A fast-charging composite graphite material, its preparation method and application

Abstract

The present invention discloses a fast-charging composite graphite material, its preparation method and application, which relate to the technical field of graphite materials. The preparation method of the fast-charging composite graphite material comprises the following steps: (1) uniformly mixing single-particle raw materials with resin to obtain a mixed material, wherein the single-particle raw materials are single-particle artificial graphite or mesocarbon microbeads; (2) subjecting the mixed material to four-stage heat treatment to obtain the fast-charging composite graphite material; the temperature of the first-stage heat treatment is 100°C to 550°C, the temperature of the second-stage heat treatment is 1000°C to 1500°C, the temperature of the third-stage heat treatment is 2700°C to 3200°C, and the heating power is gradually reduced during the fourth-stage heat treatment, followed by natural cooling. The fast-charging composite graphite material has high specific capacity, high efficiency and fast-charging characteristics. Further, the battery core prepared by using the fast-charging composite graphite material has a small internal resistance, strong high-rate charge-discharge performance and long cycle performance.

Description

Technical Field

[0001] The present invention relates to the technical field of graphite materials, and particularly relates to a fast-charging composite graphite material, a preparation method thereof, and an application thereof. Background Art

[0002] Fast charging and long life are the bottlenecks and research hotspots in the development of the lithium-ion battery industry. At present, the existing fast-charging lithium-ion batteries still cannot well balance the requirements for energy density, charging time, service life, etc. of fast-charging batteries. Graphite itself has the characteristics of a crystallized layered structure, with a small theoretical interlayer spacing, which cannot meet the requirements of high-current charging. There is a risk of lithium deposition during fast charging, posing a serious safety hazard to the battery and the entire power consumption system. In the prior art, the graphite material is usually modified, coated, etc. in order to prepare a graphite negative electrode material with large capacity and long cycle life.

[0003] The Chinese patent document with the publication number CN113697804A discloses a fast-charging high-first-efficiency hard carbon / artificial graphite negative electrode material and a preparation method thereof. In this invention, a carbon-containing raw material is heat-treated to obtain a hard carbon material; the hard carbon material is crushed and then mixed uniformly with a coating agent and heat-treated to obtain a coated hard carbon material; the coated hard carbon material is subjected to high-temperature graphitization heat treatment, and the fast-charging high-first-efficiency hard carbon artificial graphite negative electrode material is obtained after completion. This preparation method selects hard carbon as the main body to improve the capacity and fast-charging performance of the negative electrode material; by coating graphite on the surface of the hard carbon, the specific surface area of the hard carbon is reduced, side reactions are reduced, and thus the irreversible capacity is reduced and the first efficiency is improved; through high-temperature treatment, the residual defective structure in the hard carbon is reduced, and the first efficiency and cycle stability are improved. However, although the first efficiency of this material is improved, its rate performance and cycle performance will be reduced.

[0004] The Chinese patent document with the publication number CN106654235A discloses a composite graphite material, a preparation method thereof, and a use thereof. The preparation method of this composite graphite material includes: (1) uniformly mixing activated natural graphite, artificial graphite precursor, and asphalt, and fusing and granulating in an inert atmosphere; (2) uniformly mixing the fused granulation product with a graphitization catalyst and performing high-temperature graphitization to obtain a composite graphite material. The electrode sheet prepared by using this composite graphite material has the advantages of high compaction density, fast liquid absorption rate of the electrode sheet, and good compatibility with the electrolyte, but the capacity retention rate of the finished battery after 500 cycles of charge and discharge at room temperature is not good.

[0005] The Chinese patent document with the publication number CN115706230A discloses a composite graphite anode material, an anode sheet and a lithium-ion battery. The composite graphite anode material includes graphite particles and a coating layer coated on the surface of the graphite particles, and limits the specific surface area change rate range and the particle size D50 change rate range of the composite graphite. However, this invention does not essentially solve the problems of poor cycling performance of natural graphite and the characteristics of gas generation and bulging during cycling. It is only a modification and improvement of the application of natural graphite, so its cycling performance cannot be greatly improved.

