Negative electrode sheet and battery

Abstract

The present application relates to the field of battery, specifically relates to a negative electrode sheet and a battery comprising the same. The negative electrode sheet comprises a current collector, and a first active material layer and a second active material layer respectively arranged on two surfaces of the current collector; the specific surface charge Q surface1 / S BET1 of the first active material layer is less than the specific surface charge Q surface2 / S BET2 of the second active material layer. The specific surface charge of the active material layers on both sides of the negative electrode sheet of the present application is different, so that one side has more lithium ion liquid phase diffusion channels relative to the other side, which is beneficial to the deintercalation of lithium and can effectively improve the lithium precipitation problem of the battery.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of batteries, in particular to a negative electrode sheet and a battery comprising the same. BACKGROUND

[0002] In recent years, with the rapid growth of the electric vehicle market, and the continuous emergence of consumer electronics such as smart phones, lithium ion batteries as power sources for these products have also received more and more attention. Therefore, the service life of lithium ion batteries is crucial, and for the wound battery, lithium is easily deposited at the center of the winding, which seriously affects the service life of the battery.

[0003] Therefore, it is necessary to find a method to improve the lithium deposition problem of the battery to prolong the service life of the battery. SUMMARY

[0004] The present application aims to overcome the problem of lithium deposition in the prior art, and provides a negative electrode sheet and a battery comprising the same. The specific surface charge storage of the active material layer on both sides of the negative electrode sheet of the present application is different, so that one side has more lithium ion liquid phase diffusion channels than the other side, which is beneficial to the deintercalation of lithium and can effectively improve the lithium deposition problem of the battery.

[0005] The first aspect of the present application provides a negative electrode sheet, which comprises a current collector, and a first active material layer and a second active material layer respectively arranged on two surfaces of the current collector; the specific surface charge storage Q surface1 / S BET1 of the first active material layer is less than the specific surface charge storage Q surface2 / S BET2 .

[0006] The second aspect of the present application provides a battery comprising the negative electrode sheet of the first aspect of the present application.

[0007] Through the above technical solution, the negative electrode sheet of the present application has at least the following advantages compared with the prior art: the specific surface charge storage of the active material layer on both sides of the negative electrode sheet of the present application is different, so that one side has more lithium ion liquid phase diffusion channels than the other side, which is beneficial to the deintercalation of lithium and can effectively improve the lithium deposition problem of the battery.

[0008] The endpoints of the ranges and any values disclosed herein are not limited to the precise values recited as the exact dimensions are not critical to the present application. Any numerical value, however, can be expressed as a range compatible with this application, for example, a range of 1 to 10 can be expressed as a range of 2 to 9, 3 to 8, 3 to 7, 4 to 6, 3 to 6, 3 to 5, 3 to 4, 4 to 5, and 4 to 5, etc. The ranges apply equally, for example, to the ranges of points, the endpoints of which are themselves defined by the endpoints of other ranges. The ranges are intended to be inclusive of the endpoints. BRIEF DESCRIPTION OF DRAWINGS

[0009] Figure 1 The core structure of the winding type battery is shown, in which the tab is arranged in the empty foil area.

[0010] Figure 2 The core structure of the winding type battery is shown, in which the tab is arranged in the empty foil area. Figure 1 The partial enlarged view of the part enclosed by the dotted circle frame. DETAILED DESCRIPTION

[0011] The specific embodiments of the present application are described in detail below. It should be understood that the specific embodiments described herein are merely intended to illustrate and explain the present application, and are not intended to limit the present application.

[0012] The first aspect of the present application provides a negative electrode sheet, which can include a current collector, and a first active material layer and a second active material layer arranged on two surfaces of the current collector, respectively; the specific surface charge Q surface1 / S BET1 of the first active material layer is less than the specific surface charge Q surface2 / S BET2 of the second active material layer.

[0013] In the present application, the term "specific surface charge Q surface / S BET " has the conventional meaning in the art. It is generally believed that "specific surface charge Q surface / S BET " refers to the amount of charge stored on the surface of the material per unit specific surface area.

