Battery cell, battery and electronic equipment
By adopting the active layer and glue layer design with a laminated structure in the negative electrode sheet of the lithium-ion battery, the volume expansion and extension of the negative electrode sheet during the charging and discharging process is solved, and the cycle life and safety of the battery are improved.
Patent Information
- Application Number
- CN202311871044.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2023-12-28
- Publication Date
- 2025-07-08
AI Technical Summary
The negative electrode sheet of lithium-ion battery will undergo large volume expansion and extension during the charging and discharging process, resulting in coating breakage, material dropping, sharp deterioration in circulation, and short-circuiting of the positive and negative electrode sheet, affecting the safety and life of the battery cell.
The negative electrode sheet is designed as a laminated structure, including a current collector and an active structural layer arranged thereon. The active structural layer consists of a plurality of active layers and glue layers. The glue layer separates the active layers, absorbs deformation stress, and increases the contact area to suppress expansion and extension.
Effectively suppress the expansion and extension of the negative electrode sheet, improve cycle life and safety performance, and avoid problems such as coating breakage, material dropout and thermal runaway.
Smart Images
Figure CN120280443A_ABST
Abstract
Description
Technical Field
[0001] The embodiments of the present application relate to the technical field of batteries, and particularly to a battery cell, a battery, and an electronic device. Background Art
[0002] A lithium-ion battery is a secondary battery that mainly works by the movement of lithium ions between the positive electrode and the negative electrode. During the charging and discharging process, lithium ions are embedded and de-embedded between the two electrodes back and forth; during charging, lithium ions are de-embedded from the positive electrode and embedded in the negative electrode through the electrolyte, and the negative electrode is in a lithium-rich state; during discharging, the opposite occurs. Lithium-ion batteries are widely used in the electronic terminal industry, the new energy industry, and the energy storage industry, etc., due to their advantages such as high energy density, high voltage platform, small volume, long life, no memory effect, low self-discharge rate, and environmental friendliness.
[0003] In the related art, a lithium-ion battery generally includes a housing and a battery cell. The battery cell is located inside the housing, and the housing is filled with electrolyte. The battery cell includes a positive electrode plate, a separator, and a negative electrode plate. Both the positive electrode plate and the negative electrode plate include a current collector and an active layer coated on the surface of the current collector. Among them, a positive electrode active material layer is coated on the positive electrode plate, and a negative electrode active material layer is coated on the negative electrode plate. The active layer is used to undergo a chemical reaction in the electrolyte to generate electric energy. There is a separator between the positive electrode plate and the negative electrode plate. After the three are stacked, a stacked battery cell can be formed, or after the three are stacked, a wound battery cell can be formed. Among them, the negative electrode plate generally uses silicon material, and the positive electrode plate generally uses materials such as lithium cobaltate or lithium iron phosphate.
[0004] However, the negative electrode plate will undergo a large volume expansion during the charging and discharging process, resulting in not only a large volume expansion of the electrode plate along the z direction but also a large extension along the x and y directions during the cycling process, bringing problems such as coating fragmentation, material dropping, and a sharp deterioration of the cycle, and even a series of problems such as short circuit between the positive and negative electrode plates and thermal runaway and fire of the battery cell. Summary of the Invention
[0005] The embodiments of the present application provide a battery cell, a battery, and an electronic device, which can avoid or reduce the large volume expansion of the electrode plate during the charging and discharging process, and thus can avoid or reduce the large volume expansion of the electrode plate along the z direction and the large extension along the x and y directions during the cycling process, so as to avoid or reduce technical problems such as coating fragmentation, material dropping, a sharp deterioration of the cycle, short circuit between the positive and negative electrode plates, and thermal runaway and fire of the battery cell.
[0006] In a first aspect, the embodiments of the present application provide a battery cell, which at least includes: a negative electrode plate and a separator arranged in a stacked manner;
[0007] The negative electrode plate includes: a current collector and an active structure layer located on at least one surface of the current collector;
[0008] The active structure layer at least includes, arranged in a stacked manner: a plurality of active layers and an adhesive layer located between two adjacent active layers.
[0009] In the battery cell provided by the embodiment of the present application, the negative electrode tab is designed to include a current collector and an active structure layer provided on one or both sides of the current collector. Among them, the active structure layer is designed to include a plurality of active layers arranged in a stacked manner and an adhesive layer located between two adjacent active layers. The adhesive layer separates the active layers. In this way, after the negative electrode tab repeatedly expands or contracts in volume, the adhesive layer distributed between the multiple active layers can absorb the deformation stress and delay the fatigue failure of the negative electrode material. In addition, in the embodiment of the present application, by increasing the contact area between the adhesive layer and the active layer, the binding ability to the negative electrode tab can also be improved in all directions, inhibiting the expansion and extension of the negative electrode tab, thereby improving the cycle life and safety performance.
[0010] Therefore, the battery cell provided by the embodiment of the present application can avoid or reduce large volume expansion of the electrode tab during charge and discharge, and further can avoid or reduce large volume expansion of the electrode tab along the z direction and large extension along the x and y directions during the cycle, thereby avoiding or reducing technical problems such as coating fragmentation, material loss, sharp deterioration of the cycle, short circuit between the positive and negative electrode tabs, and thermal runaway and fire of the battery cell.
[0011] In a possible implementation manner, among the plurality of active layers, from the active layer close to the current collector to the active layer far from the current collector, the thickness of the active layer is the same or gradually decreases.
