Battery

Abstract

The utility model discloses a battery, which is applied to the technical field of lithium battery process, under the condition that a shell is not changed, two layers of pole pieces on the outermost side of a battery cell adopt single-sided pole pieces, and the single-sided pole pieces adopt composite current collectors to replace conventional metal current collectors, so that compared with the conventional metal current collectors, the weight of the composite current collectors is smaller, and the weight of the composite current collectors is smaller. The insulation matrix layer in the composite current collector is better in ductility, and curling of a single-sided pole piece can be avoided without increasing too much thickness, so that on one hand, the weight of the battery is reduced, the weight energy density of the battery is improved, and on the other hand, the space utilization rate of the battery is improved, and the volume energy density of the battery is improved; meanwhile, the insulating substrate layer of the composite current collector in the single-sided pole piece is positioned on the surface of the battery cell, so that when the battery cell is punctured and collided, the insulating substrate layer can block the risk of short circuit of an internal positive electrode and an internal negative electrode, local thermal runaway is avoided, excellent safety is given to the battery, and the safety performance of the shell battery is improved.

Description

Technical Field

[0001] This utility model relates to the field of lithium battery technology, and in particular to a battery. Background Technology

[0002] Energy density, safety, and fast charging at the battery cell level, and heat dissipation, photography, and battery life at the mobile phone level have always been popular areas of focus. As a result, numerous solutions have been proposed by the technology side to meet the needs of the users.

[0003] Compared to pouch batteries, metal-cased batteries offer higher energy density for the same volume due to their greater space utilization. The stronger casing also helps prevent volume expansion during long-term cycling, extending battery life. Furthermore, the metal casing provides better heat dissipation, making metal-cased batteries popular with many customers. However, their greater weight, potentially lower energy density, and increased destructive power upon casing explosion raise concerns among consumers.

[0004] Furthermore, existing metal-cased battery cells typically employ single-sided and double-sided electrodes, including metal current collectors. The relatively large weight of the metal current collector also affects the battery's gravimetric energy density. In addition, because one side of the single-sided electrode is coated with paste while the other side is not, uneven stress can easily occur, leading to curling. To prevent electrode curling, the thickness of the metal current collector in the single-sided electrode needs to be much greater than that in the double-sided electrode, typically a thickness ratio of 2 to 3 times. This results in a thicker cell, which also affects the battery's volumetric energy density. Utility Model Content

[0005] In view of this, the purpose of this utility model is to provide a battery that, without changing the outer casing, further enhances and improves the battery's gravimetric energy density, volumetric energy density, and safety performance.

[0006] To solve the above-mentioned technical problems, this utility model provides a battery, including: a shell and a battery cell; the shell is configured to form a cavity, and the battery cell is located within the cavity; the battery cell includes a plurality of stacked electrode plates, with adjacent electrode plates having different polarities;

[0007] In the thickness direction of the battery cell, the uppermost and lowermost electrode sheets are single-sided electrode sheets, and the middle electrode sheets are double-sided electrode sheets; the single-sided electrode sheet includes a first current collector and a first functional layer; the first current collector is a composite current collector, which includes an insulating substrate layer and a conductive layer; the insulating substrate layer is located on the side of the conductive layer opposite to the middle electrode sheet of the battery cell; the double-sided electrode sheet includes a second current collector and a second functional layer;

[0008] The ratio of the thickness of the first current collector in the single-sided electrode to the thickness of the second current collector in the double-sided electrode of the same polarity is 1 to 1.1, including the values ​​at both ends.

[0009] Optionally, in the direction perpendicular to the thickness, the area in the single-sided electrode sheet where the first functional layer is disposed is the first functional layer coverage area, and the area where the first functional layer is not disposed is the first tab area.

[0010] Optionally, the projections of the insulating substrate layer and the conductive layer in the thickness direction completely overlap;

[0011] And / or, the ratio of the thickness of the insulating substrate layer in the first tab region to the thickness of the insulating substrate layer in the first functional layer coverage region is 0.3 to 1, including the values ​​at both ends;

[0012] And / or, the thickness of the conductive layer in the first tab region is the same as the thickness of the conductive layer in the first functional layer coverage region;

[0013] And / or, the insulating substrate layer is a PET layer, a PP layer, or a hybrid layer comprising PET and PP;

[0014] And / or, the conductive layer is a metal plating layer.

