Patent ID: 12191533

MODE FOR CARRYING OUT THE INVENTION

Hereinafter, preferred embodiments will be described in detail with reference to the accompanying drawings.

The present invention may, however, be embodied in many different forms and should not be construed as being limited to the embodiments set forth herein; rather, these embodiments are provided so that those skilled in the art thoroughly understand the present invention. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the present invention to those skilled in the art.

Also, in the drawing figures, the dimensions of layers and regions may be exaggerated for clarity of illustration. Like reference numerals refer to like elements throughout. As used herein, the term “and/or” may include any and all combinations of one or more of the associated listed items. In this specification, it will also be understood that when a member A is referred to as being connected to a member B, the member A can be directly connected to the member B or indirectly connected to the member B with a member B therebetween.

The terms used herein are for illustrative purposes of the present invention only and should not be construed to limit the meaning or the scope of the present invention. As used in this specification, a singular form may, unless definitely indicating a particular case in terms of the context, include a plural form. Also, the expressions “comprise/include” and/or “comprising/including” used in this specification neither define the mentioned shapes, numbers, steps, operations, members, elements, and/or groups of these, nor exclude the presence or addition of one or more other different shapes, numbers, steps, operations, members, elements, and/or groups of these, or addition of these. The term “and/or” used herein includes any and all combinations of one or more of the associated listed items.

As used herein, terms such as “first,” “second,” etc. are used to describe various members, components, regions, layers, and/or portions. However, it is obvious that the members, components, regions, layers, and/or portions should not be defined by these terms. The terms do not mean a particular order, up and down, or superiority, and are used only for distinguishing one member, component, region, layer, or portion from another member, component, region, layer, or portion. Thus, a first member, component, region, layer, or portion which will be described may also refer to a second member, component, region, layer, or portion, without departing from the teaching of the present invention.

Spatially relative terms, such as “below”, “beneath”, “lower”, “above”, “upper” and the like, may be used herein for ease of description to describe one element or feature's relationship to another element(s) or feature(s) as illustrated in the figures. These spatially relative terms are intended for easy comprehension of the prevent invention according to various process states or usage states of the prevent invention, and thus, the present invention is not limited thereto. For example, an element or feature shown in the drawings is turned inside out, the element or feature described as “beneath” or “below” may change into “above” or “upper”. Thus, the term “lower” may encompass the term “upper” or “below”.

FIGS.1aand1bare cross-sectional views illustrating an exemplary secondary battery100. In an example illustrated inFIGS.1aand1b, the exemplary secondary battery100may include a cylindrical can110, a cylindrical electrode assembly120, a first current collecting plate130, a second current collecting plate140, an insulating plate150, and a cap assembly160. In addition, the secondary battery100may further include an insulating gasket170that insulates the cylindrical can110from the cap assembly160.

The cylindrical can110includes an approximately circular bottom part111and a side part112extending by a predetermined length upward from the bottom part111. During a process of manufacturing the secondary battery100, an upper portion of the cylindrical can110may be opened. Thus, during a process of assembling the secondary battery100, the electrode assembly120, the first current collecting plate130, the second current collecting plate140, and the insulating plate150may be integrated into one structure and be into the cylindrical can110. Of course, thereafter, the electrolyte may be additionally injected into the cylindrical can110. In some examples, the cylindrical can110may include or be referred to as a case, a housing, or an exterior.

The cylindrical can110may include steel, a steel alloy, nickel-plated steel, a nickel-plated steel alloy, aluminum, an aluminum alloy, or an equivalent thereof. In addition, the cylindrical can110may include a beading part113recessed inward at a lower portion thereof and a crimping part114bent inward at an upper portion thereof with respect to the cap assembly160to prevent the cap assembly160from being separated to the outside.

