Soft package battery structure and laminated lithium battery

Abstract

The utility model provides a soft package battery structure and a laminated lithium battery, the structure comprises a shell, a battery cell and a tab, the battery cell comprises a diaphragm, a positive pole piece, a negative pole piece, a positive current collector and a negative current collector, the diaphragm comprises a ceramic layer, a non-woven fabric layer and a polyethylene layer, the ceramic layer covers one side of the non-woven fabric layer and is arranged towards the positive current collector, and the polyethylene layer is arranged at the other side of the non-woven fabric layer. The polyethylene layer covers the other surface of the non-woven fabric layer and is arranged towards the negative electrode current collector; the negative current collector comprises a conductive layer and a plastic part, and the conductive layer covers the plastic part to form a conductive current collector. The non-woven fabric layer is not prone to heat shrinkage when the battery is short-circuited or abused, the ceramic layer can prevent the diaphragm from being oxidized under high potential, the polyethylene layer can isolate electrons and fine particles, and the low voltage rate of the battery is reduced. And when the battery passes through tests such as impact, short circuit or needling, even if the conductive layer is broken down, the conductive layer is not easy to contact with the positive electrode under the buffer action of the plastic part, and the battery is not easy to cause fire or even explosion.

Description

Technical Field

[0001] The present disclosure relates to the field of battery technology, and in particular to a soft-pack battery structure and a laminated lithium battery. Background Art

[0002] Among the existing batteries, ternary and lithium iron phosphate lithium-ion batteries are widely used in passenger cars and trucks. Lithium cobalt oxide is used in mobile phones, notebooks, drones and other products closely related to people because of its high volume energy density and strong discharge explosive power. Safety is the first factor.

[0003] At present, when common lithium-ion batteries are short-circuited or thermally abused, the diaphragm shrinks and causes the positive and negative electrodes to come into contact, making the battery very prone to fire or even explosion. To solve the above problems, there are many lithium-ion batteries on the market with improved diaphragms.

[0004] For example, the existing patent CN106328867B discloses a heat-shrinkage-resistant lithium-ion battery separator for lithium-ion batteries, wherein the separator includes a first outer layer, a second outer layer and an inner layer sandwiched therebetween, the first outer layer, the second outer layer and the inner layer have different micropore structures, and the micropore shape and pore size of each layer are different, the micropores are evenly distributed, and the porosity is high.

[0005] Although the designed battery separator has excellent heat shrinkage resistance and takes into account multiple physical and chemical properties, when the porosity of the three-layer structure is too high, the battery will have a low voltage rate problem due to lithium ion self-discharge, resulting in a low voltage defective rate in the product.

[0006] In addition, common lithium-ion batteries use copper foil as the negative electrode current collector. The copper foil is easily deformed or punctured when subjected to needle puncture, impact and other tests or when accidentally bumped by the user, making it easy for the positive electrode to contact the negative electrode, resulting in a short circuit. At this time, the surface temperature of the battery increases dramatically, causing the battery to catch fire or even explode in a short period of time. As a result, the safety performance of existing lithium-ion batteries is poor. Utility Model Content

[0007] The purpose of the present disclosure is to overcome the deficiencies in the prior art and to provide a soft-pack battery structure and a laminated lithium battery that are not prone to thermal shrinkage of the diaphragm under short circuit or thermal abuse conditions, can solve the problem of low voltage rate of the battery, and can safely pass impact or puncture tests.

[0008] The purpose of this disclosure is achieved through the following technical solutions:

[0009] A soft-pack battery structure, comprising a shell, a battery cell and a tab, wherein the battery cell is located in the shell, the tab comprises a positive tab and a negative tab, the shell is provided with a first opening and a second opening, the battery cell comprises a diaphragm, a positive electrode sheet, a negative electrode sheet, a positive current collector and a negative current collector, the positive electrode sheet, the negative electrode sheet, the positive current collector and the negative current collector are all in plurality, each of the positive current collectors and the corresponding negative current collectors are alternately arranged through the diaphragm, one end of the plurality of positive current collectors are connected to the corresponding positive electrode sheet, the plurality of positive electrode sheets are connected to the positive tab after being stacked, one end of the plurality of negative current collectors are connected to the corresponding negative electrode sheet, the plurality of negative electrode sheets are connected to the negative tab after being stacked, the positive tab extends out of the shell through the first opening, and the negative tab extends out of the shell through the second opening;

[0010] The separator comprises a ceramic layer, a non-woven fabric layer and a polyethylene layer, wherein the ceramic layer covers one side of the non-woven fabric layer and is disposed toward the positive electrode plate, and the polyethylene layer covers the other side of the non-woven fabric layer and is disposed toward the negative electrode plate;

[0011] The negative electrode current collector comprises a conductive layer and a plastic part, wherein the conductive layer covers the plastic part to form a conductive current collector.