[0012] The thickness of each active layer among the multiple active layers is the same, or the thickness of the active layer farther from the current collector is smaller.
[0013] Since the ductility of the active layer farther from the current collector is greater during charge and discharge of the negative electrode tab, by designing the thickness of the active layer far from the current collector to be smaller, the binding ability to the active layer can be increased, thereby suppressing the expansion and extension of the negative electrode tab to a certain extent.
[0014] In a possible implementation manner, among the plurality of active layers, the thickness of each active layer is between 20 μm and 500 μm.
[0015] In a possible implementation manner, when the number of the adhesive layers is multiple, among the multiple adhesive layers, from the adhesive layer close to the current collector to the adhesive layer far from the current collector, the thickness of the adhesive layer is the same or gradually increases.
[0016] The thickness of each adhesive layer among the multiple adhesive layers is the same, or the thickness of the adhesive layer farther from the current collector is greater.
[0017] During the charge and discharge process of the negative electrode plate, the ductility of the active layer farther away from the current collector is greater. By designing the thickness of the adhesive layer farther away from the current collector to be larger, the binding ability to the active layer can be increased, thereby suppressing the expansion and extension of the negative electrode plate to a certain extent.
[0018] In a possible implementation, the ratio of the total thickness of the plurality of adhesive layers to the total thickness of the plurality of active layers is 1:30 - 1:2000.
[0019] In a possible implementation, each of the active layers includes: an active material, a first conductive agent, and a first binder that are doped with each other;
[0020] Among them, the first binder is a lithiated binder.
[0021] By designing the first binder in the active layer as a lithiated binder, the lithium ion transmission ability in the active layer can be improved preferably.
[0022] In a possible implementation, each of the adhesive layers includes: a second conductive agent and a second binder that are doped with each other;
[0023] Among them, the adhesive force of the second binder is greater than that of the first binder.
[0024] In this way, the bonding ability between the active layers can be improved.
[0025] In a possible implementation, the second binder is any one or more of polyamide, polyvinylamine, polymethyl methacrylate, and polyacrylic acid.
[0026] In a possible implementation, among the plurality of adhesive layers, from the second binder of the adhesive layer close to the current collector to the second binder of the adhesive layer far from the current collector, the adhesive force of the second binder is the same or gradually increases.
[0027] Among the plurality of adhesive layers, the adhesive force of the second binder in each adhesive layer is the same, or the adhesive force of the second binder in the adhesive layer farther away from the current collector is greater.
[0028] During the charge and discharge process of the negative electrode plate, the ductility of the active layer farther away from the current collector is greater. By designing the adhesive force of the second binder in the adhesive layer far from the current collector to be larger, the binding ability to the active layer can be increased, thereby suppressing the expansion and extension of the negative electrode plate to a certain extent.
[0029] In a possible implementation, each of the adhesive layers further includes: a solid electrolyte;
[0030] The solid electrolyte is doped with the second conductive agent and the second binder.
[0031] The second binder, in cooperation with the second conductive agent and the solid electrolyte, can preferably maintain the electron and lithium ion transmission channels in the adhesive layer.
[0032] In a possible implementation manner, each of the adhesive layers is disposed entirely and uniformly between two adjacent active layers.
[0033] The adhesive layer disposed entirely and uniformly can achieve the maximum contact area between the second binder and the active layer, and thus can achieve the strongest binding ability in all directions of the active layer.
[0034] In a possible implementation manner, each of the adhesive layers is disposed in a grid shape between two adjacent active layers.
[0035] The adhesive layer disposed in a grid shape can preferably balance the relationship between the energy density, expansion and extension of the adhesive layer and the active layer.
[0036] In a possible implementation manner, each of the adhesive layers is located at at least part of the outer edge position between two adjacent active layers.
[0037] By designing the adhesive layer at at least part of the outer edge position between two adjacent active layers, the solution to the extension problem of the negative electrode tab can be more emphasized, and thus the binding ability to the side edge of the active layer can be improved.
[0038] In a possible implementation manner, it further includes: a positive electrode tab, a positive electrode ear and a negative electrode ear;
[0039] The positive electrode tab and the negative electrode tab and the separator are stacked, and the separator is located between the positive electrode tab and the negative electrode tab;
[0040] The positive electrode ear is connected to the positive electrode tab, the negative electrode ear is connected to the negative electrode tab, and the positive electrode ear and the negative electrode ear do not overlap in the thickness direction of the battery cell.
[0041] In a second aspect, an embodiment of the present application provides a battery, which at least includes: a housing and any one of the above battery cells;
[0042] The battery cell is located inside the housing, and the housing has an electrolyte inside.
[0043] The battery provided by the embodiment of the present application includes at least a housing and an electric core located inside the housing. The electric core is designed such that the negative electrode tab includes a current collector and an active structure layer provided on one or both sides of the current collector. The active structure layer is designed to include a plurality of stacked active layers and an adhesive layer located between two adjacent active layers. The adhesive layer separates the active layers. In this way, after the negative electrode tab repeatedly expands or contracts in volume, the adhesive layer distributed between the multiple active layers can absorb the deformation stress and delay the fatigue failure of the negative electrode material. In addition, in the embodiment of the present application, by increasing the contact area between the adhesive layer and the active layer, the binding ability to the negative electrode tab can also be improved in all directions, inhibiting the expansion and extension of the negative electrode tab, thereby improving the cycle life and safety performance.
