Negative electrode sheet and preparation method therefor, and battery and electric device

Abstract

A negative electrode sheet (100) and a preparation method therefor, and a battery and an electric device. The negative electrode sheet (100) comprises a current collector (10) and n active layers (20), wherein the current collector (10) has a first surface (11); the n active layers (20) are sequentially stacked on the first surface (11) in a first direction (X), the first direction (X) being perpendicular to the first surface (11); each active layer (20) comprises a first hard carbon material and / or a second hard carbon material; the content of the first hard carbon material in an (m+1)th active layer (20) is less than the content of the first hard carbon material in an mth active layer (20), the content of the second hard carbon material in the (m+1)th active layer (20) is greater than the content of the second hard carbon material in the mth active layer (20), the mth active layer (20) is closer to the first surface (11) than the (m+1)th active layer (20), and 1≤m≤n-1 is satisfied, both m and n being positive integers; and the proportion of the sloping-region capacity of the first hard carbon material is b1, and the proportion of the sloping-region capacity of the second hard carbon material is b2, satisfying b1<b2. By means of the negative electrode sheet (100), a battery achieves both a high energy density and a good charging capability.

Description

Negative electrode sheet, preparation method thereof, battery and electric device

[0001] The present application claims priority to the Chinese patent application No. 202410711813.5, filed on June 03, 2024, and entitled "Negative electrode sheet, preparation method thereof, battery and electric device", the whole content of which is incorporated herein by reference. TECHNICAL FIELD

[0002] The present application relates to the technical field of batteries, in particular to a negative electrode sheet, a preparation method thereof, a battery and an electric device. BACKGROUND

[0003] Sodium-ion batteries have lower cost than lithium-ion batteries, but the existing sodium-ion battery system has much lower energy density than lithium-ion batteries, which limits the application scenarios of sodium-ion batteries.

[0004] Among them, the specific capacity of the negative electrode of the sodium-ion battery and the compaction improvement space are larger. However, the specific capacity of the negative electrode needs to be improved in the platform region around 0V, and the corresponding platform region capacity ratio will be improved, but this will bring about a decrease in the slope region capacity ratio, i.e. a decrease in the power performance, and it is difficult to balance the two. SUMMARY

[0005] The purpose of the present application is to provide a negative electrode sheet, a preparation method thereof, a battery and an electric device, to solve the problem that the power performance and the battery capacity of the sodium-ion battery are difficult to balance.

[0006] To achieve the purpose of the present application, the present application provides the following technical solutions:

[0007] In a first aspect, the present application provides a negative electrode sheet, comprising:

[0008] a current collector having a first surface;

[0009] n active layers arranged in sequence along a first direction on the first surface, the first direction being perpendicular to the first surface;

[0010] Each of the active layers comprises a first hard carbon material and / or a second hard carbon material; the content of the first hard carbon material in the m+1th active layer is less than the content of the first hard carbon material in the mth active layer, the content of the second hard carbon material in the m+1th active layer is greater than the content of the second hard carbon material in the mth active layer, the mth active layer is closer to the first surface than the m+1th active layer, and 1≤m≤n-1, m and n are positive integers;

[0011] The capacity proportion of the ramp region of the first hard carbon material is b1, the capacity proportion of the ramp region of the second hard carbon material is b2, and b1 < b2 is satisfied.

[0012] The capacity of the ramp region of the first hard carbon material and the second hard carbon material is the capacity of the battery during the sodium intercalation process at 0.1V vs. Na + / Na or above.

[0013] In an implementation form, 2 ≤ n ≤ 4 is also satisfied.

[0014] In an implementation form, the reversible gram capacity of the first hard carbon material is a1, and a1 ≥ 290mAh / g is satisfied.

[0015] In an implementation form, 20% ≤ b1 ≤ 40% is also satisfied.

[0016] In an implementation form, 40% ≤ b2 ≤ 70% is also satisfied.

[0017] In an implementation form, the thickness of the active layer is h, and h ≥ 20μm is satisfied.

[0018] In an implementation form, 30μm ≤ h ≤ 60μm is also satisfied.

[0019] In an implementation form, the capacity proportion of the platform region of the first hard carbon material is e1, and 60% ≤ e1 ≤ 80% is satisfied; the capacity proportion of the platform region of the second hard carbon material is e2, and 30% ≤ e2 ≤ 60% is satisfied, and the capacity of the platform region of the first hard carbon material and the second hard carbon material is the capacity of the battery during the sodium intercalation process at 0V vs. Na + / Na to 0.1V vs. Na + / Na.

