Negative pole piece, battery and electric device
The lithium-added mother plate electrode sheet is cut through laser cutting process to form an independent negative electrode sheet, which solves the problem of lithium-added electrode sheet edge lithium-added electrode sheet and improves the safety and energy density of the battery.
Patent Information
- Application Number
- CN202510403974.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-04-01
- Publication Date
- 2025-07-04
AI Technical Summary
In the prior art, lithium extraction phenomenon exists at the edges of lithium supplementation electrode sheets, which affects battery safety and performance.
The lithium-added mother plate electrode sheet is cut by laser cutting process, and a high-energy laser beam is used to hit the area to be cut, so that it melts, gasifies and fuses, forming an independent negative electrode sheet, reducing the prelithiation effect through high-temperature carbonization, releasing redundant capacity to prevent lithium evolution.
It effectively prevents battery short circuit, improves safety performance and energy density, and enhances the cycle stability and safety of the battery.
Smart Images
Figure CN120261467A_ABST
Abstract
Description
Technical Field
[0001] The present application relates to the field of energy storage devices, and particularly to a negative electrode sheet, a battery and an electrical device. Background Art
[0002] With the rapid development of new energy vehicles and electronic communication devices, consumers' demand for lithium-ion batteries with high capacity, long life, high stability and high power density characteristics is increasing rapidly. The electrode is the key factor determining the above performance. As is well known, the silicon negative electrode has a higher specific capacity than the traditional graphite negative electrode and is a hot direction for future development. However, due to its low initial Coulomb efficiency, the actual capacity of the silicon negative electrode is relatively low. An effective method is to pre-lithiate the electrode sheet to supplement the irreversible capacity consumed in the first cycle, improve the first efficiency of the silicon-doped battery, and then improve the energy density of the battery.
[0003] The electrode sheet to be pre-lithiated needs to be divided to form independent pre-lithiated electrode sheets. In the related art, the formed pre-lithiated electrode sheets have discontinuous pre-lithiation, especially lithium deposition at the edges of the pre-lithiated electrode sheets. Summary of the Invention
[0004] Embodiments of the present application provide a negative electrode sheet, a battery and an electrical device to at least solve the problem of lithium deposition at the edges of the pre-lithiated electrode sheets in the prior art.
[0005] A first aspect of an embodiment of the present application provides a negative electrode sheet, including:
[0006] A negative electrode current collector;
[0007] A negative electrode active layer, in the thickness direction of the negative electrode current collector, the negative electrode active layer is disposed on at least one side of the negative electrode current collector, and the negative electrode active layer includes a pre-lithiation region; the negative electrode active layer includes a first region and a second region adjacent to the first region, and the outer edge of the first region away from the center of the negative electrode active layer is the outer edge of the negative electrode sheet; wherein, the negative electrode active layer includes carbon element and lithium element, the ratio of the lithium element content to the carbon element content in the pre-lithiation region of the first region is A1, the ratio of the lithium element content to the carbon element content in the pre-lithiation region of the second region is A2, A1 is less than A2, and A1 is greater than 0 and less than 1 / 6; and / or, A2 is less than 1 / 6.
[0008] In a possible implementation manner, in a first direction, the size of the first region is less than or equal to 100 μm; wherein, the size is the average size.
[0009] And / or, the area of the pre-lithiation region accounts for 30% - 100% of the total area of the negative electrode active layer.
[0010] In a possible implementation, the lithium supplementation region includes a plurality of sub-lithium supplementation regions, and the plurality of sub-lithium supplementation regions are arranged in sequence along a second direction; the second direction intersects with the first direction.
[0011] In a possible implementation, the negative electrode active layer further includes a second region, and the second region is disposed on a side of the first region close to the center of the negative electrode tab; the lithium content in the lithium supplementation region of the second region is greater than the lithium content in the lithium supplementation region of the first region;
[0012] wherein, the lithium content in the lithium supplementation region of the first region is 10% - 30%, and / or, the lithium content in the lithium supplementation region of the second region is 20% - 40%.
[0013] In a possible implementation, the negative electrode active layer further includes a third region, and the third region is disposed on a side of the second region away from the first region;
[0014] the lithium content in the lithium supplementation region of the third region is greater than the lithium content in the lithium supplementation region of the first region; and / or, the lithium content in the lithium supplementation region of the third region is greater than or equal to the lithium content in the lithium supplementation region of the second region.
[0015] In a possible implementation, the negative electrode active layer further includes oxygen element, and the ratio of the oxygen element content to the total amount of all elements in the negative electrode active layer is less than or equal to 20%.
[0016] and / or, the negative electrode active layer further includes fluorine element, and the ratio of the fluorine element content to the total amount of all elements in the negative electrode active layer is 7% - 32%.
[0017] In a possible implementation, the absolute value of the difference between the fluorine element content in the lithium supplementation region of the second region and the fluorine element content in the lithium supplementation region of the third region is greater than or equal to 0 and less than or equal to 5%, and / or,
[0018] the fluorine element content in the lithium supplementation region of the second region is 13.5% - 14.5%, and / or,
[0019] the fluorine element content in the lithium supplementation region of the third region is 12.5% - 14.5%, and / or,
[0020] The ratio of the lithium element content to the carbon element content in the lithium supplementation region of the first region is A1, the ratio of the lithium element content to the carbon element content in the lithium supplementation region of the third region is A3, A1 is less than A3, and A1 is greater than 0, and A3 is less than 1 / 6.
[0021] In a possible implementation, the negative electrode active layer further includes silicon; the ratio of the lithium element content to the silicon element content in the lithium supplementation region of the first region is A4, the ratio of the lithium element content to the silicon element content in the lithium supplementation region of the second region is A5, A4 is less than A5, and A4 is greater than 0 and less than 3.7; and / or, A5 is less than 3.7;
[0022] And / or, the ratio of the lithium element content to the silicon element content in the lithium supplementation region of the first region is A4, the ratio of the lithium element content to the silicon element content in the lithium supplementation region of the third region is A6, A4 is less than A6, and A4 is greater than 0 and less than 3.7; and / or, A6 is less than 3.7.
[0023] The second aspect of the embodiments of the present application provides a battery, including a positive electrode plate, a separator, and the negative electrode plate described in the first aspect; the positive electrode plate, the separator, and the negative electrode plate are stacked in sequence.
