Electrode sheet, and preparation method therefor and application therefof

Abstract

An electrode sheet, and a preparation method therefor and application thereof. The electrode sheet comprises a current collector, and an active substance layer, which is arranged on the surface of the current collector, wherein the active substance layer comprises a carbon conductive network, a conductive agent and an active substance, the conductive agent and the active substance being dispersed in the carbon conductive network, and the carbon conductive network being obtained from a carbonized polymer precursor; and a continuous carbon network is included in the electrode sheet to tightly connect a porous electrode sheet layer to the current collector, and the active substance, conductive carbon black and other particles in the porous electrode sheet layer are uniformly dispersed in the continuous carbon network structure, thereby greatly improving the conductivity of an electrode while ensuring that a physical contact of the electrode sheet is not damaged, and thus enhancing the rate capability and the reaction kinetics of a battery.

Description

An electrode plate and its preparation method and application Technical Field

[0001] The present application relates to the field of battery material technology, such as an electrode plate and its preparation method and application. Background Art

[0002] With the advancement of the times, the widespread adoption of new energy vehicles and the significant increase in energy storage demand driven by the development of clean energy have led to a surge in demand for secondary lithium and sodium batteries. Clean energy sources such as hydropower, solar power, and wind power are subject to weather-related constraints and lack stable power generation, creating a need for low-cost, large-scale energy storage systems. Lithium and sodium sulfide batteries, with their high energy density and low cost, are well-suited for large-scale energy storage.

[0003] Due to the poor conductivity and reaction kinetics of lithium and sodium sulfides, they still face many difficulties in their commercialization process, and there is an urgent need to develop electrode technology with excellent conductive networks. On the other hand, the new energy vehicle field has developed very rapidly in recent years. The rapid development has brought about phenomena such as slow charging and difficulty in charging. Although lithium / sodium ion batteries with excellent rate performance are currently widely used in new energy vehicles, further improvement is still needed. In order to solve the user experience problems caused by long charging times, it is necessary to develop a battery system that can meet high-power charging and discharging, which also puts forward requirements for electrodes with excellent conductivity.

[0004] The electrode plates disclosed in the related art are generally composed of active materials, conductive agents, and binders, which are combined together by dissolving in an organic solvent and performing steps such as slurry mixing, coating, and evaporation. Since the active material, conductive agent, and solvent have no adhesion to the current collector, they cannot be made into plates for the preparation of lithium batteries. The binder can bond the particles of the above-mentioned various electrode materials together to form a slurry with adhesion. Therefore, the binder can effectively bond and maintain the physical state of the active material, enhance the electronic contact between the active material and the conductive agent in the electrode and between the active material and the current collector, and play a role in better stabilizing the physical structure of the plate. However, the binder itself is generally a high molecular polymer, and its intrinsic electronic conductivity has certain limitations, which will affect the conductivity of the entire electrode, thereby affecting the reaction kinetics of the battery, having a certain impact on the rate performance, and even increasing the polarization phenomenon of charge and discharge, especially in metal sulfide batteries, where lower conversion kinetics will cause more problems.

[0005] Summary of the Invention

[0006] The following is a summary of the subject matter described in detail herein. This summary is not intended to limit the scope of the claims.

[0007] The present application provides an electrode plate and its preparation method and application. The electrode plate contains a continuous carbon network inside to tightly connect the porous electrode plate layer and the current collector. The active material and conductive carbon black particles in the porous electrode plate layer are evenly dispersed in the continuous carbon network structure. While ensuring that the physical contact of the electrode plate is not destroyed, the conductivity of the electrode is greatly improved, thereby enhancing the battery's rate performance and reaction kinetics.

[0008] In the first aspect, the present application provides an electrode plate, which includes a current collector and an active material layer arranged on the surface of the current collector, the active material layer includes a carbon conductive network, a conductive agent and an active material, the conductive agent and the active material are dispersed in the carbon conductive network, and the carbon conductive network is obtained by carbonizing a carbonized polymer precursor.