[0020] In a second aspect, the application provides a method for preparing a negative electrode sheet, comprising the following steps:

[0021] Providing a current collector, the current collector having a first surface;

[0022] Stacking n active layers in sequence along a first direction on the first surface, the first direction being perpendicular to the first surface;

[0023] Each of the active layers comprises a first hard carbon material and / or a second hard carbon material; a content of the first hard carbon material in the m+1th active layer is less than a content of the first hard carbon material in the mth active layer, a content of the second hard carbon material in the m+1th active layer is greater than a content of the second hard carbon material in the mth active layer, the mth active layer is closer to the first surface than the m+1th active layer, and 1≤m≤n-1 is satisfied, m and n are both positive integers;

[0024] A slope region capacity proportion of the first hard carbon material is b1, and a slope region capacity proportion of the second hard carbon material is b2, and b1<b2 is satisfied.

[0025] The capacity of the slope region of the first hard carbon material and the second hard carbon material is the capacity of the battery in the process of embedding sodium above 0.1 V vs. Na + / Na.

[0026] In a third aspect, the application provides a battery, comprising a positive electrode sheet, a separator and the negative electrode sheet according to any one of the first aspect, the separator being arranged between the positive electrode sheet and the negative electrode sheet.

[0027] In a fourth aspect, the application provides a power consumption device, comprising a power consumption device and the battery according to the third aspect, the battery supplying power to the power consumption device.

[0028] The negative electrode sheet of the application is provided with a plurality of active layers, the active layers are provided with a first hard carbon material for improving the capacity of the battery and a second hard carbon material for improving the rate of the battery, and the first hard carbon material is gradiently reduced in the active layers along the direction away from the current collector, and the second hard carbon material is gradiently increased in the active layers along the direction away from the current collector, i.e., the direction close to the electrode, the first hard carbon material and the second hard carbon material with gradient change are arranged in the plurality of active layers, so that the ion exchange rate is improved in the part close to the electrode, and the ion accommodation capacity is improved in the part close to the current collector, and the corresponding sodium ion battery can improve the power performance and the capacity of the battery, so that the capacity of the battery is improved while the rate performance is better and the fast charging time is shorter. BRIEF DESCRIPTION OF DRAWINGS

[0029] In order to more clearly illustrate the technical solutions in the embodiments of the application or the prior art, the following will briefly introduce the drawings needed to be used in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the application, and for those skilled in the art, other drawings can also be obtained from these drawings without creative labor.

[0030] FIG. 1 is a side view of a negative electrode sheet and a separator according to an embodiment;

[0031] FIG. 2 is a flow chart of a method of manufacturing a negative electrode sheet according to an embodiment.

[0032] BRIEF DESCRIPTION OF DRAWINGS 100 - negative electrode sheet, 10 - current collector, 11 - first surface, 20 - active layer, 200 - separator, X - first direction. DETAILED DESCRIPTION

[0033] The technical solutions in the embodiments of the present application will be clearly and completely described in combination with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of protection of the present application.

[0034] It should be noted that when a component is referred to as being "fixed" to another component, it can be directly on the other component or there can be an intervening component. When a component is referred to as being "connected" to another component, it can be directly connected to the other component or there can be an intervening component.

[0035] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used in the description of the application herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The use of the terms "and / or" includes a combination of one or more of the associated listed items.

[0036] Some embodiments of the present application will be described in detail with reference to the drawings. The following embodiments and features of the embodiments can be combined with each other in the case of no conflict.

[0037] Referring to FIG. 1, the present application provides a negative electrode sheet 100, comprising a current collector 10 and n active layers 20. The current collector 10 has a first surface 11. The n active layers 20 are sequentially stacked on the first surface 11 along a first direction X, and the first direction X is perpendicular to the first surface 11. Each active layer 20 comprises a first hard carbon material and / or a second hard carbon material. The content of the first hard carbon material in the m+1th active layer 20 is less than the content of the first hard carbon material in the mth active layer 20, the content of the second hard carbon material in the m+1th active layer 20 is greater than the content of the second hard carbon material in the mth active layer 20, the mth active layer 20 is closer to the first surface 11 than the m+1th active layer 20, and 1≤m≤n-1, m and n are positive integers.

[0038] The first hard carbon material and the second hard carbon material have specific specific properties, specifically: the capacity proportion of the ramp region of the first hard carbon material is b1, and the capacity proportion of the ramp region of the second hard carbon material is b2, and b1 < b2 is satisfied.

[0039] The capacity of the ramp region of the first hard carbon material and the second hard carbon material is the capacity of the battery sodium intercalation process at 0.1 V vs. Na + above.

[0040] When the pole piece is a negative pole piece 100, the corresponding current collector 10 can be any one of a copper foil, a composite copper foil, or a carbon-coated copper foil, or any one of an aluminum foil, a composite aluminum foil, or a carbon-coated aluminum foil.

