CN1920075A

CN1920075A - Method of preparing tin copper alloy material used for negative electrode of lithium ion battery

Info

Publication number: CN1920075A
Application number: CNA2006101130690A
Authority: CN
Inventors: 赵海雷; 贾喜娣; 郭洪; 仇卫华
Original assignee: University of Science and Technology Beijing USTB
Current assignee: University of Science and Technology Beijing USTB
Priority date: 2006-09-08
Filing date: 2006-09-08
Publication date: 2007-02-28

Abstract

The invention relates the method for preparing copper tin alloy material used for lithium battery negative pole. The method comprises the following steps: mixing the tin and copper oxide compounds according the rate of Sn and Cu, adding carbon powder as reducing agent, ball grinding the mixture at the argon gas or nitrogen, heating at the speed of 5-30Deg/min, keeping the temperature, then interrupting, and cooling. The method has the advantages of low cost and simple technology, and the product has homogeneous particles and good crystallinity, and the Sn-Cu lithium battery negative pole material has high specific capacity and stable circularity. The maximum reversible capacitance is 470mAh/g, and circulation volume retention for ten times is 96.6%.

Description

A kind of preparation method of tin copper alloy material used for negative electrode of lithium ion battery

Technical field

The invention belongs to technical field of lithium ion, be specifically related to a kind of preparation method of tin copper alloy material used for negative electrode of lithium ion battery.

Background technology

Since Sony company in 1991 releases chargeable secondary lithium battery, owing to compare with traditional plumbic acid, NI-G secondary cell, have operating voltage height, specific energy height, advantages such as operating temperature range is wide, discharge is steady, volume is little, light weight, memory-less effect, serondary lithium battery is developed rapidly.Having showed wide application prospect in fields such as portable electric appts, electromobile, space technology, national defense industry, is a kind of secondary cell with fastest developing speed after Ni/Cd and Ni/MH battery, that market outlook are the brightest.

Negative material has worldwide obtained extensive studies as the important factor that improves lithium ion battery energy and cycle life.The negative material of commercial use is a carbon class material, its lithium intercalation compound LiC ₆Theoretical capacity is 372mAh/g, 800mAh/cc, and the capacity of carbon current negative pole is very near its theoretical capacity, thereby it is very little further to develop the potentiality that improve its specific storage.Simultaneously, because it is very approaching with the current potential of metallic lithium to insert behind the lithium current potential of carbon dioxide process carbon electrode, carbon electrodes is easily separated out very active metallic lithium, and it and the easy generation of electrolytic solution reaction combustible gas mixture influence the security of battery.Therefore, the lithium ion battery negative material of research and development a new generations' height ratio capacity more positive slightly than lithium current potential becomes present material worker and electrochemist's major objective.

Nearest some studies show that some alloy cpd may become the new approaches of ion cathode material lithium research.Alloy have lot of advantages as: good processability, good conductivity, to the susceptibility of environment do not have carbon material obviously, have the fast charging and discharging ability, prevent the common insertion of solvent etc.The more important thing is with the carbon material in the lithium ion battery and compare that the alloy type negative material generally has higher specific storage, typical lithium alloy as Si, Ge, Sn, Pb, Al, Ga, Sb etc.Wherein the theoretical specific capacity of metallic tin is 994mAh/g, and antimony is 660mAh/g, and silicon is 4200mAh/g, far above the 372mAh/g of carbon.Alloy anode is compared with carbon material, and bigger advantage is being arranged aspect the specific discharge capacity especially volume and capacity ratio.But lithium embedding repeatedly deviates to cause alloy type negative pole volume change in charging and discharging process bigger, and easily efflorescence was lost efficacy gradually, thereby cyclicity is relatively poor.The way that addresses this problem mainly comprise 1. can with lithium bonded " activity " metal in introduce not and lithium bonded " nonactive " metal, 2. in reactive metal, introduce and lithium bonded " second metalloid " under different potentials.When Li took off embedding, inactive substance can cushion and disperse the mechanical stress brought owing to the active substance volume change, thereby makes alloy material have good cyclical stability; And " second metalloid " owing to be different from the reactive metal of parent phase with lithium bonded current potential, thereby can make the chemical combination proceed step by step of lithium and alloy, thus the volumetric expansion of buffering alloy material in the removal lithium embedded process, the cyclical stability of raising alloy electrode.The research of relevant this respect is both at home and abroad actively carried out, and in first kind alloy (activity/nonactive elements compounding), that has reported comprises SnCu, Sn/SnAg _x, Sn/SnNi and SnCo etc. shows better electrochemical performance.Wherein SnCu is the more a kind of alloy of research.