[0006] Although the above-mentioned prior art modifies and decorates graphite materials to prepare lithium-ion batteries with excellent performance, there are still areas that need improvement. Therefore, it is necessary to develop a fast-charging composite graphite material to achieve the optimal comprehensive performance (high rate, long life, high efficiency). Summary of the Invention

[0007] The present invention provides a preparation method of a fast-charging composite graphite material. By performing four-stage heat treatment on a mixture of single-particle raw materials and resin, a fast-charging composite graphite material with high specific capacity, high efficiency and fast-charging characteristics is prepared. Further, the anode sheet prepared by using this fast-charging composite graphite material has small expansion and is suitable for the characteristic of quickly accepting lithium-ion charging. The prepared battery core has a small internal resistance, strong high-rate charge and discharge performance and long cycling performance.

[0008] The specific technical solutions adopted are as follows:

[0009] A preparation method of a fast-charging composite graphite material includes the following steps:

[0010] (1) Mix single-particle raw materials and resin evenly to obtain a mixture. The single-particle raw materials are single-particle artificial graphite or mesophase carbon microspheres;

[0011] (2) Perform four-stage heat treatment on the mixture to obtain the fast-charging composite graphite material. The temperature of the first-stage heat treatment is 100°C to 550°C, the temperature of the second-stage heat treatment is 1000°C to 1500°C, the temperature of the third-stage heat treatment is 2700°C to 3200°C, and the heating power is gradually reduced during the fourth-stage heat treatment, followed by natural cooling.

[0012] The method of the present invention performs four-stage heat treatment on the mixture composed of single-particle raw materials and resin. In the first-stage heat treatment, the resin softens and melts and coats the single-particle raw materials integrally, while removing moisture, small-molecule volatiles, etc.; in the second-stage heat treatment, the carbonization of the outer coating is ensured; in the third-stage heat treatment, it is a temperature ramping and high-temperature graphitization process; in the fourth-stage heat treatment, the heating power is gradually reduced, and natural cooling can prevent cracks caused by rapid cooling and protect the structure of the material; thus, a fast-charging composite graphite material in the shape of a quasi-sphere, with artificial graphite or mesophase carbon microspheres as the core and hard carbon as the shell, is prepared.

[0013] Preferably, the range of the particle size D50 of the single-particle raw materials is: 7 μm ≤ D50 ≤ 12 μm; the single-particle raw materials within the above range can ensure that the prepared composite graphite material has excellent rate performance and the ability to adapt to the rapid insertion and extraction of lithium ions during charge and discharge.

[0014] Preferably, the resin includes β-resin, phenolic resin, epoxy resin, urea-formaldehyde resin, polyacrylic acid resin, vinyl ester, bismaleimide, cyanate ester, melamine formaldehyde resin, furan resin, or silicone resin, etc.

[0015] Preferably, in the mixture, the mass ratio of the single-particle raw materials to the resin is 85 - 99.5:0.5 - 15.

[0016] Preferably, the time of the first-stage heat treatment is 3h to 20h; the time of the second-stage heat treatment is 2h to 4h; during the third-stage heat treatment, it takes 30h to 50h to heat up to 2700°C to 3200°C and then keep it warm for 10h to 15h.

[0017] The present invention also provides a fast-charging composite graphite material prepared by the preparation method of the fast-charging composite graphite material described above. The fast-charging composite graphite material is in the shape of a quasi-sphere, has a core-shell structure, with artificial graphite or mesophase carbon microspheres as the core and hard carbon as the shell.

[0018] In the fast-charging composite graphite material, the thickness of the shell layer is 3 to 500 nm.

[0019] The present invention also provides a negative electrode sheet including the fast-charging composite graphite material.

[0020] Preferably, the negative electrode sheet includes a negative electrode current collector and a composite coating provided on the surface of the negative electrode current collector. The composite coating includes a carbon-coated layer, an artificial graphite layer, and a fast-charging composite graphite material layer from the inside to the outside; the thickness of the carbon-coated layer is 0.2 μm to 2 μm; the thickness of the artificial graphite layer is 3 μm to 80 μm; the thickness of the fast-charging composite graphite material layer is 20 μm to 100 μm;

[0021] The present invention designs a multi-layer electrode with a specific structure, which can improve the lithium-ion insertion / extraction ability of the negative electrode and reduce the interfacial transfer impedance.