[0041] The first hard carbon material and the second hard carbon material can be resin carbon (such as phenolic resin, epoxy resin, polyfurfuric alcohol resin, etc.), organic polymer carbon (such as polyvinyl alcohol, polyvinyl chloride, polyvinylidene fluoride, polyacrylonitrile, etc.), carbon black (such as acetylene black prepared by chemical vapor deposition), biomass carbon (such as plant residues and shells, etc.), without limitation. As a negative material of a sodium ion battery, the hard carbon material has a large interlayer spacing and an irregular structure, which is suitable for sodium ion deintercalation.

[0042] In an embodiment, the reversible gram capacity of the first hard carbon material is a1, and a1 ≥ 290 mAh / g is satisfied. a1 can be 290 mAh / g, 300 mAh / g, 350 mAh / g, 400 mAh / g, etc., without limitation.

[0043] In an embodiment, 20% ≤ b1 ≤ 40% is also satisfied. b1 can be 20%, 25%, 30%, 35%, 40%, without limitation. Optionally, 30% ≤ b1 ≤ 40% is also satisfied.

[0044] a1 ≥ 290 mAh / g of the first hard carbon material and the capacity proportion b1 of the ramp region satisfy 20% ≤ b1 ≤ 40%, so that the first hard carbon material is a capacity-type hard carbon material, and the energy density of the battery is greater, and the amount of electricity that can be stored is greater.

[0045] In an embodiment, 40% ≤ b2 ≤ 70% is also satisfied. b2 can be 40%, 50%, 60%, 70%, without limitation. Optionally, 40% ≤ b2 ≤ 60% is also satisfied. And when b1 is 40%, b2 cannot be 40%. The second hard carbon material is a rate-type hard carbon material, so that the battery can release or absorb energy faster, the charging and discharging speed of the battery is fast, and the working efficiency of the equipment can be improved.

[0046] The total mass of the first hard carbon material and the second hard carbon material in each active layer 20 can be consistent or inconsistent.

[0047] The number of layers n of the active layer 20 satisfies 1≤m≤n-1. Optionally, it also satisfies 2≤n≤4, and specifically, n can be 2, 3, or 4. The plurality of active layers 20 are stacked on the current collector 10, and when moving away from the current collector 10 along the first direction X, the content gradient of the first hard carbon material in the active layer 20 decreases, and the content gradient of the second hard carbon material in the active layer 20 increases. Referring to FIG. 1, the active layer 20 directly stacked on the first surface 11 is the first layer active layer 20, and the active layer 20 farthest from the first surface 11 is the nth layer active layer 20, and the nth layer active layer 20 is in close contact with the separator 200. Optionally, the hard carbon material in the first layer active layer 20 is all the first hard carbon material, and the hard carbon material in the nth layer active layer 20 is all the second hard carbon material.

[0048] The negative electrode sheet 100 of the present application is provided with a plurality of active layers 20, the active layers 20 are provided with a first hard carbon material for improving the capacity of the battery and a second hard carbon material for improving the rate of the battery, and the first hard carbon material has a gradient decrease in the active layer 20 along the direction away from the current collector 10, and the second hard carbon material has a gradient increase in the active layer 20 along the direction away from the current collector 10, i.e., the direction close to the electrode. The first hard carbon material and the second hard carbon material with gradient change are provided in the plurality of active layers 20, so that the ion exchange rate is improved in the part close to the electrode, and the ion accommodation capacity is improved in the part close to the current collector. Correspondingly, the sodium ion battery can have better rate performance and shorter fast charging time while improving the capacity of the battery.

[0049] In an embodiment, the thickness of the active layer 20 is h, which satisfies h≥20μm. Specifically, 30μm≤h≤60μm. h can be 20μm, 30μm, 40μm, 50μm, or 60μm, without limitation.

[0050] When h≥20μm, the active layer 20 can provide more electrochemical reaction area, thereby improving the capacity and energy density of the battery.

[0051] When h>60μm, the excessively thick active layer 20 can increase the transmission distance of electrons and ions, thereby increasing the internal resistance and charging / discharging time of the battery. The excessively thick active layer 20 is also prone to be affected by lithium dendrites, thereby causing the performance of the battery to decrease. When 30μm≤h≤60μm, the active layer 20 can balance the capacity, energy density, and charging / discharging speed of the battery, and also can reduce the weight of the battery, thereby improving the energy density and portability of the battery.

[0052] In an embodiment, the platform region capacity proportion of the first hard carbon material is e1, which satisfies 60%≤e1≤80%; the platform region capacity proportion of the second hard carbon material is e2, which satisfies 30%≤e2≤60%, and the capacity of the platform region of the first hard carbon material and the second hard carbon material is the capacity of the battery in the process of embedding sodium at 0V vs. Na + / Na to 0.1V vs. Na + / Na.

[0053] e1 can be 60%, 65%, 70%, 75%, 80%, etc., without limitation. e2 can be 30%, 40%, 50%, 60%, etc., without limitation. Specifically, the sum of e1 and b1 is 100%, and the sum of e2 and b2 is 100%.

