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

Abstract

The utility model provides an anti-precipitation lithium battery core and an anti-precipitation lithium battery, which comprise 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; one surface, facing the first pole piece, of the diaphragm is provided with a bonding layer, the bonding layer is used for bonding the diaphragm on the first pole piece, one surface, facing the second pole piece, of the diaphragm is provided with a ceramic layer, and the ceramic layer is used for fixing the shape of the diaphragm. A liquid absorption layer is arranged on one surface, back to the diaphragm, of the ceramic layer and is used for absorbing electrolyte. According to the lithium precipitation prevention battery cell, the energy density of the battery cell can be ensured, and meanwhile, lithium precipitation of the battery cell can be effectively avoided.

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] With continuous technological advancements and innovation, the demand for various smart devices, especially smartphones, computers, and other electronic products, is growing daily. The widespread adoption of these devices has led to higher requirements for the performance and safety of smart products. Among numerous performance indicators, energy density and safety have become the primary focus for both consumers and manufacturers. To meet these demands, higher coating weights and compaction are employed, posing increasing challenges to the charging capacity of the system, especially at weak corners where lithium plating is particularly prone to occur later in the cycle life, significantly impacting the safety and reliability of the battery cell. Current technologies typically involve applying coatings to the separator to improve the cell's liquid retention capacity and reduce lithium plating. However, when applying these coatings to the separator, it is prone to deformation and even breakage. This can lead to direct contact between the active materials at the anode and cathode, causing a short circuit within the cell. Therefore, a new type of lithium plating-resistant battery cell is needed. 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 that can effectively prevent lithium plating while ensuring the energy density of the cell.

[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 sequentially stacked and wound into a core; an adhesive layer is provided on the side of the separator facing the first electrode, the adhesive layer being used to adhere the separator to the first electrode; a ceramic layer is provided on the side of the separator facing the second electrode, the ceramic layer being used to fix the shape of the separator; and an absorbent layer is provided on the side of the ceramic layer facing away from the separator, the absorbent 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 ceramic layer on the separator, the hardness of the separator is increased and the shape of the separator is fixed, thereby avoiding separator deformation, avoiding direct contact between the first electrode and the second electrode, and thus avoiding short circuits inside the battery cell. Furthermore, by setting a liquid-absorbing layer on the non-deformable separator, the electrolyte is absorbed by the liquid-absorbing layer, thus preventing lithium plating due to lack of electrolyte inside the battery cell.

[0007] According to some embodiments of the present invention, the first electrode, the diaphragm and the second electrode are stacked in a first direction, and the thickness of the liquid-absorbing layer in the first direction is not less than 2 μm and not more than 8 μm.

[0008] According to some embodiments of the present invention, the liquid-absorbing layer includes pore-forming particles and particulate solvent, wherein the pore-forming particles and the particulate solvent are mixed into a mixed solution and coated on the ceramic layer to form the liquid-absorbing layer.

[0009] According to some embodiments of this utility model, the particle size of the pore-forming particles does not exceed 200 μm.

[0010] According to some embodiments of the present invention, in the mixed solution, the weight percentage of the pore-forming particles does not exceed 10%, and the surface density of the mixed solution coated on the ceramic layer is not less than 0.1 g / m² and not greater than 2 g / m².

[0011] According to some embodiments of the present invention, the second electrode is a cathode plate.

[0012] According to some embodiments of this utility model, the adhesive layer is made of polymethyl methacrylate or polyvinylidene fluoride.

[0013] According to some embodiments of the present invention, the winding direction of the diaphragm is a second direction, and the liquid-absorbing layer is disposed at intervals on the ceramic layer along the second direction.

[0014] According to some embodiments of the present invention, the diaphragm includes a curved section and a straight section, the curved section and the straight section are alternately and cyclically arranged on the diaphragm, the curved section has a bending arc in the core, the straight section is a plane in the core, and the liquid-absorbing layer is disposed in the curved section.

[0015] According to a second aspect of the present invention, the lithium-plating-resistant battery is characterized in that it includes the lithium-plating-resistant battery 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 1 This is a schematic cross-sectional view of the diaphragm in an anti-lithium plating battery cell according to the present invention;

[0018] Figure 2 This is a schematic diagram of the core structure of an anti-lithium plating battery cell according to the present invention;

[0019] Figure 3This is a schematic diagram of the diaphragm structure of an anti-lithium plating battery cell according to the present invention;

[0020] Figure 4 This is a cross-sectional schematic diagram of an anti-lithium plating battery cell according to the present invention.

[0021] Icon labels:

[0022] 1. First electrode; 2. Diaphragm; 21. Curved section; 22. Straight section; 3. Second electrode; 4. Ceramic layer; 5. Liquid absorption layer; 6. Adhesive layer. Detailed Implementation

[0023] 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.

[0024] 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.

[0025] 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.

[0026] 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.

[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] 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.

