Battery cell and battery

Abstract

The utility model provides a kind of electric core and battery, comprising: anode sheet, diaphragm and cathode sheet, the diaphragm separates the anode sheet with the cathode sheet, the anode sheet and the cathode sheet are alternately stacked;Anode lug, the anode lug is set on the anode sheet;Resistance coating, the resistance coating is set on the cathode sheet adjacent to the anode lug, the resistance coating is coated in the cathode sheet one side of cathode current collector opposite the anode lug, active material layer on the cathode current collector covers the resistance coating, the projection of the resistance coating in first direction corresponds with the projection of the anode lug in first direction, the first direction is the thickness direction of the anode sheet, the resistivity of the resistance coating is greater than the resistivity of the cathode current collector.For the electric core of the utility model, lithium precipitation phenomenon can be effectively prevented in the process of long cycle of electric core.

Description

Technical Field

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

[0002] Currently, battery products are all developing towards higher energy density, using higher coating weight and compaction. However, as the charging time of battery cells becomes shorter and the charging rate becomes higher, the temperature rise of battery cells during charging also increases. This makes it easy for black spots and lithium plating to appear in some areas of the tab alignment region of the negative electrode during long-term cycling, which can even lead to the failure of the entire battery cell during cycling. Therefore, a new type of battery cell is needed to effectively prevent lithium plating during long-term cycling. Utility Model Content

[0003] This invention aims to solve at least one of the technical problems existing in the prior art. To this end, this invention proposes a battery cell that can effectively prevent lithium plating during long-term cycling.

[0004] This utility model also proposes a battery.

[0005] A battery cell according to a first aspect of the present invention includes: an anode plate, a separator, and a cathode plate, wherein the separator separates the anode plate and the cathode plate, and the anode plate and the cathode plate are alternately stacked; an anode tab disposed on the anode plate; and a resistive coating formed on the cathode plate adjacent to the anode tab, wherein the resistive coating is applied to the side of the cathode current collector of the cathode plate opposite to the anode tab, an active material layer on the cathode current collector covers the resistive coating, the projection of the resistive coating in a first direction corresponds to the projection of the anode tab in a first direction, wherein the first direction is the thickness direction of the anode plate, and the resistivity of the resistive coating is greater than the resistivity of the cathode current collector.

[0006] The battery cell according to the first aspect of the present invention has at least the following beneficial effects: During the cyclic charging and discharging process of the battery cell, due to temperature changes and other reasons, especially at the position of the anode tab, the temperature changes are more drastic. This makes it very easy for lithium plating to occur at the position of the cathode plate corresponding to the anode tab, especially on the side of the cathode plate opposite to the anode tab. Therefore, by applying a resistive coating at this position, the resistance at this position is increased, thereby reducing the current at this position and effectively avoiding lithium plating at this position.

[0007] According to some embodiments of the present invention, it further includes a first groove and a first adhesive tape. The first groove is formed on the anode sheet and is used to accommodate the anode tab. The first adhesive tape is disposed on the anode sheet and covers the surface of the first groove along a first direction.

[0008] According to some embodiments of the present invention, the battery cell further includes a second adhesive paper, which is disposed on the side of the cathode plate adjacent to the anode tab facing the anode tab, and the projection of the first adhesive paper in a first direction is within the projection of the second adhesive paper in the first direction.

[0009] According to some embodiments of the present invention, the distance between the edge of the projection of the first adhesive paper in the first direction and the edge of the projection of the second adhesive paper in the first direction is not less than 1 mm.

[0010] According to some embodiments of the present invention, the battery cell further includes a second groove, which is formed on the cathode sheet and is used to accommodate the second adhesive paper.

[0011] According to some embodiments of the present invention, the first groove is formed on the active material layer on the cathode current collector, the depth of the resistive coating in the first direction is G, and the thickness of the active material layer coated on the side of the cathode current collector opposite to the anode tab is H, 0.5≥G / H.

[0012] According to some embodiments of the present invention, the anode sheet is provided with a plurality of anode tabs, the plurality of anode tabs are spaced apart in a second direction, the second direction being the extension direction of the anode sheet, and the projections of the plurality of anode tabs in the first direction are spaced apart from each other.