[0012] In one embodiment, after the plurality of positive electrode plates are stacked, they are located at the same level as the first opening.

[0013] In one embodiment, after the plurality of negative electrode plates are stacked, they are located at the same level as the second opening.

[0014] In one of the embodiments, the soft-pack battery structure further includes a positive electrode protective adhesive, and the positive electrode protective adhesive is sleeved on the end surface of the positive electrode tab.

[0015] In one of the embodiments, a portion of the structure of the positive electrode protective glue is wrapped around the end of the plurality of stacked positive electrode sheets.

[0016] In one of the embodiments, the soft-pack battery structure further includes a negative electrode protective adhesive, and the negative electrode protective adhesive is sleeved on the end surface of the negative electrode tab.

[0017] In one embodiment, a portion of the structure of the negative electrode protective glue is wrapped around the end of the plurality of stacked negative electrode sheets.

[0018] In one embodiment, the ceramic layer is an aluminum oxide layer.

[0019] In one embodiment, the conductive layer is a copper layer.

[0020] In one embodiment, the thickness of the conductive layer is 2-4 μm.

[0021] In one embodiment, the thickness of the plastic part is 1-4 μm.

[0022] A laminated lithium battery comprises the soft-pack battery structure described in any of the above embodiments.

[0023] Compared with the prior art, the present invention has at least the following advantages:

[0024] 1. In the above-mentioned soft-pack battery structure, the diaphragm includes a ceramic layer, a non-woven fabric layer and a polyethylene layer, wherein the non-woven fabric layer is not prone to thermal shrinkage when the battery is short-circuited or thermally abused, the ceramic layer can prevent the diaphragm from being oxidized at a high potential, and the polyethylene layer has a low porosity and can isolate electrons and fine particles. The structure of the diaphragm makes it difficult for the battery to shrink and cause contact between the positive and negative electrodes, and can reduce the problem of low voltage rate of the battery caused by self-discharge of lithium ions.

[0025] 2. The negative electrode current collector adopts a combination of a conductive layer and a plastic part, that is, the surface of the plastic part is copper-plated. When passing impact, short circuit or puncture tests, even if the conductive layer is broken down, under the buffering effect of the plastic part, the conductive layer is not easy to contact the positive electrode, so the battery is less likely to cause fire or even explosion. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the technical solutions of the embodiments of the present disclosure, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present disclosure and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0027] Figure 1 This is a schematic diagram of a soft-pack battery structure in one embodiment;

[0028] Figure 2 A schematic diagram of the structure of a battery cell in a soft-pack battery structure according to an embodiment;

[0029] Figure 3 for Figure 2 A schematic diagram of the structure of the separator in the battery cell shown;

[0030] Figure 4 for Figure 3 A schematic diagram of the expansion of the diaphragm shown;

[0031] Figure 5 for Figure 2 Schematic diagram of the structure of the negative electrode plate in the battery cell shown.

[0032] Figure numerals: 10, soft-pack battery structure; 100, shell; 101, first port; 102, second port; 200, battery cell; 210, diaphragm; 211, ceramic layer; 212, non-woven fabric layer; 213, polyethylene layer; 220, positive electrode collector; 230, negative electrode collector; 231, conductive layer; 232, plastic part; 300, tab; 310, positive electrode tab; 320, negative electrode tab; 400, positive electrode protective glue; 500, negative electrode protective glue. DETAILED DESCRIPTION

[0033] In order to facilitate the understanding of the present disclosure, the present disclosure will be described more fully below with reference to the relevant drawings. The preferred embodiments of the present disclosure are given in the drawings. However, the present disclosure can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present disclosure more thoroughly and comprehensively understood.

[0034] It should be noted that when an element is referred to as being "fixed to" another element, it may be directly on the other element or there may be a central element. When an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be a central element at the same time. The terms "vertical", "horizontal", "left", "right" and similar expressions used herein are for illustrative purposes only and do not represent the only implementation method.

[0035] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present disclosure. The terms used herein in the specification of the present disclosure are only for the purpose of describing specific embodiments and are not intended to limit the present disclosure. The term "and / or" used herein includes any and all combinations of one or more related listed items.