[0054] The first hard carbon material has a large proportion of platform region capacity, so that the first hard carbon material can have a high specific capacity; the second hard carbon material has a large proportion of platform region, so that the second hard carbon material can have good rate performance.

[0055] Referring to FIGS. 1 and 2, the application also provides a preparation method of the negative electrode sheet 100, comprising the following steps:

[0056] Step S10, providing a current collector 10, the current collector 10 having a first surface 11;

[0057] Step S20, sequentially stacking n active layers 20 on the first surface 11 along a first direction X, the first direction X being perpendicular to the first surface 11.

[0058] Each active layer 20 comprises a first hard carbon material and / or a second hard carbon material; the content of the first hard carbon material in the m+1th active layer 20 is less than the content of the first hard carbon material in the mth active layer 20, the content of the second hard carbon material in the m+1th active layer 20 is greater than the content of the second hard carbon material in the mth active layer 20, the mth active layer 20 is closer to the first surface 11 than the m+1th active layer, and satisfies 1≤m≤n-1, m and n are positive integers;

[0059] The proportion of the ramp region capacity of the first hard carbon material is b1, and the proportion of the ramp region capacity of the second hard carbon material is b2, which satisfies: b1<b2; wherein the capacity of the ramp region of the first hard carbon material and the second hard carbon material is the capacity above 0.1V vs. Na+ / Na in the process of sodium intercalation of the battery.

[0060] In step S20, the n active layers 20 can be sequentially stacked on the first surface 11 along the first direction X by using a multi-layer coating method.

[0061] The application provides a battery, comprising a positive electrode sheet, a separator 200 and the negative electrode sheet 100 as described in any one of the preceding embodiments, the separator 200 being arranged between the positive electrode sheet and the negative electrode sheet 100.

[0062] The battery can be a square cell, a cylindrical cell, etc., and can also be other types such as a prismatic cell, etc., without limitation.

[0063] The battery further comprises a shell, the shell is provided with a receiving cavity, and the positive sheet, the separator 200 and the negative sheet 100 are accommodated in the receiving cavity. The shell is made of a material with high structural strength, which can be a metal material, a high-strength plastic, a ceramic or the like. The metal material can be, for example, aluminum, an aluminum alloy, a magnesium alloy, iron or an iron alloy. The shell comprises a bottom plate and a side plate. The shell can be an integrated structure, that is, the bottom plate and the side plate are integrally formed by an integrated forming process, which can be, for example, stamping or casting, without limitation. The shell can also be a split structure, and the side plate and the bottom plate can be connected and fixed by welding, bonding, clamping or screwing. The thickness of the shell can be substantially uniform, that is, the thickness of the side plate can be substantially uniform, and the thickness of the bottom plate and the side plate can also be substantially the same.

[0064] The positive material of the battery can be a sodium battery positive active material, which, in specific embodiments, comprises one or more of a sodium transition metal oxide, a prussian blue / white compound, a polyanion compound, a mixed metal oxide and a layered oxide.

[0065] The separator 200 can be any one of a woven membrane, a non-woven membrane, a microporous membrane, a composite membrane and a calendered membrane, without limitation. The positive and negative sheets 100 are separated by a plurality of layers of the separator 200.

[0066] The positive material, the conductive agent and the binder are uniformly mixed and dispersed in NMP (N-methyl pyrrolidone), coated on the foil and baked to obtain the positive sheet. The conductive agent comprises one or more of graphite, carbon black, acetylene black, graphene, carbon fiber, C60 and carbon nanotube. The binder comprises one or more of polyvinylidene chloride, soluble polytetrafluoroethylene, butadiene rubber, hydroxypropyl methyl cellulose, methyl cellulose, carboxymethyl cellulose, polyvinyl alcohol, acrylonitrile copolymer, sodium alginate, chitosan and a chitosan derivative, without limitation. The materials are not limited in the application and can be selected according to actual application requirements.

[0067] The application provides a power utilization device comprising the battery as described in the foregoing embodiments and a power utilization device, and the battery supplies power to the power utilization device.

[0068] The preparation process of the battery according to an embodiment of the application is as follows:

[0069] The first hard carbon material and the second hard carbon material are uniformly mixed with the conductive agent, the binder and the like in deionized water, uniformly coated on the surface of the current collector 10, and baked and rolled to obtain the negative sheet 100.

[0070] The positive sheet, the separator 200 and the negative sheet 100 are sequentially and orderly wound to obtain the core.

[0071] After the core shell is sleeved, electrolyte is injected, and a complete secondary sodium ion battery is obtained through aging, aging, formation and partial filling.

[0072] The technical solutions of the present application are described in detail below through specific examples.

[0073] Example 1

[0074] The present embodiment provides a negative electrode sheet 100, which comprises a current collector 10 and two layers of active layers 20.