[0013] According to some embodiments of the present invention, the width of the resistive coating in the second direction is A, the width of the anode tab in the second direction is B, the second direction is the extension direction of the anode sheet, and A ≥ 1.2B.

[0014] According to some embodiments of this utility model, the material of the resistive coating is conductive ceramic.

[0015] The lithium-plating-resistant cycling battery according to a second aspect of the present invention includes the lithium-plating-resistant cycling cell described in any one of the above embodiments.

[0016] Additional aspects and advantages of this invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0017] Figure 1This is a schematic diagram of the battery cell of this utility model having a first groove;

[0018] Figure 2 This is a schematic diagram of the structure of the cathode current collector of the battery cell of this utility model exposed in the first groove;

[0019] Figure 3 This is a schematic diagram of the structure of the battery cell of this utility model, which has an insulating layer.

[0020] Icon labels:

[0021] 1. Anode plate; 11. Anode tab; 2. Cathode plate; 21. Cathode current collector; 22. Cathode active material layer; 3. Diaphragm; 41. Resistor coating; 42. First groove; 43. Second groove; 51. First adhesive tape; 52. Second adhesive tape. Detailed Implementation

[0022] The embodiments of this utility model are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this utility model, and should not be construed as limiting this utility model.

[0023] In the description of this utility model, it should be understood that the orientation descriptions, such as up and down, are based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model.

[0024] In the description of this utility model, "multiple" refers to two or more. The use of "first" and "second" is for distinguishing technical features only and should not be construed as indicating or implying relative importance, or implicitly indicating the number of technical features or their sequential relationship.

[0025] In the description of this utility model, unless otherwise explicitly defined, terms such as "setting," "installation," and "connection" should be interpreted broadly, and those skilled in the art can reasonably determine the specific meaning of the above terms in this utility model in conjunction with the specific content of the technical solution.

[0026] The manufacturing process of a battery cell mainly includes the following steps: First, prepare all raw materials such as positive electrode material, negative electrode material, electrolyte, and separator. The positive electrode material is usually composed of lithium metal oxide, while the negative electrode material is mostly graphite or silicon-based. The electrolyte is generally made by dissolving lithium salt in an organic solvent. Next, the positive electrode material is mixed with a conductive agent and binder and coated onto aluminum foil to form a positive electrode sheet. Similarly, the negative electrode material is mixed with a conductive agent and binder and coated onto copper foil to form a negative electrode sheet. Then, the coated positive and negative electrode sheets and the separator are stacked in a specific order, wound or laminated to form the initial shape of the battery cell. Afterward, the wound or laminated battery cell is placed in a casing, electrolyte is injected, and then it is sealed. After sealing, the battery cell needs to undergo a formation process, i.e., charging and discharging under specific conditions to form a stable SEI film (solid electrolyte interface film). Finally, a series of tests are conducted on the battery cells, including capacity testing, internal resistance testing, and cycle life testing, to ensure that the performance of the battery cells meets the standards. Only then is the battery cell manufacturing process considered complete.

[0027] The energy density of a battery cell refers to the energy that can be stored per unit volume or unit mass of the cell. It is usually expressed in watt-hours per liter (Wh / L) for volumetric energy density and in watt-hours per kilogram (Wh / kg) for gravimetric energy density. Higher energy density means the cell can store more electrical energy per unit volume or mass, which is crucial for applications such as portable electronic devices and electric vehicles. How is the energy density of a battery cell calculated? The energy density of a battery cell, i.e., the energy stored per unit volume or unit mass of the battery, is one of the key indicators for measuring battery performance. It is influenced by a variety of complex factors, spanning a wide range of fields from materials science to engineering design. First, the chemical composition of the cell is the core factor affecting energy density. Different cathode materials, such as lithium cobalt oxide (LiCoO2), lithium nickel cobalt manganese oxide (NCM), or lithium iron phosphate (LFP), have different energy storage capacities. Anode materials, such as graphite or silicon-based materials, also affect the overall energy density due to their different electrochemical properties. The choice of electrolyte and the material of the separator are equally important, as they determine the efficiency and safety of ion transport within the battery. Design and manufacturing processes are also crucial factors affecting energy density. The battery's structural design, including electrode thickness, active material loading, and packaging method, significantly impacts energy density. For example, thinner electrodes reduce the use of inactive materials, thus increasing energy density per unit volume. The precision of the manufacturing process, such as coating uniformity, compaction density, and assembly accuracy, all affect battery performance. Furthermore, material quality and purity also have a significant impact on energy density. High-purity materials reduce internal side reactions and improve energy utilization. The microstructure of materials, such as particle size and distribution, also affects the surface area of ​​electrode materials and ion diffusion paths, thereby influencing the battery's charge and discharge performance.