[0015] Optionally, the thickness of the conductive layer in the first functional layer coverage area is greater than or equal to 0.5 times the thickness of the second current collector.

[0016] Optionally, the second functional layer is located at least on both sides of the second current collector in the thickness direction; in the direction perpendicular to the thickness direction, the area in the double-sided electrode where the second functional layer is disposed is the second functional layer coverage area, and the area where the second functional layer is not disposed is the second tab area.

[0017] Optionally, the second current collector is a metal current collector or the composite current collector.

[0018] Optionally, the battery further includes: a thermal adhesive layer; the thermal adhesive layer is disposed on the surface of the cell and between the cell and the casing.

[0019] Optionally, the thermal adhesive layer is disposed on the upper and / or lower surface of the battery cell in the thickness direction;

[0020] And / or, the shape of the thermal adhesive layer is similar to that of the battery cell;

[0021] And / or, the projection of the insulating substrate layer in the thickness direction covers the projection of the thermal adhesive layer in the thickness direction;

[0022] And / or, the thickness of the thermal adhesive layer is 5μm~20μm, including the values ​​at both ends;

[0023] And / or, the heat dissipation adhesive layer is a mixed adhesive layer comprising a polysiloxane mixture, a metal catalyst, an alcohol retarder, alumina, aluminum hydroxide, and boron nitride;

[0024] And / or, the viscosity of the heat-dissipating adhesive layer is 20,000 Pa·s to 100,000 Pa·s, including the values ​​at both ends;

[0025] And / or, the tensile strength of the heat-dissipating adhesive layer is greater than or equal to 2 MPa;

[0026] And / or, the thermal conductivity of the solid thermal adhesive layer is 0.85 W / (m·k) to 3 W / (m·k), including the values ​​at both ends.

[0027] Optionally, the distance between the projection of the heat-dissipating adhesive layer in the thickness direction and the outer edge of the projection of the insulating substrate layer in the thickness direction is 0.5mm to 5mm, including the values ​​at both ends.

[0028] Optionally, the outer casing includes a shell and a cover; the shell is configured to form a cavity, and the cover is connected to the shell to form the receiving cavity; the shell is a metal shell.

[0029] And / or, the cover is a metal cover;

[0030] And / or, the thickness of the shell is 10μm to 500μm, including the values ​​at both ends;

[0031] And / or, the thickness of the shell cover is 10μm to 500μm, including the values ​​at both ends.

[0032] As can be seen, the battery provided by this utility model, under the condition that the outermost two layers of the cell are single-sided electrodes, and the single-sided electrodes use composite current collectors instead of conventional metal current collectors. Compared with conventional metal current collectors, composite current collectors are lighter and have better ductility of the insulating substrate layer in the composite current collector. They do not need to increase the thickness too much and can also avoid the curling of the single-sided electrodes. On the one hand, the weight of the battery is reduced, thereby increasing the weight energy density of the battery. On the other hand, the space utilization of the battery is improved, thereby increasing the volume energy density of the battery. At the same time, the insulating substrate layer of the composite current collector in the single-sided electrode is located on the surface of the cell. When the cell is punctured or collided, the insulating substrate layer can block the risk of short circuit to the internal positive and negative electrodes, avoid local thermal runaway, and give the battery excellent safety. This improves the safety performance of the battery under risk conditions such as puncture, collision, and compression, and reduces the damage caused by the explosion of the casing. Attached Figure Description

[0033] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0034] Figure 1 A schematic diagram of the structure of a battery provided in an embodiment of this utility model;

[0035] Figure 2 A schematic diagram of the structure of a battery cell provided in an embodiment of this utility model;

[0036] Figure 3 A schematic diagram of the structure of a single-sided electrode sheet provided for an embodiment of this utility model;

[0037] Figure 4 This is a schematic diagram of another battery cell provided in an embodiment of the present invention.

[0038] The annotations in the attached figures are explained as follows:

[0039] 11-Housing shell; 12-Shell cover; 2-Battery cell; 201-First functional layer coverage area; 202-First electrode area; 21-Insulating substrate layer; 22-Conductive layer; 23-First functional layer; 3-Heat dissipation adhesive layer; 41-First electrode; 42-Second electrode. Detailed Implementation

[0040] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, and not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this utility model.

