CN1301560C

CN1301560C - Method of preparing Sn-Sb alloy material for negative electrode of lithium ion cell

Info

Publication number: CN1301560C
Application number: CNB2005100116831A
Authority: CN
Inventors: 赵海雷; 尹朝丽; 吴恒亮; 仇卫华
Original assignee: University of Science and Technology Beijing USTB
Current assignee: University of Science and Technology Beijing USTB
Priority date: 2005-05-08
Filing date: 2005-05-08
Publication date: 2007-02-21
Anticipated expiration: 2025-05-08
Also published as: CN1688044A

Abstract

The present invention provides a method using a carbon thermal reduction method for preparing the Sn-Sb alloy cathode material of a lithium ion battery, which belongs to the field of lithium ion batteries. The present invention is characterized in that the oxide of tin and stibium is matched according to the proportion of the Sn and the Sb in the generated alloy compound, and then the carbon powder of proper proportion is introduced to be used as a reducing agent. After the obtained mixture is uniformly mixed and ground, the mixture is placed into a flowing nitrogen gas or argon gas atmosphere to obtain different required temperatures at the temperature increasing rate from 5 to 30 DEG C per minute. After a certain heat insulation time, the power is cut off, and the mixture is cooled to the room temperature with a furnace. The present invention has the advantages that compared with other methods of liquid phase chemical reduction, powder metallurgy, etc., the method has low cost and simple preparing technical process, the synthesized Sn-Sb alloy powder has uniform and fine granules and good crystallinity, the prepared Sn-Sb cathode material of a lithium ion battery has high specific capacity and stable circulating performance, the highest reversible capacity can be 730 mAh/g, and the capacitance is still higher than 90% after ten times of circulation.

Description

A kind of preparation method of Sn-Sb alloy material for negative electrode of lithium ion cell

Technical field

The invention belongs to the lithium ion battery field, particularly a kind of technology of preparing that is used for the SnSb alloy material of lithium ion battery negative.

Background technology

The fast development of portable electric appts increases day by day to the demand of secondary cell, and the performance to secondary cell has also proposed more and more higher requirement simultaneously.Lithium ion battery has been exactly since the nineties latest generation rechargeable battery behind the MH-Ni battery.It has operating voltage height, energy density big, have extended cycle life, advantages such as self discharge is little, memory-less effect, it is used and has been penetrated into leading-edge fields such as space flight, military affairs at present.

Present business-like lithium ion battery negative material adopts carbon class material mostly, though the chemical property excellence of this material, its lithium storage content is lower.Its actual specific capacity is at present very near its theoretical specific capacity (the theory storage lithium amount as graphite is 372mAh/g), further to improve the potentiality of its specific capacity very little in exploitation, thereby be difficult to adapt to the widespread demand of the development of the miniaturization development of present various portable electric appts and electric automobile to the large-capacity high-power chemical power source.Therefore, research and develop the research focus that the new type lithium ion battery negative material with height ratio capacity becomes present material worker and electrochemist.

Many metals and semimetal (as: Al, Mg, Ga, In, Sn, Zn, Cd, Si, Ge, Pb, Sb, Bi, Au, Ag, Pt etc.) can form alloy with lithium, and their storage lithium amount is considerable, is far longer than the graphite-like negative material.But in the charge and discharge process of battery, the reversible generation of lithium metal (Li-M) alloy is accompanied by huge change in volume (2-3 doubly) with decomposition, easily cause the division (producing crack and efflorescence) of alloy, influence the cycle performance of electrode, hindered the practical application of alloy anode.The change in volume that inhibition or mitigation are followed in the removal lithium embedded process, a kind of feasible method can close with lithiumation introduce in " activity " metal not " nonactive " metal that closes with lithiumation or with lithium " second metalloid " of chemical combination under different potentials, this material will play buffering stress, prevent the effect of electrode efflorescence and chemical property deterioration, promptly prepare alloy or intermetallic compound base negative material.In the alloy anode of being studied, the most noticeable is Sn base alloy.Wherein, SnSb is the good alloy anode candidate material of a class, from M.Wachtler, and M.Winter, J.O.Bessenhard, J.Power Sources, 2002, as can be known, because Sn, Sb all can close (Sn → Li with lithiumation in the 105:151-160 report ₂₂Sn ₅: 994mAh/g, Sb → Li ₃Sb:660mAh/g), thus it have higher specific capacity; Simultaneously, according to document M.Winter and J.O.Besenhard, Electrochimica Acta, 1999, the report of 45:31-50 is because active Sn, the embedding lithium current potential difference of Sb, the volumetric expansion of material will occur under the different current potentials, thereby can alleviate the internal stress of bringing thus, improve the cyclical stability of material.