[0024] The third aspect of the embodiments of the present application provides an electrical device, including the battery of the second aspect.
[0025] In the negative electrode plate, battery, and electrical device provided by the embodiments of the present application, the negative electrode active layer of the negative electrode plate contains lithium, and the negative electrode plate is obtained by laser cutting a lithium supplementation mother plate electrode plate. When using the laser cutting process to cut the lithium supplementation mother plate electrode plate, a high-energy laser beam is used to hit the area to be cut of the lithium supplementation mother plate electrode plate, so that the area melts and vaporizes and fuses, and then an independent negative electrode plate is formed. During this process, the area to be cut has undergone high-temperature carbonization, increasing the carbon element content in the first region, reducing the prelithiation effect in the first region, releasing more redundant capacity to cope with the edge lithium deposition phenomenon, and further preventing short circuit, thereby improving the safety performance of the battery. Description of the Drawings
[0026] Figure 1 It is a cross-sectional view of the negative electrode plate provided by the embodiments of the present application;
[0027] Figure 2 It is a top view of the negative electrode plate provided by the embodiments of the present application;
[0028] Figure 3 It is an XPS C 1s analysis spectrum of the first region of the negative electrode plate provided by the embodiments of the present application;
[0029] Figure 4 It is an XPS C 1s analysis spectrum of the second region of the negative electrode plate provided by the embodiments of the present application;
[0030] Figure 5 It is an XPS C 1s analysis spectrum of the third region of the negative electrode plate provided by the embodiments of the present application;
[0031] Figure 6 It is the XPS O 1s analysis spectrum of the first region of the negative electrode plate provided by the embodiment of the present application;
[0032] Figure 7 It is the XPS O 1s analysis spectrum of the second region of the negative electrode plate provided by the embodiment of the present application;
[0033] Figure 8 It is the XPS O 1s analysis spectrum of the third region of the negative electrode plate provided by the embodiment of the present application;
[0034] Figure 9 It is a schematic diagram of the battery provided by the embodiment of the present application.
[0035] Description of the reference numerals:
[0036] 100: negative electrode plate; 110: negative current collector; 120: negative active layer; 121: first region; 122: second region; 123: third region; 130: lithium compensation region; 131: sub-lithium compensation region;
[0037] 200: positive electrode plate; 210: positive electrode tab; 220: negative electrode tab. Detailed implementation manners
[0038] The electrode plate is an important component of the battery. Common negative electrode plates are graphite negative electrodes and silicon negative electrodes. The silicon negative electrode has a higher specific capacity than the graphite negative electrode, which is an effective means to improve the energy density of the battery. However, silicon materials also have obvious defects in actual applications, that is, the Coulomb efficiency (first efficiency) of the first charge-discharge cycle is lower than that of the graphite negative electrode (generally, the first efficiency of the silicon negative electrode is between 69% and 85%, and the first efficiency of the graphite negative electrode is between 90% and 94%). Therefore, in related technologies, the silicon-doped mother plate electrode is usually pre-lithiated to form a pre-lithiated mother plate electrode. The pre-lithiated mother plate electrode can supplement the irreversible capacity consumed during the first cycle to a certain extent, improve the first efficiency of the silicon-doped battery, and thus improve the energy density of the battery.
[0039] After the lithium compensation process is completed, the pre-lithiated mother plate electrode needs to be cut by a cutting process to form multiple independent negative electrode plates. However, metallic lithium exists throughout the surface of the pre-lithiated mother plate electrode. During the pre-lithiation process, it is equivalent to pre-charging the negative electrode plate. In this way, the reserved redundant capacity at the edge of the negative electrode plate is reduced, and the risk of lithium deposition is increased.
[0040] In view of this, the embodiments of the present application provide a negative electrode sheet, a battery and an electrical device. The negative electrode sheet is obtained by laser cutting a lithium supplement mother plate sheet. When the lithium supplement mother plate sheet is cut by the laser cutting process, a high-energy laser beam is used to hit the area to be cut of the lithium supplement mother plate sheet, so that the area melts, vaporizes and fuses, and then an independent negative electrode sheet is formed. During this process, the area to be cut undergoes high-temperature carbonization, increasing the carbon element content in the first area, reducing the prelithiation effect in the first area, releasing more redundant capacity to cope with the phenomenon of lithium deposition at the edge, and further preventing short circuit, thereby improving the safety performance of the battery.
[0041] In order to make the above objects, features and advantages of the embodiments of the present application more obvious and understandable, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present application without creative efforts shall fall within the protection scope of the present application.
[0042] The embodiments of the present application provide a negative electrode sheet 100, which is obtained by laser cutting a lithium supplement mother plate sheet. Specifically, usually, a metal lithium strip is film-pressed on the mother plate sheet to form a lithium supplement mother plate sheet; then, the lithium supplement mother plate sheet is subjected to laser cutting and other treatments to form a plurality of independent negative electrode sheets 100 with a preset shape.
[0043] In view of the fact that when the lithium supplement mother plate sheet is cut by the laser cutting process, a high-energy laser beam is used to hit the area to be cut of the lithium supplement mother plate sheet, so that the area melts, vaporizes and fuses, and then an independent negative electrode sheet is formed. With such a setting, it is possible to avoid the direct contact between the traditional cutting tool and the metal lithium strip or the negative electrode active layer, prevent the metal lithium strip from adhering to the cutting tool, and further prevent the phenomenon of burrs and powder falling off at the outer edge of the first area, and further prevent short circuit and improve safety.
[0044] It should be understood that during the preparation process of forming the negative electrode sheet, especially during the laser cutting process, it often affects the element composition and performance of each area of the negative electrode sheet. Therefore, the structure of the negative electrode sheet is defined in the embodiments of the present application.
[0045] Please refer to the appendix Figure 1, the negative electrode sheet 100 provided by the embodiment of the present application includes a negative electrode current collector 110. The negative electrode current collector 110 serves as the carrier component of the negative electrode sheet 100 and is used to carry the subsequent negative electrode active layer 120. Among them, the shape of the negative electrode current collector 110 is sheet-like. For example, the shape of the negative electrode current collector 110 is rectangular. The material of the negative electrode current collector 110 is copper foil. Copper foil is widely used in the manufacture of lithium-ion batteries due to its good electrical conductivity, ductility, and mechanical strength.