[0041] Please refer to Figure 1 , Figure 1 This is a schematic diagram of the structure of a battery provided in an embodiment of the present invention. The battery may include: a casing and a battery cell 2; the casing is configured to form a cavity, and the battery cell 2 is located within the cavity; the battery cell 2 includes multiple stacked electrode plates, with adjacent electrode plates having different polarities;

[0042] In the thickness direction of cell 2, the uppermost and lowermost electrode sheets are single-sided electrode sheets, and the middle electrode sheets are double-sided electrode sheets; the single-sided electrode sheet includes a first current collector and a first functional layer 23; the first current collector is a composite current collector, which includes an insulating substrate layer 21 and a conductive layer 22; the insulating substrate layer 21 is located on the side of the conductive layer 22 away from the middle electrode sheet of cell 2; the first functional layer 23 is located on the side of the conductive layer 22 close to the middle electrode sheet of cell 2; the double-sided electrode sheet includes a second current collector and a second functional layer;

[0043] The ratio of the thickness of the first current collector in a single-sided electrode to the thickness of the second current collector in a double-sided electrode of the same polarity is 1 to 1.1, including the values ​​at both ends.

[0044] It should be noted that the electrode sheets in this embodiment include positive electrode sheets and negative electrode sheets; the battery cell 2 is a stacked core, specifically including alternating layers of positive electrode sheets, negative electrode sheets, and a separator located between the positive electrode sheets and the negative electrode sheets. Furthermore, the accommodating cavity may also be filled with electrolyte.

[0045] It should be noted that a single-sided electrode is an electrode with a functional layer on only one surface of the current collector along its thickness direction, while a double-sided electrode is an electrode with a functional layer on both surfaces of the current collector along its thickness direction.

[0046] This embodiment does not limit the specific structure of the single-sided electrode sheet, and may include, but is not limited to, the area in the single-sided electrode sheet where the first functional layer 23 is provided is the first functional layer coverage area 201, and the area where the first functional layer 23 is not provided is the first tab area 202.

[0047] It should be noted that the composite current collector is a novel type of current collector with a polymer insulating matrix layer 21 in the middle and at least one conductive layer 22 on each side of the polymer insulating matrix layer 21. Compared with conventional metal current collectors, it has three significant advantages: First, compared with conventional metal current collectors of the same thickness, the composite current collector can achieve weight reduction by replacing the metal with a polymer layer. According to existing data, the weight reduction can reach 60%; with the development of technology, the weight reduction is expected to increase further. Second, the polymer insulating matrix layer 21 is composed of single or composite materials such as PET / PP. As a plastic material, it has better ductility and can avoid the curling of single-sided electrode sheets without increasing the thickness, thereby improving the energy density of the battery. Third, the polymer insulating matrix layer 21, which replaces the metal in the middle, can effectively prevent lithium-ion batteries from catching fire or exploding due to internal short circuits when encountering abnormal conditions such as collisions, extrusion, or punctures. In this embodiment, the substrate of the first current collector of the single-sided electrode is a composite current collector, the structure of which includes an insulating substrate layer 21 and a single-sided conductive layer 22. The functional layer is disposed on the single-sided conductive layer 22, and there is no functional layer on the insulating substrate layer 21. The insulating substrate layer 21 is disposed on the surface of the cell 2. Figure 2 As shown. When the cell 2 is punctured or impacted, the insulating substrate layer 21 can block the risk of short circuit to the internal positive and negative electrodes, avoid local thermal runaway, and give the battery excellent safety.

[0048] This embodiment does not limit the specific type of the first functional layer 23. The first functional layer 23 may be, but is not limited to, an active material layer. It should be noted that active materials are common materials in the prior art. This embodiment does not limit the internal composition of the first functional layer 23, but directly uses a film layer made of existing materials as the first functional layer 23.

[0049] This embodiment does not limit the specific relative size relationship between the insulating substrate layer 21 and the conductive layer 22. The insulating substrate layer 21 and the conductive layer 22 may, but are not limited to, have completely overlapping projections in the thickness direction.