[0014] The inventors of the present application found that for a winding type battery, the negative electrode active material layer on the side of the negative electrode sheet far from the winding center corresponds to the positive electrode active material layer on the side of the positive electrode sheet close to the winding center, and since the circumference of each coil of the winding type battery gradually increases from the inside to the outside, the negative electrode active material layer on the side of the negative electrode sheet far from the winding center and the corresponding positive electrode active material layer on the side of the positive electrode sheet close to the winding center are unbalanced, and cannot completely receive the lithium ions stripped from the positive electrode sheet, resulting in lithium precipitation at the winding center of the battery. The charge Q charge stored by the negative electrode active material can be divided into surface charge Q surface and bulk charge Q interclation , i.e. Q charge = Q surface + Q interclation , wherein the surface charge Q surface can be regarded as the amount of Li + quickly adsorbed on the surface of the negative electrode active material, and a greater surface charge storage means that more Li + will be adsorbed on the surface of the negative electrode active material at the beginning of charging, reducing the liquid phase concentration polarization. That is, the Q surface / SBET The higher the surface is, the higher the concentration of lithium ions that can be adsorbed on the surface is, so that lithium ions can be quickly adsorbed on the surface of the active material layer, thereby increasing the channel for lithium ion liquid-phase diffusion, facilitating the intercalation of lithium ions, and further improving the problem of lithium precipitation.

[0015] In the present application, the specific surface stored charge Q surface / S BET The calculation method is as follows: wherein the surface charge Q surface can be obtained by CV (cyclic voltammetry scanning) with different scanning speeds; the specific surface area S BET can be tested by injecting the sample to be tested into a certain pressure of adsorbate gas according to the pressure or weight change value before and after adsorption.

[0016] Q surface1 / S BET1 may be 0.1C / m 2 -0.5C / m 2 (e.g. 0.1C / m 2 , 0.2C / m 2 , 0.3C / m 2 , 0.4C / m 2 or 0.5C / m 2 ), Q surface2 / S BET2 may be 1C / m 2 -2C / m 2 (e.g. 1C / m 2 , 1.1C / m 2 , 1.2C / m 2 , 1.3C / m 2 , 1.4C / m 2 , 1.5C / m 2 , 1.6C / m 2 , 1.7C / m 2 , 1.8C / m 2 , 1.9C / m 2 or 2C / m 2 ).

[0017] In an example, Q surface1 / S BET1 is 0.15C / m 2 -0.4C / m 2 , and Q surface2 / S BET2 is 1.2C / m 2 -1.7C / m 2 .

[0018] In an example, Q surface1 / S BET10.2 C / m 2 -0.3 C / m 2 , Q surface2 / S BET2 1.3 C / m 2 -1.5 C / m 2 .

[0019] Q surface1 / S BET1 and Q surface2 / S BET2 may be 1:(2-20), for example 1:2, 1:3, 1:4, 1:5, 1:6, 1:7, 1:8, 1:9, 1:10, 1:11, 1:12, 1:13, 1:14, 1:15, 1:16, 1:17, 1:18, 1:19, or 1:20.

[0020] The inventors of the present application found that there is a specific ratio between Q surface1 / S BET1 and Q surface2 / S BET2 , which makes the battery have a higher capacity retention rate.

[0021] In an example, the ratio of Q surface1 / S BET1 and Q surface2 / S BET2 is 1:(3-11).

[0022] In an example, the ratio of Q surface1 / S BET1 and Q surface2 / S BET2 is 1:(5-7).

[0023] The inventors of the present application found that the first active material layer and the second active material layer have a specific composition, which makes Q surface1 / S BET1 of the first active material layer smaller than Q surface2 / S BET2 of the second active material layer.

[0024] The first active material layer can include a first active material, a first conductive agent, and a first binder.

[0025] The first active material layer can include a first active material, a first conductive agent, and a first binder.

[0026] In one example, the first active material layer includes 92 wt% to 95 wt% of the first active material, 1 wt% to 2 wt% of the first conductive agent, and 4 wt% to 6 wt% of the first binder, based on the total weight of the first active material layer.

[0027] The first active material can be selected from at least one of graphite, soft carbon, hard carbon, silicon, silicon oxide compounds, and silicon carbon compounds.

[0028] In one example, the first active material is graphite.

[0029] The second active material layer can include a second active material, a second conductive agent, and a second binder.

[0030] The second active material layer can include a second active material, a second conductive agent, and a second binder.

[0031] In one example, the second active material layer includes 94 wt% to 98 wt% of the second active material, 1.5 wt% to 4 wt% of the second conductive agent, and 0.5 wt% to 2 wt% of the second binder, based on the total weight of the second active material layer.

