[go: up one dir, main page]
More Web Proxy on the site http://driver.im/

CN118448586A - Negative electrode and preparation method thereof - Google Patents

Negative electrode and preparation method thereof Download PDF

Info

Publication number
CN118448586A
CN118448586A CN202410547821.0A CN202410547821A CN118448586A CN 118448586 A CN118448586 A CN 118448586A CN 202410547821 A CN202410547821 A CN 202410547821A CN 118448586 A CN118448586 A CN 118448586A
Authority
CN
China
Prior art keywords
slurry
negative electrode
double
layer
graphite
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
CN202410547821.0A
Other languages
Chinese (zh)
Inventor
项胜
王义飞
夏伦鹏
刘岩
汪品
马颖华
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Gotion High Tech Co Ltd
Original Assignee
Gotion High Tech Co Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Gotion High Tech Co Ltd filed Critical Gotion High Tech Co Ltd
Priority to CN202410547821.0A priority Critical patent/CN118448586A/en
Publication of CN118448586A publication Critical patent/CN118448586A/en
Pending legal-status Critical Current

Links

Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/139—Processes of manufacture
    • H01M4/1395—Processes of manufacture of electrodes based on metals, Si or alloys
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/04—Processes of manufacture in general
    • H01M4/0402—Methods of deposition of the material
    • H01M4/0404—Methods of deposition of the material by coating on electrode collectors
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/04—Processes of manufacture in general
    • H01M4/043—Processes of manufacture in general involving compressing or compaction
    • H01M4/0435—Rolling or calendering
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/134—Electrodes based on metals, Si or alloys
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • H01M4/624—Electric conductive fillers
    • H01M4/625—Carbon or graphite
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/409—Separators, membranes or diaphragms characterised by the material
    • H01M50/449—Separators, membranes or diaphragms characterised by the material having a layered structure
    • H01M50/457—Separators, membranes or diaphragms characterised by the material having a layered structure comprising three or more layers
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M2004/021—Physical characteristics, e.g. porosity, surface area
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M2004/026—Electrodes composed of, or comprising, active material characterised by the polarity
    • H01M2004/027—Negative electrodes

Landscapes

  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • General Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Materials Engineering (AREA)
  • Battery Electrode And Active Subsutance (AREA)

Abstract

The invention discloses a negative electrode and a preparation method thereof, and belongs to the field of lithium ion battery design and manufacturing processes. The preparation method of the double-layer heterogeneous silicon-based anode comprises the following steps: preparing two coating slurries according to a design formula, wherein slurry A contains high-capacity graphite, silicon carbon, a binder and a conductive agent, and slurry B contains quick-charging graphite, mesophase carbon microspheres, silicon carbon, a binder and a conductive agent; controlling physical parameters of slurry A, B, respectively coating the slurry on the upper layer and the lower layer of a current collector, performing double-roller rolling on a pole coil, controlling different compaction ratios, standing, and performing single-roller rolling; and obtaining the double-layer heterogeneous silicon-based anode. The heterogeneous double-layer negative electrode structure accelerates electron conduction and simultaneously keeps higher ion conduction, so that the full battery can meet the fast charge performance of 3.5 ℃; and the manufacturing process is completely matched with the process for producing the battery cells, thereby having good industrial prospect.

