NUM> is located in a recess formed by the abutting sub-surface <NUM>, and the surface of the sealing cap <NUM> close to the first surface <NUM> is flush with the first sub-surface <NUM>. This can prevent the sealing cap <NUM> from exceeding the top cover <NUM>, so that the surface of the top cover <NUM> is flatter and can thus be better attached to the top patch during attachment of the top patch, so that the liquid-injection hole <NUM> can be better sealed.

It can be understood that the liquid-injection hole <NUM> extends through the abutting sub-surface <NUM>.

Referring to <FIG>, in some embodiments, the top cover <NUM> further has a second surface <NUM> away from the first surface <NUM>, and the liquid-injection hole <NUM> further extends through the second surface <NUM>. The second surface <NUM> includes a third sub-surface <NUM> and a fourth sub-surface <NUM> connected to the third sub-surface <NUM>. The third sub-surface <NUM> is around the periphery of the liquid-injection hole <NUM>, the fourth sub-surface <NUM> is around the periphery of the third sub-surface <NUM>, and the third sub-surface <NUM> exceeds the fourth sub-surface <NUM> to form a protrusion <NUM>.

It may be noted that when the end cover assembly <NUM> is for the energy-storage apparatus <NUM>, the first surface <NUM> is closer to an appearance surface of the energy-storage apparatus <NUM> than the second surface <NUM>, that is, the surface to which the top patch is attached.

In this embodiment, when the end cover assembly <NUM> is mounted to the energy-storage apparatus <NUM>, when the electrolyte is filled through the liquid-injection hole <NUM>, the electrolyte is filled into the energy-storage apparatus <NUM> from the side of the liquid-injection hole <NUM> close to the first surface <NUM>, and the protrusion <NUM> provided on the second surface <NUM> has the effect of guiding and limiting the electrolyte and can better prevent the electrolyte from flowing to the second surface <NUM> of the top cover <NUM>, which will cause the waste of the electrolyte and increase the risk of corrosion of the top cover <NUM>.

Referring to <FIG>, in other embodiments, the second surface <NUM> further includes a fifth sub-surface <NUM>. The fifth sub-surface <NUM> is around the periphery of the fourth sub-surface <NUM> and is connected to the fourth sub-surface <NUM>, the fifth sub-surface <NUM> exceeds the fourth sub-surface <NUM>, the third sub-surface <NUM> exceeds the fifth sub-surface <NUM>, and the third sub-surface <NUM> exceeds the fourth sub-surface <NUM> to form the protrusion <NUM>. The third sub-surface <NUM>, the fourth sub-surface <NUM>, and the fifth sub-surface <NUM> cooperatively define a groove <NUM> around the protrusion <NUM>. It can be understood that the third sub-surface <NUM>, the fourth sub-surface <NUM>, and the fifth sub-surface <NUM> are sequentially connected to one another. When the end cover assembly <NUM> is mounted to the energy-storage apparatus <NUM>, when the electrolyte is filled through the liquid-injection hole <NUM>, since the groove <NUM> is defined at the periphery of the protrusion <NUM>, when the electrolyte accidentally flows to the second surface <NUM>, the groove <NUM> allows the electrolyte to be retained in the groove <NUM>, so as to prevent the electrolyte from continuing to spread to the fifth sub-surface <NUM>, causing the waste of the electrolyte and corroding the top cover <NUM>.

Referring to <FIG>, optionally, the protrusion <NUM> has a linewidth S1 in a range of <NUM> ≤ S1 ≤ <NUM>; and specifically, the linewidth S1 of the protrusion <NUM> may be, but not limited to, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, etc. Before the sealing cap <NUM> is welded to the liquid-injection hole <NUM>, the liquid-injection hole <NUM> is plugged with a sealing plug (e.g., a rubber plug), the sealing cap <NUM> is then arranged on the first surface <NUM>, and the sealing cap <NUM> is welded. If the linewidth S1 of the protrusion <NUM> is too large, the recessed space is too large, and after the liquid-injection hole <NUM> is plugged with the rubber plug, there is still a space for radial movement, reducing the sealing performance of the liquid-injection hole <NUM>. If the linewidth S1 of the protrusion <NUM> is too small, the accommodating space provided for a convex cap at the top of the rubber plug of the liquid-injection hole <NUM> is insufficient, so that the sealing cap <NUM> is prone to protruding from the first surface <NUM> of the top cover <NUM> after the sealing cap <NUM> is welded. When the linewidth S1 of the protrusion <NUM> is between <NUM> and <NUM>, it is possible to provide enough space for the convex cap at the top of the rubber plug of the liquid-injection hole <NUM>, so that the whole sealing cap <NUM> (i.e., an aluminum cover sheet of the liquid-injection hole <NUM>) after closing for sealing is flush with the first surface <NUM> of the top cover <NUM>, and it is also possible to avoid reduction of the sealing performance which is caused by the presence of a radial movement space due to an excessively large recessed space after the liquid-injection hole <NUM> is plugged with the rubber plug.