[0046] The negative electrode sheet 100 further includes a negative electrode active layer 120. In the thickness direction of the negative electrode current collector 110, the negative electrode active layer 120 is disposed on at least one side of the negative electrode current collector 110. That is to say, the negative electrode active layer 120 is disposed on the upper surface and / or the lower surface of the negative electrode current collector 110.
[0047] The negative electrode active layer 120 includes negative electrode active materials. Among them, the negative electrode active materials may include graphite and / or silicon-based active materials. Among them, the silicon-based active materials include, for example, pure silicon negative electrodes, etc.
[0048] Exemplarily, the negative electrode active material is graphite. At this time, the negative electrode sheet is a graphite negative electrode sheet; or, the negative electrode active material includes graphite and silicon-based active materials. At this time, the negative electrode sheet is a silicon-doped graphite negative electrode sheet; or, the negative electrode active material is a silicon-based active material. At this time, the negative electrode sheet is a silicon negative electrode sheet.
[0049] In this embodiment, taking the negative electrode sheet 100 as a silicon negative electrode sheet as an example, the content of silicon in the negative electrode sheet 100 is 20%.
[0050] In the embodiment of the present application, the negative electrode active layer 120 can be disposed on the surface of the negative electrode current collector 110 by coating. Among them, the thickness of the negative electrode active layer 120 can be set according to requirements and is not limited herein in this embodiment.
[0051] The negative electrode active layer 120 includes a lithium compensation region 130. The setting of the lithium compensation region 130 can increase the lithium content of the negative electrode sheet 100, can supplement the irreversible capacity consumed during the first cycle to a certain extent, improve the first efficiency of the silicon-doped battery, and further improve the energy density of the battery.
[0052] In the actual preparation process, the slurry of the negative electrode active layer 120 is coated on the negative electrode current collector 110, and is pressed to a set compaction density by a roll press, and then a prefabricated metallic lithium tape film is pressed onto the surface of the negative electrode active layer 120 by a lithium compensation device to complete prelithiation to form a lithium compensation master plate electrode sheet; subsequently, the formed lithium compensation master plate electrode sheet is processed by a laser die-cutting device to form the negative electrode sheet 100.
[0053] During the laser die-cutting process, a high-energy laser beam hits the area to be cut of the lithium supplement master plate electrode, melting, vaporizing, and fusing this area to form a first area 121 on the negative electrode plate 100. That is to say, the negative electrode active layer 120 includes the first area 121. The outer edge of the first area 121 that deviates from the center of the negative electrode active layer 120 is the outer edge of the negative electrode plate 100. That is, the first area 121 is the outer edge area of the negative electrode plate 100. Among them, the first area 121 can be understood as the area between the outer edge S1 and the inner edge S2 in Figure 2 .
[0054] The negative electrode active layer 120 further includes a second area 122. The second area 122 is adjacent to the first area 121 and is located on the side of the first area 121 that deviates from the edge of the negative electrode active layer 120.
[0055] Among them, the negative electrode active layer 120 includes carbon and lithium elements. The ratio of the lithium element content to the carbon element content in the lithium supplement area of the first area 121 is A1, and the ratio of the lithium element content to the carbon element content in the lithium supplement area of the second area 122 is A2. A1 is less than A2, and A1 is greater than 0 and less than 1 / 6; and / or A2 is less than 1 / 6. In one embodiment, 0 < A1 < A2 < 1 / 6.
[0056] During the laser die-cutting process, the high-energy laser beam has a great impact on the first area 121. For example, the temperature of the first area 121 is relatively high, making the first area 121 in a molten state, so a part of the lithium element will be consumed; for another example, the lithium element in the first area 121 will also react with oxygen in the air to form a certain amount of lithium oxide or lithium carbonate. Specifically, in the X-ray photoelectron spectroscopy (XPS) analysis result of the negative electrode active layer, the oxygen element content in the first area 121 accounts for 21.9% of all elements. In this way, it can be characterized that the lithium and lithium compounds in the first area 121 are affected, deteriorating the prelithiation effect of the negative electrode plate 100. In this way, more redundant capacity is released to cope with the edge lithium deposition phenomenon, further preventing short circuits and improving the safety performance of the battery.
[0057] This embodiment also limits the size of the first area 121. Exemplarily, in the first direction, the size of the first area 121 is less than or equal to 100 μm. Or rather, the first area 121 includes an outer edge and an inner edge. The inner edge is located between the outer edge of the first area 121 and the center of the negative electrode active layer 120. The size of the first area 121 can also be the vertical distance between the inner edge and the outer edge of the first area 121. In this way, the proportion of the first area 121 in the entire negative electrode active layer 120 is significantly reduced, and then the proportion of unfavorable by-products in the negative electrode plate 100 is reduced, thereby improving the overall energy density of the battery.
[0058] Wherein, the first direction can be the vertical direction from the outer edge of the first region 121 to the center of the negative electrode active layer 120. Or rather, the first direction is the Figure 2 Y direction in the attachment.
[0059] It should be noted that affected by the parameters of the cutting process, the shape of the first region 121 may be an irregular shape. Therefore, both the inner edge and the outer edge of the first region 121 may be non-linear. Thus, in order to facilitate obtaining the size of the first region 121, multiple sets of test points may be taken to obtain multiple sizes, and then the multiple sizes are averaged to obtain the average size. Specifically, the size can be the average size.
[0060] In this way, the size error of the first region 121 caused by the error of a single measurement point can be reduced, thereby improving the accuracy of the first region 121, and further ensuring the effective solution of problems such as the existence of outer-edge lithium burrs on the outer edge of the negative electrode tab and the resulting safety hazard that the outer-edge lithium burrs are prone to pierce the separator. It can also precisely and coordinately control the lithium supplementation process and the laser cutting process, so that the first region 121 is within a reasonable range, and further significantly reduces the proportion of the first region 121 in the entire negative electrode active layer 120, and further reduces the proportion of adverse by-products in the negative electrode tab 100, thereby improving the overall energy density of the battery.
[0061] In the example of the present application, the size of the area of the lithium supplementation region 130 can be freely set according to the actual lithium supplementation amount requirement of the negative electrode tab. Exemplarily, the area of the lithium supplementation region 130 accounts for 30% - 100% of the total area of the negative electrode active layer 120. For example, the area of the lithium supplementation region 130 accounts for 30%, 33%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95% and 100% of the total area of the negative electrode active layer 120.