[0032] The second active material can be selected from at least one of graphite, soft carbon, hard carbon, silicon, silicon oxide compounds, and silicon carbon compounds.

[0033] In one example, the second active material is graphite.

[0034] The first conductive agent and the second conductive agent can each independently be selected from conductive agents conventionally used in the art, for example at least one selected from the group consisting of conductive carbon black, acetylene black, conductive graphite, carbon nanotubes, and carbon fibers.

[0035] The first binder and the second binder can each independently be selected from binders conventionally used in the art, for example at least one selected from the group consisting of polyvinylidene fluoride, polyvinyl alcohol, polytetrafluoroethylene, polyacrylic acid, and carboxymethyl cellulose.

[0036] The thickness of the first active material layer can be 20 μm to 75 μm, for example 20 μm, 25 μm, 30 μm, 35 μm, 40 μm, 45 μm, 50 μm, 55 μm, 60 μm, 65 μm, 70 μm, or 75 μm.

[0037] In an example, the thickness of the first active material layer is 35 μm to 55 μm.

[0038] The thickness of the second active material layer can be 20 μm to 112.5 μm, for example 20 μm, 25 μm, 30 μm, 35 μm, 40 μm, 45 μm, 50 μm, 55 μm, 60 μm, 65 μm, 70 μm, 75 μm, 80 μm, 85 μm, 90 μm, 95 μm, 100 μm, 105 μm, 110 μm, or 112.5 μm.

[0039] In an example, the thickness of the second active material layer is 60 μm to 80 μm.

[0040] The inventors of the present application found that a specific ratio of the thickness of the first active material layer to the thickness of the second active material layer can further improve the lithium precipitation problem at the crimping center of the battery.

[0041] The ratio of the thickness of the first active material layer to the thickness of the second active material layer can be 1:(1-5.7), for example 1:1, 1:1.5, 1:2, 1:2.5, 1:3, 1:3.5, 1:4, 1:4.5, 1:5, 1:5.5, or 1:5.7.

[0042] In an example, the ratio of the thickness of the first active material layer to the thickness of the second active material layer is 1:(1.09-2.29).

[0043] The specific surface charge of the active material layers on both sides of the negative electrode sheet of the present application is different, so that one side has more lithium ion liquid phase diffusion channels relative to the other side, which is beneficial to the deintercalation of lithium, can effectively improve the lithium precipitation problem at the crimping center of the battery, and Q surface1 / S BET1 and Q surface2 / SBET2 There is a specific ratio between them, which gives the battery excellent capacity retention.

[0044] A second aspect of the present invention provides a battery comprising the negative electrode sheet described in the first aspect of the present invention.

[0045] The battery can be a wound battery.

[0046] The first active material layer of the negative electrode sheet may be located on the side of the wound battery closer to the center of the roll, and the second active material layer of the negative electrode sheet may be located on the side of the wound battery away from the center of the roll.

[0047] The negative electrode sheet of the present invention can be applied to wound batteries with tabs located in the empty foil area, wound batteries with tabs in the middle, and wound batteries with multiple tabs.

[0048] The following explanation uses a wound battery with tabs located in the empty foil area as an example. Figure 1 The diagram shows the cell structure of a wound battery with tabs positioned in the empty foil area. The cell is assembled from a positive electrode 1, a negative electrode 2, and a separator 3 by winding. Figure 2 As shown, Figure 1The partial enlarged view in the dotted line frame shows the winding direction of the positive plate 1, the negative plate 2 and the separator 3, the positive plate 1 comprises a positive current collector 1-1 and a positive active material layer 1-2, the negative plate 2 comprises a current collector 2-1 and a first active material layer 2-2 and a second active material layer 2-3 arranged on the two side surfaces of the current collector 2-1 respectively, the active material layer on the side of the negative plate 2 away from the winding center is the second active material layer 2-3, the second active material layer 2-3 corresponds to the active material layer on the side of the positive plate 1 close to the winding center, the active material layer on the side of the negative plate 2 close to the winding center is the first active material layer 2-2, the first active material layer 2-2 corresponds to the active material layer on the side of the positive plate 1 away from the winding center. It can be understood that, since the circumference of each coil in the winding battery is different, that is, the circumference of the coil where the first active material layer 2-2 is located is longer than the circumference of the coil where the positive active material layer 1-2 on the positive plate 1 corresponds to, therefore, the first active material layer 2-2 is balanced with the positive active material layer 1-2 on the side of the positive plate 1 away from the winding center corresponding to the first active material layer 2-2, and the first active material layer 2-2 can completely receive the lithium ions stripped from the positive plate; and the circumference of the coil where the second active material layer 2-3 is located is shorter than the circumference of the coil where the positive active material layer 1-2 on the positive plate 1 corresponds to, therefore, the second active material layer 2-3 is unbalanced with the positive active material layer 1-2 on the side of the positive plate 1 close to the winding center corresponding to the second active material layer 2-3, and the second active material layer 2-3 can not be able to completely receive the lithium ions stripped from the positive plate, resulting in lithium precipitation at the winding center of the battery, which seriously affects the service life of the battery. In the battery of the present application, the specific surface charge Q surface2 / S BET2 of the second active material layer of the negative plate is large, has more lithium ion liquid diffusion channels, is beneficial to the stripping of lithium, and can effectively improve the problem of lithium precipitation at the winding center of the battery.