Optionally, the groove <NUM> has a linewidth S2 in a range of <NUM> ≤ S2 ≤ <NUM>. Specifically, the linewidth S2 of the groove <NUM> may be, but not limited to <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, etc. If the linewidth S2 of the groove <NUM> is too small, the width is not enough to well prevent the electrolyte from spreading to the outside of the groove <NUM> to cause the waste of the electrolyte. If the linewidth S2 of the groove <NUM> is too large, the structural strength of the top cover <NUM> turning around the liquid-injection hole <NUM> will be reduced, which is likely to cause protruding deformation during subsequent use. When the linewidth S2 of the groove <NUM> is <NUM> to <NUM>, the groove <NUM> may have a sufficient width such that the electrolyte will not spread to the outside of the groove <NUM> to cause the waste of the electrolyte, and it is also possible to prevent the protruding deformation during subsequent use due to the reduction of the structural strength of the top cover <NUM> turning around the liquid-injection hole <NUM>.

Referring to <FIG>, <FIG>, in some embodiments, the energy-storage apparatus <NUM> further includes an electrode assembly <NUM>. The top cover <NUM> further has a second surface <NUM> away from the first surface <NUM>, and the liquid-injection hole <NUM> further extends through the second surface <NUM>. The top cover <NUM> further defines a first accommodating recess <NUM> from the second surface <NUM>, a second accommodating recess <NUM> recessed from a bottom wall of the first accommodating recess <NUM>, and a first through hole <NUM> extending through both a bottom wall of the second accommodating recess <NUM> and the first surface <NUM>. The first accommodating recess <NUM>, the second accommodating recess <NUM>, and the first through hole <NUM> are in communication with one another, and the first through hole <NUM> is spaced apart from the liquid-injection hole <NUM>. The end cover assembly <NUM> further includes a lower plastic member <NUM> and a pole <NUM>. The lower plastic member <NUM> is arranged on the second surface <NUM> of the top cover <NUM>. The lower plastic member <NUM> includes a body portion <NUM>, a first abutting portion <NUM> protruding from the surface of the body portion <NUM> facing the top cover <NUM>, and a second abutting portion <NUM> protruding from the surface of the first abutting portion <NUM> facing the top cover <NUM>. The first abutting portion <NUM> is located in the first accommodating recess <NUM> and abuts against the bottom wall of the first accommodating recess <NUM> and a side wall of the first accommodating recess <NUM>. The second abutting portion <NUM> is located in the second accommodating recess <NUM> and abuts against the bottom wall of the second accommodating recess <NUM> and a side wall of the second accommodating recess <NUM>. The lower plastic member <NUM> further defines a second through hole <NUM> sequentially extending through the body portion <NUM>, the first abutting portion <NUM>, and the second abutting portion <NUM>. The second through hole <NUM> is defined corresponding to the first through hole <NUM>. The pole <NUM> has one part located on the side of the lower plastic member <NUM> away from the top cover <NUM>, and the other part sequentially extending through the second through hole <NUM> and the first through hole <NUM> and insulated from the top cover <NUM>, and the pole <NUM> is configured to be electrically connected to the electrode assembly <NUM>. By means of the interference fit between the first abutting portion <NUM> and the first accommodating recess <NUM> and the interference fit between the second abutting portion <NUM> and the second accommodating recess <NUM>, it is possible to improve the sealing performance of a fitting surface between the lower plastic member <NUM> and the top cover <NUM> to prevent the electrolyte from flowing to a through hole of the pole <NUM> through the gap between the lower plastic member <NUM> and the top cover <NUM>, which can improve the sealing performance of the end cover assembly <NUM> and thus prolong the service life of the energy-storage apparatus.