[0028] To increase the energy density of the battery cell, the active material is pressed more tightly, and the electrodes are also pressed more tightly together. This results in an extremely high density of lithium ions. When lithium ions are affected by the environment and cannot be embedded on the anode plate in time, lithium plating occurs.

[0029] Electrolytes play a crucial role in batteries, serving not only as a medium for charge transfer but also as a key to the smooth operation of internal chemical reactions. Electrolytes are typically composed of a specific solvent and dissolved electrolyte salts, and the choice of materials directly impacts battery performance. In rechargeable batteries, the role of the electrolyte is particularly significant. It participates in the electrochemical reactions during charging and discharging and is responsible for efficiently transporting ions between the positive and negative electrodes, ensuring a smooth conversion between electrical and chemical energy. Taking lithium-ion batteries as an example, the electrolyte is usually composed of a series of carbonate solvents and lithium salts. These carbonate solvents, such as ethylene carbonate (EC), diethyl carbonate (DEC), and dimethyl carbonate (DMC), have good chemical stability and can withstand the high-temperature environment generated during charging and discharging. Lithium salts, such as lithium hexafluorophosphate (LiPF6), provide the necessary lithium ions, which shuttle between the positive and negative electrodes inside the battery, enabling the battery to store and release energy. The importance of electrolytes lies not only in their ability to ensure the smooth movement of ions during charging and discharging, but also in their contribution to the overall stability and safety of the battery. A well-designed electrolyte can reduce side reactions, extend battery life, and provide necessary protection under extreme conditions, preventing overheating or dangerous chemical reactions. Therefore, meticulous selection and optimization of electrolyte materials and properties during battery design and manufacturing are crucial steps in ensuring efficient, safe, and long-term stable battery operation. Consequently, during battery operation, it is essential to ensure that the electrodes are fully wetted by the electrolyte.

[0030] Reference Figure 1 and Figure 2The battery cell in the first embodiment of this utility model includes: an anode tab 11, a resistive coating 41, an anode plate 1, a separator 3, and a cathode plate 2. The separator 3 separates the anode plate 1 and the cathode plate 2, which are alternately stacked. The anode tab 11 is disposed on the anode plate 1. During the cyclic charging and discharging process of the battery cell, the current is more concentrated at the anode tab 11, thus generating more heat and causing a larger temperature change near the anode tab 11. This makes lithium plating more likely to occur in areas with large temperature changes. The resistive coating 41 is disposed on the cathode plate 2 adjacent to the anode tab 11. The closer the cathode plate is to the anode tab 11, the greater the temperature change, making lithium plating more likely. Therefore, the resistive coating 41 is disposed on the cathode plate 2 adjacent to the anode tab 11, as this position is closer to the anode tab 11, has a larger temperature change, and is more prone to lithium plating. The resistive coating 41 is disposed on the side of the cathode plate 2 opposite to the anode tab 11. The projection of the resistive coating 41 in the first direction corresponds to the projection of the anode tab 11 in the first direction, which is the stacking direction of the anode plate 1 and the cathode plate 2. When setting the anode tab 11, a groove is made on the side of the cathode plate 2 facing the anode tab 11 to accommodate it. Therefore, lithium plating does not occur on the side of the cathode plate 2 facing the anode tab 11 due to the smaller amount of cathode active material. However, the side of the cathode plate 2 facing away from the anode tab 11 does not need to accommodate the anode tab 11, so it is set more flat. Therefore, lithium plating is prone to occur on the side of the cathode plate 2 facing away from the anode tab 11. Therefore, the resistive coating 41 is set on the side of the cathode plate 2 facing away from the anode tab 11 to increase the resistance at that location, thereby reducing the current at that location and making lithium plating less likely to occur at the location of the resistive coating 41.