At present, the SnSb alloy composite materials that document is reported mainly adopts the preparation of liquid phase chemical reduction method, is to contain reducing agent NaBH as patent JP2000012014 ₄Alkaline solution with contain complexing agent and metal ion solution is mixed, reaction obtains the SnSb composite precipitation, the filtration washing vacuum drying obtains product repeatedly then.The synthetic particle size of this method can reach nanoscale, and homogeneity is fine, but the product surface area is big, easily takes place to reunite and surface oxidation, cause irreversible capacity to increase, and cost of material is higher, complex technical process, and productive rate is lower.Document J.O.Bensenhard, J.Yang, M.Winter.J.Power Sources.1997, the electrodeposition process of 68:87 record prepares alloy anode, be under certain condition, several metals are deposited simultaneously and make alloy powder, for example Fe-Ni, Fe-Cr, Sn-Sb etc.The metal dust purity of this method preparation is higher, but needs effectively control to influence the experiment condition and the technological parameter of complicated factors such as composition, granularity, apparent pattern in the preparation, and technical process is comparatively complicated.Also has document J.O.Besenhard in addition, M.Wachtler, M.Winter, R.Andreaus, I.Rom, W.Sitte.J Power Sources 1999, the solid sintering technology of introducing among the 81-82:268-272 (powder metallurgic method), be that high-purity Sn, Sb powder is even, be sealed in the quartz ampoule of vacuum that substep is calcined and formed under different temperatures.This method process conditions harshness, the cost height, productive rate is low.Thereby study that a kind of cost is low, technology is simple, the synthetic method of the SnSb alloy of being convenient to large-scale production is for promoting the practical application of SnSb alloy in lithium ion battery to have crucial meaning.

Summary of the invention

The invention provides a kind of preparation method of lithium ion battery SnSb alloy material of cathode, adopt carbothermic method, utilize the oxide of carbon dust, prepare the alloy material of cathode of different Sn/Sb ratios as reducing agent reduction tin and antimony.Not only cost is low for this method, preparation process is simple, and the uniform particles of synthetic SnSb alloy powder is tiny, and degree of crystallinity is good, SnSb lithium ion battery negative material specific capacity height, the stable cycle performance prepared.

The present invention adopts the concrete technology of the synthetic SnSb alloy material of cathode of high temeperature chemistry reduction technique to be:

With micron order, submicron order or nanoscale SnO ₂, Sb ₂O ₃Carry out weighing proportioning, SnO with active carbon or carbon black powder ₂, Sb ₂O ₃The addition atomic ratio 3: 1～1: 3 of pressing Sn/Sb calculate, the addition of active carbon or carbon black is calculated by chemical formula (1),

(1)

Adopt mechanical dry method mixed or wet mixing that it is mixed; Mixture places and is connected with flowing nitrogen, argon gas or contains 5～10vol%H ₂The heating furnace of argon gas atmosphere in, reach temperature required 700-1100 ℃ with the heating rate of 5～30 ℃/min, be incubated 1-5 hour; Outage cools to room temperature naturally with the furnace then.SnO in the control initiation material ₂And Sb ₂O ₃Ratio, can effectively control the ratio of Sn/Sb in the gained SnSb product.

According to calculation of thermodynamics, the oxide of tin and antimony (650-450 ℃) under relatively low temperature can be reduced to metal by C, again because the fusing point of Sn, Sb is lower: be respectively 232 ℃ and 631 ℃, the metal Sn that restores, Sb have higher activity, are easy to mutual alloying and generate SnSb alloy or intermetallic compound.The present invention utilizes the oxide of carbon dust as reducing agent reduction tin and antimony owing to adopt the high temeperature chemistry reduction technique, therefore, only needs raw material is evenly mixed, and the sintering cooling can obtain end product SnSb alloy composite materials under protective atmosphere.