Referring to <FIG> and <FIG>, in some embodiments, the end cover assembly <NUM> further includes a lower plastic member <NUM>. The lower plastic member <NUM> is disposed at the side of the top cover <NUM> away from the first surface <NUM>. The lower plastic member <NUM> includes a first plastic sub-member <NUM>, a second plastic sub-member <NUM>, a third plastic sub-member <NUM>, and a fourth plastic sub-member <NUM>. The first plastic sub-member <NUM> and the second plastic sub-member <NUM> are arranged at an interval in a first direction on the surface of the top cover <NUM> away from the first surface <NUM> (as shown by arrow A in <FIG>). The first plastic sub-member <NUM> defines a leakage hole <NUM> at a position of first plastic sub-member <NUM> close to the second plastic sub-member <NUM>, and the leakage hole <NUM> is in communication with the liquid-injection hole <NUM>. The first plastic sub-member <NUM> has a first peripheral side wall <NUM> and a second peripheral side wall <NUM> that are connected end-to-end and define the leakage hole <NUM>. The first peripheral side wall <NUM> is a cambered surface, the second peripheral side wall <NUM> is a flat surface, and the second peripheral side wall <NUM> is closer to the second plastic sub-member <NUM> than the first peripheral side wall <NUM>. The third plastic sub-member <NUM> and the fourth plastic sub-member <NUM> are arranged at an interval in a second direction (as shown by arrow B in <FIG>). The third plastic sub-member <NUM> is connected to both the first plastic sub-member <NUM> and the second plastic sub-member <NUM> in a snap-fit manner, and the fourth plastic sub-member <NUM> is connected to both the first plastic sub-member <NUM> and the second plastic sub-member <NUM> in a snap-fit manner. The third plastic sub-member <NUM> and the fourth plastic sub-member <NUM> are both partially located between the first plastic sub-member <NUM> and the second plastic sub-member <NUM>, where the first direction is perpendicular to the second direction. Since the leakage hole <NUM> is at a position next to an explosion-proof hole of the top cover <NUM>, providing the flat second peripheral side wall <NUM> at the position of the side wall of the leakage hole <NUM> can reduce the length of the first plastic sub-member <NUM> in the first direction, so as to better provide avoidance for the third plastic sub-member <NUM> and the fourth plastic sub-member <NUM>, so that the flow channel formed by the part of the top cover <NUM> corresponding to the explosion-proof hole and the lower plastic member <NUM> may be symmetrical, and thus the airflow pressure exerted on an explosion-proof sheet arranged on the explosion-proof hole can be more uniform.

In a specific embodiment, the second peripheral side wall <NUM> is parallel to the surface of the first plastic sub-member <NUM> facing the second plastic sub-member <NUM>. In another specific embodiment, the second peripheral side wall <NUM>, the surface of the first plastic sub-member <NUM> facing the second plastic sub-member <NUM>, and the surface of the second plastic sub-member <NUM> facing the first plastic sub-member <NUM> are parallel to one another. In this way, the first plastic sub-member <NUM> and the second plastic sub-member <NUM> each have more regular appearance, which can better provide avoidance for the third plastic sub-member <NUM> and the fourth plastic sub-member <NUM>. In addition, since the first plastic sub-member <NUM> and the second plastic sub-member <NUM> are equal in length in the first direction, the third plastic sub-member <NUM> and the fourth plastic sub-member <NUM> can be made symmetrical in the second direction, so that during assembly, the third plastic sub-member <NUM> and the fourth plastic sub-member <NUM> can be assembled interchangeably, reducing the assembly accuracy.

Also referring to <FIG>, in some embodiments, the top cover <NUM> further has a second surface <NUM> away from the first surface <NUM>, and defines an explosion-proof hole <NUM> extending through the first surface <NUM> and the second surface <NUM>, the explosion-proof hole <NUM> is spaced apart from the liquid-injection hole <NUM>. The end cover assembly <NUM> further includes an explosion-proof sheet <NUM>. The explosion-proof sheet <NUM> seals the explosion-proof hole <NUM> and is connected to the top cover <NUM>. The first plastic sub-member <NUM> further defines a vent channel <NUM> in communication with the leakage hole <NUM>. The vent channel <NUM> extends through both the surface of the first plastic sub-member <NUM> facing the second plastic sub-member <NUM> and the surface of the first plastic sub-member <NUM> facing the top cover <NUM>, and the vent channel <NUM> is in communication with the side of the explosion-proof sheet <NUM> facing the first plastic sub-member <NUM>. A gas chamber is enclosed by the explosion-proof sheet <NUM>, the top cover <NUM> and the lower plastic member <NUM>, and the vent channel <NUM> is in communication with the gas chamber, such that the gas in the energy-storage apparatus <NUM> can pass through the leakage hole <NUM> and the vent channel <NUM> to reach the gas chamber on the side of the explosion-proof sheet <NUM> facing the lower plastic member. By means of defining the vent channel <NUM> in communication with the leakage hole <NUM> and allowing the vent channel <NUM> to extend through both the surface of the first plastic sub-member <NUM> facing the second plastic sub-member <NUM> and the surface of the first plastic sub-member <NUM> facing the top cover <NUM>, an air flow channel by which the leakage hole <NUM> of the lower plastic member <NUM> is in communication with the gas chamber below the explosion-proof sheet <NUM> can be defined, increasing the number of channels for gas accumulation.