[0009] The electrode plate described in the present application has an electrode structure with an excellent conductive network, which overcomes the problems of poor conductivity caused by the binder in traditional electrode structures and optimizes its conductive network, thereby improving the reaction kinetics of the entire electrode, reducing polarization, and enhancing rate performance; in lithium / sodium sulfide batteries, this excellent conductive structure can also increase the nucleation sites of sulfur / sulfide, promote its uniform deposition, improve the utilization rate of active materials and reduce the generation of dead sulfur.

[0010] The excellent carbon conductive network in the electrode plates described in this application is derived from a carbonized polymer precursor, which includes any one or a combination of at least two of polyvinyl pyrrolidone, polyethyl acetate, polyacrylonitrile, polyacrylate, or carboxymethyl cellulose. Compared to traditional polyvinylidene fluoride binders, these polymers can still tightly adhere the active material and conductive agent to the current collector even after carbonization, preventing powdering or shedding, while simultaneously acting as a binder and conductor.

[0011] In one embodiment, based on the mass of the active material layer being 100%, the mass fraction of the carbon conductive network is 0.2-10%, for example, 0.2%, 1%, 5%, 8% or 10%.

[0012] In one embodiment, based on the mass of the active material layer being 100%, the mass fraction of the active material is 40-99%, for example, 40%, 45%, 60%, 80% or 99%.

[0013] In one embodiment, based on the mass of the active material layer being 100%, the mass fraction of the conductive agent is 0.3-30%, for example, 0.3%, 1%, 5%, 10%, 20% or 30%.

[0014] In one embodiment, the diameter of the carbon conductive network is 5 to 300 nm, for example, 5 nm, 10 nm, 50 nm, 80 nm, 100 nm, 200 nm or 300 nm, and can be optionally 50 to 200 nm.

[0015] In one embodiment, the conductive agent includes any one of conductive carbon black, acetylene black, Ketjen black, carbon nanotubes, or graphene, or a combination of at least two thereof.

[0016] In one embodiment, the active material includes a positive electrode active material or a negative electrode active material.

[0017] In one embodiment, the positive electrode active material includes any one of lithium iron phosphate, lithium cobaltate, lithium manganate, lithium nickel cobalt manganate, sodium nickel iron manganate, sodium iron sulfate, lithium sulfide, or sodium sulfide, or a combination of at least two thereof.

[0018] In one embodiment, the negative electrode active material includes any one of hard carbon, soft carbon, graphite, silicon carbon, or silicon monoxide, or a combination of at least two thereof.

[0019] In one embodiment, the current collector includes any one of aluminum foil, carbon-coated aluminum foil, copper foil, nickel foam or titanium foil, or a combination of at least two thereof.

[0020] In one embodiment, the carbonized polymer precursor includes any one of polyvinyl pyrrolidone, polyethyl acetate, polyacrylonitrile, polyacrylate or carboxymethyl cellulose, or a combination of at least two thereof.

[0021] In a second aspect, the present application provides a method for preparing the electrode sheet according to the first aspect, the preparation method comprising the following steps:

[0022] (1) mixing a carbonized polymer precursor with a solvent to obtain a solution, mixing and grinding an active material and a conductive agent, and then mixing the mixture with the solution to obtain a slurry;

[0023] (2) The slurry is coated on the surface of the current collector and subjected to high-temperature carbonization treatment to obtain the electrode plate.

[0024] This application carbonizes the carbonized polymer precursor to construct a pole piece structure with an excellent conductive network. While ensuring that the physical contact between the pole pieces is not disrupted, the conductivity of the electrode is significantly improved, thereby enhancing the battery's rate performance and reaction kinetics. This method is low-cost and can be used in both positive and negative pole pieces, meeting the needs of different lithium / sodium secondary battery systems and providing a new design approach for the commercial development of lithium / sodium secondary batteries.

[0025] In one embodiment, the solvent in step (1) comprises N-methylpyrrolidone.

[0026] In one embodiment, the high-temperature carbonization treatment in step (2) includes pre-carbonization and high-temperature calcination.

[0027] In one embodiment, the atmosphere of the high temperature carbonization treatment includes nitrogen and / or argon.

[0028] In one embodiment, the pre-carbonization temperature is 150-250°C, for example, 150°C, 180°C, 200°C, 220°C or 250°C.