[0075] The first layer of active layer 20 in the two layers of active layers 20 is arranged on the first surface 11 of the current collector 10, and the second layer of active layer 20 is arranged on the side surface of the first layer of active layer 20 away from the current collector 10. The mass ratio of the first hard carbon material and the second hard carbon material of the whole negative electrode sheet 100 is 1:1. The first hard carbon material is resin carbon, and the second hard carbon material is biomass carbon. The thickness h of the first layer of active layer 20 and the second layer of active layer 20 is 40pm±2pm.

[0076] The a1 of the first hard carbon material is 315.6mAh / g, the reversible gram capacity of the second hard carbon material is a2, a2 is 280.4mAh / g, the b1 of the first hard carbon material is 34.3%, and the b2 of the second hard carbon material is 43.4%.

[0077] The mass ratio of the first hard carbon material to the second hard carbon material in the first layer of active layer 20 is 6:4.

[0078] The mass ratio of the first hard carbon material to the second hard carbon material in the second layer of active layer 20 is 4:6.

[0079] Example 2

[0080] The present embodiment provides a negative electrode sheet 100, which is basically the same as example 1, and the difference is that:

[0081] The mass ratio of the first hard carbon material to the second hard carbon material in the first layer of active layer 20 is 8:2.

[0082] The mass ratio of the first hard carbon material to the second hard carbon material in the second layer of active layer 20 is 2:8.

[0083] Example 3

[0084] The present embodiment provides a negative electrode sheet 100, which is basically the same as example 1, and the difference is that:

[0085] The mass ratio of the first hard carbon material to the second hard carbon material in the first layer of active layer 20 is 10:0.

[0086] The mass ratio of the first hard carbon material to the second hard carbon material in the second layer of active layer 20 is 0:10.

[0087] Example 4

[0088] This example provides a negative electrode sheet 100, which is basically the same as Example 3, except that:

[0089] The second hard carbon material is resin carbon.

[0090] The a2 of the second hard carbon material is 262.6 mAh / g, and the b2 of the second hard carbon material is 60%.

[0091] Example 5

[0092] This example provides a negative electrode sheet 100, which is basically the same as Example 4, except that:

[0093] The a2 of the second hard carbon material is 248.8 mAh / g, and the b2 of the second hard carbon material is 70%.

[0094] Example 6

[0095] This example provides a negative electrode sheet 100, which is basically the same as Example 3, except that:

[0096] The a1 of the first hard carbon material is 300 mAh / g, and the b1 of the first hard carbon material is 36%.

[0097] Example 7

[0098] This example provides a negative electrode sheet 100, which is basically the same as Example 3, except that:

[0099] The a1 of the first hard carbon material is 290 mAh / g, and the b1 of the first hard carbon material is 39%.

[0100] Comparative Example 1

[0101] This comparative example provides a negative electrode sheet 100, which is basically the same as Example 1, except that:

[0102] Only one active layer 20 is provided, and the thickness of the active layer 20 of Comparative Example 1 is the same as the total thickness of the two active layers 20 of Example 1. The mass ratio of the first hard carbon material to the second hard carbon material in the active layer 20 is 5:5.

[0103] Comparative Example 2

[0104] This comparative example provides a negative electrode sheet 100, which is basically the same as Example 1, except that:

[0105] The mass ratio of the first hard carbon material to the second hard carbon material in the first active layer 20 is 4:6.

[0106] The mass ratio of the first hard carbon material to the second hard carbon material in the second active layer 20 is 6:4.

[0107] Comparative Example 3

[0108] This comparative example provides a negative electrode sheet 100 which is substantially the same as Example 2, except that:

[0109] The mass ratio of the first hard carbon material : second hard carbon material in the first layer active layer 20 is 2 : 8.

[0110] The mass ratio of the first hard carbon material : second hard carbon material in the second layer active layer 20 is 8 : 2.

[0111] Comparative Example 4

[0112] This comparative example provides a negative electrode sheet 100 which is substantially the same as Example 3, except that:

[0113] The mass ratio of the first hard carbon material : second hard carbon material in the first layer active layer 20 is 0 : 10.

[0114] The mass ratio of the first hard carbon material : second hard carbon material in the second layer active layer 20 is 10 : 0.

[0115] Comparative Example 5

[0116] This comparative example provides a negative electrode sheet 100 which is substantially the same as Example 4, except that:

[0117] Only one layer of the active layer 20 is present, and the thickness of the active layer 20 of Comparative Example 5 is the same as the total thickness of the two layers of the active layer 20 of Example 4.

[0118] Comparative Example 6

[0119] This comparative example provides a negative electrode sheet which is substantially the same as Example 5, except that:

[0120] Only one layer of the active layer 20 is present, and the thickness of the active layer 20 of Comparative Example 6 is the same as the total thickness of the two layers of the active layer 20 of Example 5.