[0062] Generally speaking, under the same requirement of lithium supplementation amount, the larger the area of the lithium supplementation region 130, the thinner the thickness of the metallic lithium source and the higher the requirement. Therefore, in this embodiment, the area of the lithium supplementation region 130 is limited, so that it can not only meet the requirement of energy density improvement after lithium supplementation, but also preferably maintain the stability of the lithium supplementation interface of the negative electrode tab 100. This balance enables the battery to have good reliability and safety while maintaining high performance.
[0063] In addition, the reasonable setting of the lithium supplementation region 130 helps to improve the cycle stability and capacity retention rate of the battery. By precisely controlling the lithium supplementation amount, the lithium loss during the first charge process can be reduced, and the first Coulomb efficiency and cycle life of the battery can be improved.
[0064] Please refer to the attachment Figure 2, as a possible implementation of the lithium supplement area 130, the lithium supplement area 130 includes a plurality of sub-lithium supplement areas 131. The plurality of sub-lithium supplement areas 131 can be arranged in sequence along the second direction; wherein, the second direction intersects with the first direction. Exemplarily, the second direction is perpendicular to the first direction, the first direction can be the length direction of the negative electrode plate, and the second direction can be the width direction of the negative electrode plate. Exemplarily, the first direction is attached Figure 2 in Y, and the second direction is attached Figure 2 in X direction in
[0065] When the area of the lithium supplement area 130 accounts for less than 100% of the total area of the negative electrode active layer 120, the area between adjacent lithium supplement areas 130 is a non-lithium supplement area, and the lithium supplement areas 130 and non-lithium supplement areas are alternately arranged and connected to each other. After the battery is disassembled, the lithium supplement area 130 appears as a bright area on the negative electrode active layer 120, and the non-lithium supplement area appears as a dark area on the negative electrode active layer 120, that is, the lithium supplement area 130 and non-lithium supplement area form bright and dark stripes on the negative electrode active layer 120.
[0066] At this time, dispersing the lithium supplement area 130 into a plurality of sub-lithium supplement areas 131 can reduce the lithium source concentration in each area, which is beneficial to the uniform deposition of lithium. This helps to reduce the formation of lithium dendrites and improve the cycle stability and safety of the battery.
[0067] When the area of the lithium supplement area 130 accounts for 100% of the total area of the negative electrode active layer 120, for the negative electrode plate provided in this embodiment, its sub-lithium supplement areas 131 are continuous, that is, there is no gap in the lithium supplement area 130 in at least one direction. After the battery made of the negative electrode plate is disassembled, there will be no bright and dark stripes on the surface of the negative electrode plate. At this time, the continuity of the lithium supplement area 130 can eliminate the boundary between the lithium supplement area 130 and the non-lithium supplement area, simplifying the production process. At the same time, since there is no need to perform complex area division and film pressing operations, this helps to reduce production costs and improve production efficiency.
[0068] It should be noted that when the lithium supplement area 130 includes a plurality of sub-lithium supplement areas 131, the shape of the sub-lithium supplement area 131 can be a regular shape. For example, the shape of the sub-lithium supplement area 131 is square; the shape of the sub-lithium supplement area 131 can also be an irregular shape.
[0069] Please refer to the attachment Figure 2, in a possible implementation, the negative electrode active layer 120 further includes a second region 122, and the second region 122 is disposed on a side of the first region 121 closer to the center of the negative electrode tab 100; or rather, the second region 122 is disposed inside the first region 121. The lithium content in the lithium supplement region 130 of the second region 122 is greater than the lithium content in the lithium supplement region of the first region 121. Among them, the lithium content in the lithium supplement region of the first region 121 is 10% - 30%. For example, the lithium content in the first region 121 is 20%. In another embodiment, the lithium content in the lithium supplement region of the second region 122 is 20% - 40%. For example, the lithium content in the second region 122 is 30%.
[0070] Given that the second region 122 is adjacent to the first region 121, the second region 122 may be affected by the temperature during the laser die-cutting process. Therefore, the second region 122 can be referred to as the heat-affected zone. Among them, the second region 122 is the area Figure 2 between S2 and S3 in the figure.
[0071] Furthermore, the negative electrode active layer 120 further includes a third region 123, and the third region 123 is disposed on a side of the second region 122 away from the first region 121; the lithium content in the lithium supplement region of the third region 123 is greater than the lithium content in the lithium supplement region of the first region 121; and / or, the lithium content in the lithium supplement region of the third region 123 is greater than or equal to the lithium content in the lithium supplement region of the second region 122.
[0072] In this embodiment, the lithium content in the lithium supplement regions of the second region 122 and the third region 123 are both greater than the lithium content in the lithium supplement region of the first region 121. In this way, a relatively high lithium element can be ensured throughout the negative electrode tab 100, which helps to increase the lithium storage capacity of the negative electrode material, thereby improving the initial capacity and cycle stability of the battery.
[0073] In addition, the lithium content in the lithium supplement region of the third region 123 is greater than or equal to the lithium content in the lithium supplement region of the second region 122, and the lithium content in the lithium supplement region of the second region 122 is made as equal as possible to the lithium content in the lithium supplement region of the third region 123, aiming to ensure the consistency of the second region 122 (as the heat-affected zone) and the third region 123 in terms of electrochemical performance, structural stability, and lithium ion migration ability, so as to avoid battery performance fluctuations caused by performance differences between regions.
[0074] During specific implementation, XPS analysis can be performed on each region (the first region 121, the second region 122, and the third region 123) of the negative electrode active layer to measure characteristics such as the elemental composition, the content of each element, and the existence form of each element. In the embodiments of the present application, the content of each element refers to the mole percentage content.
[0075] In the XPS analysis results of the negative electrode active layer, the negative electrode active layer 120 contains oxygen element. The oxygen element in the negative electrode active layer 120 mainly exists in the ionic state of negative divalence. The possible forms in this example include Li2O, LiOH, Li2CO3, etc. The above also indicates that part of the active lithium is oxidized into stable inorganic lithium salts, and these inorganic lithium salts do not participate in the prelithiation reaction. If there are too many, the prelithiation efficiency will be reduced.