[0031] According to some embodiments of this utility model, the battery cell further includes a first groove 42 and a first adhesive tape 51. The first groove 42 is formed on the anode plate 1 and is used to accommodate the anode tab 11. The first adhesive tape 51 is disposed on both sides of the anode plate 1 and covers both ends of the first groove 42 along a first direction. The first groove 42 is provided to accommodate the anode tab 11 and the first adhesive tape 51 protects the anode tab 11 from piercing the separator 3 by solder marks on the anode tab 11. Specifically, the anode active material on one or both sides of the anode current collector on the anode plate 1 at the location where the anode tab 11 needs to be disposed is removed, thereby forming the first groove 42. To provide more space to accommodate the thicker anode tab 11, the anode active material on both sides of the anode current collector is removed during the formation of the first groove 42 to create a larger accommodating space. After the first groove 42 is formed, to prevent solder burrs from penetrating the first groove 42 and piercing the separator 3, the first adhesive tape 51 is covered at both ends of the first groove 42 to isolate it. Furthermore, the resistive coating 41 has a width of A in the second direction, and the anode tab 11 has a width of B in the second direction, where A ≥ 1.2B. This better prevents lithium plating from occurring in the battery cell.

[0032] According to some embodiments of this utility model, the battery cell further includes a second adhesive tape 52, which is disposed on the side of the cathode plate 2 adjacent to the anode tab 11 facing the anode tab 11. The projection of the first adhesive tape 51 in the first direction is within the projection of the second adhesive tape 52 in the first direction. The second adhesive tape 52 is provided to further prevent burrs on the tabs from piercing the diaphragm 3 and directly contacting the cathode plate 2, thus preventing short circuits in the battery cell.

[0033] According to some embodiments of this utility model, the distance between the edge of the projection of the first adhesive tape 51 in the first direction and the edge of the projection of the second adhesive tape 52 in the first direction is not less than 1 mm. Using a larger second adhesive tape 52 can better prevent short circuits in the battery cell. Burrs on the anode tab 11 may extend from the edge of the first adhesive tape 51, and the second adhesive tape 52 can further isolate these extending burrs.

[0034] According to some embodiments of this utility model, the battery cell further includes a second groove 43, which is formed on the cathode plate 2 and used to accommodate the second adhesive tape 52. By providing the second groove 43 to accommodate the second adhesive tape 52, the side of the cathode plate 2 facing the anode tab 11 becomes flatter, which not only increases the flatness of the battery cell when compressed, but also improves the energy density of the battery cell.

[0035] According to some embodiments of this utility model, the cathode sheet 2 includes a cathode current collector 21 and a cathode active material layer 22. The cathode active material layer 22 is coated on both opposite sides of the cathode current collector 21. A first groove 42 is formed on the cathode active material layer 22, and the depth of the first groove 42 in a first direction is G. The thickness of the cathode active material layer 22 on the side of the cathode current collector facing away from the anode tab is H, where 0.5 ≥ G / H. To avoid the resistive coating 41 being too thick, which would reduce the amount of active material at that location and thus decrease the energy density of the battery, the thickness of the resistive coating 41 is limited, thereby effectively improving the energy density of the battery.

[0036] According to some embodiments of this utility model, a plurality of anode tabs 11 are provided on the anode sheet 1. The plurality of anode tabs 11 are spaced apart in a second direction, which is the extension direction of the anode sheet 1. The projections of the plurality of anode tabs 11 in the first direction are spaced apart from each other. Staggering the anode tabs 11 can avoid interference between the anode tabs 11 and also prevent the thickness from accumulating in the overlapping areas of the anode tabs 11, thus avoiding excessive local thickness of the battery cell. Furthermore, the temperature change is greater in the overlapping areas of the anode tabs 11, that is, if the anode tabs 11 are too concentrated, the temperature is more likely to rise, thus increasing the likelihood of lithium plating. Therefore, the anode tabs 11 are arranged in an alternating manner.