Optionally, the explosion-proof sheet <NUM> is provided with scorings (not shown), such that when the internal pressure of the energy-storage apparatus <NUM> increases to reach a certain value, a fracture will occur for blasting to release pressure of the energy-storage apparatus <NUM>.

In some embodiments, the end cover assembly <NUM> in the embodiment of the present disclosure further includes a protective sheet <NUM>. The protective sheet <NUM> is arranged on the side of the explosion-proof sheet <NUM> away from the lower plastic member <NUM> (i.e., the side of the first surface <NUM> of the top cover <NUM>) to seal the explosion-proof hole <NUM> and protect the explosion-proof sheet <NUM>, so as to prevent the electrolyte inside the energy-storage apparatus <NUM> from overflowing caused by foreign objects hitting the explosion-proof sheet <NUM> and damaging the explosion-proof sheet <NUM>.

In some embodiments, the end cover assembly <NUM> in the embodiments of the present disclosure further includes a top patch (not shown). The top patch is arranged on the first surface <NUM> of the top cover <NUM> and the sealing cap <NUM>.

Referring to <FIG> and <FIG>, in some embodiments, the end cover assembly <NUM> in the embodiments of the present disclosure further includes a positive-electrode metal pressing block <NUM> and a negative-electrode metal pressing block <NUM>. The positive-electrode metal pressing block <NUM> and the negative-electrode metal pressing block <NUM> are arranged at an interval on the side of the first surface <NUM> of the top cover <NUM> and are respectively insulated from the top cover <NUM>, the positive-electrode metal pressing block <NUM> is electrically connected to the positive-electrode adapter sheet <NUM>, and the negative-electrode metal pressing block <NUM> is electrically connected to the negative-electrode adapter sheet <NUM>. The positive-electrode metal pressing block <NUM> and the negative-electrode metal pressing block <NUM> cooperate to achieve electrical connection or conduction between the energy-storage apparatus <NUM> and the external electricity-consumption device or a further energy-storage apparatus <NUM>.

In some embodiments, the end cover assembly <NUM> in the embodiments of the present disclosure further includes a positive-electrode upper plastic member <NUM> and a negative-electrode upper plastic member <NUM>. The positive-electrode upper plastic member <NUM> is at least partially located between the positive-electrode metal pressing block <NUM> and the top cover <NUM> to insulate the positive-electrode metal pressing block <NUM> from the top cover <NUM>. The negative-electrode upper plastic member <NUM> is at least partially located between the negative-electrode metal pressing block <NUM> and the top cover <NUM> to insulate the negative-electrode metal pressing block <NUM> from the top cover <NUM>.

Optionally, the positive-electrode upper plastic member <NUM> may be, but not limited to, an insulating component such as a resin or rubber. The negative-electrode upper plastic member <NUM> may be, but not limited to, an insulating component such as a resin or rubber.

In some embodiments, the end cover assembly <NUM> in the embodiments of the present disclosure further includes a positive pole <NUM> and a negative pole <NUM>. The positive pole <NUM> sequentially penetrates through the lower plastic member <NUM>, the top cover <NUM>, the positive-electrode upper plastic member <NUM>, and the positive-electrode metal pressing block <NUM> and is welded to the positive-electrode metal pressing block <NUM>, and the end of the positive pole <NUM> away from the metal pressing block is welded to the positive-electrode adapter sheet <NUM> to achieve electrical connection between the positive-electrode metal pressing block <NUM> and a positive-electrode sheet. The negative pole <NUM> sequentially penetrates through the lower plastic member <NUM>, the top cover <NUM>, the negative-electrode upper plastic member <NUM>, and the negative-electrode metal pressing block <NUM> and is welded to the negative-electrode metal pressing block <NUM>, and the end of the negative pole <NUM> away from the metal pressing block is welded to the negative-electrode adapter sheet <NUM> to achieve electrical connection between the negative-electrode metal pressing block <NUM> and a negative-electrode sheet.