[0036] In order to better understand the technical solutions and beneficial effects of the present invention, the present invention is further described in detail below in conjunction with specific embodiments:

[0037] like Figures 1 to 5 As shown, it is a soft-pack battery structure 10 according to an embodiment of the present invention, including a shell 100, a battery cell 200 and a tab 300.

[0038] The battery cell 200 is located in the shell 100 (not shown in the drawings), the tab 300 includes a positive tab 310 and a negative tab 320, the shell 100 is provided with a first opening 101 and a second opening 102, the battery cell 200 includes a diaphragm 210, a positive electrode sheet (not shown), a negative electrode sheet (not shown), a positive current collector 220 and a negative current collector 230; the number of the positive electrode sheet, the negative electrode sheet, the positive current collector 220 and the negative current collector 230 is multiple, each positive current collector 220 and the corresponding negative current collector 230 are alternately arranged through the diaphragm 210, that is, the arrangement order is "positive electrode 210, negative electrode 210, positive ... Positive current collector 220-diaphragm 210-negative current collector 230-diaphragm 210-positive current collector 220-diaphragm 210-negative current collector 230…”, one end of multiple positive current collectors 220 is connected to the corresponding positive electrode sheet, and multiple positive electrode sheets are connected to the positive electrode ear 310 after being stacked, one end of multiple negative current collectors 230 is connected to the corresponding negative electrode sheet, and multiple negative electrode sheets are connected to the negative electrode ear 320 after being stacked, the positive electrode ear 310 extends out of the outside of the shell 100 through the first through hole 101, and the negative electrode ear 320 extends out of the outside of the shell 100 through the second through hole 102.

[0039] Combination Figures 2 to 4 As shown, the separator 210 includes a ceramic layer 211, a non-woven fabric layer 212 and a polyethylene layer 213, the ceramic layer 211 covers one side of the non-woven fabric layer 212 and is disposed toward the positive electrode current collector 220, and the polyethylene layer 213 covers the other side of the non-woven fabric layer 212 and is disposed toward the negative electrode current collector 230; the negative electrode current collector 230 includes a conductive layer 231 and a plastic part 232, and the conductive layer 231 covers the plastic part 232 to form the negative electrode current collector 230. In this embodiment, the housing 100 is made of an aluminum-plastic film, which has puncture resistance and easy formability, and the housing 100 can be made of an aluminum-plastic film.

[0040] It can be understood that after multiple positive electrode sheets are stacked, they are welded to the positive electrode tab 310, so that the positive electrode tab 310 is electrically connected to the positive electrode collector 220 through the positive electrode sheet, and after multiple negative electrode sheets are stacked, they are welded to the negative electrode tab 320, so that the negative electrode tab 320 is electrically connected to the negative electrode collector 230 through the negative electrode sheet, thereby allowing the battery to use electricity normally.

[0041] In this embodiment, the non-woven fabric layer 212 is not easy to shrink when the battery is short-circuited or thermally abused, the ceramic layer 211 can prevent the diaphragm 210 from being oxidized at high potential, and the polyethylene layer 213 has a low porosity, which can isolate electrons and fine particles. The structure of the diaphragm 210 makes it difficult for the battery to shrink and cause the positive and negative electrodes to contact, and can reduce the problem of low voltage rate of the battery caused by self-discharge of lithium ions. The negative electrode current collector 230 adopts a combination of a conductive layer 231 and a plastic part 232, that is, the surface of the plastic part 232 is copper-plated. When passing tests such as impact, short circuit or needle puncture, even if the conductive layer 231 is broken down, under the buffering effect of the plastic part 232, the conductive layer 231 is not easy to contact with the positive electrode, so that the battery is less likely to cause fire or even explosion.

[0042] It can be understood that the non-woven fabric layer 212 has the characteristic of not being easy to shrink at high temperature, can isolate the positive and negative electrodes, and prevent further reaction, but has poor tensile and compressive properties, so it is necessary to set the ceramic layer 211 to face the positive electrode current collector 220 to prevent the diaphragm 210 from being oxidized at high potential; however, the porosity of the ceramic layer 211 and the non-woven fabric layer 212 is large, and there is a situation of lithium ion self-discharge, which will cause the battery to have a low voltage rate problem, so it is also necessary to set a polyethylene layer 213, specifically a wet polyethylene (wet PE) layer, which has a low porosity, specifically 30% to 55%, which can prevent electrons from passing through the diaphragm 210. When the three are combined, it can be ensured that electrons are less likely to pass through the diaphragm 210 to cause self-discharge, and even if thermal abuse occurs, the diaphragm 210 will not easily shrink, which can solve the problem of fire or even explosion caused by abuse of laminated lithium batteries and low voltage rate of batteries caused by lithium ion self-discharge.