[0044] Therefore, the electric core provided by the embodiment of the present application can avoid or reduce the large volume expansion of the electrode tab during charge and discharge. Furthermore, it can avoid or reduce the large volume expansion of the electrode tab in the z direction and the large extension in the x and y directions during the cycling process, thereby avoiding or reducing technical problems such as coating breakage, material loss, sharp deterioration of the cycle, short circuit between the positive and negative electrode tabs, and thermal runaway and ignition of the electric core.
[0045] In a third aspect, the embodiment of the present application provides an electronic device, which at least includes: an electronic device body and the battery described above;
[0046] wherein, the battery provides electrical energy for the electronic device body.
[0047] The electronic device provided by the embodiment of the present application includes at least a battery, which at least includes a housing and an electric core located inside the housing. The electric core is designed such that the negative electrode tab includes a current collector and an active structure layer provided on one or both sides of the current collector. The active structure layer is designed to include a plurality of stacked active layers and an adhesive layer located between two adjacent active layers. The adhesive layer separates the active layers. In this way, after the negative electrode tab repeatedly expands or contracts in volume, the adhesive layer distributed between the multiple active layers can absorb the deformation stress and delay the fatigue failure of the negative electrode material. In addition, in the embodiment of the present application, by increasing the contact area between the adhesive layer and the active layer, the binding ability to the negative electrode tab can also be improved in all directions, inhibiting the expansion and extension of the negative electrode tab, thereby improving the cycle life and safety performance.
[0048] Therefore, the electric core provided by the embodiment of the present application can avoid or reduce the large volume expansion of the electrode tab during charge and discharge. Furthermore, it can avoid or reduce the large volume expansion of the electrode tab in the z direction and the large extension in the x and y directions during the cycling process, thereby avoiding or reducing technical problems such as coating breakage, material loss, sharp deterioration of the cycle, short circuit between the positive and negative electrode tabs, and thermal runaway and ignition of the electric core. Brief Description of the Drawings
[0049] Figure 1 It is a schematic plan view of the cell provided by an embodiment of the present application;
[0050] Figure 2 It is a schematic cross-sectional view of the negative electrode tab in the cell provided by an embodiment of the present application;
[0051] Figure 3 It is a schematic plan view of the cell in the related art;
[0052] Figure 4 It is a schematic cross-sectional view of the negative electrode tab in the cell in the related art;
[0053] Figure 5 It is a schematic plan view of the cell in the related art after multiple charge and discharge cycles;
[0054] Figure 6 It is a schematic cross-sectional view of the negative electrode tab in the cell in the related art after multiple charge and discharge cycles;
[0055] Figure 7 It is a schematic cross-sectional view of the negative electrode tab in the cell in the related art after multiple charge and discharge cycles;
[0056] Figure 8 It is a schematic cross-sectional view of the negative electrode tab in the cell provided by an embodiment of the present application after multiple charge and discharge cycles;
[0057] Figure 9 It is a schematic view of the structure of the adhesive layer in the negative electrode tab of the cell provided by an embodiment of the present application;
[0058] Figure 10 It is a schematic view of the structure of the adhesive layer in the negative electrode tab of the cell provided by an embodiment of the present application;
[0059] Figure 11 It is a schematic view of the structure of the adhesive layer in the negative electrode tab of the cell provided by an embodiment of the present application;
[0060] Figure 12 It is a schematic view of the structure of the adhesive layer in the negative electrode tab of the cell provided by an embodiment of the present application;
[0061] Figure 13 It is a schematic view of the structure of the active structure layer in the negative electrode tab of the cell provided by an embodiment of the present application.
[0062] Description of the Reference Numerals:
[0063] 100 - cell;
[0064] 110 - negative electrode tab;
[0065] 111 - current collector;
[0066] 112 - Active structure layer;
[0067] 1121 - First active layer; 1122 - Second active layer; 1123 - Third active layer; 1124 - First adhesive layer; 1125 - Second adhesive layer;
[0068] 120 - Separator;
[0069] 130 - Negative electrode tab;
[0070] 140 - Positive electrode tab. Detailed implementation manners
[0071] The terms used in the implementation manners part of this application are only used to explain the specific embodiments of this application, rather than aiming to limit this application. The implementation manners of the embodiments of this application will be described in detail below with reference to the accompanying drawings.
[0072] With the development of the times, people's demand for energy storage is constantly increasing. In recent years, new energy vehicles have developed rapidly, bringing infinite vitality and opportunities to the domestic automotive industry market. As the main power source of electric vehicles, power batteries are an important key component to promote the development of new energy vehicles. The higher the energy density of the battery, the higher the cruising range of the vehicle, and the improvement of the long cruising range can alleviate range anxiety.
[0073] Lithium - ion batteries have gradually occupied the market in a series of fields such as consumer electronics, electric vehicles, automobiles, power tools, and smart grids due to their high energy density, high single - cell working voltage, large working temperature range, low self - discharge, and long cycle life, and have broad application prospects.
[0074] Figure 1 It is a schematic plan view of the cell provided by an embodiment of this application. Figure 2 It is a schematic cross - sectional view of the negative electrode plate in the cell provided by an embodiment of this application.
[0075] An embodiment of this application provides a battery. Among them, the battery includes a housing and a cell disposed inside the housing, and moreover, there is an electrolyte inside the housing, and the cell is located in the electrolyte.
