CN103165862B - A kind of high performance lithium ionic cell cathode material and preparation method thereof - Google Patents

Abstract

The invention discloses a kind of high performance lithium ionic cell cathode material, this negative material comprises Si-SiOx/C/DC compound system, and described compound system comprises C matrix, bonding porous Si-SiOx in the base, is distributed in carbon nano-tube in matrix and Si-SiOx and outermost RESEARCH OF PYROCARBON coating layer.The invention also discloses the preparation method of this negative material.The specific discharge capacity of negative material of the present invention is high, cyclical stability better, is applicable to the high energy density cells negative material doing portable mobile termianl and digital products.

Description

A kind of high performance lithium ionic cell cathode material and preparation method thereof

Technical field

The invention belongs to materialogy field, be specifically related to a kind of lithium ion battery high specific capacity silicon-carbon composite cathode material.

Background of invention

Lithium ion battery from the nineties in last century start practical since, the outstanding advantages such as voltage is high owing to having, energy density large, good cycle, self discharge amount are little, memory-less effect, have been widely used in the fields such as mobile terminal, digital product and portable mobile apparatus, electric automobile and energy-accumulating power station.But along with the birth of intelligent mobile terminal electronic equipment, current lithium ion battery is difficult to meet its long-time instructions for use, and due to the finite volume of mobile terminal, therefore the exploitation of high-specific energy battery product is extremely urgent.

Commercial lithium battery used at present adopts cobalt acid lithium/graphite, nickel-cobalt-manganese ternary/graphite system mostly, but the theoretical lithium storage content of graphite itself is lower, has been difficult to the breakthrough of the capacity that obtains by the improvement of battery process.Elemental silicon has as negative material the theoretical specific capacity that ten are multiple times than native graphite

(4200mAh/g) the general concern of material circle and research, is subject to.But there is following problem as battery cathode active substance in elemental silicon: (1), in embedding lithium process, forms Li under full power state ₂₂si ₅alloy phase, the change in volume of material reaches more than 300%.The mechanical internal stress that so huge bulk effect produces can make electrode active material and collector peel off gradually, and silicon activity mutually itself also can efflorescence in addition, thus loses the electrical contact with collector, causes cycle performance of battery to decline rapidly; (2) conductivity is low.Silicon itself is semi-conducting material, and conductivity is low only has 6.7 × 10 ^-4scm-1, need add conductive agent to improve the electronic conductivity of silicon active matter; (3) be difficult to form stable SEI film.In charge and discharge process, huge bulk effect can cause constantly having silicon exposed in electrolyte, is difficult to form stable SEI film, causes electroactive material cycle performance to decline fast.

In the patent application of many Si-C composite negative pole materials, it is mostly the lithium storage content being improved negative material by methods such as the mixing of silicon and graphite, coated, doping, but the scattering problem of nanoscale silica flour is not thoroughly resolved always, cause electrode part region inactivation.The present invention adopts high-energy ball milling method to prepare Si-SiOx presoma, submicron metal reduction SILICA FUME is introduced in mechanical milling process, obtain the SiOx having certain compatibility with Si, while achieving good dispersion, the porosity features of presoma reduces the internal stress of silicon generation when there is bulk effect to a certain extent.The present invention adopts organic RESEARCH OF PYROCARBON coated, not only makes the Si-SiOx of porous and carbon matrix material have better bonding, also eliminates the dangling bonds on carbon base body, it also avoid activated silica and contacts with the direct of electrolyte, improve the cyclical stability of battery.

Summary of the invention

In order to solve the above-mentioned technical problem of silicium cathode material, the invention provides a kind of High-performance lithium ion battery silicon-carbon cathode material and preparation technology thereof.Negative material of the present invention is Si-SiOx/C/DC compound system, and it is scattered in uniformly in constitutionally stable material with carbon element by the Si-SiOx of submicron order, utilizes the cushioning effect of carbon base body to volumetric expansion to improve the cycle life of silicium cathode.