Description

Negative electrode and preparation method thereof
Technical Field
The invention relates to the field of lithium ion battery design and manufacturing processes, in particular to a negative electrode and a preparation method thereof.
Background
Fossil energy crisis and environmental pollution problems promote the vigorous development of the electric automobile market. As a core component of an electric automobile, a secondary lithium ion battery with high energy density is widely focused by society, and has a wide market prospect.
In the case of lithium ion batteries themselves, the major problem currently affecting their use is charge and mileage anxiety. In recent years, the main negative electrode material of the lithium ion battery is still a graphite negative electrode, and it is also important to improve the energy density of the battery, so that the silicon-based negative electrode is generally used together with graphite to improve the energy density of the battery. It is also known that the use of high-current charging is a main implementation form of fast charging, however, the high-current charging also has the problems of abnormal heat generation of the battery, lithium precipitation on the surface of the electrode, accelerated aging of the electrode material and the like; the fast charge performance of the battery is mainly related to the negative electrode, and the decisive effect on the fast charge performance is the microscopic design of the battery itself. Researchers attribute the microscopic limiting step of fast charge performance to the following aspects: (1) migration and diffusion of lithium ions in the electrode material; (2) transport of lithium ions in the electrolyte; (3) The transfer of lithium ions at the phase interface includes desolvation of electrolyte molecules, charge transfer at the interface and ion transfer.
The graphite negative electrode quick charge still has the following problems: (1) Although the unique layered structure of graphite can realize intercalation of lithium ions, the smaller interlayer spacing of graphite (0.335 nm) causes larger diffusion resistance of lithium ions and unsatisfactory diffusion kinetics, so that ideal multiplying power performance cannot be achieved. (2) The diffusion path of lithium ions intercalated into graphite is from the layered edge to the inside of the material, and a longer diffusion path also makes the rate performance of the battery undesirable. (3) Under the condition of rapid charging, the larger polarization can lead the lithium intercalation potential of graphite to be infinitely close to the deposition potential of lithium metal, so that surface lithium precipitation and even lithium dendrite generation occur, and not only can the battery performance be reduced, but also internal short circuit or thermal runaway can be caused. (4) The lamellar structures of graphite are connected by weak van der waals forces, and thus the structure is unstable. There are still challenges in developing a graphite-based fast charge anode.
Disclosure of Invention
The invention aims to provide a negative electrode and a preparation method thereof, and the heterogeneous double-layer negative electrode structure accelerates electron conduction and simultaneously keeps higher ion conduction, so that a full battery can meet the 3.5C fast charge performance, and the special electrode structure design has better safety, and the manufacturing process is completely matched with the process of producing a battery cell in quantity, thereby having good industrial prospect.
The invention firstly provides a preparation method of a quick-charging double-layer heterogeneous silicon-based anode, which comprises the following steps:
(1) Preparing high-capacity graphite, silicon carbon, single-wall carbon nano tube/multi-wall carbon nano tube/SP composite conductive agent, SP powder, adhesive 1, adhesive 2 and adhesive 3 into slurry A by using a traditional semi-dry slurry mixing process;
(2) Preparing slurry B from quick-filling graphite, mesophase carbon microspheres, silicon carbon, single-wall carbon nano tube/multi-wall carbon nano tube/SP composite conductive agent, adhesive 1 and adhesive 3 by using a traditional semi-dry slurry mixing process;
(3) Taking the slurry A as a bottom layer and the slurry B as an upper layer, respectively coating the slurry A on two sides of a copper current collector or a carbon-coated copper current collector, and drying to obtain a pole coil;
(4) And (3) rolling the pole coil obtained in the step (3) by a double roller, standing, and then rolling by a single roller to obtain the fast-charging double-layer heterogeneous silicon-based negative electrode.
In the preparation method of the rapid-charging double-layer heterogeneous silicon-based negative electrode, the capacity of the high-capacity graphite is 358-360 mAh/g;
The capacity of the quick-filling graphite is 354-356 mAh/g;
The capacity of the silicon carbon is 1600-1700mAh/g@0.8V;
the adhesive 1 is polyacrylic acid;