According to document K.D.Keple, J.T.Aughey, M.M.Thackeray.J.PowerSources, 1999, the report of 81-82:383～386, the copper powder, the glass putty that different chemical are measured ratio mix, be pressed into bead, 400 ℃ of thermal treatment 12h under argon gas atmosphere, the Cu that makes ₆Sn ₄Alloy, 20 times the round-robin reversible capacity remains on 200mAh/g.In addition, X.G.Wang, L.Sun, D.H.Bradhurst, et al.J.Alloys and compounds, 2000,299:L12～15 reports have prepared nanocrystalline Cu with high-energy ball milling method ₆Sn ₅Alloy, grain-size 5～10nm, loading capacity reaches 688mAh/g first, and 20 times the round-robin reversible capacity becomes 200mAh/g.Also can make the Sn-Cu alloy with liquid phase reduction, H.Kim, T.Kang.J Power Sources, 2002,104 (2): 221～225 with NaBH ₄Be reductive agent, from the aqueous solution, restored the Cu of nanometer ₆Sn ₅Alloy material, particle size are between 20～40nm, and 80 round-robin reversible capacities are more than 200mAh/g.S.D.Beattie, J.R.Dahn.J.Electrochemical Society, 2003,150 (7): A894～A898 has deposited the gunmetal of different ratios from single plating bath with the pulsed deposition method, when copper tin atom ratio is 3.183,40 round-robin reversible capacities are 200mA/g, and capability retention is 80%.

Report as can be known more than comprehensive that the SnCu alloy has higher specific storage and more stable cycle performance as negative material.The SnCu alloy adopts method preparations such as high-energy ball milling, liquid-phase reduction, galvanic deposit more.But high-energy ball milling method is easily introduced impurity, purity is low.And particle is inhomogeneous; Liquid-phase reduction and electrodip process experiment condition harshness, influence factor is a lot, complicated process of preparation, length consuming time, productive rate is low.Therefore, research and develop that a kind of cost is low, technological process is simple, productive rate is high, be convenient to the synthetic method of SnCu alloy material of cathode of large-scale production for promoting the practical application of SnCu alloy in lithium ion battery to have great importance.

Summary of the invention

The invention provides the preparation method of a kind of lithium ion battery, adopt carbothermic method, utilize the oxide compound of carbon dust, prepare the alloy material of cathode of different Sn/Cu ratios as reductive agent reduction tin and copper with the Sn-Cu alloy material of cathode.Not only cost is low for this method, preparation process is simple, and the uniform particles of synthetic Sn-Cu alloy powder is tiny, and degree of crystallinity is good, Sn-Cu lithium ion battery negative material specific storage height, the good cycling stability prepared.

The present invention utilizes the oxide compound of carbon dust as reductive agent reduction tin and copper, prepares the alloy material of cathode of different Sn/Cu ratios.Adopt the concrete technology of the synthetic Sn-Cu alloy material of cathode of high temperature solid-state chemical reduction technology to be:

With micron order, submicron order or nano level SnO ₂, CuO or Cu ₂O and gac or carbon black powder carry out weighing proportioning, SnO ₂, Cu ₂The add-on of O or CuO is pressed the atomic ratio 5 of Sn/Cu: 1-1: 5 calculate, and the add-on of gac or carbon black can be calculated by chemical formula (1) or (2) respectively, and is oxidized for preventing system, and the consumption of C can excessive 0～30% (atomic percent).

When being the Cu source with CuO:

(1)

Wherein, x, y are the mole number of related material, and its value y/x is Cu/Sn ratio in the synthetic Sn-Cu alloy product.

With Cu ₂When O is the Cu source:

(2)

Wherein, 2y/x is Cu/Sn ratio in the synthetic Sn-Cu alloy product.

Adopt mechanical dry method mixed or wet mixing that raw material is mixed; Mixture places the process furnace that is connected with flowing nitrogen or argon gas atmosphere, is raised to temperature required 800～1200 ℃ with the temperature rise rate of 2～30 ℃/min, is incubated 1～6 hour; Outage makes it cool to room temperature naturally with the furnace then.The ratio of stannic oxide and cupric oxide in the control starting raw material can effectively be controlled the ratio of element in the gained Sn-Cu alloy product.The mechanically mixing of described powder is that ball milling wet mixing or ball milling are dried mixed.

According to calculation of thermodynamics, the oxide compound of Sn and Cu can be reduced to metal simple-substance by C at (below 700 ℃) under the relatively low temperature.The fusing point of Sn is low to be 232 ℃, and the metal Sn that restores has higher activity, and easy and Cu alloying generates Sn-Cu alloy or the intermetallic compound with stabilization of bony shelf structure.The present invention adopts high temperature solid-state chemical reduction technology; utilize carbon dust as reductive agent; with stannic oxide, cupric oxide and carbon dust uniform mixing, place the sintering oven that is connected with under the protective atmosphere to calcine, be incubated that furnace cooling can obtain final product Sn-Cu alloy composite materials after 1-6 hour.

