Anti-precipitation lithium battery cell and anti-precipitation lithium battery

Abstract

The utility model provides an anti-precipitation lithium battery cell and an anti-precipitation lithium battery, the anti-precipitation lithium battery cell comprises a first pole piece, a diaphragm and a second pole piece, the first pole piece, the diaphragm and the second pole piece are sequentially laminated and wound into a roll core; the first pole piece comprises a current collector and an active substance layer, the active substance layer is arranged on the side, facing the diaphragm, of the current collector, a gap layer is arranged on the side, facing the diaphragm, of the active substance layer, and the gap layer is used for absorbing electrolyte. According to the lithium precipitation prevention battery cell, the liquid retention capacity of the battery cell can be improved, and the lithium precipitation phenomenon can be effectively prevented.

Description

Technical Field

[0001] This utility model relates to the field of new energy technology, and in particular to an anti-lithium-plating battery cell and an anti-lithium-plating battery. Background Technology

[0002] Currently, battery products are all developing towards higher energy density, employing higher coating weights and compaction, which poses increasing challenges to the charging capacity of the system, especially at weak corners, where lithium plating is particularly prone to occur in the later stages of cycling, significantly impacting the safety and reliability of the cell. Existing technologies typically involve applying coatings to the separator to improve the cell's liquid retention capacity and thus reduce lithium plating. However, separators are relatively fragile, and applying coatings to them is not only difficult but also highly susceptible to damage. Therefore, a new type of lithium-plating-resistant battery cell is needed to improve the cell's liquid retention capacity and effectively prevent lithium plating. 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 an anti-lithium plating battery cell, which can improve the cell's liquid retention capacity and effectively prevent lithium plating.

[0004] This utility model also proposes an anti-lithium plating battery.

[0005] According to a first aspect of the present invention, an anti-lithium plating battery cell includes: a first electrode, a separator, and a second electrode, wherein the first electrode, the separator, and the second electrode are stacked in sequence and wound into a core; the first electrode includes a current collector and an active material layer, wherein the active material layer is disposed on the side of the current collector facing the separator, and a gap layer is disposed on the side of the active material layer facing the separator, the gap layer being used to absorb electrolyte.

[0006] The lithium plating-resistant battery cell according to the first aspect of the present invention has at least the following beneficial effects: by setting a gap layer on the first electrode, it is not only more convenient but also less likely to damage the structure of the first electrode. The gap layer improves the electrolyte retention capacity of the battery cell by absorbing electrolyte, so that the first electrode can have more sufficient contact with the electrolyte, thereby effectively preventing the occurrence of lithium plating in the battery cell.

[0007] According to some embodiments of the present invention, the gap layers are spaced apart along a first direction, which is the extension direction of the first electrode.

[0008] According to some embodiments of the present invention, the first electrode includes a curved section and a straight section, the curved section and the straight section are alternately and cyclically arranged on the first electrode, the curved section has a bending arc in the winding core, the straight section is a plane in the winding core, and the gap layer is disposed in the curved section.

[0009] According to some embodiments of the present invention, the gap layer includes an adhesive material of pore-forming particles, the pore-forming particles being used to create gaps in the core, and the adhesive material being used to fix the pore-forming particles onto the active material layer.

[0010] According to some embodiments of the present invention, the areal density of the pore-forming particles is not less than 0.001 g / m² and not greater than 0.7 g / m².

[0011] According to some embodiments of this utility model, the pore-forming particles are acrylic balls or polyethylene.

[0012] According to some embodiments of the present invention, the length of the gap layer in the second direction is not greater than the length of the active material layer in the second direction, and the width direction of the first electrode is the second direction.

[0013] According to some embodiments of the present invention, the length of the gap layer on the curved section in the second direction is H1, the length of the gap layer on the straight section in the second direction is H2, H1>H2, and the width direction of the first electrode is the second direction.

[0014] According to some embodiments of the present invention, the distance between the upper edge of the gap layer on the straight section in the second direction and the upper edge of the active material layer in the second direction is D1, and the distance between the lower edge of the gap layer on the straight section in the second direction and the lower edge of the active material layer in the second direction is D2, where D1=D2.