A kind of high performance lithium ionic cell cathode material, comprises carbon base body, dispersion Si-SiOx in the base, is distributed in carbon nano-tube in matrix and Si-SiOx and outermost RESEARCH OF PYROCARBON coating layer:

Wherein, above-mentioned carbon base body is one or more in native graphite, Delanium, carbonaceous mesophase spherules (MCMB), hard carbon;

Described Si-SiOx is a kind of porous compound removed metal by silica flour, SILICA FUME, super-fine metal powder and formed after high energy mechanical chemical reaction;

The average diameter of described carbon nano-tube is 10 ~ 100nm, draw ratio is (8 ~ 24): the nanofiber of 1;

The organic RESEARCH OF PYROCARBON coating layer of described outermost layer is the organic carbon coating layer that organic substance is formed after polycondensation, carbonization.

Second object of the present invention is to provide a kind of preparation method of this high-performance negative material, and it comprises the following steps:

(1) high-purity silicon powder, SILICA FUME, submicron metal, dispersant are mixed by a certain percentage, in ball grinder, carry out ball milling;

(2) by step (1) product with 50 ~ 150 DEG C of vacuumize 1 ~ 24h; Product sinters in nitrogen and/or argon gas;

(3) step (2) product is carried out pickling, filtration, vacuum drying;

(4) C matrix is carried out high temperature oxidation process in air atmosphere;

(5) by step (3) product and step (4) product by proper proportion mixing, join be added with carbon nano-tube RESEARCH OF PYROCARBON solution in, low speed secondary ball milling disperses;

(6) by step (5) product heats, evaporation of solvent is stirred;

(7) sinter in step (6) non-oxidizing atmosphere, organic RESEARCH OF PYROCARBON carbonization treatment, and naturally cool to room temperature, realize organic RESEARCH OF PYROCARBON coated;

(8) step (7) product is sieved with 200 ~ 500 eye mesh screens, obtain Si-O-C composite negative pole material.

Negative material of the present invention can meet the requirement to cell high-capacity and high circulation.Preparation method of the present invention is simple, goes for technical scale and produces.

Accompanying drawing explanation

The crystallogram (adopting Cuk α target emanation) of the high power capacity silico-carbo composite material of Fig. 1 prepared by embodiment 1;

The SEM figure of the Si-C composite material of Fig. 2 prepared by embodiment 1.

Embodiment

In order to make technical problem solved by the invention, technical scheme and beneficial effect clearly understand, below in conjunction with drawings and Examples, the present invention is described in more detail.Should be appreciated that specific embodiment described herein only in order to explain the present invention, be not intended to limit the present invention.

A kind of high performance carbon carbon negative electrode material of lithium ion cell, comprises C matrix, bonding Si-SiOx-C in the base, is distributed in carbon nano-tube in matrix and Si-SiOx-C and outermost organic RESEARCH OF PYROCARBON coating layer.

The present embodiment is matrix used is native graphite, and the average grain diameter of described native graphite is 6 ~ 30 μm;

Described Si-SiOx-C removes the oxide of aluminium or aluminium and a kind of compound that formed with rare HCl by silica flour, SILICA FUME, ultra-fine aluminium, carbon nano-tube after high energy mechanical chemical reaction;

Described carbon nano-tube is average diameter is 10 ~ 100nm, draw ratio is (8 ~ 24): the finely disseminated nanofiber of 1;

Described RESEARCH OF PYROCARBON coating layer is the RESEARCH OF PYROCARBON coating layer that organic substance is formed after high temperature pyrolysis, carbonization, and the coated thickness of described organic RESEARCH OF PYROCARBON coating layer is 50 ~ 300nm;

In the present invention, submicron order cavernous Si-SiOx composite particles is dispersed and be bonded in the surface of native graphite matrix, and utilizes organic RESEARCH OF PYROCARBON to carry out coated to it, forms the RESEARCH OF PYROCARBON coating layer of complete densification.Be dispersed with carbon nanotube conducting network between composite particles and coating layer and between composite particles, form height ratio capacity silico-carbo composite material of the present invention.

The specific area of the preferred nucleocapsid structure composite particles of the present invention is 0.8 ~ 30m ²/ g, is more preferably 0.9 ~ 10m ²/ g.