[0029] In one embodiment, the high temperature calcination temperature is 300-600°C, for example, 300°C, 350°C, 400°C, 500°C or 600°C.

[0030] In a third aspect, the present application provides a battery, comprising the electrode plate as described in the first aspect.

[0031] Compared with the related art, this application has the following beneficial effects:

[0032] This application designs a new electrode structure and carbonizes the polymer precursor to construct a pole piece structure with an excellent conductive network. While ensuring that the physical contact of the pole piece is not destroyed, the conductivity of the electrode is greatly improved, thereby enhancing the battery's rate performance and reaction kinetics. This method is low-cost and can be used in both positive and negative pole pieces, meeting the needs of different lithium / sodium secondary battery systems, and providing a new design concept for the commercial development of lithium / sodium secondary batteries.

[0033] Still other aspects will become apparent upon reading and understanding the accompanying drawings and detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] The accompanying drawings are used to provide a further understanding of the technical solution of this article and constitute a part of the specification. Together with the embodiments of this application, they are used to explain the technical solution of this article and do not constitute a limitation on the technical solution of this article.

[0035] Figure 1 is a schematic structural diagram of the electrode provided in Example 1 of the present application, 1-current collector, 2-active material layer, 3-active material, 4-conductive agent, 5-carbon conductive network.

[0036] FIG2 is an optical image of the pole piece provided in Example 3 of the present application.

[0037] FIG3 is an optical image of the pole piece after cycling provided in Example 3 of the present application. DETAILED DESCRIPTION

[0038] The technical solution of the present application is further described below through specific implementation methods. Those skilled in the art should understand that the embodiments are only used to help understand the present application and should not be regarded as specific limitations of the present application.

[0039] Example 1

[0040] This embodiment provides a positive electrode sheet, and the preparation method of the positive electrode sheet is as follows:

[0041] (1) Take lithium iron phosphate, acetylene black (AB), and polyacrylonitrile (PAN) in a mass ratio of 8:1:1, first dissolve PAN in an appropriate amount of N-methylpyrrolidone (NMP) to form a glue solution, then evenly mix the lithium iron phosphate and AB, grind them, add the glue solution and stir, and obtain a slurry after dissolution and stirring are completed;

[0042] (2) The slurry is evenly coated on aluminum foil, dried, and cut to obtain an initial lithium iron phosphate electrode. The initial lithium iron phosphate electrode is placed in a muffle furnace and maintained at 200°C for 12 hours. It is then placed in a tube furnace and heated to 500°C and calcined for 2 hours under the condition of passing Ar gas at a heating rate of 5°C / min. After cooling, it is taken out to obtain the positive electrode electrode. The mass fraction of the carbon conductive network in the electrode is 6%, the mass fraction of the active material is 83%, and the mass fraction of the conductive agent is 11%. The structural schematic diagram of the electrode is shown in Figure 1.

[0043] Based on this electrode, a lithium iron phosphate half-cell is made. The electrolyte uses 1M LiTFSI dissolved in EC / DEC / DMC = 1:1:1, and the diaphragm uses a polyolefin diaphragm. The battery has a specific capacity of 150mAh / g at 1C, and the capacity retention rate is 95% after 200 cycles at 1C. The average coulombic efficiency reaches 99.3%.

[0044] Example 2

[0045] This embodiment provides a positive electrode sheet, and the preparation method of the positive electrode sheet is as follows:

[0046] (1) Under an inert atmosphere, lithium sulfide, Ketjen black (KB), and polyvinyl pyrrolidone (PVP) are prepared in a mass ratio of 7:1.5:1.5. PVP is first dissolved in an appropriate amount of N-methylpyrrolidone (NMP) to form a glue solution. Subsequently, lithium sulfide and KB are uniformly mixed and ground, and then the glue solution is added and stirred. After dissolution and stirring are completed, a slurry is obtained;

[0047] (2) The slurry is evenly coated on a carbon-coated aluminum foil, and the initial lithium sulfide electrode is obtained after drying and cutting. The initial lithium sulfide electrode is placed in a tube furnace, heated to 200°C and maintained for 12 hours under the condition of passing Ar gas, and then heated to 500°C and calcined for 2 hours at a heating rate of 5°C / min. After cooling, the prepared lithium sulfide electrode with excellent conductive carbon structure is taken out, wherein the mass fraction of the carbon conductive network in the electrode is 10%, the mass fraction of the active material is 75%, and the mass fraction of the conductive agent is 15%.