[0022] Preferably, the carbon-coated layer comprises a conductive agent and a binder, and the mass ratio of the conductive agent to the binder is 60-85:15-40;

[0023] Preferably, the artificial graphite layer comprises artificial graphite, a conductive agent and a binder, and the mass ratio of artificial graphite, the conductive agent to the binder is 94-98:1-3:1-3;

[0024] Preferably, the fast-charging composite graphite material layer comprises a fast-charging composite graphite material, a conductive agent and a binder, and the mass ratio of the fast-charging composite graphite material, the conductive agent to the binder is 90-93:4-5:3-5;

[0025] Specifically, the conductive agent is selected from one or more of conductive carbon black, Ketjen black, VGCF, single-walled carbon nanotubes, multi-walled carbon nanotubes, graphene;

[0026] Specifically, the binder is selected from one or more of polymethyl methacrylate, polyacrylonitrile, polyvinylidene fluoride, polyvinyl alcohol, polytetrafluoroethylene, sodium carboxymethyl cellulose, styrene-butadiene rubber, butyl acrylate, polyacrylic acid, polyethylene glycol;

[0027] Preferably, the double-sided surface density of the negative electrode is ≤200 g / m 2 , and the tap density is ≤1.55 g / cm 3 ..

[0028] The present invention also provides a secondary fast-charging battery core, comprising a positive electrode, the negative electrode, a separator and an organic electrolyte;

[0029] The positive electrode comprises a positive current collector, a positive active material and a binder, and the positive active material comprises lithium iron phosphate and a conductive agent; the mass ratio of lithium iron phosphate, the conductive agent to the binder is 92-95:2-4:3-4; the double-sided surface density of the positive electrode is ≤360 g / m 2 , and the tap density is ≤1.5 g / cm 3 ;

[0030] Further preferably, the double-sided surface density of the positive electrode is 200 g / m 2 -260 g / m 2 ; the double-sided surface density of the negative electrode is ≤150 g / m 2 , and the tap density is ≤1.45 g / mm 3 ;

[0031] Soft winding or laminating is carried out in the order of separator / negative electrode sheet / separator / positive electrode sheet, and the secondary fast-charging battery core is formed through connection with external terminals, encapsulation, injection of electrolyte, formation, and grading.

[0032] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0033] (1) The present invention provides a preparation method of a fast-charging composite graphite material. Through four-stage heat treatment of a mixture composed of single-particle raw materials and resin, a fast-charging composite graphite material with high specific capacity, high efficiency, and fast-charging characteristics is prepared.

[0034] (2) In the negative electrode sheet of the present invention, the carbon-coated layer can reduce the charge transfer impedance at the interface between the negative electrode active material and the current collector. At the same time, according to the characteristics of the negative electrode active material, the kinetic performance of the negative electrode is ensured through gradient active material design or multi-layer coating means to achieve fast-charging characteristics. At the same time, for constructing a high-porosity and strong-kinetics diaphragm, the coating surface density load and compaction density are optimized, so that the performance of the negative electrode material is maximized and it is beneficial to long cycle life at low cost and fast-charging characteristics.

[0035] (3) The battery core prepared by using the fast-charging composite graphite material of the present invention meets the performance of 5C fast charging and 10C fast discharging. In particular, the retention rate of the normal-temperature 5C cycle for 2000 times is 81.8%, and the retention rate of the 2C cycle for 8000 times is 73.0%, showing excellent rate and long cycle characteristics. Description of the Drawings

[0036] Figure 1 SEM diagram of the fast-charging composite graphite material prepared in Example 1.

[0037] Figure 2 SEM diagram of the fast-charging composite graphite material prepared in Example 2.

[0038] Figure 3 XRD diagram of the fast-charging composite graphite material prepared in Example 2.

[0039] Figure 4 Schematic structural diagram of the negative electrode sheet prepared in Example 4, where the reference numeral 1 is the negative electrode current collector, 2 is the carbon-coated layer, 3 is the artificial graphite layer, and 4 is the fast-charging composite graphite material layer.

[0040] Figure 5 Charging curve of the battery core prepared in Example 5.

[0041] Figure 6 Discharge curve of the battery core prepared in Example 5.

[0042] Figure 7 Rate cycle diagram of the battery core prepared in Example 5.

[0043] Figure 8 This is the cycle curve of the battery core prepared in Example 5. DETAILED DESCRIPTION

[0044] The present invention is further illustrated below in conjunction with the examples and accompanying drawings. It should be understood that these examples are only used to illustrate the present invention and are not intended to limit the scope of the present invention. The operating methods in the following examples without specifying specific conditions are usually carried out under conventional conditions or under conditions recommended by the manufacturer.