[0076] The cell includes electrode plates. Specifically, as Figure 1 shown, the cell 100 includes a positive electrode plate, a separator 120, and a negative electrode plate 110. The positive electrode plate, the negative electrode plate 110, and the separator 120 are stacked, and the separator 120 is located between the positive electrode plate and the negative electrode plate 110. Among them, a positive electrode tab 140 can extend from the positive electrode plate, and a negative electrode tab 130 can extend from the negative electrode plate 110.
[0077] It is easily understandable that in the embodiments of the present application, the number of the positive electrode tabs 140 and the negative electrode tabs 130 of the battery cell 100 can be multiple respectively.
[0078] In the embodiments of the present application, the battery can be a laminated battery, that is, the battery cell 100 inside the battery can be a battery cell 100 with a laminated structure.
[0079] Specifically, the battery cell 100 of the battery can be a battery cell 100 with a laminated structure, that is, the positive electrode plate, the separator 120, and the negative electrode plate 110 are stacked in sequence, so that the formed battery cell 100 is in a laminated shape.
[0080] Among them, the positive electrode plate is composed of a current collector and a positive electrode active material layer coated on one or both sides of the current collector. The positive electrode active material can be lithium cobaltate, lithium iron phosphate, lithium manganate, lithium nickel manganate, etc. Of course, in some examples, the positive electrode active material can also be other high-potential materials, etc.
[0081] The negative electrode plate 110 can be composed of a current collector and a negative electrode active material layer coated on both sides of the current collector. The negative electrode active material can be graphite, silicon, carbon, silicon oxide, silicon carbon, elemental silicon, or a composite material thereof with graphite, etc. Of course, in some examples, the negative electrode active material can also be other low-potential materials, etc.
[0082] It can be understood that the structure schematically shown in the embodiments of the present application does not constitute a specific limitation on the battery cell 100 or the battery. In other embodiments of the embodiments of the present application, the battery cell 100 may further include more or fewer components than those shown in the figure, or combine certain components, or split certain components, or have different component arrangements.
[0083] The battery cell 100 needs to be charged and discharged multiple times. Among them, taking a lithium-ion battery with the negative electrode plate 110 made of silicon material as an example, the lithium-ion battery has a high energy density. The theoretical capacity of silicon reaches 4200 mAh / g and has a wide application prospect. However, during the charge and discharge process, there is a large expansion, bringing a series of problems such as particle pulverization and sharp deterioration of the cycle, which limits the wide application of silicon.
[0084] Specifically, the silicon material will undergo a large volume expansion (generally >300%) during the charge and discharge process, resulting in that during the cycle process, in addition to the excessive volume expansion of the negative electrode plate 110 along the z direction, there will also be a large extension along the x and y directions, bringing problems such as coating breakage, material loss, sharp deterioration of the cycle, and even short circuit between the positive and negative electrode plates, thermal runaway and fire of the battery cell 100, etc., affecting its practical application.
[0085] Figure 3 It is a schematic diagram of the planar structure of the battery cell 100 in the related art. Figure 4It is a schematic cross-sectional structure diagram of the negative electrode tab 110 in the battery cell 100 in the related art. Figure 5 It is a schematic plan structure diagram of the battery cell 100 after multiple charge and discharge cycles in the related art. Figure 6 It is a schematic cross-sectional structure diagram of the negative electrode tab 110 in the battery cell 100 after multiple charge and discharge cycles in the related art.
[0086] For example, in the related art, before use, the battery cell 100 is in Figure 1 the state shown, and the negative electrode tab 110 in the battery cell 100 has the Figure 2 structure shown. After the battery cell 100 undergoes multiple charge and discharge cycles, as shown in Figure 3 and Figure 4 shown, the negative electrode tab 110 extends in the x and y directions, even exceeding the separator 120. In this way, the negative electrode tab 110 directly contacts the positive electrode tab 140 or the outer shell of the battery, posing a great risk of short circuit and even thermal runaway.
[0087] Based on this, the embodiments of the present application provide a new battery cell 100 and battery to solve the above technical problems. Specifically, in this battery cell 100, the battery cell 100 at least includes a negative electrode tab 110 and a separator 120 arranged in a stacked manner. The negative electrode tab 110 includes a current collector and an active structure layer located on at least one surface of the current collector. The active structure layer at least includes: a plurality of active layers and an adhesive layer located between adjacent two active layers arranged in a stacked manner. In this way, it is possible to avoid or reduce large volume expansion of the tab during the charge and discharge process, and further avoid or reduce large volume expansion of the tab in the z direction and large extension in the x and y directions during the cycling process, thereby being able to avoid or reduce technical problems such as coating breakage, material shedding, sharp deterioration of cycling, short circuit between the positive and negative electrode tabs, and thermal runaway and ignition of the battery cell 100.
[0088] Next, with reference to specific drawings, taking different embodiments as examples, the specific structure of the battery cell 100 will be introduced in detail.
[0089] Referring to Figure 1 and Figure 2 shown, the embodiments of the present application provide a battery cell 100, which can be applied to a battery. Specifically, this battery cell 100 can at least include: a negative electrode tab 110 and a separator 120 arranged in a stacked manner.
[0090] The separator 120 refers to a layer of separator material between the positive electrode tab and the negative electrode tab 110, which is a key part in the battery cell 100 and affects the safety and cost of the battery cell 100. The main function of the separator 120 is to isolate the positive electrode tab and the negative electrode tab 110, and prevent electrons in the battery from freely passing through, while allowing ions in the electrolyte to freely pass between the positive and negative electrodes.