The cylindrical electrode assembly120may be accommodated in the cylindrical can110. The electrode assembly120may include a first electrode plate121coated with a first electrode active material (e.g., a positive electrode active material such as transition metal oxide (LiCoO2, LiNiO2, LiMn2O4, etc.), a second electrode plate122coated with a second electrode active material (e.g., a negative electrode active material such as graphite, carbon, silicon, etc.), a separator123disposed between the first electrode plate121and the second electrode plate122to prevent electrical short circuit from occurring between the first electrode plate121and the second electrode plate122and allow only lithium ions to be movable. The first electrode plate121, the second electrode plate122, and the separator123may be wound in a substantially cylindrical shape in a stacked state. Here, for example, although not limited thereto, the first electrode plate121may include aluminum (Al) foil, and the second electrode plate122may include copper (Cu) or nickel (Ni) foil. In addition, although not limited thereto, the separator123may include, for example, a polyethylene separator (PES), a polypropylene separator (PPS), a ceramic coated separator (CCS), a polymer coated separator (PCS), a multi-layer coated separator (MCS) or a multi functional separator (MFS), and the like. In some examples, the electrode assembly120may include or be referred to as an electrode group or a jelly roll.

A first non-coating portion124which protrudes and extends upward by a predetermined length without applying the first electrode active material may be provided on the first electrode plate121, and a second non-coating portion125which protrudes or extends downward by a predetermined length without applying the second electrode active material may be provided on the second electrode plate122. Here, the protruding and extending directions of the first non-coating portion124and the second non-coating portion125may be the same as a longitudinal direction of the cylindrical can110and/or the cylindrical electrode assembly120. When the protruding and extending direction of the first non-coating portion124is defined as a first direction, the protruding and extending direction of the second non-coating portion125may be defined as a second direction that is opposite to the first direction.

Each of the first non-coating portion124and the second non-coating portion125serves as a passage for charging and discharging current. Since the first non-coating portion124and the second non-coating portion125extend directly to the outside over entire widths or entire lengths of the first electrode plate121and the second electrode plate122, respectively (illustrated as a plurality in a cross-sectional shape), deformation (that is, reduction in roundness) or cracks of the electrode assembly120may be prevented, and it may also be advantageous for a high output of the battery. In addition, since the first non-coating portion124extends from the first electrode plate121, the first non-coating portion124may be made of aluminum or an aluminum alloy, like the first electrode plate121, and the second non-coating portion125may be made of copper, a copper alloy, nickel, or a nickel alloy, like the second electrode plate122.

In addition, the first non-coating portion124of the electrode assembly120may be electrically connected (welded) to the first current collecting plate130to be described below, and the second non-coating portion125of the electrode assembly120may be electrically connected (welded) to the second non-coating portion140to be described below. Furthermore, the first current collecting plate130may be electrically connected (welded) to the cap assembly160, and the second current collecting plate140may be electrically connected (welded) to the cylindrical can110. Thus, the cap assembly160may act as a positive electrode, and the cylindrical can110may act as a negative electrode. Of course, the connection relationship is reversed so that the cap assembly160operates as a negative electrode, and the cylindrical can110operate as a positive electrode.

The first current collecting plate130may electrically connect the first non-coating portion124provided in the electrode assembly120to the cap assembly160. The first current collecting plate130may have a substantially circular plate shape and may further include a recessed part131that presses the first non-coating portion124so as to be welded to the first non-coating portion124. In addition, the first collecting plate130may further include a center through-hole through which a welding rod passes so that the second collecting plate140is resistance-welded to the bottom part111of the cylindrical can110and a peripheral through-hole so that the electrolyte is injected. The first current collecting plate130may be made of aluminum or an aluminum alloy. In some examples, the current collecting plate130may include or be referred to as a current collector or a conductor.

The first current collecting plate130may further include an insulating layer (e.g., polyimide, polypropylene, polyethylene, or metal oxide film, etc.) formed on a peripheral surface of the side part, which faces a side wall112of the cylindrical can110. Substantially, the insulating layer prevents the first current collecting plate130from being electrically short-circuited with the sidewall112of the cylindrical can110. Here, when the first current collecting plate130is made of an aluminum-based material, the above-described insulating layer may be an anodizing layer, i.e., an oxide film or an aluminum oxide layer (Al2O3). Although not limited thereto, a thickness of the insulating layer may be, for example, about 10 nm to about 100 nm.