[0043] Furthermore, the ceramic layer 211 is an aluminum oxide layer. In this embodiment, the ceramic layer 211 is an aluminum oxide layer. The surface of the aluminum element is easy to form an oxide film, that is, aluminum oxide. The surface density of the oxide film is high, which can prevent further oxidation of aluminum and has a better effect on preventing the entire diaphragm 210 from being oxidized at a high potential.

[0044] Furthermore, the thickness of the ceramic layer 211 is 2-3 μm. In this embodiment, the thickness of the ceramic layer 211 is 2 μm.

[0045] Furthermore, the thickness of the non-woven fabric layer 212 is 4 μm to 10 μm. In the present embodiment, the thickness of the non-woven fabric layer 212 is 4 μm, so as to save the thickness cost while being able to isolate the positive and negative electrodes.

[0046] Furthermore, the thickness of the polyethylene layer 213 is 2 μm to 4 μm. In this embodiment, the thickness of the polyethylene layer 213 is 2 μm.

[0047] In one embodiment, after a plurality of positive electrode sheets are stacked, they are located at the same level as the first opening 101 (not shown in the drawings). It can be understood that one end of each positive electrode collector 220 is connected to the corresponding positive electrode sheet. When a plurality of positive electrode sheets are stacked to form a positive electrode connection end, the positive electrode connection end does not need to extend to the outside of the housing 100 through the first opening 101, thereby reducing the amount of material used for the positive electrode sheets and reducing the manufacturing cost.

[0048] In one embodiment, after the multiple negative electrode sheets are stacked, they are located at the same level as the second opening 102 (not shown in the figure). It can be understood that one end of the multiple negative electrode current collectors 230 is connected to the corresponding positive electrode sheet. When the multiple negative electrode sheets are stacked to form a negative electrode connection end, the negative electrode connection end does not need to extend to the outside of the housing 100 through the second opening 102, thereby reducing the material consumption of the negative electrode sheet and reducing the manufacturing cost.

[0049] like Figure 1 As shown, in one embodiment, the soft pack battery structure 10 further includes a positive electrode protective glue 400, and the positive electrode protective glue 400 is sleeved on the end surface of the positive electrode tab 310. It can be understood that the positive electrode protective glue 400 is provided to wrap the end surface of the positive electrode tab 310, and the positive electrode protective glue 400 plays an insulating role to prevent the positive electrode tab 310 from directly contacting the shell 100 in the later process.

[0050] In one embodiment, a portion of the structure of the positive electrode protective glue 400 wraps the end of the stacked multiple positive electrode sheets (not shown in the figure). It can be understood that the end formed by the stacked multiple positive electrode sheets has a rough surface after welding, and the positive electrode protective glue 400 can also protect the stacked end to prevent the rough end of the stacked multiple positive electrode sheets from scratching the housing 100.

[0051] like Figure 1 As shown, in one embodiment, the soft pack battery structure 10 further includes a negative electrode protective glue 500, and the negative electrode protective glue 500 is sleeved on the end surface of the negative electrode tab 320. It can be understood that the negative electrode protective glue 500 is provided to wrap the end surface of the negative electrode tab 320, and the negative electrode protective glue 500 plays an insulating role to prevent the negative electrode tab 320 from directly contacting the shell 100 in the later process.

[0052] In one embodiment, a portion of the structure of the negative electrode protective glue 500 wraps the end of the stacked multiple negative electrode sheets (not shown in the figure). It can be understood that the end formed by the stacked multiple negative electrode sheets has a rough surface after welding, and the negative electrode protective glue 500 can also protect the stacked end to prevent the rough end of the stacked multiple negative electrode sheets from scratching the housing 100.

[0053] In one embodiment, the conductive layer 231 is a copper layer. Specifically, the copper layer has good conductivity, is relatively stable under the high voltage environment of the battery, and is not prone to lithium insertion reaction.

[0054] In one embodiment, the thickness of the conductive layer 231 is 2-4 μm. In this embodiment, the thickness of the conductive layer 231 is 2 μm.

[0055] In one embodiment, the thickness of the plastic part 232 is 1-4 μm. In this embodiment, the thickness of the plastic part 232 is 2 μm.