[0076] Therefore, in this embodiment, it is necessary to limit the oxygen element content so that the ratio of the oxygen element content to the total amount of all elements in the negative electrode active layer 120 is less than or equal to 20%. After research and analysis, the inventor believes that controlling the oxygen element content in the negative electrode active layer 120 to be less than or equal to 20% is more suitable for the composition of the negative electrode active layer after lithium supplementation. For example, it enables the elements in the negative electrode active layer 120 to exist in a more suitable form and content, thereby improving the performance of the battery such as the first efficiency and cycle life; in addition, from another aspect of analysis, the oxygen content to a certain extent indicates the degree of oxidation of the materials in the negative electrode active layer. The higher the oxygen content, the more materials in the negative electrode active layer will be oxidized. Especially for active substances (such as subsequent graphite and / or silicon-based active materials), the more active substances are oxidized, the fewer active substances can play their roles. Therefore, a smaller oxygen element content (less than or equal to 20%) in the negative electrode active layer 120 can ensure a lower degree and quantity of oxidation of the materials in the negative electrode active layer, thereby ensuring the function of more active substances and other materials and improving the performance of the battery such as energy density, first efficiency, and cycle life.
[0077] It should be noted that the composition of the battery also includes a separator, and the separator needs to be arranged between the negative electrode plate 100 and the positive electrode plate. During the charge and discharge process, a layer of adhesive will be formed on the separator, and the adhesive will stick to the negative electrode plate. If the oxygen element content in the negative electrode active layer 120 is relatively large, it will increase the thickness of the inorganic lithium salt formed on the surface of the negative electrode active layer 120, which will cause the negative electrode plate to be relatively hard, resulting in the separator being loose from the negative electrode plate and unable to stick to each other. During the subsequent charge and discharge process, the battery will expand and deform, which will in turn lead to a decline in the battery safety and ED benefits.
[0078] Therefore, in this embodiment, the oxygen element content in the negative electrode active layer 120 is relatively small (less than or equal to 20%). In this way, the thickness of the inorganic lithium salt formed on the surface of the negative electrode active layer 120 can be reduced, so that the thickness of the inorganic lithium salt is less than 1 um, preventing the inorganic lithium salt from hindering the effective contact between the negative electrode plate 100 and the separator, thereby preventing the formed battery from becoming soft or deformed and improving the battery safety and ED benefits.
[0079] In the XPS analysis results of the negative electrode active layer 120, the negative electrode active layer 120 contains fluorine element. The proportion of the fluorine element content to the total amount of all elements in the negative electrode active layer is 7% to 32%. Exemplarily, the proportion of the fluorine element content to the total amount of all elements in the negative electrode active layer is 7%, 7.5%, 8%, 8.5%, 9%, 9.5%, 10%, 13%, 15%, 18%, 20%, 22%, 25%, 28%, 30%, 32%, or the range composed of any two of them.
[0080] The first region 121 hardly contains fluorine element (F), and the fluorine element (F) mainly exists in the second region 122 and the third region 123. Moreover, the fluorine element (F) mainly comes from the decomposition of electrolyte lithium salt on the surface of metallic lithium to generate lithium fluoride LiF, such as the decomposition of lithium salts like LiPF6 and LiBF3.
[0081] According to the research of the inventors, the fluorine element in the negative electrode active layer can participate in the formation of the SEI film (for example, when the negative electrode plate is lithium-complemented through the electrochemical lithium-complementation process, the SEI film can be formed. Specifically, the fluorine element and the lithium element can form components such as lithium fluoride, lithium carbonate, and other lithium salts in the SEI film). To a certain extent, the fluorine content can indicate the content of the SEI film. The less the fluorine content, the more the SEI film damaged by processes such as laser cutting, and the more difficult it is to play a role. On the other hand, it indicates that the pre-lithiated metallic lithium may react with the electrolyte lithium salt, consuming the lithium salt to generate too much LiF.
[0082] In the embodiments of the present application, by controlling the proportion of the fluorine element content to the total amount of all elements in the negative electrode active layer to be 7% to 32%, the uniformity and stability of the SEI film of the battery can be ensured, the local polarization phenomenon of the battery can be reduced, and thus the cycle life and safety of the battery can be improved.
[0083] This embodiment also defines the difference in the fluorine element content between the lithium supplement area of the second region 122 and the lithium supplement area of the third region 123. Exemplarily, in the XPS analysis result of the negative electrode active layer, in one example, the fluorine element content in the lithium supplement area of the second region 122 is 13.5% to 14.5%, and in one example, the fluorine element content in the lithium supplement area of the third region 123 is 12.5% to 14.5%. In another embodiment, the absolute value of the difference in the fluorine element content between the lithium supplement area of the second region 122 and the lithium supplement area of the third region 123 is greater than or equal to 0 and less than or equal to 5%. For example, the absolute value of the difference in the fluorine element content between the lithium supplement area of the second region 122 and the lithium supplement area of the third region 123 is 0%, 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5% or the range composed of any two of them. This can indicate that the height difference between the interfaces of the second region 122 and the third region 123 and the normal region is relatively small, no undulations will be formed, the thickness uniformity of the second region 122 and the third region 123 is improved, the local polarization of the battery is reduced, and the life and safety of the battery are improved.
[0084] In the XPS analysis result of the negative electrode active layer 120, the ratio of the lithium element content to the carbon element content in the lithium supplement area of the first region 121 is less than the ratio of the lithium element content to the carbon element content in the lithium supplement area of the third region 123. For example, the ratio of the lithium element content to the carbon element content in the lithium supplement area of the first region 121 is A1, and the ratio of the lithium element content to the carbon element content in the lithium supplement area of the third region 123 is A3, A1 is less than A3, and A1 is greater than 0, and A3 is less than 1 / 6.
[0085] In this way, it can be ensured that the carbon element content in the first region 121 is the largest and the lithium element content is the smallest, thereby improving the prelithiation effect of the first region 121 and restoring more redundant capacity to cope with the lithium plating risk in the first region 121.
[0086] It should be noted that when compared with the ratio of the lithium element content to the carbon content in the lithium supplement area of the second region 122, A1 is less than A2, A2 is less than A3, and A1 is greater than 0, and A3 is less than 1 / 6. In one embodiment, 0 < A1 < A2 < A3 < 1 / 6.