The second current collecting plate140may electrically connect the second non-coating portion125provided in the electrode assembly120to the cylindrical can110. The second current collecting plate140may have a substantially circular plate shape and may further include a recessed part141that presses the second non-coating portion125so as to be welded to the second non-coating portion125. In addition, the second current collecting plate140may further include a protrusion143that is resistance-welded to the bottom part111of the cylindrical can110by a welding rod. In addition, the second current collecting plate140may further include an opening144through which a portion of the insulating plate160to be described below is coupled to pass. The second current collecting plate140may include copper, a copper alloy, nickel, or a nickel alloy. In some examples, the current collecting plate140may also include or be referred to as a current collector or a conductor.

The insulating plate150may be interposed between the second current collecting plate140and the bottom part111of the cylindrical can110to block unnecessary electrical contact between the second current collecting plate140and the bottom part111. The insulating plate150may have a substantially circular plate shape and include a through-hole161formed so that the protrusion143of the second current collecting plate140passes to be welded to the bottom part111of the cylindrical can110. In some examples, a partial area of the insulating plate150, for example, an inner diameter surface of the through-hole161may be coupled to the opening144provided in the protrusion143of the second current collecting plate140, and thus, the second current collecting plate140and the insulating plate150may be coupled to each other. The insulating plate150may include one kind or two or more kinds of materials selected from the group consisting of polypropylene (PP), polyethylene (PE), polyimide (PI), polybutyleneterephthalate (PBT), polycarbonate (PC), or polystyrene (PS). In some examples, the insulating plate150may include or be referred to as an insulator or dielectric.

The cap assembly160may include a cap-up161, a safety vent162, a cap-down163, and an insulating ring164. Here, the first current collecting plate130may be electrically connected to the cap-down163through an electrode tab135. The safety vent162may be coupled to the cap-down163, and the insulating ring164may be interposed between the cap-down163and an approximate circumference of the safety vent162. A circumferential area of the safety vent162may be bent several times to wrap a circumference of the cap-up161. As described above, the circumferential area of the safety vent162bent several times may be coupled to an upper area of the cylindrical can110through the insulating gasket170. Each of the cap-up161, the safety vent162, the cap-down163, and the electrode tab135may include aluminum or an aluminum alloy. The insulating ring164may include one kind or two or more kinds of materials selected from the group consisting of polypropylene (PP), polyethylene (PE), polyimide (PI), polybutyleneterephthalate (PBT), polycarbonate (PC), or polystyrene (PS).

The insulating gasket170may wrap the cap assembly160in a substantially circular ring shape to serve to electrically insulate the cap assembly160from the side part111of the cylindrical can110. The insulating gasket170is substantially compressed between a beading portion113, which is formed on the side portion of the cylindrical can110, and the crimping part114. Although not limited thereto, the insulating gasket170may include, for example, a heat-resistant resin. Although not limited thereto, the heat-resistant resin may include, for example, one kind or two or more kinds of materials selected from the group consisting of polypropylene (PP), polyethylene (PE), polyimide (PI), polybutyleneterephthalate (PET), polycarbonate (PC), or polystyrene (PS). In some examples, the insulating gasket170may include or be referred to as an insulator or dielectric.

Furthermore, the electrolyte (not shown in the drawing) may be injected inside the cylindrical can110to serve so that lithium ions generated by electrochemical reaction in the first electrode plate121and the second electrode plate122inside the battery during the charging and discharging are movable. The electrolyte may be a non-aqueous organic electrolyte that is a mixture of lithium salt and a high-purity organic solvent. Furthermore, the electrolyte may be a polymer using a polymer electrolyte or a solid electrolyte, and the type of the electrolyte is not limited here.

