CN100373664C

CN100373664C - Preparation method for high-capacity Sn-Ni alloy compound as lithium ion battery negative electrode material

Info

Publication number: CN100373664C
Application number: CNB2006100116183A
Authority: CN
Inventors: 赵海雷; 郭洪; 尹朝丽; 仇卫华; 贾喜娣
Original assignee: University of Science and Technology Beijing USTB
Current assignee: University of Science and Technology Beijing USTB
Priority date: 2006-04-07
Filing date: 2006-04-07
Publication date: 2008-03-05
Anticipated expiration: 2026-04-07
Also published as: CN1866587A

Abstract

The present invention provides a preparation method for a high capacity Sn-Ni alloy composite negative electrode material of a lithium ion battery, which belongs to the field of the lithium ion batteries. The present invention is characterized in that tin and nickel oxides are prepared in the proportion as those of the Sn and the Ni elements in the synthetic alloy composite, and then, carbon powders in appropriate proportion are introduced as reducing agents. Furthermore, after being mixed and ground to be uniform, the obtained mixture is positioned in the gas atmosphere of flowing inert argon gas while the temperature is raised to 800 DEG C to 1200 DEG C at a temperature raising rate of 5 to 30 DEG C/minute, and the temperature is kept constant for 1 to 6 hours. Moreover, a power supply is switched off, and the mixture is cooled by means of furnace cooling to room temperature. The method of the present invention has the advantages of low cost and simple preparation technology and process, the synthetic Sn-Ni alloy composite powders have the advantages of uniform and fine particles and favorable degree of crystallization, and the prepared Sn-Ni negative electrode material for the lithium ion battery has the advantages of high specific capacity and stable cycle performance. In addition, the highest reversible capacity can reach up to 389 mAh/g, and the specific capacity can still remain about 97.9% after 12 cycles.

Description

The preparation method of high-capacity Sn-Ni alloy compound as lithium ion battery negative electrode material

Technical field

The invention belongs to the lithium ion battery field, a kind of preparation method of high power capacity Sn-Ni alloy complex lithium ion battery negative material particularly is provided, adopt carbothermic method by preparation of metal oxides Sn-Ni alloy powder material, good as lithium ion battery negative material specific capacity height, cycle performance.

Background technology

Lithium ion battery is the latest generation rechargeable battery that has grown up behind the MH-Ni battery since the nineties, and it has the operating voltage height, energy density is big, fail safe good, light weight, self discharge are little, have extended cycle life, memory-less effect, advantage such as pollution-free.Be widely used in fields such as mobile phone, notebook computer, palmtop PC and military extraordinary electronic equipment at present, annual production, the output value increase very fast, become an emphasis of modern new energy development.

Present business-like lithium ion battery negative material adopts carbon class material mostly, but the lithium storage content that studies show that it 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), the space of further improving its specific capacity is very limited, especially is difficult to improve the material with carbon element volume and capacity ratio.In addition, material with carbon element is when the embedding lithium, and its electrode potential and lithium metal are close, and when battery overcharge, the easy precipitating metal lithium of carbon electrodes forms dendrite and causes short circuit, has a strong impact on the fail safe of battery.Therefore, exploitation specific capacity height, fail safe lithium ion battery negative material good, that cycle performance is good become present material worker and electrochemist's research focus.Many metals and semimetal (as: Al, Mg, Ga, In, Sn, Zn, Cd, Si, Ge, Pb, Sb, Bi, Au, Ag etc.) can form alloy with lithium, and their storage lithium amount is considerable, and wherein the theoretical specific capacity of metallic tin is 990mAh/g, far above the graphite-like negative material.But Li and single metal formation alloy Li _xDuring M, can be attended by very big volumetric expansion (2-3 doubly), this will cause electrode cycle performance variation, thereby hinder the practical application of alloy anode.Be the change in volume that suppresses or mitigation is followed in the removal lithium embedded process, usually take off the electrode matrix of embedding as Li with binary or multicomponent alloy, the research of activity/inactive metal alloy material becomes the focus of lithium ion battery negative material research in recent years, as SnCu, and Sn/SnAg _x, Sn/SnNi and nanometer-SnNi.Wherein one of metal mostly be that quality is softer, ductility inert matter preferably, variation to volume has stronger adaptability, when Li takes off embedding, can cushion the mechanical stress of bringing owing to the active material change in volume, thereby make alloy material have good cyclical stability, promptly prepare alloy or intermetallic compound base negative material.Sn base alloy is owing to its high lithium storage content (994mAh/g) receives people's very big concern, but it follows about 3 times change in volume in the removal lithium embedded process, and this will cause the destruction of electrode structure, thereby influence the cycle performance of electrode.Though metal Ni is not had an activity, the skeleton of toughness can be provided to alloy, can the efficient buffer electrochemical process in the mechanical swelling of system.Thereby Sn and Ni is compound, utilize the mutual supplement with each other's advantages principle, be expected to prepare specific capacity height, the good SnNi alloy material of cathode of cycle performance.Employing machine-alloyings such as the Shi Pengfei of Harbin Institute of Technology are prepared the SnNi alloy material of cathode, and initial capacity is 200mAh/g, circulate and decay to 50mAh/g following (Shu Jie, Cheng Xinqun, Shi Pengfei, battery, 2004,34 (4): 235-237) after 5 times.The Z.F.Ma of Shanghai Communications University etc. adopt liquid phase reduction, prepare the SnNi/CMS negative material, and initial capacity is 360mAh/g, circulating, capacity is 300mAh/g (X.Liao, Z.F.Ma, X.Yuan after 10 times, Electrochemistry Communications, 2003,5:657-661).The Dong Quanfeng of Xiamen University, Zhan Yading etc. control SnCl ₂And NiCl ₂The amount of substance ratio utilizes H ₂The synthetic crystalline state tin-nickel alloy of reduction at high temperature, circulation volume remain on 300mAh/g, and (gold is bright just etc., battery, 2005,35 (1): 3-5) for Dong Quanfeng, Zhan Yading.