the binder 2 is sodium carboxymethyl cellulose;
The binder 3 is styrene-butadiene rubber;
The dry mass ratio of the high-capacity graphite, the silicon carbon, the single-wall carbon nano tube/multi-wall carbon nano tube/SP composite conductive agent, the SP powder, the binder 1, the binder 2 and the binder 3 is (86-88): (8-10): (0.5-1): (0.6-0.9): (1.2-1.5): (0.3-0.6): (0.8-1.2); the specific method can be 87:8.6:0.8:0.7:1.4:0.5:1.0, 87.4:8.0:1.0:0.6:1.4:0.6:1.0 or 86.5:9.1:0.8:0.6:1.4:0.6:1.0;
The dry mass ratio of the quick-charging graphite to the intermediate phase carbon microsphere to the silicon carbon to the single-walled carbon nanotube/multiwall carbon nanotube/SP composite conductive agent to the binder 1to the binder 3 is (44-46): (46-49): (4-5): (0.9-1.2): (1.7-2.0): (0.8-1.0); specifically, 45:47.4:4.0:1.0:1.8:0.8 or 45.5:47:4.0:1.0:1.7:0.8.
In the preparation method of the quick-charge double-layer heterogeneous silicon-based negative electrode, the solid content of the slurry A is 45% -48%, and the viscosity is 2500-4500 mpas; specifically, the viscosity of the slurry A is 3785maps, 4089maps or 4289maps
The solid content of the slurry B is 47% -50%, and the viscosity is 2500-4500 mpas; specifically, the viscosity of the slurry B is 4230maps, 4398maps or 3998maps.
In the preparation method of the quick-charge double-layer heterogeneous silicon-based negative electrode, the double-sided density of the coating dressing of the slurry A is 85-95 g/m 2;
the double-sided density of the coating dressing of the slurry B is 90-105 g/m 2;
The overall double-sided density of the coated dressing is 175-200 g/m 2;
the edge of the coating material area of the slurry B covers the coating material area of the slurry A by 1+/-0.2 mm.
In the preparation method of the rapid-charging double-layer heterogeneous silicon-based anode, in the step (3), the highest temperature of drying is 78 ℃.
In the preparation method of the quick-charge double-layer heterogeneous silicon-based negative electrode, in the step (4), the compaction ratio of the first roller by the double-roller rolling is 1.35-1.4 g/cm 3, and the compaction ratio of the second roller is 1.62-1.64 g/cm 3;
the compaction ratio of the single-roller rolling is 1.64-1.66 g/cm 3;
the standing time is 2-4 hours;
the rebound rate of the final pole piece for 24 hours is less than 3%, the porosity of the upper coating after rolling is 37% -39%, and the porosity of the lower coating is 33% -35%.
In the preparation method of the rapid-charging double-layer heterogeneous silicon-based negative electrode, the slurry A and the slurry B are further subjected to a step of filtering before being coated;
The slurries A, B were filtered using 100 mesh and 200 mesh capsule cartridges, respectively, in sequence.
The invention also provides the quick-charging double-layer heterogeneous silicon-based negative electrode prepared by the preparation method.
Further, the invention provides a lithium battery, which comprises the fast-charging double-layer heterogeneous silicon-based negative electrode.
In the lithium battery, the diaphragm of the lithium battery is a PI diaphragm; the PI diaphragm consists of a PP base film, a polyvinylidene fluoride adhesive layer, a polyimide and ceramic powder mixed layer and the polyvinylidene fluoride adhesive layer;
The two sides of the PP base film are sequentially coated with the polyvinylidene fluoride adhesive layer, the polyimide and ceramic powder mixed layer and the polyvinylidene fluoride adhesive layer;
specifically, the thickness of the PP base film is 9 mu m; the thickness of the polyvinylidene fluoride adhesive layer is 1 mu m; the thickness of the polyimide and ceramic powder mixed layer is 2 mu m.
In the lithium battery, the N/P of the positive electrode plate of the lithium ion is 1.05-1.12; the main material of the positive pole piece is a monocrystal ternary material; specifically, the ternary 811 positive electrode material.
According to the rapid charging type electrode structure design and the processing technology, the special heterogeneous electrode structure can support rapid lithium ion intercalation, the local uniform overall gradient structure can reduce polarization in the charging process in the vertical direction, and the processing and manufacturing difficulty of the electrode are equivalent to that of the traditional double-layer electrode, so that the rapid charging performance of the electrode is greatly improved compared with that of the traditional graphite electrode.
The invention has the following beneficial effects:
(1) The invention provides an idea of collocating electrode materials and structures for lithium precipitation under a fast charging condition, and the fast charging lithium precipitation is easier to occur on the surface of the electrode due to polarization reasons in the vertical direction of the electrode; the lower layer of the invention uses more silicon, and the upper layer uses less silicon, so that the silicon is in a distribution trend of overall gradient reduction from bottom to top; finally, the PI membrane is introduced, and has the capability of rapid liquid absorption and backflow, so that the problem of blocked ion conduction in the rapid charging circulation process is avoided, and the lithium precipitation risk of the electrode under rapid charging is further reduced;