As described above, the present invention provides the secondary battery, in which the insulating plate150is coupled to the current collecting plate140to block leaking welding current when the current collecting plate140is welded to the can110, thereby improving welding strength between the current collecting plate140and the can100, improving welding strength distribution, and preventing damage between the current collecting plate140and the can110from occurring.

FIGS.2aand2bare plan and cross-sectional views illustrating an exemplary current collecting plate140of the secondary battery100. Here,FIG.2bis a cross-sectional view taken along line A-B ofFIG.2a. In addition, the current collecting plate140to be described below may be the above-described second current collecting plate or negative electrode current collecting plate.

In the example illustrated inFIGS.2aand2b, the current collecting plate140may include a current collecting flat portion142and a protrusion143. The current collecting flat portion142may have a substantially circular plate shape and may include substantially flat top and bottom surfaces. The protrusion143may have a substantially cylindrical shape. The protrusion143may be formed at an approximate center of the current collecting flat portion142and may protrude from the current collecting flat portion142in one direction. The protrusion143may protrude, for example, toward the bottom part111of the cylindrical can110.

The protrusion143may include an inclined surface145and a central flat portion146. The inclined surface145may extend obliquely from the current collecting flat portion142, and the central flat portion146may extend flatly from the inclined surface145. The central flat portion146may be formed to be substantially flat on the bottom part111of the cylindrical can110.

In some examples, an opening144may be formed in the protrusion143. In some examples, the opening144may be formed in the inclined surface145. Although six openings144are illustrated as being formed in the inclined surface145in the drawing, the number of openings144may be greater or less than six.

In some examples, the central flat portion146may include a side protrusion147that protrudes toward the opening144. The side protrusion147may be formed on the same plane as the central flat portion146, but may protrude from the central flat portion146in an outer lateral direction.

FIGS.3aand3bare plan and cross-sectional views illustrating an exemplary insulating plate150coupled to the current collecting plate140of the secondary battery100. Here,FIG.3bis a cross-sectional view taken along line A-B ofFIG.3a.

In the example illustrated inFIGS.3aand3b, the insulating plate150may include an insulating flat portion.152and a through-hole151. The insulating flat portion152may have a substantially circular plate shape and may include substantially flat top and bottom surfaces. The through-hole151may be formed at an approximate center of the insulating flat portion152, and an inner diameter of the through-hole151may be less than an outer diameter of the protrusion143.

In some examples, the insulating plate150may include a plurality of slits153formed in a diameter direction from the through-hole151. Here, each of the slits153may include or be referred to as a cutoff part or a cutting part. A length of the slit153is sufficient if the protrusion143of the current collecting plate140is coupled and fixed to the through-hole151of the insulating plate150. In some examples, when the protrusion143of the current collecting plate140is coupled to the through-hole151of the insulating plate150, an inner diameter surface of the through-hole151is bent so that the slit passes through and is coupled to the opening144. In some examples, after the inner diameter surface of the through-hole141passes through and is coupled to the opening144, the inner diameter surface may be flat as in its original state. Although six slits153are illustrated as being formed around the through-hole151in the insulating plate150, the number of slits153may be greater or less than six.

FIGS.4ato4dare schematic views illustrating partial processes in a process of manufacturing an exemplary secondary battery100.FIG.4ais a schematic view illustrating a state in which the current collecting plate140is seated on the electrode assembly120and then is laser-welded.

In the example illustrated inFIG.4, after the current collecting plate140having the protrusion143and the opening144is seated on the non-coating portion125of the electrode assembly120, a laser welding process may be performed. Thus, the flat current collecting portion142of the current collecting plate140may be laser-welded on the non-coating portion125of the electrode assembly120.

FIG.4bis a schematic view illustrating a state in which the insulating plate150is coupled to the current collecting plate140. In the example illustrated inFIG.4b, the insulating plate150having the through-hole151is coupled to the current collecting plate140. In some examples, the protrusion143of the current collecting plate140may be coupled to the through-hole151of the insulating plate150. In addition, when an inner diameter surface151aof the through-hole151passes through and is coupled to the opening144of the protrusion143, the inner diameter surface151aof the through-hole151may be bent by the slits153.