Compare with the liquid phase chemical reduction method of more use, this method cost of material is relatively low, and preparation process has been saved sedimentary filtration washing repeatedly and drying course, so technology is quite simple, and is consuming time less, the productive rate height.Synthesize SnSb alloy degree of crystallinity height, be the micron polycrystalline particle, thereby specific area is not too large, serious reunion and surface oxidation be difficult for to take place, thereby have reduced the irreversible capacity of negative material, improved the cyclical stability of material simultaneously.With the direct solid-phase sintering reacting phase ratio of Sn, Sb metal dust, synthesize the more tiny homogeneous of particle size of SnSb alloy powder.

Description of drawings

Fig. 1 is the XRD figure of the synthetic SnSb of carbon thermal reduction of the present invention, SnO ₂With Sb ₂O ₃Ratio be 2: 1, firing temperature is 850 ℃.

Fig. 2 is specific capacity-cycle-index curve of the synthetic SnSb of carbon thermal reduction of the present invention, SnO ₂With Sb ₂O ₃Ratio be 2: 1, firing temperature is 850 ℃.

Embodiment

Embodiment 1:

With SnO ₂(purity 99.9%), Sb ₂O ₃(99.9%) and activated carbon (purity＞99%) be initial feed, prepared burden in 2: 1: 7 in molar ratio, with mixture after ball milling wet mixing evenly, place that the heating rate with 5 ℃/min is elevated to 850 ℃ under the mobile argon gas atmosphere, be incubated 2 hours, outage naturally cools to room temperature then.The XRD material phase analysis result of gained sample shows that synthetic product is a single S nSb phase, the existence of no any other impurity phase.

The conductive agent acetylene black that synthetic material is added 10wt%, the binding agent PVDF of 8wt% makes slurry, evenly be applied on the copper platinum, after the oven dry, block circular pole piece, form test cell, carry out the constant current charge-discharge experiment with lithium metal, charging and discharging currents is 50mA/g, and the charging/discharging voltage scope is controlled between the 0.01-1.2V.The initial reversible capacity of SnSb negative material of preparation is 700mAh/g, and the specific capacity that circulates after ten times is 630mAh/g, and capacity remains on 90%.

Embodiment 2:

With SnO ₂(purity 99.9%), Sb ₂O ₃(99.9%) and carbon dust (purity＞99%) be initial feed, reactant was prepared burden in 4: 1: 11 in molar ratio, with mixture through ball milling dried be mixed even after, place that the heating rate with 20 ℃/min is elevated to 900 ℃ under the mobile argon gas atmosphere, be incubated 3 hours, outage naturally cools to room temperature then.The XRD material phase analysis surface of gained sample, synthetic product is SnSb and Sn two-phase, does not have other impurity and exists mutually.

The conductive agent acetylene black that synthetic material is added 12wt%, the binding agent PVDF of 8wt% makes slurry, evenly be applied on the copper platinum, after the oven dry, block circular pole piece, form test cell, carry out the constant current charge-discharge experiment with lithium metal, charging and discharging currents is 100mA/g, and the charging/discharging voltage scope is controlled between the 0.01-1.2V.The initial reversible capacity of the SnSb alloy material of cathode of preparation is more than the 730mAh/g.

Claims

1, a kind of preparation method of Sn-Sb alloy material for negative electrode of lithium ion cell is characterized in that, the step of preparation is:

1) with SnO ₂, Sb ₂O ₃Carry out weighing proportioning, SnO with carbon dust ₂, Sb ₂O ₃The addition atomic ratio 3: 1～1: 3 of pressing Sn/Sb calculate, the addition of carbon dust is calculated by chemical formula (1), and mixes;

(1)

2) mixture is placed be connected with flowing nitrogen, argon gas or contain 5～10vol%H ₂The heating furnace of argon gas atmosphere in, reach temperature required 700-1100 ℃ with the heating rate of 5～30 ℃/min, be incubated 1-5 hour;

3) with the heating furnace outage, cool to room temperature naturally with the furnace.

2, by the preparation method of the described Sn-Sb alloy material for negative electrode of lithium ion cell of claim 1, it is characterized in that the particle diameter of the oxide powder of described tin and antimony is micron order, submicron order or nanoscale.

By the preparation method of the described Sn-Sb alloy material for negative electrode of lithium ion cell of claim 1, it is characterized in that 3, described mixing is adopted wet mixing or done and mix.

4, by the preparation method of the described Sn-Sb alloy material for negative electrode of lithium ion cell of claim 1, it is characterized in that described carbon dust is activated carbon or carbon black.