[0048] Based on this electrode, a lithium sulfide-to-lithium half-cell was made. The electrolyte used was 1M LiTFSI dissolved in DOL / DME = 1:1 (with 3wt% LiNO3 added), and the diaphragm used was a polyolefin diaphragm. The specific capacity of the battery at 0.2C can reach 860mAh / g, and the remaining capacity after 100 cycles is 720mAh / g. The average coulombic efficiency reaches 98%.

[0049] Example 3

[0050] This embodiment provides a positive electrode sheet, and the preparation method of the positive electrode sheet is as follows:

[0051] (1) Under an inert atmosphere, sodium sulfide, Ketjen black (KB), and polyvinyl pyrrolidone (PVP) are prepared in a mass ratio of 7:2:1. PVP is first dissolved in an appropriate amount of N-methylpyrrolidone (NMP) to form a glue solution. Then, sodium sulfide and KB are uniformly mixed and ground, and then added to the glue solution and stirred until dissolved to obtain a slurry.

[0052] (2) The slurry is evenly coated on a carbon-coated aluminum foil, and after drying and cutting, an initial sodium sulfide electrode is obtained. The initial sodium sulfide electrode is placed in a tube furnace, heated to 500°C and calcined for 2 hours under the condition of passing Ar gas, with a heating rate of 5°C / min. After cooling, the prepared sodium sulfide electrode with excellent conductive carbon structure is obtained, wherein the mass fraction of the carbon conductive network in the electrode is 7%, the mass fraction of the active material is 72%, and the mass fraction of the conductive agent is 21%.

[0053] The optical picture of the pole piece is shown in FIG2 . It can be seen from FIG2 that the pole piece does not drop out. The optical picture of the pole piece after the cycle is shown in FIG3 . It can be seen from FIG3 that the pole piece does not drop out after the cycle.

[0054] A sodium sulfide half-cell was made based on this electrode. The electrolyte used was 1M NaPF6 dissolved in DME, and the diaphragm used was a glass fiber diaphragm. The specific capacity of the battery could reach 700mAh / g at 0.2C, and the remaining capacity was 500mAh / g after 100 cycles. The average coulombic efficiency reached 96%.

[0055] Example 4

[0056] This embodiment provides a positive electrode sheet, and the preparation method of the positive electrode sheet is as follows:

[0057] (1) Prepare anhydrous lithium sulfate (Li2SO4), Ketjen black (KB), and polyvinyl pyrrolidone (PVP) in a mass ratio of 6.5:2.5:1. First, dissolve PVP in an appropriate amount of N-methylpyrrolidone (NMP) to form a glue solution. Then, mix anhydrous lithium sulfate and KB evenly, grind them, add the glue solution, and stir. After dissolution and stirring are completed, a slurry is obtained.

[0058] (2) The slurry is evenly coated on a copper foil, dried, and cut to obtain an initial lithium sulfate electrode. The initial lithium sulfate electrode is placed in a tube furnace, first heated to 180°C and maintained for 12 hours, then heated to 600°C and calcined for 2 hours under the condition of passing Ar gas at a heating rate of 5°C / min. After cooling, the prepared lithium sulfide electrode with an excellent conductive carbon structure is obtained, wherein the mass fraction of the carbon conductive network in the electrode is 5%, the mass fraction of the active material is 65%, and the mass fraction of the conductive agent is 30%.

[0059] A lithium sulfide sodium half-cell was made based on this electrode. The electrolyte used was 1M NaPF6 dissolved in DME, and the diaphragm used was a glass fiber diaphragm. The specific capacity of the battery could reach 800mAh / g at 0.2C, and the remaining capacity was 600mAh / g after 100 cycles. The average coulombic efficiency reached 97%.