Optionally, the positive pole <NUM> and the negative pole <NUM> each include a flange portion (not shown) and a boss (not shown) protruding from a surface of the flange portion. The flange portion is located between the lower plastic member <NUM> and the positive-electrode adapter sheet <NUM>/negative-electrode adapter sheet <NUM> and is welded to the positive-electrode adapter sheet <NUM>/negative-electrode adapter sheet <NUM>. The boss sequentially penetrates through the lower plastic member <NUM>, the top cover <NUM>, the positive-electrode upper plastic member <NUM>/negative-electrode upper plastic member <NUM>, and the positive-electrode metal pressing block <NUM>/negative-electrode metal pressing block <NUM>, such that the positive-electrode metal pressing block <NUM> is electrically connected to the positive-electrode adapter sheet <NUM> by means of the positive pole <NUM>, and the negative-electrode metal pressing block <NUM> is electrically connected to the negative-electrode adapter sheet <NUM> by means of the negative pole <NUM>.

Optionally, the flange portion is arranged on the side of the lower plastic member <NUM> away from the top cover, and the boss penetrates through the first through hole <NUM> and the second through hole <NUM>; and the boss has a central axis, and the pole <NUM> is rotationally symmetrical about the central axis. In this way, there is no need to distinguish left and right directions during assembly of the pole <NUM>, and the assembly can be completed by insertion after direct alignment of the long side, reducing the assembly requirement of the pole <NUM>.

In some embodiments, the end cover assembly <NUM> in the embodiments of the present disclosure further includes a sealing ring <NUM>, the boss of the positive pole <NUM> and the boss of the negative pole <NUM> are each sleeved with the sealing ring <NUM>, and the sealing ring <NUM> is configured to insulate the positive pole <NUM>/negative pole <NUM> from the top cover <NUM> and seal the gap between the positive pole <NUM>/negative pole <NUM> and the top cover <NUM>.

In some embodiments, the end cover assembly <NUM> in the embodiments of the present disclosure further includes a sealing pin <NUM>. The sealing pin <NUM> penetrates through the liquid-injection hole <NUM> for sealing the liquid-injection hole <NUM>. After the energy-storage apparatus <NUM> is assembled and filled with the electrolyte, the sealing pin <NUM> is firstly arranged in the liquid-injection hole <NUM>, the sealing cap <NUM> is then arranged on the first surface <NUM> of the top cover <NUM> and the sealing pin <NUM>, and the sealing cap <NUM> is welded to the top cover <NUM>.

Optionally, the sealing pin <NUM> may be, but not limited to, an insulating component such as a resin or rubber.

Claim 1:
An end cover assembly (<NUM>) for an energy-storage apparatus (<NUM>), comprising:
a top cover (<NUM>) having a first surface (<NUM>), wherein the top cover (<NUM>) further defines a liquid-injection hole (<NUM>) extending through the first surface (<NUM>); and the first surface (<NUM>) comprises a first sub-surface (<NUM>) and a second sub-surface (<NUM>) connected to the first sub-surface (<NUM>), the first sub-surface (<NUM>) is around the liquid-injection hole (<NUM>), the second sub-surface (<NUM>) is around a periphery of the first sub-surface (<NUM>), and roughness of the first sub-surface (<NUM>) is greater than roughness of the second sub-surface (<NUM>),
characterized in that:
the end cover assembly (<NUM>) further comprises a sealing cap (<NUM>), and an annular welding portion (<NUM>) located at a junction between the sealing cap (<NUM>) and the top cover (<NUM>), wherein the sealing cap (<NUM>) seals the liquid-injection hole (<NUM>) and is connected to the top cover (<NUM>);
the top cover (<NUM>) is further provided with a first welding mark (<NUM>) at the first sub-surface (<NUM>), and the first welding mark (<NUM>) comprises a first end portion (<NUM>) and a second end portion (<NUM>) opposite to the first end portion (<NUM>); and the first end portion (<NUM>) is connected to the welding portion (<NUM>), and the second end portion (<NUM>) is located at a periphery of the welding portion (<NUM>) and is spaced apart from the welding portion (<NUM>); and
a ratio of an outer radius R4 of the welding portion (<NUM>) to a length L2 of the first welding mark (<NUM>) is in a range of <NUM> ≤ R4/L2 ≤ <NUM>.