To sum up, the method that alloy material of cathode adopts chemical liquid phase reduction, high-energy ball milling, electro-deposition or chemical heat to decompose more is prepared, thereby complicated process of preparation, length consuming time, and the cost height, productive rate is low.Thereby it is low to research and develop a kind of cost, is convenient to large-scale production, and the multicomponent alloy negative material of while electrochemical specific capacity height, good cycling stability is for promoting the practical application of alloy material in lithium ion battery to have great importance.

Summary of the invention

The objective of the invention is to: the preparation method that a kind of high power capacity Sn-Ni alloy complex lithium ion battery negative material is provided, realized that cost is low, preparation process is simple, the uniform particles of synthetic Sn-Ni alloy powder is tiny, degree of crystallinity is good, Sn-Ni lithium ion battery negative material specific capacity height, the good cycling stability prepared.

The present invention adopts carbothermic method, utilizes the oxide of carbon dust as reducing agent reduction tin and nickel, prepares the alloy material of cathode of different Sn-Ni ratios.Concrete technology is:

With micron order, submicron order or nanoscale SnO ₂, NiO and active carbon or carbon black powder carry out weighing proportioning, SnO ₂, the addition of the NiO atomic ratio 3: 1～1: 3 of pressing Sn/Ni calculates, the addition of active carbon or carbon black is calculated by chemical formula (1), considers the oxygen that may exist in the atmosphere, the consumption of C can excessive 5～30 atom %

xSnO ₂+yNiO+(2x+y)C＝Sn _xNi _y+(2x+y)CO (1)

Adopt mechanical dry method mixed or wet mixing that raw material is mixed; Mixture places the heating furnace that is connected with flowing nitrogen or argon gas atmosphere, reaches temperature required 800～1200 ℃ with 5～30 ℃/minute heating rates, is incubated 1～6 hour; Outage cools to room temperature naturally with the furnace then.The ratio of tin oxide and nickel oxide in the control initiation material can effectively be controlled the ratio of element in the gained Sn-Ni alloy product.

According to calculation of thermodynamics, the oxide of tin and nickel (500～700 ℃) under relatively low temperature can be reduced to metal Sn, Ni by C.The fusing point of Sn is low to be 232 ℃, and the metal Sn that restores has higher activity, and easy and Ni alloying generates Sn-Ni alloy or the intermetallic compound with stabilization of bony shelf structure.Simultaneously, Sn can close with lithiumation, and shows higher lithium storage content, and Ni is non-active element with respect to lithium, in the removal lithium embedded process of whole alloys, and the various change in volume of Ni in can buffer electrode, thus improve the structural stability of electrode material.The present invention adopts the carbon thermal reduction technology; utilize carbon dust as reducing agent; tin oxide, nickel oxide and carbon dust are evenly mixed, place the high temperature furnace that is connected with under the protective atmosphere to calcine, be incubated after 1-6 hour and can obtain end product Sn-Ni alloy composite materials with the stove cooling.