[0091] The ionic conductivity of the separator 120 is related to the overall performance of the battery. Its function of isolating the positive and negative electrodes enables the battery to limit the increase in current in the case of overcharging or rising temperature, preventing the battery from short - circuiting and causing an explosion, having a microporous self - closing protection function, and playing a role in protecting the safety of battery users and equipment. Among them, in the embodiments of the present application, the material of the separator 120 can be polyethylene or polypropylene. Exemplarily, in some embodiments, the separator 120 can, for example, adopt a high - porosity ceramic separator, or a polymer coating can also be provided on the surface of the separator. The embodiments of the present application do not limit this and are not limited to the above examples.
[0092] Among them, the negative electrode plate 110 may include: a current collector 111 and an active structure layer 112 located on at least one surface of the current collector 111.
[0093] For example, the negative electrode plate 110 may include a current collector 111 and an active structure layer 112 located on one surface of the current collector 111 (see Figure 2 shown), or the negative electrode plate 110 may include a current collector 111 and active structure layers 112 located on both surfaces of the current collector 111. The embodiments of the present application do not limit this.
[0094] The main function of the current collector 111 is to collect the current generated by the active substances in the battery cell 100 so as to form a larger current for external output. Therefore, the current collector 111 should be in full contact with the active substances, and the internal resistance of the current collector 111 should be as small as possible.
[0095] Among them, the current collector 111 can be a metal foil. Metal copper and metal aluminum have low resistance and good ductility. For example, the current collector 111 can be a substrate formed by copper foil, or the current collector 111 can be a substrate formed by aluminum foil. In addition, to ensure the stability of the current collector 111 inside the battery cell 100, the purity of copper foil and aluminum foil is generally required to be above 98%.
[0096] Or, in some other embodiments, the current collector 111 can also be a substrate formed by other conductive metal materials.
[0097] In the embodiments of the present application, the active structure layer 112 can at least include: a plurality of active layers stacked and an adhesive layer located between two adjacent active layers. Among them, the number of active layers can be two, three, four, five or more, and correspondingly, the number of adhesive layers can be one, two, three, four or more. One adhesive layer is provided between every two adjacent active layers.
[0098] The battery cell 100 is designed such that the negative electrode tab 110 can include a current collector 111 and an active structure layer 112 provided on one or both sides of the current collector 111. Among them, the active structure layer 112 is designed to include a plurality of active layers stacked and adhesive layers located between adjacent two active layers. The adhesive layers separate the active layers. In this way, the adhesive layers distributed between the multiple active layers can absorb deformation stress after the repeated volume expansion or contraction of the negative electrode tab 110, delaying the fatigue failure of the negative electrode material.
[0099] In addition, in the embodiments of the present application, by increasing the contact area between the adhesive layer and the active layer, the binding ability to the negative electrode tab 110 can also be improved in all directions, suppressing the expansion and extension of the negative electrode tab 110, thereby improving the cycle life and safety performance.
[0100] Therefore, the battery cell 100 provided by the embodiments of the present application can avoid or reduce large volume expansion of the electrode tab during charge and discharge, and further can avoid or reduce large volume expansion of the electrode tab in the z direction and large extension in the x and y directions during the cycle process, thereby avoiding or reducing technical problems such as coating breakage, material loss, sharp deterioration of the cycle, short circuit between the positive and negative electrode tabs, and thermal runaway and fire of the battery cell 100.
[0101] Figure 7 It is a schematic cross-sectional structure diagram of the negative electrode tab 110 of the battery cell 100 after multiple charge and discharge cycles in the related art. Figure 8 It is a schematic cross-sectional structure diagram of the negative electrode tab 110 of the battery cell 100 provided by an embodiment of the present application after multiple charge and discharge cycles.
[0102] Comparison Figure 7 and Figure 8 It can be seen that in the related art, after the repeated volume expansion or contraction of the negative electrode tab 110, the binder in the active structure layer 112 undergoes strain fatigue, resulting in molecular chain breakage or difficult-to-recover deformation, a decrease in the binding ability, and an increasing particle spacing, which easily leads to excessive expansion and extension of the negative electrode tab 110.
[0103] In the embodiments of the present application, the negative electrode tab 110 adopts a laminated structure. The tight adhesive layers between the active layers in the negative electrode tab 110 can not only absorb deformation stress and delay the fatigue failure of the material after the repeated volume expansion or contraction of the negative electrode tab 110, but also improve the binding ability to the negative electrode in the x, y, and z directions by increasing the contact area between the binder and the negative electrode material, suppressing its expansion and extension, thereby improving the cycle life and safety performance.
[0104] In the embodiments of the present application, among the multiple active layers, from the active layer close to the current collector 111 to the active layer far from the current collector 111, the thickness of the active layer is the same or gradually decreases.
[0105] That is, the thickness of each active layer in the multiple active layers is the same, or the thickness of the active layer farther away from the current collector 111 is smaller. Since the ductility of the active layer farther away from the current collector 111 is greater during the charge and discharge process of the negative electrode sheet 110, by designing the thickness of the active layer farther away from the current collector 111 to be smaller, the binding ability to the active layer can be increased, thereby suppressing the expansion and extension of the negative electrode sheet 110 to a certain extent.