(2) The negative electrode adopts a distributed rolling process, the compaction ratio of the upper layer and the lower layer is relatively close after primary rolling, the negative electrode is placed for 2-4 hours, the pole piece rebounds, the lower layer with higher proportion of silicon has lower rebound due to the difference of the formulas of the upper layer and the lower layer, and then secondary single-roller rolling is carried out to reach the target value; at the moment, the upper layer has higher porosity than the lower layer, and the higher porosity can store more electrolyte, so that the lithium ion transmission of an upper interface is improved, and the quick charge performance is improved; the lower layer has lower porosity, larger compaction ratio and higher electron conduction rate, and can exert gram capacity of bottom capacity type graphite;
(3) The invention starts from the characteristics of materials, and matches with the manufacturing process of the battery core and a special heterogeneous electrode structure, so that the manufactured single battery core has high energy density, quick charge and higher safety performance, and particularly in the structure of the electrode structure, the invention achieves the purpose of benefiting and avoiding harm, fully plays the roles of graphite and silicon in the electrode, and has high guiding significance for the design of novel electrode structures in the future.
Drawings
Fig. 1 is a graph showing the negative full charge interface of the sample of example 1 at 3.5C fast charge.
Detailed Description
The following detailed description of the invention is provided in connection with the accompanying drawings that are presented to illustrate the invention and not to limit the scope thereof.
The experimental methods in the following examples are conventional methods unless otherwise specified.
Materials, reagents and the like used in the examples described below are commercially available unless otherwise specified.
The following percentages refer to mass percentages unless otherwise indicated.
The high capacity graphite used in the examples below, having a gram capacity of 360mAh/g, was purchased from Shijia Shanghai technology Co., ltd., model ST-74;
silicon carbon with gram capacity 1650mAh/g, available from Li-Yang Tianmu lead battery materials science and technology Co., ltd., model SC2A;
The single-wall carbon nanotube/multiwall carbon nanotube/SP composite conductive agent is purchased from Kabot China Co., ltd., model EXD0030, and has an effective solid content of 9%;
PAA (polyacrylic acid) was purchased from the material technology group ltd of sienna, inc. Of sichuan, model LA612ML, solid content 10%;
CMC (sodium carboxymethyl cellulose), weiyi 2500;
SBR (styrene butadiene rubber) from shenzhen electric technology limited, model AMG83C, solid content 40%;
quick-filling graphite is purchased from Shijia Shanghai technology Co., ltd., model Q46, and has a capacity of 355mAh/g;
MCMB (mesophase carbon microsphere) was purchased from Shanghai NaYu trade Co., ltd., model NR-11.
The PI diaphragm preparation method comprises the following steps: taking a PP (polypropylene) base film with the thickness of 9 mu m, firstly, sequentially coating a PVDF (polyvinylidene fluoride) adhesive layer with the thickness of 1 mu m on two surfaces of the PP base film, then coating a PI (polyimide) and ceramic powder (Al 2O3) mixed layer with the thickness of 2 mu m, and then coating a polyvinylidene fluoride adhesive layer with the thickness of 1 mu m to form a PI diaphragm with the thickness of 1+2+1+9+1+2+1; the coating on both surfaces of the PP base film is symmetrical.
Ternary 811 positive electrode material was purchased from Xiamen Xia tungsten New energy technology Co., ltd and was designated as M83A.
In the examples below, the solvents for slurries A and B were deionized water.
Example 1
(1) Preparation of slurry A and slurry B
Preparing high-capacity graphite, silicon carbon, single-wall carbon nano tube/multi-wall carbon nano tube/SP composite conductive agent, SP powder, PAA, CMC and SBR into slurry A with good fluidity by using a traditional semi-dry slurry mixing process, and carrying out vacuum homogenization and preservation; wherein the high capacity graphite: silicon carbon: single-walled carbon nanotubes/multiwall carbon nanotubes/SP: SP powder: PAA: CMC: the dry matter mass ratio of SBR was 87:8.6:0.8:0.7:1.4:0.5:1.0; slurry A had a solids content of 47.2% (mass percent) and a viscosity of 3785maps;