[0060] Example 5

[0061] This embodiment provides a negative electrode plate, and the preparation method of the negative electrode plate is as follows:

[0062] (1) Take hard carbon, Super P (SP), and carboxymethyl cellulose (CMC) in a mass ratio of 8:1:1. First, dissolve CMC in an appropriate amount of N-methylpyrrolidone (NMP) to form a glue solution. Then, mix the hard carbon and SP evenly, grind them, add the glue solution, and stir. After dissolution and stirring are completed, a slurry is obtained.

[0063] (2) The slurry is evenly coated on a carbon-coated aluminum foil, and the initial hard carbon electrode is obtained after drying and cutting. The initial hard carbon electrode is placed in a tube furnace, and under the condition of passing Ar gas, it is first heated to 180°C and maintained for 12 hours, heated to 500°C and calcined for 2 hours, with a heating rate of 5°C / min. After cooling, it is taken out to obtain the prepared hard carbon electrode with excellent conductive carbon structure, wherein the mass fraction of the carbon conductive network in the electrode is 5%, the mass fraction of the active material is 83%, and the mass fraction of the conductive agent is 12%.

[0064] The hard carbon electrode was used as the negative electrode, and the electrode prepared in Example 4 was used as the positive electrode. A lithium sulfide-to-hard carbon full battery was equipped. The electrolyte used was 1M NaPF6 dissolved in DME, and the diaphragm used was a glass fiber diaphragm. The specific capacity of the battery at 0.2C could reach 320mAh / g, and the remaining capacity after 100 cycles was 300mAh / g. The average coulombic efficiency reached 98%.

[0065] Example 6

[0066] This embodiment provides a negative electrode plate, and the preparation method of the negative electrode plate is as follows:

[0067] (1) Take silicon oxide, Super P (SP), and carboxymethyl cellulose (CMC) in a mass ratio of 8:1:1. First, dissolve CMC in an appropriate amount of N-methylpyrrolidone (NMP) to form a glue solution. Then, mix silicon oxide and SP evenly, grind them, add the glue solution, and stir. After dissolution and stirring are completed, a slurry is obtained.

[0068] (2) The slurry is evenly coated on a carbon-coated aluminum foil, and after drying and cutting, an initial silicon oxide electrode is obtained. The initial silicon oxide electrode is placed in a tube furnace, first heated to 180°C and maintained for 12 hours, and then heated to 400°C and calcined for 2 hours under the condition of passing Ar gas, with a heating rate of 5°C / min. After cooling, the prepared silicon oxide electrode with excellent conductive carbon structure is taken out, wherein the mass fraction of the carbon conductive network in the electrode is 6%, the mass fraction of the active material is 82%, and the mass fraction of the conductive agent is 12%.

[0069] The silicon iodide electrode was used as the negative electrode, the electrode prepared in Example 1 was used as the positive electrode, and a lithium iron phosphate-silicon iodide full battery was equipped. The electrolyte used was 1M LiTFSI dissolved in EC / DEC / DMC=1:1:1, and the diaphragm used was a polyolefin diaphragm. The specific capacity of the battery at 1C could reach 140mAh / g, and the specific capacity was 130mAh / g after 200 cycles at 1C, and the average coulombic efficiency reached 99%.

[0070] Example 7

[0071] The only difference between this embodiment and embodiment 2 is that the calcination temperature is 200° C., and the other conditions and parameters are exactly the same as those in embodiment 2.

[0072] A lithium sulfide-to-lithium half-cell was made based on this electrode. The electrolyte used was 1M LiTFSI dissolved in DOL / DME = 1:1 (with 3wt% LiNO3 added), and the diaphragm used was a polyolefin diaphragm. The battery had a specific capacity of 800mAh / g at 0.2C, a capacity of 200mAh / g after 100 cycles at 0.2C, and an average coulombic efficiency of 89%.

[0073] Example 8

[0074] The only difference between this embodiment and embodiment 2 is that no pre-carbonization treatment is performed, and other conditions and parameters are exactly the same as those in embodiment 2.