[0106] Specifically, taking Figure 2 the negative electrode sheet 110 shown as an example, the negative electrode sheet 110 includes a current collector 111 and an active structure layer 112 located on one side of the current collector 111. The active structure layer 112 includes a first active layer 1121, a second active layer 1122, a third active layer 1123, a first adhesive layer 1124, and a second adhesive layer 1125 that are stacked. Among them, the second active layer 1122 is located between the first active layer 1121 and the third active layer 1123, the first adhesive layer 1124 is located between the first active layer 1121 and the second active layer 1122, and the second adhesive layer 1125 is located between the second active layer 1122 and the third active layer 1123.
[0107] Among them, as Figure 2 shown, the first active layer 1121 is relatively closest to the current collector 111, and the third active layer 1123 is relatively farthest from the current collector 111.
[0108] Among them, the first active layer 1121 can be, for example, on the current collector 111 by means of spraying, sputtering, deposition, etc. The specific forming method of the active layer on the current collector 111 is not limited in the embodiments of the present application.
[0109] In the embodiments of the present application, the thickness of the first active layer 1121 is greater than the thickness of the second active layer 1122, and the thickness of the second active layer 1122 is greater than the thickness of the third active layer 1123.
[0110] In the embodiments of the present application, among the multiple active layers, the thickness of each active layer can be between 20 μm and 500 μm.
[0111] In the embodiments of the present application, since the thickness of the active layer farther away from the current collector 111 is smaller, among the multiple active layers, the thickness of the active layer away from the current collector 111 can be greater than 20 μm, and the thickness of the active layer close to the current collector 111 can be less than 500 μm.
[0112] Specifically, taking Figure 2 the negative electrode sheet 110 shown as an example, the thickness of the first active layer 1121 can be less than 500 μm, the thickness of the third active layer 1123 can be greater than 20 μm, and the thickness of the second active layer 1122 can be between 20 μm and 500 μm.
[0113] It should be noted here that the numerical values and numerical ranges involved in this application are approximate values. Affected by the manufacturing process, there may be a certain range of errors, which can be considered negligible by those skilled in the art.
[0114] In the embodiments of this application, when the number of adhesive layers is multiple, among the multiple adhesive layers, from the adhesive layer close to the current collector 111 to the adhesive layer far from the current collector 111, the thickness of the adhesive layer is the same or gradually increases.
[0115] That is to say, the thickness of each adhesive layer among the multiple adhesive layers is the same, or the thickness of the adhesive layer farther from the current collector 111 is greater. Since during the charge and discharge process of the negative electrode tab 110, the ductility of the active layer farther from the current collector 111 is greater, by designing the thickness of the adhesive layer far from the current collector 111 to be larger, the binding ability to the active layer can be increased, thereby suppressing the expansion and extension of the negative electrode tab 110 to a certain extent.
[0116] Specifically, taking Figure 2 the negative electrode tab 110 shown as an example, in the embodiments of this application, the thickness of the first adhesive layer 1124 is less than the thickness of the second adhesive layer 1125.
[0117] In the embodiments of this application, the ratio of the total thickness of the multiple adhesive layers to the total thickness of the multiple active layers can be 1:30 - 1:2000. For example, the ratio of the total thickness of the multiple adhesive layers to the total thickness of the multiple active layers can be 1:30, 1:100, 1:500, 1:1000, 1:1500 or 1:2000, etc. The embodiments of this application do not limit this, nor are they limited to the above examples.
[0118] Specifically, taking Figure 2 the negative electrode tab 110 shown as an example, in the embodiments of this application, the ratio of the total thickness of the first adhesive layer 1124 and the second adhesive layer 1125 to the total thickness of the first active layer 1121, the second active layer 1122 and the third active layer 1123 can be 1:30 - 1:2000.
[0119] In the embodiments of this application, each active layer may include: an active material, a first conductive agent, and a first binder, wherein the active material, the first conductive agent, and the first binder are doped with each other. Among them, the material of the first conductive agent can be a carbon material.
[0120] Among them, the first binder can be a lithiated binder. For example, the first binder can be polyacrylic acid lithium (PAA-Li) or carboxymethyl cellulose lithium (CMC-Li). Or, in some other embodiments, the first binder can also be other types of lithiated binders. The embodiments of this application do not limit the specific type of the lithiated binder, nor are they limited to the above examples.
[0121] By designing the first adhesive in the active layer as a lithiated adhesive, the lithium ion transport ability in the active layer can be improved preferably.
[0122] It should be noted here that in the embodiments of the present application, the components of each active layer may be the same or different. For example, the components of the first active layer 1121 and the second active layer 1122 may be the same or different, and the embodiments of the present application do not limit this.
[0123] In the embodiments of the present application, each adhesive layer may include: a second conductive agent and a second adhesive, and the second conductive agent and the second adhesive are arranged in a doped manner. Among them, the material of the second conductive agent may be a carbon material.
[0124] It should be noted here that in the embodiments of the present application, the components of each adhesive layer may be the same or different. For example, the components of the first adhesive layer 1124 and the second adhesive layer 1125 may be the same or different, and the embodiments of the present application do not limit this.
[0125] Among them, the adhesive force of the second adhesive is greater than that of the first adhesive. In this way, the bonding ability between each active layer can be improved.
[0126] It should be noted that in the embodiments of the present application, the material used for the second adhesive may be any one or more of polyamide, polyvinylamine, polymethyl methacrylate, and polyacrylic acid.