[0050] This embodiment does not limit the specific relative thickness of the insulating substrate layer 21 of the first tab region 202 and the first functional layer covering region 201. For example, the ratio of the thickness of the insulating substrate layer 21 of the first tab region 202 to the thickness of the insulating substrate layer 21 of the first functional layer covering region 201 can be 0.3 to 1, including the values ​​at both ends. It should be noted that by adopting the above-mentioned relative size relationship in this embodiment, while improving the ductility of the composite current collector, the welding strength of the first tab region 202 in subsequent processes can be improved, thus increasing the welding strength. This embodiment does not limit the specific thickness of the insulating substrate layer 21. For example, the thickness of the insulating substrate layer 21 can be 0.5 μm to 30 μm, including the values ​​at both ends.

[0051] This embodiment does not limit the specific relative thickness of the conductive layer 22 of the first tab region 202 and the first functional layer covering region 201. For example, the thickness of the conductive layer 22 of the first tab region 202 and the thickness of the conductive layer 22 of the first functional layer covering region 201 may be, but are not limited to, the same. This embodiment does not limit the specific thickness of the conductive layer 22. For example, the thickness of the conductive layer 22 may be 0.3 μm to 30 μm, including the values ​​at both ends.

[0052] This embodiment does not limit the specific type of the insulating substrate layer 21. The insulating substrate layer 21 can be, but is not limited to, a PET layer, a PP layer, or a mixed layer including PET and PP. It should be noted that PET (Polyethylene Terephthalate) and PP (Polypropylene) are common materials in the prior art. This embodiment does not limit the internal composition of the insulating substrate layer 21, but directly uses a film layer made of one or more existing materials as the insulating substrate layer 21.

[0053] This embodiment does not limit the specific type of conductive layer 22. Conductive layer 22 can be, but is not limited to, a metal plating layer. It should be noted that metal is a common material in the prior art. This embodiment does not limit the internal composition of conductive layer 22, but directly uses a film layer made of existing materials as conductive layer 22.

[0054] This embodiment does not limit the specific polarity of the single-sided electrode sheet; for example, the single-sided electrode sheet can be a positive electrode sheet or a negative electrode sheet. It should be noted that in existing metal hard-shell batteries, the top and bottom electrode sheets in the stacked core are typically negative. Because of the corrosion resistance of stainless steel and the negative electrode design, the top and bottom electrode sheets in the stacked core are designed to be negative. In this embodiment, since the outermost layer of the top and bottom electrode sheets is an insulating substrate layer 21, the polarity of the top and bottom electrode sheets is not limited, making the stacked core structure design more flexible and allowing for an improvement in energy density compared to the original design.

[0055] This embodiment provides a single-sided electrode sheet, such as... Figure 3 As shown in the figure, the single-sided electrode sheet includes a first functional layer coverage area 201 and a first tab area 202 in the direction perpendicular to the thickness (i.e., parallel to the surface of the single-sided electrode sheet); wherein, the projections of the insulating substrate layer 21 and the conductive layer 22 in the thickness direction completely overlap, the first functional layer coverage area 201 includes a functional layer, a conductive layer 22 and an insulating substrate layer 21 arranged sequentially along the thickness direction; the first tab area 202 includes a conductive layer 22 and an insulating substrate layer 21 arranged sequentially along the thickness direction, and the conductive layer 22 and the insulating substrate layer 21 in this area constitute the tab of the single-sided electrode sheet.

[0056] This embodiment does not limit the specific structure of the double-sided electrode sheet, and may include, but is not limited to: the second functional layer being located at least on both sides of the second current collector in the thickness direction; in the direction perpendicular to the thickness, the area in the double-sided electrode sheet where the second functional layer is provided is the second functional layer coverage area, and the area where the second functional layer is not provided is the second tab area.

[0057] It should be noted that in this embodiment, the second functional layer is disposed on at least both sides of the second current collector, and the structure specifically includes a second functional layer, a second current collector, and a second functional layer arranged sequentially along the thickness direction. This embodiment does not limit the specific type of the second functional layer; for details, please refer to the first functional layer 23, which will not be elaborated here.

[0058] It should be noted that in this embodiment, the double-sided electrode includes a positive electrode and a negative electrode. When the single-sided electrode is a positive electrode, the double-sided electrode closer to the single-sided electrode is a negative electrode; when the single-sided electrode is a negative electrode, the double-sided electrode closer to the single-sided electrode is a positive electrode.