[0015] According to some embodiments of the present invention, a gap layer is also provided on the side of the second electrode facing the first electrode.

[0016] The lithium-plating-resistant battery according to a second aspect of the present invention includes the lithium-plating-resistant cell described in any one of the above embodiments.

[0017] 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

[0018] Figure 1 This is a schematic diagram of the core structure of the anti-lithium plating battery cell of this utility model;

[0019] Figure 2 This is a schematic diagram of the stacked structure of the anti-lithium plating battery cell of this utility model;

[0020] Figure 3This is a schematic diagram of the structure of the first electrode of the anti-lithium plating battery cell of this utility model;

[0021] Figure 4 This is a schematic diagram of another structure of the first electrode of the anti-lithium plating battery cell of this utility model.

[0022] Icon labels:

[0023] 1. First electrode; 11. Current collector; 12. Active material layer; 13. Bending section; 14. Straight section; 2. Second electrode; 3. Diaphragm; 4. Interstitial layer; 5. Bending section; 6. Straight section. Detailed Implementation

[0024] 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.

[0025] 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.

[0026] 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.

[0027] 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.

[0028] 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, mix the positive electrode material with a conductive agent and binder, and coat it onto aluminum foil to form a positive electrode sheet. Similarly, mix the negative electrode material with a conductive agent and binder, and coat it onto copper foil to form a negative electrode sheet. Then, stack the coated positive and negative electrode sheets and the separator in a specific order, winding or laminating them into the initial shape of the battery cell. Afterward, place the wound or laminated battery cell into a casing, inject electrolyte, and then seal it. 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.

[0029] 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.

[0030] 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 makes it difficult for the electrolyte to fully wet the electrodes, so the electrodes cannot complete the discharge and lithium plating occurs.

[0031] 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.

[0032] Reference Figure 1 and Figure 2 The lithium plating-resistant battery cell in the first embodiment of this utility model includes: a first electrode 1, a separator 3, and a second electrode 2. The first electrode 1, separator 3, and second electrode 2 are stacked and wound into a core. The first electrode 1 includes a current collector 11 and an active material layer 12. The active material layer 12 is disposed on the side of the current collector 11 facing the separator 3. A gap layer 4 is disposed on the side of the active material layer 12 facing the separator 3. The gap layer 4 is used to absorb electrolyte. By providing the gap layer 4 on the first electrode 1, the electrolyte can be contained in the gap layer 4, so that when the battery cell is squeezed, the gap layer 4 can still retain sufficient electrolyte, thereby providing the required electrolyte between the first electrode 1 and the second electrode 2 and preventing lithium plating from occurring in the battery due to lack of electrolyte.

[0033] In modern battery technology, the separator plays a crucial role. It is a fine, porous material, typically made from polyolefin polymers such as polyethylene (PE) and polypropylene (PP). These materials are chosen because of their excellent chemical stability and electrical insulation, effectively preventing direct contact between the positive and negative electrodes inside the battery, thus avoiding short circuits. The microporous structure of the separator allows ions in the electrolyte to pass freely, which is essential for the chemical reactions inside the battery, as ion flow is fundamental to the battery's charging and discharging functions. The separator not only physically separates the positive and negative electrodes but must also possess sufficient mechanical strength and flexibility to withstand the expansion and contraction pressures generated during battery charging and discharging. Furthermore, the separator must exhibit good chemical stability to cope with the corrosive effects that the electrolyte may produce. Under extreme temperature and pressure conditions, the performance of the separator must also remain stable to ensure battery safety and lifespan. When designing the separator, engineers select different thicknesses, porosities, and pore sizes based on different battery types and application requirements. For example, lithium-ion batteries typically use a thinner separator 3 to reduce internal resistance, while lead-acid batteries may use a thicker separator 3 to provide better mechanical protection. Through careful design and manufacturing, the separator 3 ensures efficient and safe operation of the battery under various working conditions. Due to the many characteristics of the separator 3, it is more susceptible to damage under external forces, making it more difficult to apply a coating to the separator 3 and causing it to deform easily. This prevents the separator 3 from being evenly positioned between the first electrode 1 and the second electrode 2, and it is also prone to breakage during battery compaction. To solve this problem, an electrolyte layer is coated onto the first electrode 1 to form a spacer layer that contains the electrolyte.