[0075] A lithium sulfide-to-lithium half-cell was made based on this electrode. The electrolyte used was 1M LiTFSI dissolved in DOL / DME = 1:1 (with 3wt% LiNO3 added), and the diaphragm used was a polyolefin diaphragm. The battery had a specific capacity of 890mAh / g at 0.2C, a capacity of 110mAh / g after 100 cycles at 0.2C, and an average coulombic efficiency of 87%.

[0076] Example 9

[0077] The difference between this embodiment and embodiment 2 is that lithium carbide sulfide powder is prepared first, and then the lithium carbide sulfide positive electrode sheet is prepared. The preparation method of the positive electrode sheet is as follows:

[0078] (1) Under an inert atmosphere, lithium sulfide, Ketjen black (KB), and polyvinyl pyrrolidone (PVP) are prepared in a mass ratio of 7:1.5:1.5. PVP is first dissolved in an appropriate amount of N-methylpyrrolidone (NMP) to form a glue solution. Subsequently, lithium sulfide and KB are uniformly mixed and ground, and then the glue solution is added and stirred. After dissolution and stirring are completed, a slurry is obtained;

[0079] (2) The slurry was placed in a tube furnace and heated to 200°C for 12 h under the condition of passing Ar gas, and then heated to 500°C and calcined for 2 h at a heating rate of 5°C / min. After cooling, the obtained lithium carbide sulfide powder was taken out and crushed under an inert atmosphere for later use;

[0080] (3) Under an inert atmosphere, lithium carbide sulfide, Ketjen black (KB), and PVDF binder are weighed in a mass ratio of 8:1:1. PVDF is first dissolved in an appropriate amount of N-methylpyrrolidone (NMP) to form a glue solution. The lithium carbide sulfide and KB are then uniformly mixed and ground, and the glue solution is added and stirred to obtain a slurry, which is then coated on an Al foil current collector and dried to obtain a lithium carbide sulfide electrode.

[0081] Based on this electrode, a lithium carbide sulfide half-cell is made. The electrolyte uses 1M LiTFSI dissolved in DOL / DME = 1:1 (3wt% LiNO3 is added), and the diaphragm uses a polyolefin diaphragm. The battery has a specific capacity of 560mAh / g at 0.2C, and the remaining capacity is 320mAh / g after 100 cycles. The average coulombic efficiency reaches 57%.

[0082] Comparative Example 1

[0083] The only difference between this comparative example and Example 2 is that polyvinylpyrrolidone (PVP) is replaced by PVDF, and the other conditions and parameters are exactly the same as those in Example 2.

[0084] Comparative Example 2

[0085] The only difference between this comparative example and Example 2 is that polyvinylpyrrolidone (PVP) is replaced with PVDF and carbonization is not performed (ie, conventional electrode). Other conditions and parameters are exactly the same as those in Example 2.

[0086] It can be seen from Examples 1-6 that the electrode plates described in the present application, whether they are positive electrodes or negative electrodes, can exhibit good coulombic efficiency and cycle performance.

[0087] From the comparison between Example 2 and Example 7, it can be seen that during the preparation process of the electrode plate described in the present application, the temperature of high-temperature calcination will affect its performance. The temperature of high-temperature calcination is controlled at 300-600°C, and the adhesion performance of the electrode plate is better. If the calcination temperature is too low, the polymer cannot be effectively carbonized, which affects the electronic conductivity inside the plate, and the rate performance and cycle performance of the battery are poor. If the calcination temperature is too high, the performance is not significantly improved and the cost required for preparation is greatly increased.

[0088] From the comparison between Example 2 and Example 8, it can be seen that the present application performs a pre-carbonization treatment on the electrode before high-temperature calcination, which can form a carbon conductive network in situ on the surface of the active material, which is beneficial for the battery to maintain good cycle stability.

[0089] By comparing Example 2 and Example 9, it can be seen that the electrode plate described in the present application is subjected to a carbonization treatment by high-temperature calcination, which not only forms an in situ carbon conductive network on the surface of the active material, but also the binder is carbonized to a certain extent, thereby overcoming the damage of the binder to the electronic conductive network of the plate when the conductivity of the active material is poor, which is beneficial to improving the capacity of the battery and maintaining good cycle stability.