[0059] It should be noted that the battery cell 2 in this embodiment may include two layers of single-sided electrode sheets and several layers of double-sided electrode sheets. The single-sided electrode sheets are disposed on the top and bottom layers of the battery cell 2, and the double-sided electrode sheets are disposed on the middle layer of the battery cell 2. The structure of the battery cell 2 from top to bottom in the thickness direction is: single-sided electrode sheet + double-sided electrode sheet + single-sided electrode sheet.

[0060] In this embodiment, the tab areas of single-sided and double-sided electrodes of the same polarity can be aligned in the thickness direction; the tab areas of double-sided electrodes of the same polarity can be aligned in the thickness direction.

[0061] This embodiment does not limit the specific relative size relationship between the single-sided electrode and the double-sided electrode of the same polarity. The projections of the single-sided electrode and the double-sided electrode of the same polarity in the thickness direction can be, but are not limited to, completely overlapping.

[0062] This embodiment does not limit the specific relative thickness of the conductive layer 22 in the single-sided electrode and the second current collector in the double-sided electrode. For example, the thickness of the conductive layer 22 in the first functional layer coverage area 201 can be greater than or equal to 0.5 times the thickness of the second current collector. It should be noted that the conductive layer 22 on the single-sided electrode carries the overcurrent of one side of the functional layer. By controlling the thickness of the conductive layer 22 to be no less than half the thickness of the current collector of the intermediate double-sided functional layer, the overcurrent capacity of the conductive layer 22 is guaranteed to be no less than the overcurrent capacity of the intermediate double-sided electrode. This can improve the current carrying capacity of the single-sided electrode and avoid problems such as overheating of the tabs in the cell 2.

[0063] This embodiment does not limit the specific type of the second current collector in the double-sided electrode. For example, the second current collector can be a metal current collector or a composite current collector. This embodiment does not limit the specific structure of the composite current collector; please refer to the above description of composite current collectors for details, which will not be repeated here.

[0064] Typically, to improve the drop test pass rate of a battery, an adhesive substance is adhered to the surface of the cell 2 to create adhesion between it and the casing, reducing relative movement between the cell 2 and the casing, thereby increasing the drop test pass rate of the cell 2. Furthermore, the battery in this embodiment may also include a heat-dissipating adhesive layer 3; the heat-dissipating adhesive layer 3 is disposed on the surface of the cell 2 and between the cell 2 and the casing. It should be noted that, on the one hand, the adhesive substance has adhesive properties; its placement between the cell 2 and the casing fixes the cell 2, improving the battery's drop test pass rate and preventing problems such as battery leakage and damage caused by the battery breaking through the solder joints during a drop; on the other hand, the adhesive substance has heat dissipation properties, promptly dissipating heat generated by the battery, improving the battery's heat dissipation capacity and enhancing the user experience. In this embodiment, the top and bottom surfaces of the cell 2 are insulating substrate layers 21, whose substrate is made of plastic materials such as PP / PET. The heat dissipation capacity is improved by the heat-dissipating adhesive layer 3, which enhances the heat dissipation capacity of the cell 2 and improves safety.

[0065] This embodiment does not limit the specific location of the heat-dissipating adhesive layer 3. For example, the heat-dissipating adhesive layer 3 can be disposed on the upper and / or lower surface of the cell 2 in the thickness direction.

[0066] This embodiment does not limit the specific shape of the heat-dissipating adhesive layer 3. For example, the shape of the heat-dissipating adhesive layer 3 can be similar to that of the battery cell 2.

[0067] This embodiment does not limit the specific relative size relationship between the insulating substrate layer 21 and the thermal adhesive layer 3. The projection of the insulating substrate layer 21 in the thickness direction may, but is not limited to, covering the projection of the thermal adhesive layer 3 in the thickness direction. Furthermore, in this embodiment, the distance from the projection of the thermal adhesive layer 3 in the thickness direction to the outer edge of the projection of the insulating substrate layer 21 in the thickness direction can be 0.5mm to 5mm, including the values ​​at both ends.

[0068] This embodiment does not limit the specific thickness of the thermal adhesive layer 3. For example, the thickness of the thermal adhesive layer 3 can be 5μm to 20μm, including the values ​​at both ends.

[0069] This embodiment does not limit the specific type of the heat-dissipating adhesive layer 3. The heat-dissipating adhesive layer 3 may be, but is not limited to, a mixed adhesive layer comprising a polysiloxane mixture, a metal catalyst, an alcohol retarder, alumina, aluminum hydroxide, and boron nitride. It should be noted that the polysiloxane mixture, metal catalyst, alcohol retarder, alumina, aluminum hydroxide, and boron nitride are common materials in the prior art. This embodiment does not limit the internal components of the heat-dissipating adhesive layer 3, but directly uses an adhesive layer made of several existing materials as the heat-dissipating adhesive layer 3.