[0087] Further, the negative electrode active layer further includes silicon element (Si); the ratio of the lithium element content to the silicon element content in the lithium supplementation area of the first region 121 is less than the ratio of the lithium element content to the silicon element content in the lithium supplementation area of the second region 122. In other words, the ratio of the lithium element content to the silicon element content in the lithium supplementation area of the first region 121 is A4, and the ratio of the lithium element content to the silicon element content in the lithium supplementation area of the second region 122 is A5, A4 is less than A5, and A4 is greater than 0 and less than 3.7; and / or, A5 is less than 3.7. In one example, 0 < A4 < A5 < 3.7.
[0088] And / or, the ratio of the lithium element content to the silicon element content in the lithium supplementation area of the first region 121 is less than the ratio of the lithium element content to the silicon element content in the lithium supplementation area of the third region 123. In other words, the ratio of the lithium element content to the silicon element content in the lithium supplementation area of the first region 121 is A4, and the ratio of the lithium element content to the silicon element content in the lithium supplementation area of the third region 123 is A6, A4 is less than A6, and A4 is greater than 0 and less than 3.7; and / or, A6 is less than 3.7. In one embodiment, 0 < A4 < A6 < 3.7.
[0089] It should be noted that when it is necessary to compare the ratios of the lithium element content to the carbon content in the lithium supplementation areas of the first region 121, the second region 122, and the third region 123 simultaneously, A4 is less than A5, A5 is less than A6, and A4 is greater than 0, and A6 is less than 3.7. That is to say, 0 < A4 < A5 < A6 < 3.7.
[0090] Among them, the magnitude of the Li / C or Li / Si ratio often represents the lithium content of the negative electrode active material 120, that is, the degree of prelithiation. The Li / C or Li / Si ratio in the second region 122 and the third region 123 is the largest, then. The higher the lithiation degree of the second region 122 and the third region 123, which further indicates that the negative electrode SOC (state of charge, or charging state) is higher and closer to full charge, improving the performance of the battery.
[0091] In order to further verify the performance of the negative electrode sheet 100, the following examples show the XPS analysis data (Tables 1 to 3) obtained by XPS analysis of the negative electrode sheet and the analysis spectra ( Figures 3 to 8 ).
[0092] Table 1 Content percentages of various elements in different regions
[0093]
[0094] From Table 1, it can be obtained that the oxygen element content in the first region 121 is 21.9%, the oxygen element content in the second region 122 is 15.9%, and the oxygen element content in the third region 123 is 14%. In this way, the oxygen element content in the negative electrode active layer 120 can be made smaller (less than or equal to 20%), which can ensure that the oxidation degree and quantity of the materials in the negative electrode active layer are low, thereby ensuring the function of more active materials and other materials, and improving the performance of the battery such as energy density, initial efficiency, and cycle life.
[0095] From Table 1, it can also be obtained that the fluorine element content in the first region 121 is 0.6%, the fluorine element content in the second region 122 is 14.2%, and the fluorine element content in the third region 123 is 13.9%. Then, the proportion of the fluorine element content to the total amount of all elements in the negative electrode active layer is 28.7%, which is between 7% and 32%. In this way, the uniformity and stability of the SEI film of the battery can be ensured, the local polarization phenomenon of the battery can be reduced, and the cycle life and safety of the battery can be improved.
[0096] The absolute value of the difference between the fluorine element content in the lithium supplement area of the second region 122 and the fluorine element content in the lithium supplement area of the third region 123 is 0.3%, which is between 0 and 5%. The absolute value of the difference between the fluorine element content in the lithium supplement area of the second region 122 and the fluorine element content in the lithium supplement area of the third region 123 is very small, indicating that the thickness of the SEI in the second region 122 is approximately equal to the thickness of the SEI in the third region 123, ensuring the thickness uniformity of the second region 122 and the third region 123.
[0097] It should be understood that in the embodiments of the present application, the element content is also the atomic content. Taking the oxygen element content as an example, in the XPS analysis result of the negative electrode active layer, the oxygen element content in the first region 1 refers to the proportion of the number of oxygen elements in the first region 121 to the total number of all elements measured by XPS in the first region 121; the oxygen element content in the second region 122 refers to the proportion of the number of oxygen elements in the second region 122 to the total number of all elements measured by XPS in the second region 122; the oxygen element content in the second region 122 refers to the proportion of the number of oxygen elements in the second region 122 to the total number of all elements measured by XPS in the second region 122.
[0098] For example, the XPS analysis results of the negative electrode active layer show that the elements in the second region 122 are Li, P, S, C, O, F, and N. Then, the oxygen element content in the second region 122 = number of O / (number of O + number of Li + number of P + number of S + number of C + number of F + number of N), the carbon element content in the second region 122 = number of C / (number of O + number of Li + number of P + number of S + number of C + number of F + number of N), the fluorine element content in the second region 122 = number of F / (number of O + number of Li + number of P + number of S + number of C + number of F + number of N), and the calculation methods for the contents of other elements are the same and will not be elaborated here.
[0099] In the embodiments of the present application, XPS analysis can also be performed on the negative electrode active layer (the first region 121, the second region 122, the third region 123, etc.), and the O1s and C1s orbits can be analyzed to determine the types of O1s valence bonds (such as C-O, C=O, P-O, O -2 etc.) and their proportions, and to determine the types of C1s valence bonds (such as C-O, C=O, C, C-F, etc.) and their proportions. The data are shown in the following table.
[0100] Table 2 XPS C1s valence bond types and proportions in different regions
[0101]
[0102] It can be clearly seen from Table 2 that the negative electrode active layer (the first region 121, the second region 122, and the third region 123) contains carbon element (C). These carbon elements can specifically include carbon elements that form C-O chemical bonds (single bonds) with oxygen, carbon elements that form C=O chemical bonds (double bonds) with oxygen, C elements in graphite carbon (C-C bonds and / or C-H bonds), and C elements in the corresponding chemical bonds formed with other elements that may exist in the negative electrode active layer such as F (for example, when the negative electrode active layer contains F element, C-F bonds are formed with F). That is, the carbon elements in the negative electrode active layer can exist in one or more forms such as C-O, C=O, graphite carbon (C-C bonds and / or C-H bonds), and other carbon-containing groups (such as C-F).