[0056] The present disclosure also provides a laminated lithium battery, comprising the soft-pack battery structure 10 of any of the above embodiments.

[0057] Compared with the prior art, the present invention has at least the following advantages:

[0058] 1. In the above-mentioned soft-pack battery structure 10, the diaphragm 210 includes a ceramic layer 211, a non-woven fabric layer 212 and a polyethylene layer 213, wherein the non-woven fabric layer 212 is not prone to thermal shrinkage when the battery is short-circuited or thermally abused, the ceramic layer 211 can prevent the diaphragm 210 from being oxidized at a high potential, and the polyethylene layer 213 has a low porosity and can isolate electrons and fine particles. The structure of the diaphragm 210 makes it difficult for the battery to thermally shrink and cause contact between the positive and negative electrodes, and can reduce the problem of low voltage rate of the battery caused by self-discharge of lithium ions.

[0059] 2. The negative electrode current collector 230 adopts a combination of a conductive layer 231 and a plastic part 232, that is, the surface of the plastic part 232 is copper-plated. When passing tests such as impact, short circuit or needle puncture, even if the conductive layer 231 is broken down, under the buffering effect of the plastic part 232, the conductive layer 231 is not easy to contact with the positive electrode, so that the battery is less likely to cause fire or even explosion.

[0060] The above-mentioned embodiments only express several implementation methods of the present disclosure, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the disclosed patent. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present disclosure, and these all belong to the protection scope of the present disclosure. Therefore, the protection scope of the disclosed patent shall be subject to the attached claims.

Claims

1. A soft pack battery structure, comprising a shell, a battery cell and a tab, wherein the battery cell is located in the shell, the tab comprises a positive tab and a negative tab, the shell is provided with a first opening and a second opening, the battery cell comprises a separator, a positive electrode sheet, a negative electrode sheet, a positive current collector and a negative current collector, The number of the positive electrode sheet, the negative electrode sheet, the positive electrode current collector and the negative electrode current collector are all multiple, each positive electrode current collector is alternately spaced with the corresponding negative electrode current collector by the separator, one end of the multiple positive electrode current collectors is connected to the corresponding positive electrode sheet, the multiple positive electrode sheets are connected to the positive electrode tab after being stacked, one end of the multiple negative electrode current collectors is connected to the corresponding negative electrode sheet, the multiple negative electrode sheets are connected to the negative electrode tab after being stacked, the positive electrode tab extends out of the shell through the first opening, and the negative electrode tab extends out of the shell through the second opening, characterized in that: The separator comprises a ceramic layer, a non-woven fabric layer and a polyethylene layer, wherein the ceramic layer covers one side of the non-woven fabric layer and is disposed toward the positive electrode current collector, and the polyethylene layer covers the other side of the non-woven fabric layer and is disposed toward the negative electrode current collector; The negative electrode current collector comprises a conductive layer and a plastic part, wherein the conductive layer covers the plastic part to form a conductive current collector.

2. The soft pack battery structure according to claim 1, characterized in that: After the plurality of positive electrode sheets are stacked, they are located at the same level as the first opening; and / or, After the plurality of negative electrode plates are stacked, they are located at the same level as the second opening.

3. The soft pack battery structure according to claim 1, characterized in that: The soft-pack battery structure also includes a positive electrode protective glue, and the positive electrode protective glue is sleeved on the end surface of the positive electrode ear.

4. The soft pack battery structure according to claim 3, characterized in that: A partial structure of the positive electrode protective glue wraps the ends of the plurality of stacked positive electrode sheets.

5. The soft pack battery structure according to claim 1, characterized in that: The soft-pack battery structure also includes a negative electrode protective glue, and the negative electrode protective glue is sleeved on the end surface of the negative electrode tab.

6. The soft pack battery structure according to claim 5, characterized in that: A partial structure of the negative electrode protective glue wraps the end portions of the stacked negative electrode sheets.

7. The soft pack battery structure according to claim 1, characterized in that: The ceramic layer is an aluminum oxide layer.

8. The soft pack battery structure according to claim 1, characterized in that: The conductive layer is a copper layer.

9. The soft pack battery structure according to claim 1, characterized in that: The thickness of the conductive layer is 2 to 4 μm; and / or, The thickness of the plastic part is 1-4 μm.

10. A laminated lithium battery, characterized in that: The soft-pack battery structure comprises the structure described in any one of claims 1 to 9.

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