A kind of graphite negative material of lithium ion battery and preparation method thereofTechnical field
The present invention relates to field of lithium ion battery, particularly relate to a kind of graphite negative material of lithium ion battery and preparation method thereof.
Background technology
Lithium rechargeable battery is one of state-of-the-art battery grown up in early 1990s, and it has high voltage, specific energy is large, the life-span is long and the feature such as memory-less effect.Since nineteen ninety-one, lithium rechargeable battery is widely used in the aspects such as mobile phone, notebook computer, video camera and electric motor car.
Lithium ion battery negative material remains graphite type material in actual applications and occupies an leading position.Delanium and native graphite respectively have merits and demerits as negative material, and Delanium has the advantage of stable circulation, but generally will lower than native graphite on capacity.Although native graphite has the high advantage of capacity, in cyclic process, capacity attenuation is its deadly defect soon.
The charge/discharge capacity of native graphite Yin Qigao, good charge and discharge platform, wide material sources, cost is low and be used widely.But due to height crystallization and the degree of orientation of native graphite, make it that solvent molecule can occur in charging process and enter graphite layers and the phenomenon causing graphite linings to peel off, cause cycle performance of battery to reduce thus.
Along with the fast development of electronics and information industry, various product constantly improves miniaturized, light-weighted requirement, day by day urgent to the performance requirement of the aspects such as lithium rechargeable battery high magnification, quick charge.The development that the high rate performance of capacity of lithium ion battery and rapid charging performance depend on carbon cathode material is perfect, therefore more and more less to the Particle size requirements of lithium ion battery negative material, small particle diameter, high magnification, reduce irreversible capacity first and improve the emphasis that cyclical stability is research and development always.
At present, the spherical natural graphite of small particle diameter does not still have complete industrialization, and the graphite cathode material of preparation small particle diameter now can only adopt Delanium.
Summary of the invention
Technical problem to be solved by this invention is the defect that the particle diameter in order to overcome existing graphite cathode material is large, charge-discharge performance is poor, provides a kind of graphite negative material of lithium ion battery and preparation method thereof.The discharge capacity first of graphite negative material of lithium ion battery of the present invention is high, and compacted density is high, good cycle, and stability in use is good.Preparation method of the present invention is simple, is easy to industrialization large-scale production, and raw material sources are extensive, and cost is low, and product yield is high.
The present invention solves the problems of the technologies described above by the following technical programs:
The invention provides a kind of preparation method of graphite negative material of lithium ion battery, the green coke roasting that it comprises the steps: to be 3 ~ 7 μm by median D50, volatilization is divided into 10wt% ~ 20wt%, charing process, graphitization processing, classification process, can obtain graphite negative material of lithium ion battery; After described classification process, the median D50 of graphite negative material of lithium ion battery controls at 6 ~ 10 μm, maximum particle diameter≤30 μm.
In the present invention, described green coke is preferably oil green coke.
Wherein, described roasting is preferably carried out in pyroreaction still, and the temperature of described roasting is preferably 500 ~ 650 DEG C.
Wherein, the method for described charing process and condition can be method and the condition of this area routine charing process, and the temperature of described charing process is preferably 800 ~ 1300 DEG C, is more preferably 1100 DEG C; The time of described charing process is preferably 8 ~ 24h.
Wherein, the method for described graphitization processing and condition can be method and the condition of this area ordinary graphite process, and the temperature of described graphitization processing is preferably 2800 DEG C ~ 3000 DEG C, and the time of described graphitization processing is preferably 15 ~ 30 days.
In the present invention, the product yield of described preparation method generally can reach 70%.
Present invention also offers a kind of graphite negative material of lithium ion battery obtained by above-mentioned preparation method.
Wherein, the median D50 of described graphite negative material of lithium ion battery is preferably 6 ~ 10 μm.
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:
1, preparation method of the present invention is simple, is easy to industrialization large-scale production, and simply, small investment, be also easy to combine with existing relevant production line, transform, and operating process is easy to implement for production technology and associated equipment.
2, the particle diameter of graphite negative material of lithium ion battery of the present invention is little, and high rate performance is excellent, and irreversible capacity is little first, good cycle, and stability in use is good.
