CN104300148A

CN104300148A - A graphite anode material of lithium-ion battery and the preparation method

Info

Publication number: CN104300148A
Application number: CN201310205007.2A
Authority: CN
Inventors: 谢秋生; 张鹏昌; 陈志明; 薄维通
Original assignee: NINGBO SHANSHAN NEW MATERILA TECHNOLOGY Co Ltd; Shanghai Shanshan Technology Co Ltd
Current assignee: NINGBO SHANSHAN NEW MATERILA TECHNOLOGY Co Ltd; Shanghai Shanshan Technology Co Ltd
Priority date: 2013-05-28
Filing date: 2013-05-28
Publication date: 2015-01-21
Anticipated expiration: 2033-05-28
Also published as: CN104300148B

Abstract

The present invention discloses a graphite anode material of lithium-ion battery and a preparation method. The method comprises the following steps: 1. mixing natural graphite, mesocarbon microbeads and asphalt evenly; the average particle size of the mesocarbon microbeads being at about 20[mu]m-30[mu]m, the average particle size of the natural graphite being at about 5-20[mu]m, the qaulity ratio of the natural graphite and mesocarbon microbeads is 9:1 to 5:5; and the amount of the asphalt is 10 to 50 percent of the sum of the quality of the natural graphite and mesocarbon microbeads; 2. thermally coating the mixture of the natural graphite, the mesocarbon microbeads and the asphalt at 300-700 degree celsius; 3. performing graphitizing treatment at high-temperature, the temperature of graphitization process is 2500-2800 degree celsius. The graphite anode material effectively reduces the specific surface area, and improves gram volume and discharge efficiency ,thereby the making battery have excellent overall performance .

Description

A kind of graphite negative material of lithium ion battery and preparation method thereof

Technical field

The present invention relates to a kind of graphite negative material of lithium ion battery and preparation method thereof.

Background technology

Lithium ion battery compared with original battery, high with its energy density, have extended cycle life, the feature such as memory-less effect, universal rapidly in mobile phone, notebook computer and electric tool etc.Along with the requirement of various product to small-size light-weight and multi-functional, long-time drivingization constantly increases, the raising of capacity of lithium ion battery depends on the development and improvement of negative material.Therefore, improve the specific capacity of lithium ion battery negative material for a long time, reduce irreversible capacity first, improve multiplying power property, be the emphasis of research and development always.

The native graphite that ion secondary battery cathode material lithium uses has desirable layer structure, there is very high discharge capacity (close to theoretical capacity 372mAh/g), cost is low but it exists structural instability, easily cause the common embedding of solvent molecule, its synusia in charge and discharge process is come off, cause cycle performance of battery poor, poor stability.

Therefore, for overcoming the deficiency in native graphite performance, prior art is all carry out modification to native graphite.It is coated that Japan Patent JP10294111 pitch carries out low temperature to graphite Carbon Materials, must not melt process and Light comminution after coated, and this method is difficult to accomplish evenly coated.Graphite and hard charcoal particle flood by Japan Patent JP11246209 at 10 ~ 300 DEG C of temperature in pitch or tar, then separated from solvent and heat treatment is carried out, this method is difficult to form the bitumen layer with certain thickness high polymeric at graphite and hard carbon surface, and the raising for native graphite structural stability will be restricted.Japan Patent JP2000003708 mechanically carries out rounding to graphite material, then floods in heavy oil, tar or pitch, then carries out being separated and washing, close with JP11246209 viewed from method for coating merely.Japan Patent JP2000182617 adopts native graphite etc. and pitch or resin or its mixture Co carbonization, and this method can reduce graphite material specific area, but is difficult to reach better control on covered effect.Japan Patent JP2000243398 is that the atmosphere utilizing asphalt pyrolysis to produce carries out surface treatment to graphite material, and this method is unlikely, and make the to be modified form of material is greatly improved, and thus makes the raising of electrical property be restricted.Japan Patent JP2002042816 is that raw material CVD is carried out coated or carries out coated with pitch phenolic resins with aromatic hydrocarbons, and this and JP2000182617 and JP2000283398 have similarity in effect.

Summary of the invention

The present invention, in order to the technical problem such as solve graphite cathode material structural instability in prior art, pitch-coating effect is bad, electrical property is restricted, provides that a kind of productive rate is high, operation is simple, discharge capacity is high and discharge-rate performance also improved graphite negative material of lithium ion battery and preparation method thereof.