[0127] Alternatively, in some embodiments, the material used for the second adhesive may also be one or more combinations of polyvinylidene fluoride, sodium carboxymethyl cellulose, lithium hydroxycellulose, styrene-butadiene rubber, a homopolymer or copolymer of tetrafluoroethylene and hexafluoropropylene, and polyvinyl alcohol.
[0128] In addition, it can be understood that in the embodiments of the present application, when the number of adhesive layers is multiple, among the multiple adhesive layers, from the second adhesive of the adhesive layer close to the current collector 111 to the second adhesive of the adhesive layer far from the current collector 111, the adhesive force of the second adhesive is the same or gradually increases.
[0129] That is to say, among the multiple adhesive layers, the adhesive force of the second adhesive in each adhesive layer is the same, or the adhesive force of the second adhesive in the adhesive layer farther from the current collector 111 is greater. Since during the charge and discharge process of the negative electrode tab 110, the ductility of the active layer farther from the current collector 111 is greater, by designing the adhesive force of the second adhesive in the adhesive layer far from the current collector 111 to be larger, the binding ability to the active layer can be increased, thereby suppressing the expansion and extension of the negative electrode tab 110 to a certain extent.
[0130] Specifically, take Figure 2Taking the negative electrode tab 110 shown as an example, in the embodiment of the present application, the thickness of the adhesion force of the second adhesive in the first adhesive layer 1124 is less than the adhesion force of the second adhesive in the second adhesive layer 1125. In this way, the binding ability to the active layer can be increased, thereby suppressing the expansion and extension of the negative electrode tab 110 to a certain extent.
[0131] The negative electrode tab 110 in the embodiment of the present application adopts a laminated structure. By introducing an adhesive layer between each active layer, the tight adhesive layer can absorb deformation stress after repeated volume expansion or contraction changes of the negative electrode tab 110, delay the fatigue failure of the material, and give full play to the bonding effect of the first binder in each active layer and the second binder in the adhesive layer.
[0132] In the embodiment of the present application, each adhesive layer may further include: a solid electrolyte, wherein the solid electrolyte is doped with the second conductive agent and the second adhesive. The second adhesive cooperates with the second conductive agent and the solid electrolyte to better maintain the electron and lithium ion transmission channels in the adhesive layer.
[0133] Figure 9 It is a schematic diagram of the structure of the adhesive layer in the negative electrode tab 110 of the battery cell 100 provided in an embodiment of the present application. Figure 10 It is a schematic diagram of the structure of the adhesive layer in the negative electrode tab 110 of the battery cell 100 provided in an embodiment of the present application. Figure 11 It is a schematic diagram of the structure of the adhesive layer in the negative electrode tab 110 of the battery cell 100 provided in an embodiment of the present application. Figure 12 It is a schematic diagram of the structure of the adhesive layer in the negative electrode tab 110 of the battery cell 100 provided in an embodiment of the present application.
[0134] In the embodiment of the present application, the specific setting method of the adhesive layer between two adjacent active layers may include but is not limited to the following possible implementation methods:
[0135] One possible implementation method is: as Figure 9 shown, each adhesive layer is arranged entirely and evenly between two adjacent active layers.
[0136] The adhesive layer arranged entirely and evenly can achieve the maximum contact area between the second binder and the active layer, and thus can achieve the strongest binding ability in all directions of the active layer.
[0137] Another possible implementation method is: as Figure 10 and Figure 11 shown, each adhesive layer is arranged in a grid pattern between two adjacent active layers.
[0138] The adhesive layer arranged in a grid pattern can better balance the relationship between the energy density, expansion and extension of the adhesive layer and the active layer.
[0139] Another possible implementation is: in the embodiments of the present application, each adhesive layer is located at at least a partial outer edge position between two adjacent active layers.
[0140] As Figure 12 shown, the adhesive layer is located at the upper and lower edge positions between two adjacent active layers. It should be noted that the positive electrode tab 140 and the negative electrode tab 130 can be formed by cutting the current collector 111 after coating. Figure 12 Fig. is a schematic structural diagram of the electrode roll before the tabs are cut. In actual processes, generally, Figure 12 it is folded in half along the middle and cut into two electrode rolls up and down.
[0141] The electrode sheet can have multiple tabs. For example, Figure 12 as shown, multiple tabs can be formed by cutting on one side edge of the negative electrode sheet 110, and the multiple tabs can be distributed at intervals along the length direction of the negative electrode sheet 110.
[0142] By designing the adhesive layer at at least a partial outer edge position between two adjacent active layers, it is possible to focus more on solving the problem of the extension of the negative electrode sheet 110, and thus improve the binding ability to the side edges of the active layer.
[0143] In the embodiments of the present application, the negative electrode sheet 110 may further include: a positive electrode sheet, a positive electrode tab 140, and a negative electrode tab 130. Among them, the positive electrode sheet is stacked with the negative electrode sheet 110 and the separator 120, the separator 120 is located between the positive electrode sheet and the negative electrode sheet 110, and moreover, the positive electrode tab 140 is connected to the positive electrode sheet, and the negative electrode tab 130 is connected to the negative electrode sheet 110.
[0144] Among them, in one possible implementation, the positive electrode tab 140 and the negative electrode tab 130 may not overlap in the thickness direction of the battery cell 100.
[0145] Figure 13 Fig. is a schematic structural diagram of the active structure layer 112 in the negative electrode sheet 110 of the battery cell 100 provided in an embodiment of the present application.