Preparing slurry B with good fluidity from quick-filling graphite, MCMB, silicon carbon, single-wall carbon nano tube/multi-wall carbon nano tube/SP composite conductive agent, PAA and SBR by using a traditional semi-dry slurry mixing process, and carrying out vacuum homogenization and preservation; wherein, fast charging graphite: MCMB: silicon carbon: single-walled carbon nanotubes/multiwall carbon nanotubes/SP composite conductive agents: PAA: the mass ratio of the dry matter of the SBR is 45:47.4:4.0:1.0:1.8:0.8; slurry B had a solids content of 48.7% and a viscosity of 4230maps.
(2) Filtering the slurry A, B by using a capsule filter element with 100 meshes and a capsule filter element with 200 meshes respectively in sequence, storing the slurry A, B in a coating standby tank, and then coating the slurry A, B on the bottom layer and the upper layer of the copper foil simultaneously, wherein the coating speed is 30m/min, and the baking highest temperature of a coating oven is 78 ℃; the double-sided density of the coating bottom layer dressing of the slurry A is 88g/m 2, the double-sided density of the coating upper layer dressing of the slurry B is 98g/m 2, the total double-sided density is 186g/m 2, the edge of the coating upper layer area covers the coating bottom layer area by about 1mm, and a large coil is obtained after coiling;
(3) Transferring the pole coil obtained in the step (2) to a roller press, rolling by double rollers, controlling the pressure and gap size of the roller press, wherein the compaction ratio of one roller is 1.38g/cm 3, and the compaction ratio of the two rollers is 1.62g/cm 3; standing for 3h at normal temperature after rolling, rolling the pole roll to a compaction ratio of 1.65g/cm 3 by a single roller, testing the rebound rate of the pole piece for 24h to be 2.45%, and calculating the porosity of the upper coating after rolling to be 37.98% and the porosity of the lower coating to be 34.52%.
(4) Cutting a pole coil in the step (3) into pole lugs according to set specifications through a laser cutting procedure, taking the pole lugs as a negative pole, preparing a ternary 811 positive pole material, PVDF (polyvinylidene fluoride) and a conductive agent carbon nano tube into slurry according to the mass ratio of 97.8:1.2:1.0, coating the slurry on aluminum foil with the thickness of 12 mu m, stacking the slurry into a stacked core according to the design capacity through a cutting and stacking integrated thermal composite process, assembling the stacked core into a soft package lithium ion battery, wherein the battery core capacity is 80Ah, and baking the battery; and (3) a negative electrode: the N/P of the positive pole piece is designed to be 1.06, the ternary main material is a monocrystal ternary material, the voltage interval of the battery is 2.5-4.3V, the baking and vacuum conditions are 85 ℃, -90Kpa,24h, and the moisture content is 125ppm when tested at 170 ℃.
(5) And (3) injecting liquid (New Sakubang LBC3421B 33) into the battery cell with qualified moisture, wherein the liquid injection coefficient is 2.0, carrying out gradient infiltration after the liquid injection is completed, respectively carrying out quick filling, circulation and safety test on the battery cell with the energy density 323Wh/Kg of the single battery cell, wherein the negative pressure and the time of the gradient infiltration are respectively-40 Kpa/-50Kpa/-60Kpa/-70Kpa/-80Kpa,1min/3min/5min/5min/5min, sealing, transferring the battery cell to a temperature of Wen Jinrun h at 45 ℃, then carrying out formation at the high temperature of 45 ℃, degassing, and carrying out normal temperature capacity division.
1. The quick charge test conditions are shown in table 1.
TABLE 1 quick charge test conditions
2. The conditions for the cycling test are shown in table 2.
TABLE 2 conditions for testing
3. The safety test conditions are shown in table 3.
TABLE 3 conditions for testing
Example 2
(1) Preparation of slurry A and slurry B
Preparing high-capacity graphite, silicon carbon, single-wall carbon nano tube/multi-wall carbon nano tube/SP composite conductive agent, SP powder, PAA, CMC and SBR into slurry A with good fluidity by using a traditional semi-dry slurry mixing process, and carrying out vacuum homogenization and preservation; wherein the high capacity graphite: silicon carbon: single-walled carbon nanotubes/multiwall carbon nanotubes/SP: SP powder: PAA: CMC: the dry matter mass ratio of SBR was 87.4:8.0:1.0:0.6:1.4:0.6:1.0; slurry A had a solids content of 46.8% and a viscosity of 4089maps;
Preparing slurry B with good fluidity from quick-filling graphite, MCMB, silicon carbon, single-wall carbon nano tube/multi-wall carbon nano tube/SP composite conductive agent, PAA and SBR by using a traditional semi-dry slurry mixing process, and carrying out vacuum homogenization and preservation; wherein, fast charging graphite: MCMB: silicon carbon: single-walled carbon nanotubes/multiwall carbon nanotubes/SP composite conductive agents: PAA: the dry matter mass ratio of SBR was 45.5:47:4.0:1.0:1.7:0.8; slurry B had a solids content of 49.0% and a viscosity of 4398maps.