[0049] The materials and preparation methods of the battery except the negative plate can be carried out in a conventional manner in the art, and the effect of improving the safety performance can be achieved.

[0050] The battery further comprises, for example, a positive plate, a separator and an electrolyte.

[0051] It should be noted that the numerical representation of "first", "second" and the like in the present application is only used to distinguish different substances or use methods, and does not represent the difference in order.

[0052] The application will be described in detail below by way of examples. The examples described in the application are only a part of the examples of the application, but not all the examples. Based on the examples in the application, all other examples obtained by those skilled in the art without creative labor fall within the scope of protection of the application.

[0053] In the following examples, the materials used are commercially available analytical pure unless otherwise specified.

[0054] The following Group I examples are used to illustrate the negative electrode sheet of the application.

[0055] Group I examples

[0056] Example I1

[0057] The negative electrode sheet is prepared according to the following steps:

[0058] (1) First active material layer:

[0059] First active material: graphite, 93.5wt%;

[0060] First conductive agent: conductive carbon black, 1.5wt%;

[0061] First binder: polyvinylidene fluoride, 5wt%;

[0062] The first active material, the first conductive agent and the first binder are mixed, deionized water is added and stirred until uniform, coated on one side of the outer surface of the copper foil, and placed in an oven at 80°C for drying;

[0063] (2) Second active material layer:

[0064] Second active material: graphite, 94wt%;

[0065] Second conductive agent: conductive carbon black, 4wt%;

[0066] Second binder: polyvinylidene fluoride, 2wt%;

[0067] The second active material, the second conductive agent and the second binder are mixed, deionized water is added and stirred until uniform, coated on the other side of the outer surface of the copper foil, and placed in an oven at 80°C for drying;

[0068] The negative electrode sheet is obtained, wherein the Q surface1 / S BET1 of the first active material layer is 0.25C / m 2 , and the Q surface2 / S BET2 of the second active material layer is 1.3C / m 2, the thickness of the first active material layer is 45 pm, and the thickness of the second active material layer is 70 pm.

[0069] Example I2

[0070] The negative electrode sheet was prepared according to the following steps:

[0071] (1) First active material layer:

[0072] First active material: graphite, 92 wt%;

[0073] First conductive agent: acetylene black, 2 wt%;

[0074] First binder: polyvinyl alcohol, 6 wt%;

[0075] The first active material, the first conductive agent, and the first binder were mixed, deionized water was added and stirred uniformly, coated on one side of the outer surface of the copper foil, and placed in an oven at 80°C for drying;

[0076] (2) Second active material layer:

[0077] Second active material: graphite, 96 wt%;

[0078] Second conductive agent: acetylene black, 3 wt%;

[0079] Second binder: polyvinyl alcohol, 1 wt%;

[0080] The second active material, the second conductive agent, and the second binder were mixed, deionized water was added and stirred uniformly, coated on the other side of the outer surface of the copper foil, and placed in an oven at 80°C for drying;

[0081] The negative electrode sheet was obtained, wherein the Q surface1 / S BET1 of the first active material layer is 0.2 C / m 2 , the Q surface2 / S BET2 of the second active material layer is 1.4 C / m 2 , the thickness of the first active material layer is 35 pm, and the thickness of the second active material layer is 80 pm.