[0045] In the embodiment, the single-particle artificial graphite was purchased from Shanghai Shanshan Technology Co., Ltd., and the mesophase carbon microspheres were purchased from Sinosteel Carbon Chemical Co., Ltd. The particle size range of the single-particle artificial graphite and the mesophase carbon microspheres was 7 microns ≤ D50 ≤ 12 microns.

[0046] Example 1

[0047] (1) mixing mesocarbon microspheres and phenolic resin in a mass ratio of 20:1 to obtain a mixture;

[0048] (2) The mixture is subjected to four-stage heat treatment to obtain the fast-charging composite graphite material; the temperature of the first stage heat treatment is 550°C and the time is 3 hours; the temperature of the second stage heat treatment is 1200°C and the time is 3 hours; during the third stage heat treatment, it takes 36 hours to heat up to 2800°C and then keep warm for 12 hours; in the fourth stage heat treatment, the heating power is gradually reduced and naturally cooled.

[0049] The SEM image of the fast-charging composite graphite material prepared in this embodiment is as follows: Figure 1 As shown, the fast-charging composite graphite material has a spherical structure, the particles are relatively regular, and the spherical surface has a loose and porous structure.

[0050] Example 2

[0051] (1) mixing single-particle artificial graphite and β-resin in a mass ratio of 15:1 to obtain a mixture;

[0052] (2) The mixture is subjected to four-stage heat treatment to obtain the fast-charging composite graphite material; the temperature of the first stage heat treatment is 120°C and the time is 18 hours; the temperature of the second stage heat treatment is 1300°C and the time is 3 hours. During the third stage heat treatment, it takes 40 hours to heat up to 3000°C and then keep warm for 10 hours. In the fourth stage heat treatment, the heating power is gradually reduced and naturally cooled.

[0053] The SEM image of the fast-charging composite graphite material prepared in this embodiment is as follows: Figure 2 As shown, the spherical surface is relatively smooth and the particles are evenly distributed. The XRD diagram is as follows Figure 3As shown, it can be seen from the figure that the characteristic peak at 23° indicates the presence of hard carbon on its surface, which is a characterization of the coating layer; it can be observed from the characteristic peaks at 40° - 50° and 25 - 28° that it has the characteristics of artificial graphite.

[0054] Example 3

[0055] (1) Mix single-particle artificial graphite and epoxy resin evenly at a mass ratio of 9:1 to obtain a mixed material;

[0056] (2) Subject the mixed material to four-stage heat treatment to obtain the fast-charging composite graphite material; the temperature of the first-stage heat treatment is 105°C and the time is 20h; the temperature of the second-stage heat treatment is 1500°C and the time is 2h. During the third-stage heat treatment, it is heated to 2900°C in 30h and then held for 10h. In the fourth-stage heat treatment, the heating power is gradually reduced and it is cooled naturally.

[0057] Example 4

[0058] Prepare a negative electrode sheet with a structure as Figure 4 shown. The negative electrode sheet includes a negative electrode current collector 1 and a composite coating provided on the surface of the negative electrode current collector 1. The composite coating includes a carbon-coated layer 2, an artificial graphite layer 3, and a fast-charging composite graphite material layer 4 from the inside to the outside;

[0059] First, mix conductive carbon black and polyacrylic acid at a mass ratio of 70:30 to prepare a carbon-coated slurry, coat the negative electrode current collector, and prepare a carbon-coated layer with a target thickness of 1 micron; then mix artificial graphite, conductive carbon black, and polytetrafluoroethylene at a mass ratio of 95.5:1.5:3 to prepare an artificial graphite layer slurry, coat the artificial graphite layer slurry on the surface of the carbon-coated layer, and prepare an artificial graphite layer with a target thickness of 10 microns; then mix the fast-charging composite graphite material obtained in Example 1, conductive carbon black, carbon nanotubes, and polyvinylidene fluoride HSV900 at a mass ratio of 93:3:1:3 to prepare an artificial fast-charging composite graphite material layer slurry, coat the artificial fast-charging composite graphite material layer slurry on the surface of the artificial graphite layer, and prepare an artificial fast-charging composite graphite material layer with a target thickness of 30 microns to obtain the negative electrode sheet, and optimize the double-sided surface density of the negative electrode sheet to 138 g / m 2 , and the compaction density is 1.43 g / cm 3 .