The invention provides a kind of preparation method of graphite negative material of lithium ion battery, comprise the steps: 1. native graphite and MCMB green-ball to be mixed with pitch; The average grain diameter of described MCMB green-ball is 20 μm ~ 30 μm; The average grain diameter of described native graphite is at 5 ~ 20 μm; The mass ratio of the consumption of described native graphite and MCMB green-ball is 9:1 ~ 5:5; The consumption of described pitch is 10 ~ 50% of native graphite and MCMB quality of green pellets sum; 2. the mixture of native graphite, MCMB green-ball, pitch is carried out hot coated process at 300 ~ 700 DEG C; 3. graphitizable high temperature process is carried out; The temperature of described graphitization processing is 2500 ~ 2800 DEG C.

Wherein, described MCMB green-ball is that this area is conventional.Refer generally to the MCMB green-ball prepared through liquid-phase polymerization by pitch, as MCMB green-ball prepared by coal tar asphalt or petroleum asphalt.

Wherein, preferably, the average grain diameter of described MCMB green-ball is 20 μm ~ 25 μm; Better, described MCMB green-ball obtains through crushing and classification process.

Wherein, preferably, the average grain diameter of described native graphite is 6 ~ 18 μm.

Wherein, described pitch is that this area is conventional, is generally petroleum asphalt or coal tar pitch.Described petroleum asphalt is preferably high temperature petroleum asphalt, and described coal tar pitch is preferably coal tar pitch.

Wherein, preferably, the mass ratio of the consumption of described native graphite and MCMB green-ball is 8:2 ~ 6:4.

Wherein, preferably, the consumption of described pitch is 20 ~ 40% of native graphite and MCMB quality of green pellets sum.

Wherein, preferably, step 2. described in the temperature of the coated process of heat be 400 ~ 600 DEG C, the time of the coated process of described heat is 2 ~ 6 hours; The coated process of described heat is conveniently carried out in atmosphere of inert gases; Described inert gas is preferably nitrogen.

Wherein, preferably, step 3. described in time of graphitization processing be 20 ~ 60 hours; Better, the time of described graphitization processing is 40 ~ 60 hours.

The present invention also provides the lithium ion battery graphite cathode material as above-mentioned preparation method obtains.

On the basis meeting this area general knowledge, above-mentioned each optimum condition, can combination in any, obtains the preferred embodiments of the invention.

Agents useful for same of the present invention and raw material are all commercially.

Positive progressive effect of the present invention is:

Preparation method's simple process of the present invention is easy, raw material sources extensively and cost, obtained product discharge capacity and efficiency for charge-discharge high, good rate capability.

Graphite cathode material of the present invention, significantly reduces specific area, improves gram volume and discharging efficiency, the high comprehensive performance of its battery made.

Accompanying drawing explanation

Fig. 1 is the first charge-discharge curve of the lithium ion battery graphite cathode material of the embodiment of the present invention 2.

Fig. 2 is the scanning electron microscope (SEM) photograph of the lithium ion battery graphite cathode material of the embodiment of the present invention 2.

Fig. 3 is the discharge-rate curve of the lithium ion battery graphite cathode material of the embodiment of the present invention 2.

Embodiment

Mode below by embodiment further illustrates the present invention, but does not therefore limit the present invention among described scope of embodiments.The experimental technique of unreceipted actual conditions in the following example, conventionally and condition, or selects according to catalogue.

Native graphite used is the native graphite that Qingdao Hensen Graphite Co., Ltd. produces;

MCMB green-ball used is the SSA25 MCMB green-ball that Shanghai Shanshan Science and Technology Co., Ltd produces;

Petroleum asphalt used is the high temperature petroleum asphalt that Dalian bright strengthening work Materials Co., Ltd produces.

The lithium ion battery graphite cathode material particle diameter that various embodiments of the present invention obtain uses laser method to measure, the specific area determination of nitrogen adsorption of lithium ion battery graphite cathode material.

The method of testing of discharge capacity, the first efficiency of the present invention's button cell used is: in carboxymethyl cellulose (CMC) aqueous solution, add conductive black, then lithium ion battery graphite cathode material is added, finally add butadiene-styrene rubber (SBR), stir, slurry is coated on Copper Foil by coating machine uniformly and makes pole piece.The pole piece coated being put into temperature is 110 DEG C of vacuum drying chamber vacuumizes 4 hours, takes out pole piece roll extrusion on roll squeezer, for subsequent use.Simulated battery is assemblied in the German Braun glove box of applying argon gas and carries out, and electrolyte is 1M LiPF6+EC: DEC: DMC=1: 1: 1 (volume ratio), and metal lithium sheet is to electrode.Volume test is carried out on U.S. ArbinBT2000 type cell tester, and charging/discharging voltage scope is 0.005 to 2.0V, and charge-discharge velocity is 0.1C.