[0082] Example I3

[0083] The negative electrode sheet was prepared according to the following steps:

[0084] (1) First active material layer:

[0085] First active material: graphite, 95 wt%;

[0086] First conductive agent: carbon nanotube, 1 wt%;

[0087] First binder: polytetrafluoroethylene, 4wt%;

[0088] The first active material, the first conductive agent and the first binder were mixed, deionized water was added and stirred until uniform, coated on one side of the outer surface of the copper foil, and placed in an oven at 80°C for drying;

[0089] (2) Second active material layer:

[0090] Second active material: graphite, 98wt%;

[0091] Second conductive agent: carbon nanotube, 1.5wt%;

[0092] Second binder: polytetrafluoroethylene, 0.5wt%;

[0093] The second active material, the second conductive agent and the second binder were mixed, deionized water was added and stirred until uniform, coated on the other side of the outer surface of the copper foil, and placed in an oven at 80°C for drying;

[0094] The negative electrode sheet was obtained, wherein the Q surface1 / S BET1 of the first active material layer was 0.3C / m 2 , the Q surface2 / S BET2 of the second active material layer was 1.5C / m 2 , the thickness of the first active material layer was 55μm, and the thickness of the second active material layer was 60μm.

[0095] Example I4

[0096] The present group of examples is used to illustrate the effects of changes in the first active material layer and the second active material layer.

[0097] The present group of examples is made with reference to Example I1, except that the first active material layer and the second active material layer are changed, specifically:

[0098] In Example I4a:

[0099] (1) First active material layer:

[0100] First active material: graphite, 90wt%;

[0101] First conductive agent: conductive carbon black, 2wt%;

[0102] First binder: polyvinylidene fluoride, 8wt%;

[0103] (2) Second active material layer:

[0104] Second active material: graphite, 99 wt.-%;

[0105] Second conductive agent: conductive carbon black, 0.5 wt.-%;

[0106] Second binder: polyvinylidene fluoride, 0.5 wt.-%;

[0107] wherein Q surface1 / S BET1 of the first active material layer is 0.15 C / m 2 and Q surface2 / S BET2 of the second active material layer is 1.7 C / m 2 ;

[0108] In example I4b:

[0109] First active material: graphite, 94 wt.-%;

[0110] First conductive agent: conductive carbon black, 2.5 wt.-%;

[0111] First binder: polyvinylidene fluoride, 3.5 wt.-%;

[0112] (2) Second active material layer:

[0113] Second active material: graphite, 93 wt.-%;

[0114] Second conductive agent: conductive carbon black, 4 wt.-%;

[0115] Second binder: polyvinylidene fluoride, 3 wt.-%;

[0116] wherein Q surface1 / S BET1 of the first active material layer is 0.5 C / m 2 and Q surface2 / S BET2 of the second active material layer is 1 C / m 2 .

[0117] Example I5

[0118] This group of examples serves to illustrate the influence of changes in the thickness of the first active material layer and the thickness of the second active material layer.

[0119] This group of examples refers to example I1, except that the thickness of the first active material layer and the thickness of the second active material layer are changed, in particular:

[0120] In example I5a, the thickness of the first active material layer is 20 pm and the thickness of the second active material layer is 20 pm;

[0121] In Example I5b, the thickness of the second active material layer is 75 pm, and the thickness of the second active material layer is 112.5 pm.

[0122] Comparative Example D1

[0123] Comparative Example D1

[0124] Example II

[0125] The Example II is used to illustrate the battery of the present application.

[0126] The batteries are prepared using the negative electrode sheets obtained in the Example I and Comparative Example D1, respectively, and specifically:

[0127] The positive electrode uses a lithium cobalt oxide positive electrode sheet, the separator uses a polypropylene separator, and the electrolyte uses an ethylene carbonate and lithium hexafluorophosphate system. After the prepared negative electrode sheet is rolled, cut, and sheeted, the positive electrode sheet, the separator, and the negative electrode sheet are stacked in turn and wound, wherein the first active material layer of the negative electrode sheet is close to the winding center, and the second active material layer of the negative electrode sheet is away from the winding center. After the packaging, liquid injection, formation, sorting, and OCV steps, the battery is prepared.

[0128] Test Example

[0129] (1) 25℃ cycle performance test:

[0130] Test method: constant current charging to 4.25V at 2C rate, constant voltage charging to 1.5C at 4.25V, constant current charging to 4.45V at 1.5C rate, constant voltage charging to 0.025C at 4.45V, 0.7C discharging, cut-off voltage 3.0V, test 500T capacity retention rate, and disassemble the battery after the test is completed, observe whether lithium precipitation occurs, and record the test results in Table 1.