[0103] Table 3 XPS O1s valence bond types and proportions in different regions
[0104]
[0105] It can be clearly seen from Table 3 that the negative electrode active layer (the first region 121, the second region 122, and the third region 123) contains oxygen element (O). These oxygen elements can specifically include oxygen elements that form C-O chemical bonds (single bonds) with carbon, oxygen elements that form C=O chemical bonds (double bonds) with carbon, and divalent oxygen ions (O -2) one or more of the oxygen element in, and the O element in the corresponding chemical bonds formed with other elements that may exist in the negative electrode active layer such as P (for example, when the negative electrode active layer contains P element, forming P-O bond with P), etc., that is, the oxygen element in the negative electrode active layer can be in the form of one or more of C-O, C=O, O -2 and other oxygen-containing groups (such as P-O), etc.
[0106] It can be clearly obtained from the data in Table 3 that the ratio of the oxygen element content to the total amount of all elements in the negative electrode active layer is less than or equal to 20%. In this way, it can ensure that the oxidation degree and quantity of the materials in the negative electrode active layer are low, so as to ensure the function of more active substances and other materials, and improve the performance of the battery such as energy density, initial efficiency and cycle life.
[0107] Please refer to the attached Figure 9 , an embodiment of the present application provides a battery, including a positive electrode tab 200, a separator (not shown in the figure), and the negative electrode tab 100 described in any of the above embodiments; the positive electrode tab 200, the separator and the negative electrode tab 100 are stacked in sequence. Or rather, the separator is located between any adjacent positive electrode tab 200 and negative electrode tab 100 to prevent the positive electrode tab and the negative electrode tab from contacting and short-circuiting.
[0108] Among them, the positive electrode tab may further include a positive electrode current collector, and a positive electrode active material layer located on at least one surface of the positive electrode current collector. For example, the positive electrode active material layer can be provided on one surface of the positive electrode current collector, or on both the front and back surfaces of the positive electrode current collector. The positive electrode current collector can be a conventional positive electrode current collector in the art, such as including aluminum foil, etc. The positive electrode active material layer can also be a conventional material. For example, it includes lithium-containing active materials, such as including at least one of lithium cobaltate, lithium manganate, lithium nickelate, ternary materials, lithium iron phosphate, lithium manganese iron phosphate, lithium vanadium phosphate, lithium vanadium oxyphosphate, lithium-rich manganese-based materials. The ternary materials can include lithium nickel cobalt manganate and / or lithium nickel cobalt aluminate, etc.
[0109] It should be noted that the battery may further include an electrolyte and a package for packaging the above components.
[0110] In the embodiment of the present application, the orthographic projection of the positive electrode tab 200 on the plane where the negative electrode tab 100 is located covers the second region and the third region of the negative electrode tab 100, so that the first region of the negative electrode tab 100 is exposed.
[0111] During the charge and discharge process, the active lithium ions in the battery mainly come from the positive electrode tab 200, while the negative electrode tab 100 is mainly used to store the active lithium ions. Therefore, the capacity of the negative electrode tab 100 needs to be greater than the capacity of the positive electrode tab 200. Otherwise, the negative electrode tab 100 cannot carry the active lithium ions electrolyzed from the positive electrode tab 200, and then lithium will be deposited on the negative electrode tab 100, causing a short circuit of the battery.
[0112] Therefore, in the embodiments of the present application, by controlling the areas of the negative electrode plate 100 and the positive electrode plate 200, the area of the negative electrode plate 100 is made larger than that of the positive electrode plate 200. In this way, the capacity of the negative electrode plate 100 can be increased, and it can better carry the active lithium ions electrolyzed from the positive electrode plate 200.
[0113] In addition, in the embodiments of the present application, the first region 121 of the negative electrode plate 100 is used as a surplus region and is coordinated with the characteristics of the first region 121. For example, the ratio of Li / C or Li / Si in the first region 121 is much smaller than that in the second region 122 and the third region 123. In this way, it can be ensured that the first region 121 can release enough capacity to carry the active lithium ions electrolyzed from the positive electrode plate 200, and thus the risk of local lithium deposition in the lithium-compensated battery can be improved to the greatest extent, and the safety of the battery is enhanced.
[0114] It should be noted that, please continue to refer to Figure 9 , in this embodiment, the battery further includes a negative electrode tab 220 and a positive electrode tab 210. As a connection bridge between the inside and the outside of the battery, the tabs ensure that the current inside the battery cell can be smoothly transmitted to both ends of the battery. Specifically, the negative electrode tab 220 is connected to the negative electrode of the battery cell, and the positive electrode tab 210 is connected to the positive electrode of the battery cell, thereby realizing the connection between the current inside the battery and the external circuit.
[0115] Taking the battery model 785075-S-W-3 as an example, the embodiments of the present application use lithium cobaltate as the positive electrode and a 20% silicon-doped negative electrode as the negative electrode, and the designed lithium compensation amount is 0.23 mg / cm². Using a lithium metal strip as the lithium source, the silicon-doped negative electrode is pre-lithiated, and its preparation process is as follows:.
[0116] 1. Preparation of the negative electrode plate
[0117] (1) Prepare the negative electrode slurry. It should be noted that the negative electrode slurry in this embodiment is in the ratio of the prior art, and will not be elaborated in this embodiment.
[0118] Coat the negative electrode slurry on both the front and back sides of a copper foil with a certain thickness, and then press it to a set compaction density by a roller press to make a substrate (i.e., the negative electrode plate to be pre-lithiated).
[0119] (2) Pre-lithiation
[0120] Use a lithium compensation device to compound a prefabricated lithium metal strip onto the surface of the negative electrode plate to be pre-lithiated to complete the pre-lithiation and obtain a pre-lithiated lithium compensation mother plate electrode.
[0121] (3) Laser cutting
[0122] Use a laser cutting device to cut the prelithiated lithium supplement master electrode sheet prepared in step (2) to obtain a negative electrode sheet 100; wherein, during cutting, the laser power is 200W to 300W, preferably, after cutting with a laser power of 300W, the obtained negative electrode sheet 100 includes a first region 121, a second region 122, and a third region 123.
[0123] It should be noted that during the cutting process, an inert protective gas needs to be introduced into the pre-cutting area. On the one hand, it can prevent the excessive oxidation of the lithium metal strip. On the other hand, the ignition point of the lithium metal strip is relatively low, which can prevent the lithium metal strip from spontaneous combustion, thereby improving the process safety of the negative electrode sheet.