[0070] This embodiment does not limit the specific viscosity of the heat-dissipating adhesive layer 3. For example, the viscosity of the heat-dissipating adhesive layer 3 can be 20,000 Pa·s to 100,000 Pa·s, including the values ​​at both ends.

[0071] This embodiment does not limit the specific tensile strength of the thermal adhesive layer 3. For example, the tensile strength of the thermal adhesive layer 3 can be greater than or equal to 2 MPa.

[0072] This embodiment does not limit the specific thermal conductivity of the thermal adhesive layer 3. For example, the thermal conductivity of the solid thermal adhesive layer 3 can be 0.85 W / (m·k) to 3 W / (m·k), including the values ​​at both ends. It should be noted that the solid thermal adhesive layer 3 refers to the cured thermal adhesive layer 3.

[0073] This embodiment provides a type of battery cell 2, such as... Figure 4As shown in the figure, the battery cell 2 includes a first electrode 41 and a second electrode 42. The first electrode 41 may include a positive electrode tab region (or a negative electrode tab region), and the corresponding second electrode 42 may include a negative electrode tab region (or a positive electrode tab region). A heat-dissipating adhesive layer 3 is provided on the upper surface of the battery cell 2, and the projection of the insulating substrate layer 21 in the thickness direction covers the projection of the heat-dissipating adhesive layer 3 in the thickness direction.

[0074] This embodiment does not limit the specific structure of the outer casing. The outer casing may include, but is not limited to, a housing 11 and a cover 12. The housing 11 forms a cavity, and the cover 12 is connected to the housing 11 to form an accommodating cavity. It should be noted that the battery cell 2 is located inside the cavity, and the cover 12 is connected to the housing 11 to seal the housing 11 and the battery cell 2.

[0075] In this embodiment, the cavity formed by the shell 11 is not limited to a square shape and can be any irregular structure.

[0076] This embodiment does not limit the specific type of housing 11. Housing 11 may be, but is not limited to, a metal housing 11. Furthermore, the metal housing 11 may be, but is not limited to, a stainless steel housing 11.

[0077] This embodiment does not limit the specific type of the cover 12. The cover 12 may be, but is not limited to, a metal cover 12. Furthermore, the metal cover 12 may be, but is not limited to, a stainless steel cover 12.

[0078] It should be noted that in this embodiment, the casing 11 and the cover 12 are made of metal materials, such as stainless steel, which provides stronger resistance to deformation of the battery cell 2 and better heat dissipation. When the casing in this embodiment is made of a metal hard shell, when combined with the composite current collector stacked battery cell 2, it is possible to improve the battery's weight energy density, volumetric energy density, and safety performance without reducing the thickness of the metal hard shell.

[0079] This embodiment does not limit the specific thickness of the shell 11. For example, the thickness of the shell 11 can be 10μm to 500μm, including the values ​​at both ends.

[0080] This embodiment does not limit the specific thickness of the cover 12. For example, the thickness of the cover 12 can be 10μm to 500μm, including the values ​​at both ends.

[0081] Based on the above embodiments, under the condition that the outer shell remains unchanged, the two outermost electrode layers of the battery cell adopt single-sided electrode sheets, and the single-sided electrode sheets use composite current collectors instead of conventional metal current collectors. Compared with conventional metal current collectors, composite current collectors are lighter and have better ductility of the insulating substrate layer in the composite current collector. It is not necessary to increase the thickness too much to avoid the curling of the single-sided electrode sheets. On the one hand, the weight of the battery is reduced, thereby increasing the weight energy density of the battery. On the other hand, the space utilization of the battery is improved, thereby increasing the volume energy density of the battery. At the same time, the insulating substrate layer of the composite current collector in the single-sided electrode sheet is located on the surface of the battery cell. When the battery cell is punctured or collided, the insulating substrate layer can block the risk of short circuit to the internal positive and negative electrodes, avoid local thermal runaway, and give the battery excellent safety. This improves the safety performance of the battery under risk conditions such as puncture, collision, and compression, and reduces the damage caused by the explosion of the outer shell.