The coated thickness of preferred substrate coating layer of the present invention is 50 ~ 300nm, is more preferably 80 ~ 200nm;

In the present invention, the specific capacity size of composite material is determined by the ratio of Si-SiOx compound and native graphite, and the present invention preferably 1: 100 ~ 50: 100, are more preferably 10: 100 ~ 30: 100; The ratio of the preferred SILICA FUME of the present invention and silica flour is 1: 100 ~ 100: 100, is more preferably 10: 100 ~ 50: 100; The ratio of the preferred aluminium powder of the present invention and SILICA FUME is 10: 100 ~ 100: 100, is more preferably 30: 100 ~ 60: 100; The mass ratio of the preferred carbon nano-tube of the present invention and Si-SiOx-C is 0.1: 100 ~ 20: 100, is more preferably 0.5: 100 ~ 5: 100; The mass ratio of the coated preferred organic RESEARCH OF PYROCARBON of the present invention and Si-SiOx-C is 1: 100 ~ 50: 100, is more preferably 5: 100 ~ 30: 100.

The preparation method of negative material of the present invention, it comprises the steps:

(1) high-purity silicon powder, SILICA FUME, superfine aluminium power, dispersant will be had to mix by a certain percentage;

(2) step (1) material is positioned in ball grinder, adds a certain proportion of zirconia ball, high-energy ball milling;

(3) step (2) product is carried out vacuumize;

(4) step (3) product is sintered in non-oxide atmosphere;

(5) step (4) product is carried out pickling, filtration, vacuum drying;

(6) by commercialization C raw material high-temperature oxydation certain hour in air atmosphere;

(7) step (5) product and step (6) product are mixed by proper proportion, join and be added with in the certain density RESEARCH OF PYROCARBON solution of carbon nano-tube, low speed secondary ball milling disperses;

(8) by step (7) product heats, stir and remove desolventizing;

(9) sinter in step (8) non-oxidizing atmosphere, RESEARCH OF PYROCARBON carbonization treatment, and naturally cool to room temperature, realize RESEARCH OF PYROCARBON coated;

(10) step (9) product is sieved, obtain Si-C composite negative pole material.

Organic RESEARCH OF PYROCARBON coating layer raw material is known in those skilled in the art.Conventional organic RESEARCH OF PYROCARBON has glucose, sucrose, polyvinyl chloride, phenolic resins, furfural resin, poly furfuryl alcohol, polyacrylonitrile, coal tar pitch, petroleum asphalt etc.Preferably sucrose of the present invention.

The present invention adopt solvent be selected from deionized water, ethanol, hexane, octane, cyclohexane, benzene, toluene, biphenyl, naphthalene, anthracene, pyridine, oxolane one or more.The preferred deionized water of the present invention.

The average diameter of the carbon nano-tube that the present invention adopts is 20nm, average length is draw ratio 8: 1 ~ 12: 1.

The preferred non-oxidizing atmosphere of the present invention is one or both of nitrogen and argon gas.

The preferred operations of step (1) is: high-purity silicon powder, SILICA FUME, aluminium powder are mixed by a certain percentage, and adds alcohol as dispersant.Ultrasonic disperse 30-120 minute;

The preferred operations of step (2) is: will proceed in stainless steel jar mill in step (1) product, and add the zirconia ball of 0.2 ~ 20mm, ratio of grinding media to material example 10: 1 ~ 20: 1, at 150 ~ 450r/min ball milling, 4 ~ 48h after deaeration, be more preferably 350 ~ 450r/min ball milling, 12 ~ 24h;

The preferred operations of step (3) is: by the product elimination zirconia ball of step (2), 60 ~ 100 DEG C of vacuum dryings, mechanical crushing;

The preferred operations of step (4) is: by step (3) product under the protection of industrial nitrogen, and 400 ~ 900 DEG C sinter 1 ~ 10 hour;

The preferred operations of step (5) is: add in rare HCl by step (4) product, stirring at normal temperature 10min ~ 6h, filters and washs to neutral;

The preferred operations of step (6) is: by natural graphite starting material in air atmosphere 200 ~ 600 DEG C oxidation 2 ~ 4 hours;

The preferred operations of step (7) is: be dispersed with in organic RESEARCH OF PYROCARBON dispersion liquid of carbon nano-tube by adding after step (5) and step (6) product by a certain percentage proportioning, in stainless steel jar mill, 150 ~ 200r/min ball milling 1 ~ 8 hour, is more preferably 2 ~ 4 hours; Ratio of grinding media to material example 5: 1 ~ 20: 1, is more preferably 10: 1 ~ 15: 1; Zirconia sphere diameter 5 ~ 20mm, is more preferably 10 ~ 20mm;

The preferred operations of step (8) is: after step (7) product being considered deoxidation zirconium ball, dry out solvent in a dynamic condition, and temperature preferably 60 ~ 150 DEG C, is more preferably 80 ~ 120 DEG C;

The preferred operations of step (9) is: step (8) product is sintered 2 ~ 10h at 400 ~ 1000 DEG C under industrial nitrogen atmosphere protection, is more preferably 600 ~ 900 DEG C of sintering 4 ~ 8h, then naturally cools to room temperature;

The preferred operations of step (10) is: step (9) product is crossed 150 ~ 500 mesh sieves, is more preferably 250 ~ 350 mesh sieves..