[0124] 2. Prepare a positive electrode sheet.
[0125] It should be noted that the preparation process of the positive electrode sheet can refer to related technologies, and this embodiment will not elaborate further here.
[0126] 3. Preparation of a lithium-ion battery
[0127] Stack the positive electrode sheet, the separator, and the negative electrode sheet in sequence (the separator is placed between the positive electrode sheet and the negative electrode sheet to play a role in isolation), and then form a bare battery cell.
[0128] Finally, encapsulate the bare battery cell and the electrolyte in a package to form a battery. Among them, the package can be a soft shell or a hard shell.
[0129] The embodiment of the present application also provides an electrical device, including the battery described in any of the above embodiments. The battery can provide electrical energy for the electrical device. The electrical device in the embodiment of the present application can be a vehicle. For example, the vehicle can be a new energy vehicle, and the new energy vehicle can be a pure electric vehicle, a hybrid vehicle, an extended-range vehicle, etc.
[0130] In addition, the device can also be other energy storage devices, such as mobile phones, portable devices, laptop computers, electric toys, electric tools, ships, and spacecraft. Among them, the spacecraft can include airplanes, rockets, space shuttles, or spaceships.
[0131] In view of the fact that the electrical device provided in this embodiment includes the battery described in any of the above embodiments, it has the structure and beneficial effects of the battery, and this embodiment will not make specific limitations here.
[0132] The embodiments or implementation manners in this specification are described in a progressive manner. Each embodiment focuses on the differences from other embodiments, and the same or similar parts among the various embodiments can be referred to each other.
[0133] It should be noted that the "one embodiment", "embodiment", "exemplary embodiment", "some embodiments", etc. mentioned in the specification indicate that the described embodiments may include specific features, structures or characteristics, but not necessarily every embodiment includes such specific features, structures or characteristics. In addition, such phrases do not necessarily refer to the same embodiment. Further, when combining a specific feature, structure or characteristic with an embodiment, it is within the knowledge of those skilled in the art to implement such a feature, structure or characteristic in combination with other embodiments, whether explicitly or implicitly described.
[0134] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application and are not intended to limit them; although the present application has 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 for some or all of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present application.
Claims
1. A negative electrode plate, characterized in that, Comprising: A negative electrode current collector; A negative electrode active layer, in the thickness direction of the negative electrode current collector, the negative electrode active layer is disposed on at least one side of the negative electrode current collector, and the negative electrode active layer includes a lithium supplement region; the negative electrode active layer includes a first region and a second region adjacent to the first region, and the outer edge of the first region away from the center of the negative electrode active layer is the outer edge of the negative electrode tab; Wherein, the negative electrode active layer includes carbon element and lithium element, the ratio of the lithium element content to the carbon element content in the lithium supplement region of the first region is A1, the ratio of the lithium element content to the carbon element content in the lithium supplement region of the second region is A2, A1 is less than A2, and A1 is greater than 0 and less than 1 / 6; and / or, A2 is less than 1 / 6.
2. The negative electrode sheet according to claim 1, wherein In a first direction, the size of the first region is less than or equal to 100 μm, wherein the size is an average size; And / or, the area of the lithium supplement region accounts for 30% to 100% of the total area of the negative electrode active layer.
3. The negative electrode sheet according to claim 2, characterized in that, The lithium supplement region includes a plurality of sub-lithium supplement regions, and the plurality of sub-lithium supplement regions are arranged in sequence along a second direction; the second direction intersects with the first direction.
4. The negative electrode sheet according to claim 3, characterized in that, The negative electrode active layer further includes a second region, and the second region is disposed on a side of the first region close to the center of the negative electrode tab; the lithium content in the lithium supplement region of the second region is greater than the lithium content in the lithium supplement region of the first region; Wherein, the lithium content in the lithium supplement region of the first region is 10% to 30%, and / or, the lithium content in the lithium supplement region of the second region is 20% to 40%.
5. The negative electrode sheet according to claim 4, wherein The negative electrode active layer further includes a third region, and the third region is disposed on a side of the second region away from the first region; The lithium content in the lithium supplement region of the third region is greater than the lithium content in the lithium supplement region of the first region; and / or, the lithium content in the lithium supplement region of the third region is greater than or equal to the lithium content in the lithium supplement region of the second region.
6. The negative electrode sheet according to any one of claims 1-5, characterized in that, The negative electrode active layer further includes oxygen element, and the proportion of the oxygen element content to the total amount of all elements in the negative electrode active layer is less than or equal to 20%; And / or, the negative electrode active layer further includes fluorine element, and the proportion of the fluorine element content to the total amount of all elements in the negative electrode active layer is 7% to 32%.
7. The negative electrode sheet according to claim 6, characterized in that, The absolute value of the difference between the fluorine element content in the lithium supplement region of the second region and the fluorine element content in the lithium supplement region of the third region is greater than or equal to 0 and less than or equal to 5%, and / or, The fluorine element content in the lithium supplement region of the second region is 13.5% to 14.5%, and / or, The fluorine element content in the lithium supplement region of the third region is 12.5% to 14.5%, And / or, the ratio of the lithium element content to the carbon element content in the lithium supplement region of the first region is A1, the ratio of the lithium element content to the carbon element content in the lithium supplement region of the third region is A3, A1 is less than A3, and A3 is less than 1 / 6.
8. The negative electrode sheet according to claim 7, wherein The negative electrode active layer further includes silicon; the ratio of the lithium element content to the silicon element content in the lithium supplementation area of the first region is A4, the ratio of the lithium element content to the silicon element content in the lithium supplementation area of the second region is A5, A4 is less than A5, and A4 is greater than 0 and less than 3.7; and / or, A5 is less than 3.7; and / or, the ratio of the lithium element content to the silicon element content in the lithium supplementation area of the first region is A4, the ratio of the lithium element content to the silicon element content in the lithium supplementation area of the third region is A6, A4 is less than A6, and A4 is greater than 0 and less than 3.7; and / or, A6 is less than 3.
7.
9. A battery, characterized in that, It includes a positive electrode tab, a separator, and the negative electrode tab according to any one of claims 1-8; the positive electrode tab, the separator, and the negative electrode tab are stacked in sequence.
10. An electrical device, characterized in that, It includes the battery according to claim 9.