[0082] The present invention has been described in detail above. For those skilled in the art, based on the ideas of the embodiments of the present invention, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A battery, characterized by, Comprise: A shell and an electric core; the shell surrounds a containing cavity, and the electric core is located in the containing cavity; the electric core comprises a plurality of electrode sheets arranged in layers, and adjacent electrode sheets have different polarities; In the thickness direction of the electric core, the uppermost electrode sheet and the lowermost electrode sheet are single-sided electrode sheets, and the intermediate electrode sheets are double-sided electrode sheets; the single-sided electrode sheet comprises a first current collector and a first functional layer; the first current collector is a composite current collector, which comprises an insulating matrix layer and a conductive layer; the insulating matrix layer is located on the side of the conductive layer away from the intermediate electrode sheets in the electric core; the first functional layer is located on the side of the conductive layer close to the intermediate electrode sheets in the electric core; the double-sided electrode sheet comprises a second current collector and a second functional layer; The ratio of the thickness of the first current collector in the single-sided electrode sheet to the thickness of the second current collector in the double-sided electrode sheet with the same polarity is 1-1.1, and includes both ends.

2. The battery of claim 1, wherein, In the direction perpendicular to the thickness direction, the area of the single-sided electrode sheet provided with the first functional layer is the first functional layer coverage area, and the area without the first functional layer is the first tab area.

3. The battery of claim 2, wherein, The projection of the insulating matrix layer and the conductive layer in the thickness direction completely overlaps; And / or, the ratio of the thickness of the insulating matrix layer in the first tab area to the thickness of the insulating matrix layer in the first functional layer coverage area is 0.3-1, and includes both ends; And / or, the thickness of the conductive layer in the first tab area is the same as the thickness of the conductive layer in the first functional layer coverage area; And / or, the insulating matrix layer is a PET layer, a PP layer, or a mixed layer comprising PET and PP; And / or, the conductive layer is a metal plating layer.

4. The battery of claim 2, wherein, The thickness of the conductive layer in the first functional layer coverage area is greater than or equal to 0.5 times the thickness of the second current collector.

5. The battery of claim 1, wherein, The second functional layer is located on at least two sides of the second current collector in the thickness direction; in the direction perpendicular to the thickness direction, the area of the double-sided electrode sheet provided with the second functional layer is the second functional layer coverage area, and the area without the second functional layer is the second tab area.

6. The battery of claim 1, wherein, The second current collector is a metal current collector or a composite current collector.

7. The battery of claim 1, wherein, Also include: A heat dissipation adhesive layer; the heat dissipation adhesive layer is arranged on the surface of the electric core and between the electric core and the shell.

8. The battery of claim 7, wherein, The heat dissipation adhesive layer is arranged on the upper surface and / or lower surface of the electric core in the thickness direction; And / or, the shape of the heat dissipation adhesive layer is shaped according to the electric core; And / or, the projection of the insulating matrix layer in the thickness direction covers the projection of the heat dissipation adhesive layer in the thickness direction; And / or, the thickness of the heat dissipation adhesive layer is 5-20 microns, and includes both ends; And / or, the heat dissipation adhesive layer is a mixed adhesive layer comprising a polysiloxane mixture, a metal catalyst, an alcohol retarder, aluminum oxide, aluminum hydroxide, and boron nitride; And / or, the viscosity of the heat dissipation adhesive layer is 20000-100000 pa.s, and includes both ends; And / or, the tensile strength of the heat dissipation adhesive layer is greater than or equal to 2MPa; And / or, the thermal conductivity of the solid heat dissipation adhesive layer is 0.85 W / (m·k)~3 W / (m·k), and the both ends are included.

9. The battery of claim 8, wherein, The distance from the projection of the heat dissipation adhesive layer in the thickness direction to the outer edge of the projection of the insulating base layer in the thickness direction is 0.5mm~5mm, and the both ends are included.

10. The battery of claim 1, wherein, The shell comprises a shell body and a shell cover; the shell body surrounds a cavity, and the shell cover is connected with the shell body to surround the accommodation cavity; the shell body is a metal shell body; And / or, the shell cover is a metal shell cover; And / or, the thickness of the shell body is 10um~500um, and the both ends are included; And / or, the thickness of the shell cover is 10um~500um, and the both ends are included.

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