[0090] From the comparison between Example 2 and Comparative Example 1, it can be seen that the selection of the carbonized polymer precursor described in the present application is crucial. The PVDF binder no longer has an adhesive effect after carbonization, and the active material falls off from the current collector.

[0091] From the comparison between Example 2 and Comparative Example 2, it can be seen that compared with conventional electrodes, the electrode plate prepared in the present application has better electronic conductivity, thereby ensuring a good electron transmission path around the lithium sulfide particles, which is beneficial to the performance of capacity and improving the cycle stability of the plate.

[0092] The applicant declares that the above is only a specific implementation method of the present application, but the protection scope of the present application is not limited thereto. Technical personnel in the relevant technical field should understand that any changes or substitutions that can be easily thought of by technical personnel in the relevant technical field within the technical scope disclosed in this application fall within the protection scope and disclosure scope of this application.

Claims

1. An electrode plate, in, The electrode plate includes a current collector and an active material layer arranged on the surface of the current collector, the active material layer includes a carbon conductive network, a conductive agent and an active material, the conductive agent and the active material are dispersed in the carbon conductive network, and the carbon conductive network is obtained by carbonizing a carbonized polymer precursor.

2. The electrode sheet according to claim 1, in, Taking the mass of the active material layer as 100%, the mass fraction of the carbon conductive network is 0.2-10%.

3. The electrode plate according to claim 1 or 2, in, Taking the mass of the active material layer as 100%, the mass fraction of the active material is 40 to 99%.

4. The electrode sheet according to any one of claims 1 to 3, in, Based on the mass of the active material layer being 100%, the mass fraction of the conductive agent is 0.3 to 30%.

5. The electrode sheet according to any one of claims 1 to 4, in, The diameter of the carbon conductive network is 5 to 300 nm, and can be optionally 50 to 200 nm.

6. The electrode sheet according to any one of claims 1 to 5, in, The conductive agent includes any one of conductive carbon black, acetylene black, Ketjen black, carbon nanotubes or graphene, or a combination of at least two thereof; Optionally, the active material includes a positive electrode active material or a negative electrode active material; Optionally, the positive electrode active material includes any one or a combination of at least two of lithium iron phosphate, lithium cobalt oxide, lithium manganese oxide, lithium nickel cobalt manganese oxide, sodium nickel iron manganese oxide, sodium iron sulfate, lithium sulfide or sodium sulfide; Optionally, the negative electrode active material includes any one of hard carbon, soft carbon, graphite, silicon carbon or silicon dioxide, or a combination of at least two thereof; Optionally, the current collector includes any one of aluminum foil, carbon-coated aluminum foil, copper foil, nickel foam or titanium foil, or a combination of at least two thereof.

7. The electrode plate according to any one of claims 1 to 6, in, The carbonized polymer precursor includes any one of polyvinyl pyrrolidone, polyethyl acetate, polyacrylonitrile, polyacrylate or carboxymethyl cellulose, or a combination of at least two thereof.

8. A method for preparing an electrode sheet according to any one of claims 1 to 7, wherein The following steps are involved: (1) mixing a carbonized polymer precursor with a solvent to obtain a solution, mixing and grinding an active material and a conductive agent, and then mixing the mixture with the solution to obtain a slurry; (2) The slurry is coated on the surface of the current collector and subjected to high-temperature carbonization treatment to obtain the electrode plate.

9. The preparation method according to claim 8, in, The solvent in step (1) includes N-methylpyrrolidone.

10. The preparation method according to claim 8 or 9, in, The high-temperature carbonization treatment in step (2) includes pre-carbonization and high-temperature calcination.

11. The preparation method according to any one of claims 8 to 10, in, The atmosphere of the high temperature carbonization treatment includes nitrogen and / or argon.

12. The preparation method according to claim 10, in, The pre-carbonization temperature is 150-250°C.

13. The preparation method according to claim 10, in, The high temperature calcination temperature is 300-600°C.

14. A battery, in, The battery comprises the electrode sheet as described in any one of claims 1 to 7.

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