FIG.4cis a schematic view illustrating a state after the insulating plate150is coupled to the current collecting plate140. In the example illustrated inFIG.4c, an insulating flat portion152of the insulating plate150may be in close contact with a current collecting flat portion142of the collecting plate140, and the protrusion143of the current collecting plate140may be coupled to the through-hole151of the insulating date150. In addition, since the inner diameter surface151aof the through-hole151passes through and is coupled to the opening144of the protrusion143, the insulating plate150is not separated from the current collecting plate140by external force during the process of manufacturing the secondary battery100.

FIG.4dis a schematic view illustrating a state in which the current collecting plate140is welded to the bottom part111of the cylindrical can110. In the example illustrated inFIG.4d, an inner welding rod191may pass through the electrode assembly120and be in close contact with the protrusion143of the current collecting plate140, and an outer welding rod192may be in close contact with the bottom part111of the cylindrical can110. In some examples, when the inner welding rod191applies a negative voltage, and the outer welding rod192applies a positive voltage, welding current flows between the inner welding rod191and the outer welding rod192. In some examples, the welding current only flows between the protrusion143of the current collecting plate140and the bottom part111of the can110, but does not flow in an outer region thereof. In some examples, since the insulating plate150is interposed outside the protrusion143of the current collecting plate140, welding leakage current does not flow in a region corresponding to the insulating plate150. Thus, since the welding current flows to be concentrated to only the protrusion143of the current collecting plate140, the protrusion143of current collecting plate140is well welded to the bottom part111of the can110. Thus, welding strength between the protrusion143of the current collector140and the bottom part111of the can110may be improved. Furthermore, welding strength distribution between the current collecting plate140and the can110for each secondary battery100may be also reduced, and damage of the current collecting plate140and the can110may be prevented.

FIG.5is a cross-sectional view illustrating a current collecting plate140and an insulating plate250in a secondary battery according to another embodiment of the present invention. In the example illustrated inFIG.5, an insulating plate250may be similar to the configuration of the insulating plate150described above except that the insulating plate250includes a circumferential portion251surrounding a circumference of a current collecting plate140.

In the example illustrated inFIG.5, the insulating plate250may further include a circumferential portion251surrounding a circumference of the current collecting plate140along the circumference of the insulating flat portion152. The circumferential portion251may extend in a substantially vertical direction from the circumference of the insulating flat portion152and be in close contact with the circumference of the current collecting plate140.

In some examples, the current collecting plate140may include a chamfered surface149formed on the circumference thereof, and the insulating plate250may further include a protrusion253that protrudes inward from the circumferential portion251so as to be proximity to or in close contact with the chamfered surface. Thus, since the insulating plate250is more stably coupled and fixed to the current collecting plate140, the insulating plate250is not separated from the current collecting plate140during the process of manufacturing the secondary battery100.

FIGS.6aand6bare cross-sectional views illustrating an exemplary current collecting plate340of the secondary battery100. Here,FIG.6bis a cross-sectional view taken along line A-B ofFIG.6a. In the example illustrated inFIGS.6aand6b, the current collecting plate340may be similar to the configuration of the current collecting plate140described above except that a plurality of embossments341are formed on the protrusion143.

In the example illustrated inFIGS.6and6b, the current collecting plate340may further include a plurality of embossments341formed in a central flat portion146of the protrusion143. Each of the embossments341more increases contact resistance between the current collecting plate140and the bottom part111of the can110to further improve welding strength according to resistance welding. Although seven embossments341are formed at the central flat portion146in the drawing, the number of embossments148may be greater or less than seven.

The above-mentioned embodiment is merely an embodiment of the secondary battery, and thus, the present invention is not limited to the foregoing embodiment, and also it will be understood by those of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope of the present invention as defined by the following claims.