[0034] According to some embodiments of this utility model, refer to Figure 3 The gap layers 4 are spaced apart along a first direction, which is the extension direction of the first electrode 1. The extension direction of the first electrode 1 is also the winding direction of the core. In order to improve the energy density of the cell, the gap layers 4 are only set in a part of the first electrode 1, rather than in all positions of the first electrode 1. The gap layers 4 can be set evenly or in positions where electrolyte is more likely to be lacking.

[0035] According to some embodiments of this utility model, refer to Figure 3The first electrode 1 includes a curved section 13 and a straight section 14, which are alternately arranged on the first electrode 1. The curved section 13 has a bending arc in the core, while the straight section 14 is flat in the core. The gap layer 4 is disposed in the curved section 13. During the winding process to form the core, a curved portion 5 and a straight portion 6 are formed. The first electrode 1 has a curved section 13 in the region of the curved portion 5 and a straight section 14 in the region of the straight portion 6. The straight section 14 is set flat, and the force is more uniform here, and the force-bearing surface is larger. Therefore, the electrolyte is less affected when pressed here, and it is less likely to be lacking electrolyte. Therefore, by only setting the gap layer 4 in the curved section 13 of the first electrode 1, it is possible to ensure that the battery cell can be fully wetted by electrolyte in the high-density battery cell, and it is also possible to improve the energy density of the battery cell.

[0036] According to some embodiments of this utility model, the gap layer 4 includes an adhesive material containing pore-forming particles. The pore-forming particles are used to create gaps in the core, and the adhesive material is used to fix the pore-forming particles onto the active material layer 12. There are various methods for manufacturing the gap layer 4. One method is to first coat a layer of adhesive material onto the first electrode 1, and then spray the pore-forming particles onto the adhesive material. Another method is to mix the pore-forming particles and the adhesive material, and then coat or spray the coated material onto the first electrode 1 to form the gap layer 4. When the gap layer 4 is provided, the first electrode 1 can be either an anode or a cathode.

[0037] According to some embodiments of this utility model, the areal density of the pore-forming particles is not less than 0.001 g / m² and not more than 0.7 g / m². If the areal density of the pore-forming particles is too low, the interstitial layer 4 will not be able to hold sufficient electrolyte, thus failing to ensure that the battery cell is fully wetted by the electrolyte, which may cause lithium plating in the battery cell. Conversely, if the areal density of the pore-forming particles is too high, the thickness of the interstitial layer 4 will be too large, which will reduce the energy density of the battery cell. Therefore, the areal density of the pore-forming particles is set between 0.001 and 0.7 g / m².

[0038] According to some embodiments of this utility model, the pore-forming particles are acrylic spheres or polyethylene. The pore-forming particles need to possess both physical and chemical stability, preventing electrochemical reactions and reactions with substances such as the electrolyte in the separator 3. Therefore, acrylic spheres or polyethylene are chosen to stably form the interstitial layer 4 on the first electrode 1 of the battery cell, accommodating the electrolyte.

[0039] According to some embodiments of this utility model, the length of the gap layer 4 in the second direction is not greater than the length of the active material layer 12 in the second direction, and the width direction of the first electrode 1 is the second direction. The gap layer 4 is provided on the first electrode 1 so that the active material layer 12 can make sufficient contact with the electrolyte. The current collector 11 on the first electrode 1 does not need to make sufficient contact with the electrolyte, so the gap layer 4 only needs to be provided in the area of ​​the active material layer 12.