Below in conjunction with specific embodiment, the present invention is further elaborated.

Embodiment 1

Each component is as follows:

High pure metal silica flour: 11.0g (99.9%), average grain diameter is 1.0 ~ 2.5 μm;

SILICA FUME: 4.8g (99%), average grain diameter 3 ~ 10 μm;

Superfine metal aluminium powder: 2.2g (99%), average grain diameter 5 ~ 10 μm;

Rare HCl:120g (10% mass concentration);

Carbon nano tube paste: 40g (LITHIUM BATTERY, water system 5% concentration), average diameter is 20 ~ 30nm, average aspect ratio 8 ~ 12;

Native graphite: 89g (spherical graphite, LITHIUM BATTERY) average grain diameter is 6 ~ 12 μm, interlamellar spacing d ₀₀₂be 0.3353 ~ 0.3354nm;

Sucrose: 25g (food grade).

Preparation method is as follows:

(1) high pure metal silica flour, SILICA FUME, superfine aluminium power is got, and with 100ml alcohol as dispersant ultrasonic disperse 1h;

(2) above-mentioned dispersion is proceeded in stainless steel jar mill, and to add 300g diameter be 0.2 ~ 10mm zirconia ball, after preservative film sealing, use argon gas deaeration, 400r/min batch (-type) ball milling 16h on planetary ball mill;

(3) by step (2) product elimination zirconia ball, vacuum drying, pulverizing, the lower 670 DEG C of sintering 4h of industrial nitrogen protective condition, and naturally cool to room temperature;

(4) step (3) product is added in rare HCl, stir 2h, filter and wash to neutral;

(5) by native graphite 400 DEG C of sintering 2h in air atmosphere, room temperature is naturally cooled to;

(6) by sucrose dissolved in 200ml distilled water, add carbon nano tube paste and step (4), (5) product, ball grinder is added after ultrasonic disperse 30min, and add the zirconia ball that 400g diameter is 5 ~ 20mm, 200r/min ball milling 2h on planetary ball mill;

(7) by after step (6) product filtering zirconia ball, solvent evaporated under stirring;

(8) step (7) product is warming up to 750 and constant temperature 6h with the programming rate of 3 ~ 5 DEG C under industrial nitrogen protection, 900 DEG C of constant temperature 2h, naturally cool to room temperature, cross 300 mesh sieves.

Finally obtained composite silica carbon negative pole material, is denoted as A.

Comparative example 1

With embodiment 1 difference be: without " step (4) rare HCl washs ";

Other steps are as embodiment 1.Finally obtained silicon-carbon cathode material, is denoted as B1.

Comparative example 2

With embodiment 1 difference be: (1) step does not have " adding superfine aluminium power ", without " the rare HCl washing of step (4) ";

Other steps are with embodiment 1.Finally obtained silicon-carbon cathode material, is denoted as B2.

Comparative example 3:

With embodiment 1 difference be: (1) step does not have " adding SILICA FUME ";

Other steps are with embodiment 1.Finally obtained silicon-carbon cathode material, is denoted as B3.

Comparative example 4

With embodiment 1 difference be: " step (1) does not add aluminium powder and SILICA FUME ", without " step (3) 670 DEG C sintering and the rare HCl of step (4) wash " process;

Other steps are with embodiment 1.Finally obtained silicon-carbon cathode material, is denoted as B4.

Electrochemical property test

The preparation of simulated battery: water is as dispersion, 1.5 parts of sodium carboxymethylcelluloses (CMC) and 2.5 parts of butadiene-styrene rubber (SBR) are as binding agent, the super-P of 2 parts is as conductive agent, the active material A1 of 94 parts, A2, A3 and B, stirring is polished into uniform sizing material and is coated on Copper Foil after drying moisture, 80 DEG C of vacuum dry 12h and compressing tablet as electrode to be measured, metal lithium sheet is to electrode, electrolyte is the LiPF6 (EC+DMC mixes with the volume ratio of 1: 1) of 1mol/L, barrier film adopts cellgard2400 film, the button cell of CR2025 is assembled in argon shield glove box.