[0029] To increase the energy density of the battery cell, the active material is pressed more tightly, as are the electrodes. This makes it difficult for the electrolyte to fully penetrate the electrodes, preventing complete discharge and leading to lithium plating. Therefore, a liquid absorbing layer is needed between the first and second electrodes to store electrolyte and ensure sufficient electrolyte levels. This layer is placed on the separator. However, the separator is prone to deformation. Firstly, the liquid absorbing layer can cause deformation of the separator. Secondly, the separator can deform due to heat during battery cell operation. Therefore, it is necessary to prevent separator deformation.

[0030] Reference Figure 1 , Figure 2 , Figure 3 and Figure 4The lithium-ion battery cell according to the first embodiment of this utility model includes: a first electrode 1, a separator 2, and a second electrode 3. The first electrode 1, separator 2, and second electrode 3 are stacked and wound into a core in sequence. An adhesive layer 6 is provided on the side of the separator 2 facing the first electrode 1, which is used to adhere the separator 2 to the first electrode 1. Because the separator 2 is thin and lightweight, it is easily affected by external airflow during its installation, which can cause displacement and potentially wrinkles between the first electrode 1 and the second electrode 3. Therefore, the adhesive layer 6 is provided on the separator 2 to adhere it to either the first electrode 1 or the second electrode 3, thereby fixing the separator 2 and preventing displacement when it is installed between the first electrode 1 and the second electrode 3. A ceramic layer 4 is provided on the side of the separator 2 facing the second electrode 3. During the use of the battery cell, the internal temperature of the cell will continuously rise. After the internal temperature of the battery cell rises, if the separator 2 is not fixed, it will shrink due to heat and deform. Therefore, a ceramic layer 4 is provided to fix the separator 2. First, the ceramic layer 4 has high temperature resistance and will not deform after being exposed to high temperatures. At the same time, when the separator 2 is affected by high temperatures, the ceramic layer 4 can also prevent the separator 2 from deforming, thereby avoiding direct contact between the first electrode 1 and the second electrode 3, thus greatly reducing the risk of short circuit in the battery cell. The ceramic layer 4 is used to fix the shape of the separator 2. A liquid-absorbing layer 5 is provided on the side of the ceramic layer 4 facing away from the separator 2. The liquid-absorbing layer 5 is used to absorb electrolyte. The liquid-absorbing layer 5 is provided on the ceramic layer 4 to ensure that there is sufficient electrolyte between the first electrode 1 and the second electrode 3, thereby preventing lithium plating in the battery cell due to lack of electrolyte. However, if the liquid-absorbing layer 5 is directly placed on the separator 2, it is very easy for the separator 2 to deform. At the same time, the coating of the liquid-absorbing layer 5 is also very easy to damage the separator 2. Therefore, setting the ceramic layer 4 and placing the liquid-absorbing layer 5 on the ceramic layer 4 not only avoids deformation and damage to the diaphragm 2 when setting the liquid-absorbing layer 5, greatly improving the product qualification rate, but also prevents the diaphragm 2 from deforming after being heated.

[0031] 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 2 to reduce internal resistance, while lead-acid batteries may use a thicker separator 2 to provide better mechanical protection. Through careful design and manufacturing, the separator 2 ensures efficient and safe operation of the battery under various working conditions. Due to the many characteristics of the separator 2, it is more susceptible to damage under external forces, making it more difficult to apply a coating to it and causing it to deform easily. This prevents the separator 2 from being evenly positioned between the first electrode 1 and the second electrode 3, and it is also prone to breakage during battery compaction. To solve this problem, a ceramic layer 4 is first applied to the separator 2 before the coating is applied, and an absorbent layer 5 is then applied to the ceramic layer 4 to contain the electrolyte.

[0032] According to some embodiments of this utility model, the first electrode 1, the separator 2, and the second electrode 3 are stacked in a first direction, and the thickness of the liquid-absorbing layer 5 in the first direction is not less than 2 μm and not more than 8 μm. If the thickness of the liquid-absorbing layer 5 is too small, the gaps in the liquid-absorbing layer 5 cannot retain enough electrolyte, resulting in insufficient electrolyte in the battery cell. If the thickness of the liquid-absorbing layer 5 is too large, air bubbles are easily generated in the gaps within the liquid-absorbing layer 5, preventing the electrolyte from completely penetrating the liquid-absorbing layer 5, leading to a broken bridge phenomenon in the liquid-absorbing layer 5, which in turn worsens lithium plating. Therefore, setting the thickness of the liquid-absorbing layer 5 between 2 μm and 8 μm not only allows sufficient electrolyte to be retained between the first electrode 1 and the second electrode 3 but also avoids the formation of air bubbles in the liquid-absorbing layer 5 that could cause a broken bridge phenomenon.

[0033] According to some embodiments of this utility model, the liquid-absorbing layer 5 includes pore-forming particles and a particulate solvent. The pore-forming particles and the particulate solvent are mixed into a mixed solution and coated onto the ceramic layer 4 to form the liquid-absorbing layer 5. After the pore-forming particles and the particulate solvent are mixed, the pore-forming particles can be fixed on the ceramic layer 4. At this time, gaps are formed between the pore-forming particles, and the electrolyte can be retained in these gaps, thus forming the liquid-absorbing layer 5. The pore-forming particles can be agglomerated particles such as acrylic balls or polyethylene. The pore-forming particles include water-soluble pore-forming particles and oil-soluble pore-forming particles. When the pore-forming particles are water-soluble, the particulate solvent is an aqueous solvent. After the water-soluble pore-forming particles dissolve in the aqueous solvent, they are coated onto the ceramic layer 4. After the aqueous solvent evaporates, the water-soluble pore-forming particles precipitate out, creating pores between the pore-forming particles, thereby forming the liquid-absorbing layer 5 on the ceramic layer 4.