[0040] According to some embodiments of this utility model, refer to Figure 4 The length of the gap layer 4 on the curved section 13 in the second direction is H1, and the length of the gap layer 4 on the straight section 14 in the second direction is H2, where H1>H2. The width direction of the first electrode 1 is the second direction. Electrolyte is more likely to be lacking in the curved section 13, while it is relatively easier to obtain electrolyte in the straight section 14. Therefore, only a smaller number of gap layers 4 need to be set in the straight section 14.

[0041] According to some embodiments of the present invention, the distance between the upper edge of the gap layer 4 on the straight section 14 in the second direction and the upper edge of the active material layer 12 in the second direction is D1, and the distance between the lower edge of the gap layer 4 on the straight section 14 in the second direction and the lower edge of the active material layer 12 in the second direction is D2, where D1=D2. In the straight section 14, the edge position of the straight section 14 is more likely to come into contact with the electrolyte and is also more likely to be wetted by the electrolyte, while the middle position of the straight section 14 is more likely to lack electrolyte than the edge position. Therefore, the gap layer 4 on the straight section 14 is set in the middle part of the straight section 14.

[0042] According to some embodiments of this utility model, a gap layer 4 is also provided on the side of the second electrode 2 facing the first electrode 1. Depending on the situation where the battery cell lacks electrolyte, a gap layer 4 can also be provided on the second electrode 2. That is, when the battery cell experiences lithium plating due to a severe lack of electrolyte, a gap layer 4 can be provided on both the first electrode 1 and the second electrode 2, thereby giving the battery cell a stronger electrolyte retention capacity.

[0043] The lithium-ion-resistant battery according to a second aspect of the present invention includes any of the lithium-ion-resistant cells described in the above embodiments.

[0044] 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 lithium-ion battery cell with anti-lithium plating properties, characterized in that, include: A first electrode, a diaphragm, and a second electrode are sequentially stacked and wound into a core. The first electrode includes a current collector and an active material layer. The active material layer is disposed on the side of the current collector facing the membrane. A gap layer is disposed on the side of the active material layer facing the membrane, and the gap layer is used to absorb electrolyte.

2. The lithium-ion battery cell according to claim 1, characterized in that, The gap layers are spaced apart along a first direction, which is the extension direction of the first electrode.

3. The lithium plating-resistant battery cell according to claim 2, characterized in that, The first electrode includes a curved section and a straight section, which are alternately and cyclically arranged on the first electrode. The curved section has a bending arc in the core, and the straight section is a plane in the core. The gap layer is disposed in the curved section.

4. The lithium plating-resistant battery cell according to claim 3, characterized in that, The gap layer includes an adhesive material for the pore-forming particles, which are used to create gaps in the core, and the adhesive material is used to fix the pore-forming particles onto the active material layer.

5. The lithium-ion battery cell according to claim 4, characterized in that, The areal density of the pore-forming particles is not less than 0.001 g / m² and not more than 0.7 g / m².

6. The lithium-ion battery cell according to claim 4, characterized in that, The pore-forming particles are acrylic balls or polyethylene.

7. The lithium plating-resistant battery cell according to claim 1, characterized in that, The length of the gap layer in the second direction is not greater than the length of the active material layer in the second direction, and the width direction of the first electrode is the second direction.

8. The lithium plating-resistant battery cell according to claim 3, characterized in that, The length of the gap layer on the curved section in the second direction is H1, and the length of the gap layer on the straight section in the second direction is H2, where H1>H2, and the width direction of the first electrode is the second direction.

9. The lithium plating-resistant battery cell according to claim 8, characterized in that, The distance between the upper edge of the gap layer on the straight section in the second direction and the upper edge of the active material layer in the second direction is D1, and the distance between the lower edge of the gap layer on the straight section in the second direction and the lower edge of the active material layer in the second direction is D2, where D1=D2.

10. The lithium-ion battery cell according to claim 1, characterized in that, A gap layer is also provided on the side of the second electrode facing the first electrode.

11. A lithium-ion battery with anti-lithium plating properties, characterized in that, The lithium-ion battery cell included in any one of claims 1-10 is a lithium-ion battery cell designed to prevent lithium plating.

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