Reversible specific capacity test: at LAND CT2001A battery testing cashier's office in a shop with the electric current of 0.1C by above-mentioned button cell from 0.02V initial charge to 1.2V, calculate specific capacity by the charging capacity recorded, computing formula is: specific capacity=de-lithium capacity/active material quality first.The results are shown in Table 1.

First charge-discharge efficiency is tested: with the constant current of 0.1C ~ 0.002C, above-mentioned button cell is discharged to 0.02V cashier's office in a shop at LAND CT2001A battery testing, then with the constant current of 0.1C, battery is charged to 1.2V, record discharge capacity and initial charge capacity first, thus calculating first charge-discharge efficiency, computing formula is: first charge-discharge efficiency=initial charge capacity/discharge capacity × 100% first.The results are shown in Table 1.

Loop test: at LAND CT2001A battery testing cashier's office in a shop, under 25 DEG C of constant temperatures, button cell is carried out charge-discharge test with 0.1C electric current between 0.02-1.2V.To circulate 50 weeks or capacity is reduced to initial capacity less than 70%, stop test.The results are shown in Table 1.

Table 1: physical and chemical performance and button cell performance test

As can be seen from Table 1, in comparative example, B3 with B4 compares with embodiment A, reversible specific capacity, first charge-discharge efficiency all present B4 > B3 > A first, illustrate that the introducing of SiOx increases its irreversible specific capacity first; In comparative example, B1, B2 compare with embodiment A with B3, and pilot process introduces the raising that active metal is conducive to cyclical stability, and active metal or its compound cause capacity to have very fast decay without removal.Analyze data more than comprehensive, illustrate that the cycle performance of high-specific-capacity silicon carbon negative pole of the present invention is greatly improved.

Below be only that feature of the present invention implements example, scope is not constituted any limitation.The technical scheme that all employings exchange on an equal basis or equivalence is replaced and formed, all drops within rights protection scope of the present invention.

Claims (8)

1. a high performance lithium ionic cell cathode material, it is 1 ~ 30m that described negative material comprises specific area ²the Si-SiOx/C/DC compound system of/g, described compound system comprises C matrix, bonding Si-SiOx in the base, is distributed in carbon nano-tube in matrix and Si-SiOx-C and outermost organic RESEARCH OF PYROCARBON coating layer, it is characterized in that:

(1) described C matrix is one or more in the native graphite of oxidation processes, Delanium, carbonaceous mesophase spherules MCMB, hard carbon;

(2) described Si-SiOx be by particle diameter be 0.01 ~ 10 μm of high-purity silicon powder, particle diameter is a kind of porous compound that 0.1 ~ 10 μm of SILICA FUME and super-fine metal powder are removed metal and formed after high energy mechanical chemical reaction;

(3) average diameter of described carbon nano-tube is 5 ~ 100nm, draw ratio is the nanofiber of 2 ~ 25: 1;

(4) the organic RESEARCH OF PYROCARBON coating layer of the outermost layer described in is the carbon coating layer that organic substance is formed after polycondensation, carbonization;

Described super-fine metal powder is one or more in aluminium powder, glass putty, zinc powder, magnesium powder, calcium powder and titanium valve, and described super-fine metal powder particle diameter is 0.1 ~ 10 μm; Described Si-SiOx compound and the ratio of native graphite are 1: 100 ~ 100: 10, described SILICA FUME and the ratio of high-purity silicon powder are 1: 100 ~ 100: 100, described aluminium powder and the ratio of SILICA FUME are 1: 100 ~ 100: 100, and described carbon nano-tube and the mass ratio of Si-SiOx-C are 0.1: 100 ~ 20: 100; Described organic RESEARCH OF PYROCARBON and the mass ratio of Si-SiOx-C are 1: 100 ~ 50: 100.

2. negative material according to claim 1, is characterized in that: described organic RESEARCH OF PYROCARBON raw material be selected from glucose, sucrose, polyvinyl chloride, phenolic resins, furfural resin, poly furfuryl alcohol, polyacrylonitrile, coal tar pitch and petroleum asphalt one or more.