The present invention's discharge-rate method of testing used is: the lithium ion battery graphite cathode material of the embodiment of the present invention or comparative example makes negative pole, cobalt acid lithium makes positive pole, 1M-LiPF6EC: DMC: EMC=1: 1: 1 (volume ratio) solution is done electrolyte assembling and is helped battery, the lithium ion battery graphite cathode material of embodiment 2 after tested discharge-rate (2C/0.2C) more than 90%, as shown in Figure 3.

Table 1

The technological parameter of various embodiments of the present invention and comparative example is as shown in table 1, and concrete operations are as follows:

MCMB green-ball is crushing and classification process in pulverizing grading machine; obtain MCMB green-ball F1 to expect; native graphite is expected with MCMB green-ball F1, coal tar pitch adds in mixer and mix; under the protection of nitrogen; carry out hot coated process; after end, after product being cooled to room temperature, carry out graphitizable high temperature process, obtained graphite negative material of lithium ion battery of the present invention.The performance parameter of various embodiments of the present invention and comparative example is as shown in table 2:

Table 2

The lithium ion battery negative material of the embodiment of the present invention 2 measures first charge-discharge curve, scanning electron microscope (SEM) photograph and discharge-rate curve as Figure 1-3, respond well.As can be seen from data above, the discharge capacity in comparative example and efficiency for charge-discharge low, the efficiency for charge-discharge of non-bituminous coated graphite is minimum is 87.2%, and discharge-rate (2C/0.2C) only reaches 70.8%; Adopt graphite negative material of lithium ion battery prepared by method of the present invention, particle diameter D50 is 10 ~ 25 μm, and specific area reduces greatly, is less than 2.0m ²/ g, discharge capacity is greater than 360mAh/g, and efficiency for charge-discharge is greater than 90%, and discharge-rate (2C/0.2C) is all more than 90%.

Claims

1. a preparation method for graphite negative material of lithium ion battery, is characterized in that, it comprises the steps: 1. native graphite and MCMB green-ball to be mixed with pitch; The average grain diameter of described MCMB green-ball is 20 μm ~ 30 μm; The average grain diameter of described native graphite is at 5 ~ 20 μm; The mass ratio of the consumption of described native graphite and MCMB green-ball is 9:1 ~ 5:5; The consumption of described pitch is 10 ~ 50% of native graphite and MCMB quality of green pellets sum; 2. the mixture of native graphite, MCMB green-ball, pitch is carried out hot coated process at 300 ~ 700 DEG C; 3. carry out graphitizable high temperature process, the temperature of described graphitization processing is 2500 ~ 2800 DEG C.

2. preparation method as claimed in claim 1, it is characterized in that, the average grain diameter of described MCMB green-ball is 20 μm ~ 25 μm; And/or the average grain diameter of described native graphite is 6 ~ 18 μm.

3. preparation method as claimed in claim 1 or 2, it is characterized in that, described MCMB green-ball obtains through crushing and classification process.

4. preparation method as claimed in claim 1, it is characterized in that, described petroleum asphalt is high temperature petroleum asphalt, and described coal tar pitch is coal tar pitch.

5. preparation method as claimed in claim 1, it is characterized in that, the mass ratio of the consumption of described native graphite and MCMB green-ball is 8:2 ~ 6:4.

6. preparation method as claimed in claim 1, it is characterized in that, the consumption of described pitch is 20 ~ 40% of native graphite and MCMB quality of green pellets sum.

7. preparation method as claimed in claim 1, is characterized in that, step 2. described in the temperature of the coated process of heat be 400 ~ 600 DEG C, the time of the coated process of described heat is 2 ~ 6 hours.

8. preparation method as claimed in claim 7, it is characterized in that, the coated process of described heat is carried out in atmosphere of inert gases; Preferably, described inert gas is nitrogen.

9. preparation method as claimed in claim 1, is characterized in that, step 3. described in time of graphitization processing be 20 ~ 60 hours; Preferably, the time of described graphitization processing is 40 ~ 60 hours.

10. the graphite negative material of lithium ion battery that the preparation method as described in any one of claim 1 ~ 9 obtains.