(2) The same as in example 1, except that the coating oven baking maximum temperature was 80 ℃; slurry A coated bottom dressing had a double-sided density of 90g/m 2, slurry B coated top dressing had a double-sided density of 95g/m 2, and an overall double-sided density of 185g/m 2.
(3) The same as in example 1, except that the compaction ratio of the first roller was 1.41g/cm 3, and the compaction ratio of the second roller was 1.62g/cm 3; standing for 2 hours at normal temperature after rolling; the rebound rate of the test pole piece for 24h is 2.69%, the porosity of the upper coating after rolling is calculated to be 38.08%, and the porosity of the lower coating is calculated to be 34.19%.
(4) The same as in example 1, except that the negative electrode: the N/P design of the positive pole piece is 1.10; moisture was tested at 170℃as 138ppm.
(5) The same as in example 1, except that the liquid injection coefficient was 2.03; finally, the energy density of the single battery cell is 325Wh/Kg, and quick charge, circulation and safety test are carried out.
Example 3
(1) Preparation of slurry A and slurry B
Preparing high-capacity graphite, silicon carbon, single-wall carbon nano tube/multi-wall carbon nano tube/SP composite conductive agent, SP powder, PAA, CMC and SBR into slurry A with good fluidity by using a traditional semi-dry slurry mixing process, and carrying out vacuum homogenization and preservation; wherein the high capacity graphite: silicon carbon: single-walled carbon nanotubes/multiwall carbon nanotubes/SP: SP powder: PAA: CMC: the dry matter mass ratio of SBR was 86.5:9.1:0.8:0.6:1.4:0.6:1.0; slurry A had a solids content of 47.8% and a viscosity of 4289maps;
Preparing slurry B with good fluidity from quick-filling graphite, MCMB, silicon carbon, single-wall carbon nano tube/multi-wall carbon nano tube/SP composite conductive agent, PAA and SBR by using a traditional semi-dry slurry mixing process, and carrying out vacuum homogenization and preservation; wherein, fast charging graphite: MCMB: silicon carbon: single-walled carbon nanotubes/multiwall carbon nanotubes/SP composite conductive agents: PAA: the dry matter mass ratio of SBR was 45.5:47:4.0:1.0:1.7:0.8; slurry B had a solids content of 49.2% and a viscosity of 3998maps.
(2) The same as in example 1, except that the coating oven baking maximum temperature was 76 ℃; slurry A coated bottom dressing had a double-sided density of 92g/m 2, slurry B coated top dressing had a double-sided density of 98g/m 2, and an overall double-sided density of 190g/m 2.
(3) The same as in example 1, except that the compaction ratio of the first roller was 1.38g/cm 3, and the compaction ratio of the second roller was 1.63g/cm 3; standing for 2 hours at normal temperature after rolling; the rebound rate of the test pole piece for 24h is 2.39%, the porosity of the upper coating after rolling is calculated to be 38.55%, and the porosity of the lower coating is calculated to be 34.45%.
(4) The same as in example 1, except that the negative electrode: the N/P design of the positive pole piece is 1.09; the moisture was 145ppm at 170 ℃.
(5) The same as in example 1, except that the liquid injection coefficient was 2.03; and finally obtaining the energy density 327Wh/Kg of the single cell, and carrying out quick charge, circulation and safety test.
Comparative example 1
Comparative example 1 differs from example 1 in that:
Only slurry a of example 1 was used to coat the film as a single layer with a double sided density of 178g/cm 2, and one roll was used for the roll press with a compaction ratio of 1.65g/cm 3. The other operations were the same as in example 1.
Comparative example 2
Comparative example 2 differs from example 1 in that:
Only slurry B of example 1 was used to coat the slurry as a single layer with a double sided density of 186g/cm 2, and one roll was used for the roll press with a compaction ratio of 1.65g/cm 3. The other operations were the same as in example 1.
Comparative example 3
Comparative example 3 differs from example 1 in that:
The rolling was carried out in one pass, and the compaction ratio was 1.65g/cm 3, the remainder being identical to example 1.
Comparative example 4
Comparative example 4 differs from example 1 in that:
the same high capacity graphite was used for the graphite of slurry A, B in example 1, and the remainder was identical to example 1.
Comparative example 5
Comparative example 5 differs from example 1 in that:
the slurry A, B of example 1 was applied in the opposite upper and lower layers, a was applied in the upper layer, B was applied in the lower layer, and the remainder was identical to example 1.
Table 4 pole piece and full die data comparison for examples and comparative examples
From the data in Table 4, it can be seen that the performance in the examples cannot be achieved by using single coating applied by slurry A or B alone, or by using one roll, or by using opposite upper and lower layer designs, or by using the same graphite for both upper and lower layers, indicating that the present invention has a special structural design and an optimal formulation, thereby achieving optimal performance.