3. a preparation method for high performance lithium ionic cell cathode material, is characterized in that high performance lithium ionic cell cathode material is that to comprise specific area be 1 ~ 30m to described negative material ²the Si-SiOx/C/DC compound system of/g, described compound system comprises C matrix, bonding Si-SiOx in the base, is distributed in carbon nano-tube in matrix and Si-SiOx-C and outermost organic RESEARCH OF PYROCARBON coating layer;

(1) described C matrix is one or more in the native graphite of oxidation processes, Delanium, carbonaceous mesophase spherules MCMB, hard carbon;

(2) described Si-SiOx be by particle diameter be 0.01 ~ 10 μm of high-purity silicon powder, particle diameter is a kind of porous compound that 0.1 ~ 10 μm of SILICA FUME and super-fine metal powder are removed metal and formed after high energy mechanical chemical reaction;

(3) average diameter of described carbon nano-tube is 5 ~ 100nm, draw ratio is the nanofiber of 2 ~ 25: 1;

(4) the organic RESEARCH OF PYROCARBON coating layer of the outermost layer described in is the carbon coating layer that organic substance is formed after polycondensation, carbonization;

Described super-fine metal powder is one or more in aluminium powder, glass putty, zinc powder, magnesium powder, calcium powder and titanium valve, and described super-fine metal powder particle diameter is 0.1 ~ 10 μm;

The preparation method of high performance lithium ionic cell cathode material comprises the steps:

(1) high-purity silicon powder, SILICA FUME, submicron metal, dispersant are mixed by a certain percentage, in ball grinder, carry out ball milling;

(2) by step (1) product with 50 ~ 150 DEG C of vacuumize 1 ~ 24h; Product sinters in nitrogen and/or argon gas;

(3) step (2) product is carried out pickling, filtration, vacuum drying;

(4) C matrix is carried out high temperature oxidation process in air atmosphere, high-temperature oxydation temperature is 200 ~ 500 DEG C, and oxidization time is 0.5 ~ 10h;

(5) step (3) product and step (4) product are mixed by proper proportion, join be added with carbon nano-tube RESEARCH OF PYROCARBON solution in, low speed secondary ball milling disperses, and the dispersion of low speed secondary ball milling is 150 ~ 200r/min ball milling 1 ~ 8 hour in stainless steel jar mill;

(6) by step (5) product heats, evaporation of solvent is stirred;

(7) sinter in step (6) non-oxidizing atmosphere, organic RESEARCH OF PYROCARBON carbonization treatment, and naturally cool to room temperature, realize organic RESEARCH OF PYROCARBON coated;

(8) step (7) product is sieved with 200 ~ 500 eye mesh screens, obtain Si-SiOx/C/DC compound system.

4. the preparation method of negative material according to claim 3, it is characterized in that: described Si-SiOx compound and the ratio of native graphite are 1: 100 ~ 100: 10, described SILICA FUME and the ratio of high-purity silicon powder are 1: 100 ~ 100: 100, described aluminium powder and the ratio of SILICA FUME are 1: 100 ~ 100: 100, and described carbon nano-tube and the mass ratio of Si-SiOx-C are 0.1: 100 ~ 20: 100; Described organic RESEARCH OF PYROCARBON and the mass ratio of Si-SiOx-C are 1: 100 ~ 50: 100.

5. the preparation method of negative material according to claim 3, it is characterized in that: the ball milling of described step (1) is planetary milling, zirconia ball diameter is 0.1 ~ 50mm, and described Ball-milling Time is 1 ~ 30 hour, described drum's speed of rotation 150 ~ 500r/min.

6. the preparation method of negative material according to claim 3, it is characterized in that: in described step (3) acid cleaning process, acid used is selected from one or more in hydrochloric acid, sulfuric acid and nitric acid that mass fraction is 3%-15%, and pickling time is 30 ~ 300 minutes.

7. the preparation method of negative material according to claim 3, is characterized in that: the solvent that described step (5) dissolves organic RESEARCH OF PYROCARBON selects water, ethanol, benzene, toluene, one or more how, in anthracene, cyclohexane, trichloroethylene, acetone, ethyl acetate, pyridine and oxolane.

8. the preparation method of negative material according to claim 3, is characterized in that: the temperature that described step (6) stirs except desolventizing is 80 ~ 250 DEG C, and mixing time is 1 ~ 10 hour.