[0034] According to some embodiments of this invention, the particle size of the pore-forming particles does not exceed 200 μm. The pore-forming particles can be spherical or elliptical. When the particle size is large, the gaps in the absorbent layer 5 decrease, resulting in less electrolyte being stored in the absorbent layer 5. Therefore, the particle size of the pore-forming particles needs to be limited to below 200 μm to increase the gaps in the absorbent layer 5, thereby improving the electrolyte storage capacity of the absorbent layer 5.

[0035] According to some embodiments of this invention, the weight percentage of pore-forming particles in the mixed solution does not exceed 10%, and the areal density of the mixed solution coated on the ceramic layer 4 is not less than 0.1 g / m² and not greater than 2 g / m². When the proportion of pore-forming particles is too high, the absorbent layer 5 will be too thick, and the adhesion within the absorbent layer 5 will be too weak. Therefore, the proportion of pore-forming particles and the coating density of the mixed solution are limited to ensure that the formed absorbent layer 5 has an appropriate thickness and spacing.

[0036] According to some embodiments of this utility model, the second electrode 3 is a cathode plate. Lithium plating is more likely to occur when the cathode plate lacks electrolyte in the battery cell. Therefore, the electrolyte-absorbing layer 5 is positioned close to the cathode plate to ensure sufficient electrolyte on the cathode plate, effectively preventing lithium plating.

[0037] According to some embodiments of this invention, the adhesive layer 6 is made of polymethyl methacrylate or polyvinylidene fluoride. This allows the diaphragm 2 to adhere tightly to the first electrode 1.

[0038] According to some embodiments of this utility model, the winding direction of the separator 2 is the second direction, and the liquid-absorbing layer 5 is disposed at intervals along the second direction on the ceramic layer 4. In order to improve the energy density of the battery cell, the liquid-absorbing layer 5 is only disposed in a portion of the separator 2, rather than in all locations of the separator 2. The liquid-absorbing layer 5 can be disposed at uniform intervals or in locations where electrolyte is more likely to be lacking.

[0039] According to some embodiments of this utility model, the diaphragm 2 includes a curved section 21 and a straight section 22, which are alternately and cyclically arranged on the diaphragm 2. The curved section 21 has a bending arc in the core, and the straight section 22 is a plane in the core. The absorbent layer 5 is disposed in the curved section 21. During the winding process to form the core, curved and straight areas are formed. The diaphragm 2 has a curved section 21 in the curved area and a straight section 22 in the straight area. The straight section 22 is set flat, where the force is more uniform and the force-bearing surface is larger. Therefore, the electrolyte is less affected when pressed, and it is less likely to lack electrolyte. Therefore, by only setting the absorbent layer 5 in the curved section 21 of the diaphragm 2, it is possible to ensure that the battery cell can be fully wetted by electrolyte in the high-density battery cell, and the energy density of the battery cell can also be improved.

[0040] According to a second aspect of the present invention, the lithium-plating-resistant battery is characterized in that it includes any of the lithium-plating-resistant cells described in the above embodiments.

[0041] 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. An adhesive layer is provided on the side of the diaphragm facing the first electrode, the adhesive layer being used to adhere the diaphragm to the first electrode. A ceramic layer is provided on the side of the diaphragm facing the second electrode, the ceramic layer being used to fix the shape of the diaphragm. An absorbent layer is provided on the side of the ceramic layer facing away from the diaphragm, the absorbent layer being used to absorb electrolyte.

2. The lithium-ion battery cell according to claim 1, characterized in that, The first electrode, the diaphragm, and the second electrode are stacked in the first direction, and the thickness of the liquid-absorbing layer in the first direction is not less than 2 μm and not more than 8 μm.

3. The lithium plating-resistant battery cell according to claim 1, characterized in that, The second electrode is a cathode plate.

4. The lithium-ion battery cell according to claim 1, characterized in that, The adhesive layer is made of polymethyl methacrylate or polyvinylidene fluoride.

5. The lithium-ion battery cell according to claim 1, characterized in that, The diaphragm is wound in the second direction, and the liquid-absorbing layers are spaced apart on the ceramic layer along the second direction.

6. The lithium-ion battery cell according to claim 1, characterized in that, The diaphragm includes curved sections and straight sections, which are alternately and cyclically arranged on the diaphragm. The curved sections have a bending arc in the core, and the straight sections are flat in the core. The liquid-absorbing layers are all disposed in the curved sections.

7. A lithium-ion battery with anti-lithium plating properties, characterized in that, The lithium-ion battery cell included in any one of claims 1-6 is a lithium-ion battery cell designed to prevent lithium plating.

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