The invention has the advantages that raw materials cost is relatively low, technological process is simple, and is consuming time less, and the productive rate height is fit to scale operation.Synthesize Sn-Cu alloy degree of crystallinity height, be micron-sized spherical particle, thereby specific surface area is less, serious reunion and surface oxidation be difficult for to take place, thereby have reduced the irreversible capacity of negative material.

Description of drawings

Fig. 1 is the XRD figure of carbothermic reduction synthetic Sn-Cu powdered alloy of the present invention, and the atomic ratio of Sn/Cu is 1: 1, and synthesis temperature is 950 ℃.

Fig. 2 is the specific storage-cycle index curve of carbothermic reduction synthetic Sn-Cu alloy anode of the present invention, and the atomic ratio of Sn/Cu is 2: 1, and synthesis temperature is 950 ℃.

Embodiment

Embodiment 1:

With SnO ₂(purity＞99.9%), CuO (purity＞99.9%) and activated carbon (purity＞99%) are initial feed, prepared burden in 1: 1: 3 in molar ratio (atomic ratio that is equivalent to Sn:Cu is 1:1), after the mixture ball milling mixed, place that the temperature rise rate with 5 ℃/min is elevated to 800 ℃ under the mobile argon gas atmosphere, be incubated 2 hours, outage naturally cools to room temperature then.The XRD material phase analysis of gained sample shows that synthetic product is Sn/Sn ₅Cu ₆Alloy complex does not have the existence of any oxide impurity phase.

The conductive agent acetylene black that the synthetic material is added 10wt%, the binding agent PVDF of 10wt% makes slurry, evenly be applied on the Copper Foil, after the oven dry, block circular pole piece, form test cell, carry out the constant current charge-discharge experiment with metallic lithium, charging and discharging currents density is 100mA/g, and the charging/discharging voltage scope is controlled between the 0.01-1.2V.The maximum reversible capacity of Sn-Cu negative material of preparation is 470mAh/g, and the specific storage that circulates after 10 times is 454mAh/g, and capability retention is 96.6%.

Embodiment 2:

With SnO ₂(purity＞99.9%), CuO (purity＞99.9%) and activated carbon (purity＞99%) are initial feed, prepared burden in 2: 1: 5 in molar ratio (atomic ratio that is equivalent to Sn: Co is 2: 1), after the mixture ball milling mixed, place under the mobile argon gas atmosphere, temperature rise rate with 10 ℃/min is elevated to 950 ℃, be incubated 4 hours, outage naturally cools to room temperature then.The XRD material phase analysis of gained sample shows that synthetic product is Sn/Sn ₅Cu ₆Alloy complex does not have the existence of any oxide impurity phase.

The conductive agent acetylene black that the synthetic material is added 10wt%, the binding agent PVDF of 10wt% 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 metallic lithium, charging and discharging currents is 100mA/g, and the charging/discharging voltage scope is controlled between the 0.01-1.2V.The reversible capacity first of Sn-Cu alloy composite anode material of preparation is 348mAh/g, and the slotting lithium capacity that circulates after 10 times is 318mAh/g, and capability retention is 91.4%.

Claims

1, a kind of preparation method of tin copper alloy material used for negative electrode of lithium ion battery is characterized in that, the step of preparation is:

A, with SnO ₂, CuO or Cu ₂O and carbon dust carry out weighing proportioning, SnO ₂, CuO or Cu ₂The atomic ratio that the add-on of O is pressed Sn/Cu calculated in 5: 1～1: 5, and the add-on of carbon dust is calculated by chemical formula (1) or (2) respectively; Excessive 0～30 atom % of the consumption of C wherein;

When being the Cu source with CuO:

(1)

Wherein, x, y are the mole number of related material, and its value y/x is Cu/Sn ratio in the synthetic Sn-Cu alloy product;

With Cu ₂When O is the Cu source:

(2)

Wherein, 2y/x is Cu/Sn ratio in the synthetic Sn-Cu alloy product;

B, employing mechanical dry are mixed or the method for wet mixing mixes raw material; Mixture placed be connected with flowing nitrogen, argon gas or contain 5-10vol%H ₂The process furnace of argon gas atmosphere in, reach temperature required 800-1200 ℃ with 2-30 ℃/minute temperature rise rate, be incubated 1～6 hour;

C, with process furnace outage, cool to room temperature naturally with the furnace, obtain final product Sn-Cu alloy combination electrode material.

2, by the preparation method of the described tin copper alloy material used for negative electrode of lithium ion battery of claim 1, it is characterized in that the particle diameter of the oxide powder of described tin and copper is micron order, submicron order or nano level.

By the preparation method of the described tin copper alloy material used for negative electrode of lithium ion battery of claim 1, it is characterized in that 3, the mechanically mixing of described powder is that ball milling wet mixing or ball milling are dried mixed.

4, by the preparation method of the described tin copper alloy material used for negative electrode of lithium ion battery of claim 1, it is characterized in that described carbon dust is activated carbon or carbon black.