[0131] (2) 45℃ cycle performance test:

[0132] Test method: constant current charging to 4.15V at 3C rate, constant voltage charging to 1.5C at 4.25V, constant current charging to 4.35V at 1.5C rate, constant voltage charging to 0.025C at 4.45V, 0.7C discharging, cut-off voltage 3.0V, test 300T capacity retention rate, and disassemble the battery after the test is completed, observe whether lithium precipitation occurs, and record the test results in Table 1.

[0133] Table 1

[0134]

[0135]

[0136] As can be seen from Table 1, the battery prepared from the negative electrode sheet of the present application has significantly improved 500T capacity retention at 25℃ and 300T capacity retention at 45℃ compared with the comparative examples, and effectively improves the problem of lithium precipitation of the battery.

[0137] The above describes the preferred embodiments of the present application, but the present application is not limited thereto. Within the technical concept of the present application, various simple modifications can be made to the technical solutions of the present application, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be considered as disclosed by the present application and belong to the protection scope of the present application.

Claims

1. A battery, characterized in that, The battery is a wound battery, and the battery includes a negative electrode sheet; The negative electrode includes a current collector, and a first active material layer and a second active material layer respectively disposed on two surfaces of the current collector; The first active material layer of the negative electrode is located on the side of the wound battery closer to the center of the roll, and the second active material layer of the negative electrode is located on the side of the wound battery away from the center of the roll. The specific surface area of ​​the first active material layer stores the charge Q. surface1 / S BET1 The specific surface area stored charge Q is smaller than that of the second active material layer. surface2 / S BET2 Q surface1 / S BET1 With Q surface2 / S BET2 The ratio is 1:(2-20); The specific surface area of ​​the first active material layer stores the charge Q. surface1 / S BET1 The specific surface area of ​​the second active material layer stores the charge Q. surface2 / S BET2 The testing methods include: surface charge Q surface The specific surface area S is obtained by taking the intercepts of CV (cyclic voltammetric scan) at different scan rates. BET The specific surface area is measured by injecting the sample under test with an adsorbate gas at a certain pressure and measuring the change in pressure or weight before and after adsorption.

2. The battery according to claim 1, wherein, Q surface1 / S BET1 0.1C / m 2 -0.5C / m 2 Q surface2 / S BET2 1C / m 2 -2C / m 2 .

3. The battery according to claim 2, wherein, Q surface1 / S BET1 0.2C / m 2 -0.3C / m 2 Q surface2 / S BET2 1.3C / m 2 -1.5C / m 2 .

4. The battery according to any one of claims 1-3, wherein, Q surface1 / S BET1 With Q surface2 / S BET2 The ratio is 1:(5-7).

5. The battery according to claim 1, wherein, The first active material layer comprises a first active substance, a first conductive agent, and a first binder. Based on the total weight of the first active material layer, the content of the first active substance is 90wt%-96wt%, the content of the first conductive agent is 0.5wt%-3wt%, and the content of the first binder is 3.5wt%-10wt%. And / or, the first active material is selected from at least one of graphite, soft carbon, hard carbon, silicon, silicon oxides and silicon carbide compounds.

6. The battery according to claim 5, wherein, The first active substance is selected from graphite.

7. The battery according to claim 1, wherein, The second active material layer comprises a second active substance, a second conductive agent, and a second binder; based on the total weight of the second active material layer, the content of the second active substance is 92wt%-99wt%, the content of the second conductive agent is 0.5wt%-6wt%, and the content of the second binder is 0.5wt%-3wt%. And / or, the second active material is selected from at least one of graphite, soft carbon, hard carbon, silicon, silicon oxides and silicon carbide compounds.

8. The battery according to claim 7, wherein, The second active substance is selected from graphite.

9. The battery according to claim 1, wherein, The thickness of the first active material layer is 20μm-75μm, and the thickness of the second active material layer is 20μm-112.5μm.

10. The battery according to claim 9, wherein, The ratio of the thickness of the first active material layer to the thickness of the second active material layer is 1:(1-5.7).

11. The battery according to claim 10, wherein, The ratio of the thickness of the first active material layer to the thickness of the second active material layer is 1:(1.09-2.29).

Images