[0146] Testing the negative electrode sheet 110 with a stacked structure, the conductivity of the adhesive layer is slightly worse than that of the active layer. In one mode, within the field of view, the negative electrode sheet 110 can be seen to be divided into multiple layers by light-colored long strips (such as Figure 13 shown), and the light-colored long strips are the adhesive layers. In addition, observing the adhesive layer part at a magnified scale, continuous adhesive layers and solid electrolyte and conductive agent particles dispersed in the adhesive layer can be seen.
[0147] In addition, an embodiment of the present application further provides an electronic device, which may include an electronic device body and the battery provided in the embodiment of the present application, and the battery provides electrical energy for the electronic device body.
[0148] Among them, the electronic device body may be a wearable electronic device or other electronic products, or a medical electronic device used in medical treatment, etc., and the embodiment of the present application does not limit this.
[0149] In the description of the embodiment of the present application, it should be noted that unless otherwise clearly specified and limited, the terms "installation", "connection", and "connection" should be understood in a broad sense. For example, it may be a fixed connection, or indirectly connected through an intermediate medium, or it may be the internal communication of two components or the interaction relationship between two components. For those of ordinary skill in the art, the specific meanings of the above terms in the embodiment of the present application can be understood according to specific situations.
[0150] In the embodiment of the present application or the device or component implied must have a specific orientation, be constructed and operated in a specific orientation, so it cannot be understood as a limitation on the embodiment of the present application. In the description of the embodiment of the present application, the meaning of "a plurality" is two or more, unless otherwise specifically and precisely specified.
[0151] The terms "first", "second", "third", "fourth", etc. (if any) in the specification, claims and the above drawings of the embodiment of the present application are used to distinguish similar objects, and do not have to be used to describe a specific order or sequence. It should be understood that such data can be interchanged under appropriate circumstances, so that the embodiments of the present application described here can be implemented in an order other than those illustrated or described here. In addition, the terms "may include" and "have" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product or device that includes a series of steps or units does not have to be limited to those steps or units clearly listed, but may include other steps or units not clearly listed or inherent to these processes, methods, products or devices.
[0152] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the embodiments of the present application, and not to limit them. Although the embodiments of the present application have been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features, and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.
Claims
1. A battery cell, characterized in that, Comprising at least: A negative electrode tab and a separator arranged in a stacked manner; The negative electrode tab includes: a current collector and an active structure layer located on at least one surface of the current collector; The active structure layer at least includes: a plurality of active layers arranged in a stacked manner and an adhesive layer located between two adjacent active layers; 2. The battery cell according to claim 1, wherein, Among the plurality of active layers, from the active layer close to the current collector to the active layer far from the current collector, the thickness of the active layer is the same or gradually decreases.
3. The battery cell according to claim 2, characterized in that, Among the plurality of active layers, the thickness of each active layer is between 20 μm and 500 μm.
4. The battery cell according to any one of claims 1-3, characterized in that, When the number of the adhesive layers is multiple, among the multiple adhesive layers, from the adhesive layer close to the current collector to the adhesive layer far from the current collector, the thickness of the adhesive layer is the same or gradually increases.
5. The battery cell according to claim 4, wherein, The ratio of the total thickness of the multiple adhesive layers to the total thickness of the multiple active layers is 1:30 - 1:2000.
6. The battery cell according to claim 4 or 5, characterized in that, Each active layer includes: an active material, a first conductive agent, and a first binder arranged in an inter-doped manner; Wherein, the first binder is a lithiated binder.
7. The battery cell according to claim 6, wherein, Each adhesive layer includes: a second conductive agent and a second binder arranged in an inter-doped manner; Wherein, the adhesive force of the second binder is greater than that of the first binder.
8. The battery cell according to claim 7, wherein, The second binder is any one or more of polyamide, polyvinylamine, polymethyl methacrylate, and polyacrylic acid.
9. The cell according to claim 7 or 8, characterized in that, Among the multiple adhesive layers, from the second binder of the adhesive layer close to the current collector to the second binder of the adhesive layer far from the current collector, the adhesive force of the second binder is the same or gradually increases.
10. The battery cell according to any one of claims 7-9, characterized in that, Each adhesive layer further includes: a solid electrolyte; The solid electrolyte is arranged in an inter-doped manner with the second conductive agent and the second binder.
11. The battery cell according to any one of claims 1-10, characterized in that, Each adhesive layer is arranged in a whole-surface and uniform manner between two adjacent active layers.
12. The battery cell according to any one of claims 1-10, characterized in that, Each adhesive layer is arranged in a grid pattern between two adjacent active layers.
13. The battery cell according to any one of claims 1-10, characterized in that, Each adhesive layer is located at at least a partial outer edge position between two adjacent active layers.
14. The battery cell according to any one of claims 1-13, characterized in that, Further comprising: A positive electrode tab, a positive electrode ear, and a negative electrode ear; The positive electrode tab is arranged in a stacked manner with the negative electrode tab and the separator, and the separator is located between the positive electrode tab and the negative electrode tab; The positive electrode ear is connected to the positive electrode tab, the negative electrode ear is connected to the negative electrode tab, and the positive electrode ear and the negative electrode ear do not overlap in the thickness direction of the battery cell.
15. A battery, characterized in that, Comprising at least: a housing and the battery cell according to any one of claims 1 - 14 above; The battery cell is located inside the housing, and the housing has an electrolyte inside.
16. An electronic device, characterized in that, Comprising: An electronic device body and the battery according to claim 15 above; Wherein, the battery provides electrical energy for the electronic device body.