[0121] Comparative Example 7

[0122] This comparative example provides a negative electrode sheet which is substantially the same as Example 6, except that:

[0123] Only one layer of the active layer 20 is present, and the thickness of the active layer 20 of Comparative Example 7 is the same as the total thickness of the two layers of the active layer 20 of Example 6.

[0124] Comparative Example 8

[0125] This comparative example provides a negative electrode sheet which is substantially the same as Example 7, except that:

[0126] Only has 1 layer of active layer 20, and the thickness of the active layer 20 of Comparative Example 8 is the same as the total thickness of the two layers of active layer 20 of Example 7.

[0127] Table 1 is the distribution of the mass ratio of the first hard carbon material and the second hard carbon material in each layer on the current collector 10 in the negative electrode sheet of Examples 1-7 and Comparative Examples 1-8, Table 2 is the data of the reversible gram capacity and the slope region ratio of the first hard carbon material and the second hard carbon material of Examples 1-7 and Comparative Examples 1-8, and Table 3 is the energy density and charging capacity of the corresponding batteries of Examples 1-7 and Comparative Examples 1-8.

[0128] Table 1

[0129] Table 2

[0130] Table 3

[0131] Referring to Tables 1-3, it can be seen from Comparative Examples 1-3 that as the gradient change of the first hard carbon material and the second hard carbon material of the battery with two layers of active layer 20 increases, the gram capacity of the battery increases, and the fast charging time of the battery decreases.

[0132] It can be seen from Comparative Example 1 and Comparative Example 2, Example 2 and Comparative Example 3, and Example 3 and Comparative Example 4 that the mass ratio of the first hard carbon material and the second hard carbon material in the corresponding active layer 20 is adjusted, and the fast charging time of the battery increases.

[0133] It can be seen from Comparative Examples 1-3 and Comparative Example 1 that under the condition that the gram capacity of the battery is similar, the fast charging time of the battery with only the first layer of active layer 20 is greater than that of the battery with two layers of active layer 20.

[0134] It can be seen from Comparative Example 4 and Example 5 that the greater the slope region ratio b2 of the second hard carbon material, the smaller the reversible gram capacity a2 of the second hard carbon material. It can be seen from Comparative Example 6 and Example 7 that the greater the slope region ratio b1 of the first hard carbon material, the smaller the reversible gram capacity a1 of the first hard carbon material.

[0135] It can be seen from Comparative Examples 1-3 and Comparative Examples 2-4 that the gram capacity of the battery of Examples 1-3 is similar to that of the battery of Comparative Examples 2-4, but the fast charging time of the battery of Examples 1-3 is less than that of the battery of Comparative Examples 2-4. The maximum difference in fast charging time is between Example 3 and Comparative Example 4, which can reach 9.2 min. Therefore, the battery of the present application improves the charging capacity of the battery while ensuring the gram capacity of the battery, that is, the battery of the present application can balance the battery capacity and the power performance.

[0136] As can be seen from Comparative Examples 4 and Comparative Example 5, Example 5 and Comparative Example 6, Example 6 and Comparative Example 7, and Example 7 and Comparative Example 8, when the distribution of the first hard carbon material and the second hard carbon material is changed without changing the reversible gram capacity and the slope region proportion of the first hard carbon material and the second hard carbon material, the gram capacity of the battery is not greatly affected, but the fast charging time of the battery using the negative plate (the double-layer coated negative plate with the first hard carbon material closer to the current collector) of the application is significantly reduced, and thus it can be considered that the batteries of Examples 4-7 reduce the fast charging time while ensuring the capacity of the battery, that is, the battery of the application can balance the capacity and power performance of the battery.

[0137] As can be seen from Comparative Examples 3-5, changing the slope region proportion b2 of the second hard carbon material causes the gram capacity of the battery to decrease, and the fast charging time of the corresponding battery is increased, but when the gram capacity of the battery is reduced by 5.25%, the fast charging time of the battery is shortened by 26.2%, indicating that the battery of the application can balance the capacity and power performance of the battery. As can be seen from Comparative Examples 1-5, the battery with a higher proportion of the first hard carbon material has a higher gram capacity but a longer fast charging time; the battery with a higher proportion of the second hard carbon material has a shorter fast charging time but a higher gram capacity; simultaneously adding the first hard carbon material and the second hard carbon material can balance the gram capacity and fast charging performance of the battery; and further gradient design of the first hard carbon material and the second hard carbon material of the battery can further improve the fast charging performance of the battery.

[0138] In the description of the embodiments of the application, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", and the like indicate the orientation or positional relationship based on the drawings, and are only used to facilitate the description of the application and simplify the description, and thus cannot be understood as indicating or implying that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus cannot be understood as limiting the application.