[0037] According to some embodiments of this utility model, the resistive coating material is conductive ceramic. The resistance of the conductive ceramic can be adjusted according to the needs of the battery. There are various types of conductive ceramic materials, such as oxide conductive ceramics, non-oxide conductive ceramics, and composite conductive ceramics. Oxide conductive ceramics can be divided into N-type semiconductor materials, such as TiO2, Nb2O5, WO3, etc.; P-type semiconductor materials, such as Cr2O3, MnO, CoO, etc.; and amphoteric semiconductor materials, such as SiC, PbTe, etc. Non-oxide conductive ceramics mainly include silicon carbide, silicon nitride, etc., with typical examples including WC, TiC, NbC, and SiC. Composite conductive ceramics are mixtures composed of two or more materials, such as zirconium oxide / yttrium oxide composite ceramics.

[0038] Adjusting the resistance of conductive ceramics can typically be achieved through methods such as adjusting material composition, controlling the sintering process, and utilizing reversible chemical reactions and crystal transformations. Changing the proportions of components in the conductive ceramic, such as adding or removing elements with high carrier concentrations, can adjust its resistance. For example, in a ternary compound containing Mn, appropriately increasing the Cu content can decrease the resistance, while appropriately increasing the Co content or adding a small amount of Al ions will increase the resistance. Factors such as temperature, time, and atmosphere during the sintering process affect the microstructure and phase composition of the conductive ceramic, thus influencing its resistance. Careful control of these conditions can achieve the goal of adjusting the resistance. Utilizing certain reversible chemical reactions and crystal transformations can improve the microstructure of the material, alter the phase ratios and phase boundary conditions, thereby achieving the effect of adjusting the resistance.

[0039] The battery according to the second aspect of the present invention includes the battery cell of any of the above embodiments.

[0040] The embodiments of the present utility model have been described in detail above with reference to the accompanying drawings. However, the present utility model is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present utility model.

Claims

1. A battery cell, characterized in that, include: An anode plate, a diaphragm, and a cathode plate, wherein the diaphragm separates the anode plate and the cathode plate, and the anode plate and the cathode plate are stacked alternately; Anode tab, wherein the anode tab is disposed on the anode plate; A resistive coating is formed on the cathode plate adjacent to the anode tab. The resistive coating is applied to the side of the cathode current collector of the cathode plate that is opposite to the anode tab. An active material layer on the cathode current collector covers the resistive coating. The projection of the resistive coating in a first direction corresponds to the projection of the anode tab in a first direction, where the first direction is the thickness direction of the anode plate. The resistivity of the resistive coating is greater than the resistivity of the cathode current collector.

2. The battery cell according to claim 1, characterized in that, It also includes a first groove and a first adhesive tape. The first groove is formed on the anode plate and is used to accommodate the anode tab. The first adhesive tape is disposed on the anode plate and covers the surface of the first groove along a first direction.

3. The battery cell according to claim 2, characterized in that, The battery cell also includes a second adhesive tape, which is disposed on the side of the cathode plate adjacent to the anode tab facing the anode tab, and the projection of the first adhesive tape in a first direction is within the projection of the second adhesive tape in the first direction.

4. The battery cell according to claim 3, characterized in that, The distance between the edge of the projection of the first adhesive tape in the first direction and the edge of the projection of the second adhesive tape in the first direction is not less than 1 mm.

5. The battery cell according to claim 3, characterized in that, The battery cell also includes a second groove, which is formed on the cathode sheet and is used to accommodate the second adhesive tape.

6. The battery cell according to claim 2, characterized in that, The first groove is formed on the active material layer on the cathode current collector, the depth of the resistive coating in the first direction is G, and the thickness of the active material layer on the side of the cathode current collector opposite to the anode tab is H, 0.5≥G / H.

7. The battery cell according to claim 1, characterized in that, The anode plate is provided with a plurality of anode tabs, which are spaced apart in a second direction, the second direction being the extension direction of the anode plate, and the projections of the plurality of anode tabs in the first direction are spaced apart from each other.

8. The battery cell according to claim 6, characterized in that, The width of the resistive coating in the second direction is A, and the width of the anode tab in the second direction is B, where the second direction is the extension direction of the anode sheet, and A ≥ 1.2B.

9. The battery cell according to claim 6, characterized in that, The resistive coating is made of conductive ceramic.

10. A battery, characterized in that, The battery cell includes any one of claims 1-9.

Images