Claims (10)

1. A method for preparing a negative electrode, comprising the steps of:
(1) Preparing high-capacity graphite, silicon carbon, single-wall carbon nano tube/multi-wall carbon nano tube/SP composite conductive agent, SP powder, adhesive 1, adhesive 2 and adhesive 3 into slurry A by using a traditional semi-dry slurry mixing process;
(2) Preparing slurry B from quick-filling graphite, mesophase carbon microspheres, silicon carbon, single-wall carbon nano tube/multi-wall carbon nano tube/SP composite conductive agent, adhesive 1 and adhesive 3 by using a traditional semi-dry slurry mixing process;
(3) Taking the slurry A as a bottom layer and the slurry B as an upper layer, respectively coating the slurry A on two sides of a copper current collector or a carbon-coated copper current collector, and drying to obtain a pole coil;
(4) And (3) rolling the pole coil obtained in the step (3) by a double roller, standing, and then rolling by a single roller to obtain the fast-charging double-layer heterogeneous silicon-based negative electrode.
2. The method for producing a negative electrode according to claim 1, characterized in that: the capacity of the high-capacity graphite is 358-360 mAh/g;
The capacity of the quick-filling graphite is 354-356 mAh/g;
The capacity of the silicon carbon is 1600-1700mAh/g@0.8V;
the adhesive 1 is polyacrylic acid;
the binder 2 is sodium carboxymethyl cellulose;
The binder 3 is styrene-butadiene rubber;
The dry mass ratio of the high-capacity graphite, the silicon carbon, the single-wall carbon nano tube/multi-wall carbon nano tube/SP composite conductive agent, the SP powder, the binder 1, the binder 2 and the binder 3 is (86-88): (8-10): (0.5-1): (0.6-0.9): (1.2-1.5): (0.3-0.6): (0.8-1.2);
The dry mass ratio of the quick-charging graphite to the intermediate phase carbon microsphere to the silicon carbon to the single-walled carbon nanotube/multiwall carbon nanotube/SP composite conductive agent to the binder 1 to the binder 3 is (44-46): (46-49): (4-5): (0.9-1.2): (1.7-2.0): (0.8-1.0).
3. The method for producing a negative electrode according to claim 1, characterized in that: the solid content of the slurry A is 45% -48%, and the viscosity is 2500-4500 mpas;
The solid content of the slurry B is 47% -50% and the viscosity is 2500-4500 mpas.
4. The method for producing a negative electrode according to claim 1, characterized in that: the double-sided density of the coating dressing of the slurry A is 85-95 g/m 2;
the double-sided density of the coating dressing of the slurry B is 90-105 g/m 2;
The overall double-sided density of the coated dressing is 175-200 g/m 2;
the edge of the coating material area of the slurry B covers the coating material area of the slurry A by 1+/-0.2 mm.
5. The method for producing a negative electrode according to claim 1, characterized in that: in the step (4), the compaction ratio of the first roller in the double-roller rolling is 1.35-1.4 g/cm 3, and the compaction ratio of the second roller is 1.62-1.64 g/cm 3;
the compaction ratio of the single-roller rolling is 1.64-1.66 g/cm 3;
the standing time is 2-4 hours;
the rebound rate of the final pole piece for 24 hours is less than 3%, the porosity of the upper coating after rolling is 37% -39%, and the porosity of the lower coating is 33% -35%.
6. The method for producing a negative electrode according to claim 1, characterized in that: the slurry A and the slurry B are also subjected to a step of filtering before being coated;
The slurries A, B were filtered using 100 mesh and 200 mesh capsule cartridges, respectively.
7. The negative electrode produced by the production method according to any one of claims 1 to 6.
8. A lithium battery comprising the negative electrode of claim 7.
9. The lithium battery of claim 8, wherein: the diaphragm of the lithium battery is a PI diaphragm; the PI diaphragm consists of a PP base film, a polyvinylidene fluoride adhesive layer, a polyimide and ceramic powder mixed layer and the polyvinylidene fluoride adhesive layer;
And the two sides of the PP base film are sequentially coated with the polyvinylidene fluoride adhesive layer, the polyimide and ceramic powder mixed layer and the polyvinylidene fluoride adhesive layer.
10. The lithium battery of claim 8, wherein: the N/P of the positive pole piece of the lithium ion is 1.05-1.12; and the main material of the positive pole piece is a monocrystal ternary material.
CN202410547821.0A 2024-05-06 2024-05-06 Negative electrode and preparation method thereof Pending CN118448586A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN202410547821.0A CN118448586A (en) 2024-05-06 2024-05-06 Negative electrode and preparation method thereof