[0139] The above disclosure is only one preferred embodiment of the application, and of course cannot limit the scope of the application, and those skilled in the art can understand that all or part of the above-mentioned embodiments can be implemented, and equivalent changes made in accordance with the claims of the application still fall within the scope of the application.

Claims

1. A negative electrode sheet (100) characterized by, The application relates to a negative electrode sheet and a battery. The application relates to a negative electrode sheet and a battery. The application relates to a negative electrode sheet and a battery. The application relates to a negative electrode sheet and a battery. The application relates to a negative electrode sheet and a battery. wherein the capacity of the ramp region of the first hard carbon material and the second hard carbon material is above 0.1 V vs. Na + Na above.

2. The negative electrode sheet (100) according to claim 1, characterized by The application relates to a negative electrode sheet and a battery.

3. The negative electrode sheet (100) according to claim 1, characterized by The application relates to a negative electrode sheet and a battery.

4. The negative electrode sheet (100) according to claim 1, characterized by The application relates to a negative electrode sheet and a battery.

5. The negative electrode sheet (100) according to claim 1, characterized by The application relates to a negative electrode sheet and a battery.

6. The negative electrode sheet (100) according to claim 1, characterized by The application relates to a negative electrode sheet and a battery.

7. The negative electrode sheet (100) according to claim 6, characterized by The application relates to a negative electrode sheet and a battery.

8. The negative electrode sheet (100) according to claim 1, characterized by, The capacity proportion of the platform region of the first hard carbon material is e1, and satisfies: 60%≤e1≤80%; the capacity proportion of the platform region of the second hard carbon material is e2, and satisfies: 30%≤e2≤60%, the capacity of the platform region of the first hard carbon material and the second hard carbon material is the capacity of the battery in the process of embedding sodium from 0V vs.Na + to 0.1V vs.Na + to 0.1V vs.Na.

9. A method for producing a negative electrode sheet (100), characterized by, The application relates to a negative electrode sheet and a battery. The application relates to a negative electrode sheet and a battery. The application relates to a negative electrode sheet and a battery. The application relates to a negative electrode sheet and a battery. The application relates to a negative electrode sheet and a battery. wherein the capacity of the ramp region of the first hard carbon material and the second hard carbon material is above 0.1 V vs. Na + / Na above.