[0060] Example 5

[0061] Prepare a positive electrode sheet including a positive electrode current collector, a positive electrode active material, and a binder. The positive electrode active material includes lithium iron phosphate and a conductive agent; the mass ratio of lithium iron phosphate, the conductive agent, and the binder is 995:2:3; optimize the double-sided surface density of the positive electrode sheet to 256 g / m 2 , and the compaction density is 2.25 g / cm3 ;

[0062] Preparation of a square aluminum shell 55Ah battery cell: A separator (dry single-drawn, three-layer co-extruded 16-micron separator), the negative electrode sheet obtained in Example 4, the separator, and the positive electrode sheet are formed into a core by winding or laminating. The positive and negative electrodes are led out with terminals through ultrasonic welding, and the housing is sealed by laser welding. After the battery cell is dried (moisture control of the positive electrode sheet: ≤300 PPM under the condition of 200 °C by a Karl Fischer moisture tester), electrolyte is injected. After standing and soaking, it enters the formation process. After secondary electrolyte addition, the housing is sealed. The battery cell is aged and capacity-fractionated to obtain the secondary fast-charging type battery cell.

[0063] Perform a rate charge test on this battery cell. The charge-discharge voltage range is 2.5 - 3.65 V. Under normal temperature conditions, perform 1C / 1C charge-discharge, 2C / 1C charge-discharge, 3C / 1C charge-discharge, 4C / 1C charge-discharge, 5C / 1C charge-discharge. The intermediate standing time is 30 min. The results are as Figure 5 shown, indicating that this battery cell has the rate charge ability from 1C to 5C, and its 5C charge capacity / 1C charge capacity ≥ 96%, showing good rate charge performance;

[0064] Perform a rate discharge test on this battery cell. The charge-discharge voltage range is 2.5 - 3.65 V. Under normal temperature conditions, perform 1C / 1C charge-discharge, 1C / 2C charge-discharge, 1C / 3C charge-discharge, 1C / 4C charge-discharge, 1C / 5C charge-discharge, 1C / 6C charge-discharge, 1C / 7C charge-discharge, 1C / 8C charge-discharge, 1C / 9C charge-discharge, 1C / 10C charge-discharge. The intermediate standing time is 30 min. The results are as Figure 6 shown, indicating that the battery cell has the rate discharge ability from 1C to 10C, its 5C discharge capacity / 1C discharge capacity ≥ 99%, and 10C discharge capacity / 1C discharge capacity ≥ 96%, showing good rate discharge performance;

[0065] Perform a rate cycling 5C (1C = 55 A) test on two battery cells prepared by the same method for different batches with reference to GB31484. The charge-discharge voltage range is 2.5 - 3.65 V. Under normal temperature 5C / 5C conditions, the intermediate standing time is 30 min. Perform cyclic tests in this way. From Figure 7 the 5C charge-discharge curve, it can be seen that the retention rate of this battery cell after 2000 cycles ≥ 86%, showing excellent rate cycling characteristics. At the same time, the performance difference between the two battery cells is not significant, indicating that the method of the present invention has good reproducibility.

[0066] Perform a rate 2P (1P = 176 W) cycling test on this battery cell with reference to GB36276. The charge-discharge voltage range is 2.5 - 3.65 V. Under normal temperature 2P / 2P conditions, the intermediate standing time is 30 min. Perform cyclic tests in this way. From Figure 8From the cycle curve, it can be seen that the retention rate of the battery cell after 8000 cycles is ≥ 73.0%, showing excellent cycle characteristics.

[0067] Comparative Example 1

[0068] The difference in the preparation method of the negative electrode sheet in this example from that in Example 4 is only that mesophase carbon microspheres are used to replace the fast-charging composite graphite material to prepare the negative electrode sheet; and a square aluminum shell 55Ah battery cell is prepared according to the steps in Example 5; the test results show that the rate performance of this battery cell can meet the 5C charge / 10C discharge capacity, but its cycle performance shows a retention rate of 80% after 1000 cycles at 5C and a retention rate of 80% after 3500 cycles at 2P.

[0069] Comparative Example 2

[0070] The difference between the composite graphite material in this example and the fast-charging composite graphite material in Example 1 is only that MG11 of Zhonggang Carbon Chemical Co., Ltd. is used to replace the mesophase carbon microspheres in Example 1; further, the difference in the preparation method of the negative electrode sheet from that in Example 4 is only that the coating on the surface of the negative electrode current collector is only a composite graphite material layer; and a square aluminum shell 55Ah battery cell is prepared according to the steps in Example 5; the test results show that the rate performance of this battery cell can meet the 5C charge capacity / 1C charge capacity = 93%, 10C discharge capacity / 1C discharge capacity = 95%, and the cycle performance shows a retention rate of 70% after 2000 cycles under the same conditions at 5C and a retention rate of 80% after 5000 cycles at 2P.