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN202410547821.0A CN118448586A (en) 2024-05-06 2024-05-06 Negative electrode and preparation method thereof

Publications (1)

Publication Number Publication Date
CN118448586A true CN118448586A (en) 2024-08-06

Family

ID=92311744

Family Applications (1)

Application Number Title Priority Date Filing Date
CN202410547821.0A Pending CN118448586A (en) 2024-05-06 2024-05-06 Negative electrode and preparation method thereof

Country Status (1)

Country Link
CN (1) CN118448586A (en)

Similar Documents

Publication Publication Date Title
CN112271271B (en) Negative plate, preparation method, lithium ion battery core, lithium ion battery pack and application of lithium ion battery pack
CN114665065B (en) Positive electrode plate and preparation method and application thereof
WO2014032406A1 (en) Silicon-carbon composite negative electrode material, preparation method therefor and lithium ion battery
WO2024031867A1 (en) Nitrogen-doped graphene-coated silicon-carbon composite material, and preparation method therefor and use thereof
CN111129428A (en) Multilayer positive plate electrode structure, preparation method thereof and positive and negative battery structure
WO2024124969A1 (en) Secondary battery and electrical device
CN111146410A (en) Negative electrode active material and battery
CN117613239A (en) Positive electrode plate, preparation method thereof and lithium ion battery
EP4145476A1 (en) Positive electrode of hybrid capacitor and manufacturing method therefor and use thereof
CN114824226B (en) Negative electrode plate, preparation method thereof, lithium ion battery and electric equipment
CN116417658A (en) Secondary battery and application thereof
CN115621463B (en) Graphene composite conductive agent, preparation method and application
CN113097453A (en) Lithium pre-embedding method for positive electrode of lithium ion battery
CN114497440B (en) Negative plate and battery comprising same
CN113299919B (en) Positive pole piece and lithium ion battery comprising same
CN115275166A (en) Long-life graphite composite material and preparation method thereof
CN111029538B (en) Carbon-coated silicon composite silicate material and preparation method and application thereof
CN118448586A (en) Negative electrode and preparation method thereof
CN114864867A (en) Positive pole piece of lithium ion battery and preparation method and application thereof
CN115036458A (en) Lithium ion battery
CN115020638B (en) Lithium ion battery
CN114094076B (en) Negative plate and lithium ion battery comprising same
CN113964326B (en) Modified cobalt-free positive pole piece and preparation method and application thereof
CN114725361B (en) Iron-containing oxide coated sulfur doped expanded graphite/silicon electrode material and preparation method thereof
CN117438225A (en) Preparation method of battery type lithium ion capacitor electrode plate

Legal Events

Date Code Title Description
PB01 Publication
PB01 Publication
SE01 Entry into force of request for substantive examination
SE01 Entry into force of request for substantive examination