3, raw material sources are extensive, and cost is low, and product yield is high.
Accompanying drawing explanation
Fig. 1 is the curve of double curvature of the graphite negative material of lithium ion battery of embodiment 1.
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.
If no special instructions, the particle diameter in following embodiment all refers to median D50.
Embodiment 1
The preparation of graphite negative material of lithium ion battery: raw material is oil green coke A(volatile matter 14wt%), through being crushed to the particle diameter of powder at 5 μm, in pyroreaction still, final temperature 550 DEG C is reacted, charing process 12h at 1100 DEG C, graphitization processing 20 days at 2800 DEG C again, last classification process size controlling is at 8 μm, and yield is 72%.
Embodiment 2
The preparation of graphite negative material of lithium ion battery: raw material is oil green coke A(volatile matter 14wt%), through being crushed to the particle diameter of powder at 3 μm, in pyroreaction still, final temperature 550 DEG C is reacted, charing process 12h at 1100 DEG C, graphitization processing 20 days at 2800 DEG C again, last classification process size controlling is at 6 μm, and yield is 69%.
Embodiment 3
The preparation of graphite negative material of lithium ion battery: raw material is oil green coke A(volatile matter 14wt%), through being crushed to the particle diameter of powder at 5 μm, in pyroreaction still, final temperature 500 DEG C is reacted, charing process 12h at 1100 DEG C, graphitization processing 20 days at 2800 DEG C again, last classification process size controlling is at 8 μm, and yield is 68%.
Embodiment 4
The preparation of graphite negative material of lithium ion battery: raw material is oil green coke A(volatile matter 14wt%), through being crushed to the particle diameter of powder at 5 μm, in pyroreaction still, final temperature 550 DEG C is reacted, charing process 15h at 1100 DEG C, graphitization processing 20 days at 2800 DEG C again, last classification process size controlling is at 8 μm, and yield is 75%.
Embodiment 5
The preparation of graphite negative material of lithium ion battery: raw material is oil green coke A(volatile matter 14wt%), through being crushed to the particle diameter of powder at 7 μm, in pyroreaction still, final temperature 550 DEG C is reacted, charing process 12h at 1100 DEG C, graphitization processing 20 days at 2800 DEG C again, last classification process size controlling is at 10 μm, and yield is 68%.
Comparative example 1
The preparation of lithium ion battery negative material: raw material is oil green coke A(volatile matter 14wt%), through being crushed to the particle diameter of powder at 10 μm, in pyroreaction still, final temperature 550 DEG C is reacted, charing process 12h at 1100 DEG C, graphitization processing 20 days at 2800 DEG C again, last classification process size controlling is at 15 μm, and yield is 74%.
Comparative example 2
The preparation of lithium ion battery negative material: raw material is after-smithing petroleum coke B(volatile matter 0.4wt%), through being crushed to the particle diameter of powder at 5 μm, in pyroreaction still, final temperature 550 DEG C is reacted, charing process 12h at 1100 DEG C, graphitization processing 20 days at 2800 DEG C again, last classification process size controlling is at 15 μm, and yield is 70%.
Effect example
Adopt conventional determining method to measure the graphite negative material of lithium ion battery of above-described embodiment 1 ~ 5 and comparative example 1, the physical property of lithium ion battery negative material of comparative example 2 and chemical property, detailed performance parameter sees the following form 1.The high rate performance test of the graphite negative material of lithium ion battery of embodiment 1 measures by this area conventional method, and it the results are shown in Figure 1.
The properties of sample parameter of table 1 embodiment 1 ~ 5 and comparative example 1,2
From table 1, the tap density of graphite negative material of lithium ion battery of the present invention is close with conventional negative material, discharge capacity can up to more than 340mAh/g first, and discharging efficiency is high first, compared with comparative example 2, its visit first capacitance and first discharging efficiency all improve a lot.
As seen from Figure 1, the good rate capability of graphite negative material of lithium ion battery of the present invention, 5C/0.2C capability retention is 97.7%, and graphite cathode material high rate performance is 80% at 5C/0.2C capability retention in prior art, therefore the high rate performance of graphite negative material of lithium ion battery of the present invention is better than existing graphite cathode material.