[0071] The above-described embodiments have described the technical solutions of the present invention in detail. It should be understood that the above are only specific embodiments of the present invention and are not used to limit the present invention. Any modifications, supplements, or substitutions in a similar manner within the principle scope of the present invention should be included within the protection scope of the present invention.

Claims

1. A secondary fast-charging battery cell, characterized in that, It includes a positive electrode sheet, a negative electrode sheet, a separator, and an organic electrolyte solution; The positive electrode sheet described above includes a positive electrode current collector, a positive electrode active material, and a binder. The positive electrode active material includes lithium iron phosphate and a conductive agent; the mass ratio of lithium iron phosphate, the conductive agent, and the binder is 92 to 95: 2 to 4: 3 to 4; the areal density of both sides of the positive electrode sheet is ≤ 360 g / m 2 , and the tap density is ≤ 1.5 g / cm 3 ; The negative electrode sheet includes a negative electrode current collector and a composite coating provided on the surface of the negative electrode current collector. The composite coating includes a carbon-coated layer, an artificial graphite layer, and a fast-charging composite graphite material layer from the inside to the outside; The thickness of the carbon-coated layer is 0.2 μm to 2 μm; the thickness of the artificial graphite layer is 3 μm to 80 μm; the thickness of the fast-charging composite graphite material layer is 20 μm to 100 μm; The carbon-coated layer includes a conductive agent and a binder, and the mass ratio of the conductive agent to the binder is 60 to 85:15 to 40; The artificial graphite layer includes artificial graphite, a conductive agent, and a binder, and the mass ratio of artificial graphite, the conductive agent, and the binder is 94 to 98:1 to 3:1 to 3; The fast-charging composite graphite material layer includes a fast-charging composite graphite material, a conductive agent, and a binder, and the mass ratio of the fast-charging composite graphite material, the conductive agent, and the binder is 90 to 93:4 to 5:3 to 5; The conductive agent is selected from one or more of conductive carbon black, VGCF, carbon nanotubes, and graphene; The binder is selected from one or more of polymethyl methacrylate, polyacrylonitrile, polyvinylidene fluoride, polyvinyl alcohol, polytetrafluoroethylene, polyvinylidene difluoride, sodium carboxymethyl cellulose, styrene-butadiene rubber, butyl acrylate, polyacrylic acid, and polyethylene glycol; The double-sided areal density of the negative electrode sheet ≤ 200 g / m 2 , and the tap density ≤ 1.55 g / cm 3 ; The fast-charging composite graphite material has a core-shell structure, with artificial graphite or mesophase carbon microspheres as the core and hard carbon as the shell. The preparation method includes the following steps: (1) Mix single-particle raw materials evenly with a resin to obtain a mixture. The single-particle raw materials are single-particle artificial graphite or mesophase carbon microspheres; (2) Perform four-stage heat treatment on the mixture to obtain the fast-charging composite graphite material; the temperature of the first-stage heat treatment is 100°C to 550°C, the temperature of the second-stage heat treatment is 1000°C to 1500°C, the temperature of the third-stage heat treatment is 2700°C to 3200°C, and the heating power is gradually reduced during the fourth-stage heat treatment and then cooled naturally; the time of the first-stage heat treatment is 3 h to 20 h; the time of the second-stage heat treatment is 2 h to 4 h; during the third-stage heat treatment, it takes 30 h to 50 h to heat up to 2700°C to 3200°C and then keep it warm for 10 h to 15 h; Wind or stack it softly in the order of separator / negative electrode sheet / separator / positive electrode sheet, and form the secondary fast-charging battery core through connection with external terminals, encapsulation, liquid injection, formation, and grading.

2. The secondary fast-charging battery cell according to claim 1, characterized in that, The range of the particle size D50 of the single-particle raw materials is: 7 μm ≤ D50 ≤ 12 μm.

3. The secondary fast-charging battery cell according to claim 1, wherein, The resin includes β resin, phenolic resin, epoxy resin, urea-formaldehyde resin, polyacrylic acid resin, vinyl ester, bismaleimide, cyanate ester, melamine formaldehyde resin, furan resin, or silicone resin; in the mixture, the mass ratio of the single-particle raw materials to the resin is 85 - 99.5:0.5 - 15.

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