10. A battery, characterized by The application relates to a negative electrode sheet and a battery.

11. An electrical device, characterized by The application relates to a negative electrode sheet and a battery. The application relates to a negative electrode sheet and a battery. The application relates to a negative electrode sheet and a battery. The application relates to a negative electrode sheet and a battery. The application relates to a negative electrode sheet and a battery. The application relates to a negative electrode sheet and a battery. The application relates to a negative electrode sheet and a battery. The application relates to a negative electrode sheet and a battery. The application relates to a negative electrode sheet and a battery. The application relates to a negative electrode sheet and a battery. The application relates to a negative electrode sheet and a battery. The application relates to a negative electrode sheet and a battery. The application relates to a negative electrode sheet and a battery. The application relates to a negative electrode sheet and a battery. The application relates to a negative electrode sheet and a battery. The application relates to a negative electrode sheet and a battery. The application relates to a negative electrode sheet and a battery. The application relates to a negative electrode sheet and a battery. The application relates to a negative electrode sheet and a battery. The application relates to a negative electrode sheet and a battery. The application relates to a negative electrode sheet and a battery. The application relates to a negative electrode sheet and a battery. The application relates to a negative electrode sheet and a battery. The application relates to a negative electrode sheet and a battery. The application relates to a negative electrode sheet and a battery. The application relates to a negative electrode sheet and a battery. The application relates to a negative electrode sheet and a battery. The application relates to a negative electrode sheet and a battery. The application relates to a negative electrode sheet and a battery. The application relates to a negative electrode sheet and a battery. The application relates to a negative electrode sheet and a battery. The application relates to a negative electrode sheet and a battery. The application relates to a negative electrode sheet and a battery. The application relates to a negative electrode sheet and a battery. The application relates to a negative electrode sheet and a battery. The application relates to a negative electrode sheet and a battery. The application relates to a negative electrode sheet and a battery. The application relates to a negative electrode sheet and a battery. The application relates to a negative electrode sheet and a battery. The application relates to a negative electrode sheet and a battery. The application relates to a negative electrode sheet and a battery. The application relates to a negative electrode sheet and a battery. The application relates to a negative electrode sheet and a battery. The application relates to a negative electrode sheet and a battery. The application relates to a negative electrode sheet and a battery. The application relates to a negative electrode sheet and a battery. The application relates to a negative electrode sheet and a battery. The application relates to a negative electrode sheet and a battery. The application relates to a negative electrode sheet and a battery. The application relates to a negative electrode sheet and a battery. The application relates to a negative electrode sheet and a battery. The application relates to a negative electrode sheet and a battery. The application relates to a negative electrode sheet and a battery. The application relates to a negative electrode sheet and a battery. The application relates to a negative electrode sheet and a battery. The application relates to a negative electrode sheet and a battery. The application relates to a negative electrode sheet and a battery. The application relates to a negative electrode sheet and a battery. The application relates to a negative electrode sheet and a battery. The application relates to a negative electrode sheet and a battery. The application relates to a negative electrode sheet and a battery. The application relates to a negative electrode sheet and a battery. The application relates to a negative electrode sheet and a battery. The application relates to a negative electrode sheet and a battery. The application relates to a negative electrode sheet and a battery. The application relates to a negative electrode sheet and a battery. The application relates to a negative electrode sheet and a battery. The application relates to a negative electrode sheet and a battery. The application relates to a negative electrode sheet and a battery. The application relates to a negative electrode sheet and a battery. The application relates to a negative electrode sheet and a battery. The application relates to a negative electrode sheet and a battery. The application relates to a negative electrode sheet and a battery. The application relates to a negative electrode sheet and a battery. The application relates to a negative electrode sheet and a battery. The application relates to a negative electrode sheet and a battery. The application relates to a negative electrode sheet and a battery. The application relates to a negative electrode sheet and a battery. The application relates to a negative electrode sheet and a battery. The application relates to a negative electrode sheet and a battery. The application relates to a negative electrode sheet and a battery. The application relates to a negative electrode sheet and a battery. The application relates to a negative electrode sheet and a battery. The application relates to a negative electrode sheet and a battery. The application relates to a negative electrode sheet and a battery. The application relates to a negative electrode sheet and a battery. The application relates to a negative electrode sheet and a battery. The application relates to a negative electrode sheet and a battery. The application relates to a negative electrode sheet and a battery. The application relates to a negative electrode sheet and a battery. The application relates to a negative electrode sheet and a battery. The application relates to a negative electrode sheet and a battery. The application relates to a negative electrode sheet and a battery. The application relates to a negative electrode sheet and a battery. The application relates to a negative electrode sheet and a battery. The application relates to a negative electrode sheet and a battery. The application relates to a negative electrode sheet and a battery. The application relates to a negative electrode sheet and a battery. The application relates to a negative electrode sheet and a battery. The application relates to a negative electrode sheet and a battery. The application relates to a negative electrode sheet and a battery. The application relates to a negative electrode sheet and a battery. The application relates to a negative electrode sheet and a battery. The application relates to a negative electrode sheet and a battery. The application relates to a negative electrode sheet and a battery. The application relates to a negative electrode sheet and a battery. The application relates to a negative electrode sheet and a battery. The application relates to a negative electrode sheet and a battery. The application relates to a negative electrode sheet and a battery. The application relates to a negative electrode sheet and a battery. The application relates to a negative electrode sheet and a battery. The application relates to a negative electrode sheet and a battery. The application relates to a negative electrode sheet and a battery. The application relates to a negative electrode sheet and a battery. The application relates to a negative electrode sheet and a battery. The application relates to a negative electrode sheet and a battery. The application relates to a negative electrode sheet and a battery. The application relates to a negative electrode sheet and a battery. The application relates to a negative electrode sheet and a battery. The application relates to a negative electrode sheet and a battery. The application relates to a negative electrode sheet and a battery. The application relates to a negative electrode sheet and a battery. The application relates to a negative electrode sheet and a battery. The application relates to a negative electrode sheet and a battery. The application relates to a negative electrode sheet and a battery. The application relates to a negative electrode sheet and a battery. The application relates to a negative electrode sheet and a battery. The application relates to a negative electrode sheet and a battery. The application relates to a negative electrode sheet and a battery. The application relates to a negative electrode sheet and a battery. The application relates to a negative electrode sheet and a battery. The application relates to a negative electrode sheet and a battery. The application relates to a negative electrode sheet and a battery. The application relates to a negative electrode sheet and a battery. The application relates to a negative electrode sheet and a battery. The application relates to a negative electrode sheet and a battery. The application relates to a negative electrode sheet and a battery. The application relates to a negative electrode sheet and a battery. The application relates to a negative electrode sheet and a battery. The application relates to a negative electrode sheet and a battery. The application relates to a negative electrode sheet and a battery. The application relates to a negative electrode sheet and a battery. The application relates to a negative electrode sheet and a battery. The application relates to a negative electrode sheet and a battery. The application relates to a negative electrode sheet and a battery. The application relates to a negative electrode sheet and a battery. The application relates to a negative electrode sheet and a battery. The application relates to a negative electrode sheet and a battery. The application relates to a negative electrode sheet and a battery. The application relates to a negative electrode sheet and a battery. The application relates to a negative electrode sheet and a battery. The application relates to a negative electrode sheet and a battery. The application relates to a negative electrode sheet and a battery. The application relates to a negative electrode sheet

Images