The invention has the advantages that: technical process is simple, and is consuming time less, the productive rate height.Synthesize Sn-Ni alloy degree of crystallinity height, be 3～100 microns polycrystalline particle, thereby specific area is lower, serious reunion and surface oxidation be difficult for to take place, thereby have reduced the irreversible capacity of negative material.Simultaneously, there is inactive buffering phase in the tactic pattern of bianry alloy, has cushioned the change in volume of material in the removal lithium embedded process, thereby has improved the cyclical stability of material.Sn-Ni lithium ion battery negative material specific capacity height, the stable cycle performance prepared, reversible capacity is up to 389mAh/g, and specific capacity remains on about 97.9% after 12 circulations.

Description of drawings

Fig. 1 is the XRD figure of the synthetic SnNi of carbon thermal reduction of the present invention, and the atomic ratio of Sn, Ni is 3: 1, and synthesis temperature is 900 ℃.

Fig. 2 is specific capacity-cycle-index curve of the synthetic SnNi of carbon thermal reduction of the present invention, and the atomic ratio of Sn, Ni is 3: 1, and synthesis temperature is 900 ℃.

Embodiment

Embodiment 1:

With SnO ₂(purity〉99.9%), NiO (purity〉99.9%) and activated carbon (purity〉99%) be initial feed, prepared burden in 3: 1: 7.5 in molar ratio (be equivalent to Sn: the Ni atomic ratio is 3: 1), after grinding mixture evenly, place that the heating rate with 5 ℃/min is elevated to 900 ℃ 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 Sn/Ni ₃Sn ₂/ Ni ₃Sn ₄Alloy complex does not have the existence of any oxide impurity phase.

The conductive agent acetylene black that 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 lithium metal, charging and discharging currents is 100mA/g, and the charging/discharging voltage scope is controlled between the 0.01-1.2V.The maximum reversible capacity of Sn-Ni negative material of preparation is 389mAh/g, and the specific capacity that circulates after 12 times is 381mAh/g, and capability retention is 97.9%.

Embodiment 2:

With SnO ₂(purity〉99.9%), NiO (purity〉99.9%) and activated carbon (purity〉99%) be initial feed, prepared burden in 2: 1: 5.3 in molar ratio (atomic ratio that is equivalent to Sn: Ni is 2: 1), after grinding mixture evenly, place under the mobile argon gas atmosphere, heating rate with 10 ℃/min is elevated to 1000 ℃, be incubated 1 hour, outage naturally cools to room temperature then.The XRD material phase analysis of gained sample shows that synthetic product is Ni/Ni ₃Sn ₂/ Ni ₃Sn ₄Alloy complex does not have the existence of any oxide impurity phase.

The conductive agent acetylene black that synthetic material is added 13wt%, the binding agent PVDF of 12wt% 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 maximum reversible capacity of the Sn-Ni alloy composite anode material of preparation is 226mAh/g.The specific capacity that circulates after 15 times is 213mAh/g, and capability retention is 94%.

Claims

1. the preparation method of a high power capacity Sn-Ni alloy complex lithium ion battery negative material adopts carbothermic method, utilizes carbon dust as reducing agent, the oxide of reduction tin and nickel, the alloy complex negative material of preparation different proportion; Technology is:

A, with SnO ₂, NiO and carbon dust carry out weighing proportioning, SnO ₂, NiO addition press the atomic ratio 3 of Sn/Ni: 1-1: 3 calculate, and the addition of carbon dust is pressed chemical formula xSnO ₂+ yNiO+ (2x+y) C=Sn _xNi _y+ (2x+y) CO calculates, and mix; Wherein excessive 5～30 atom % of the consumption of C are as reduction protection;

B, employing mechanical dry are mixed or the method for wet mixing mixes raw material; Mixture places the heating furnace that is connected with flowing nitrogen or argon gas atmosphere, is heated to 800～1200 ℃ with 5～30 ℃/minute heating rates, is incubated 1～6 hour; Outage cools to room temperature naturally with the furnace then, obtains end product Sn-Ni alloy combination electrode material.

2. it is characterized in that in accordance with the method for claim 1: SnO ₂With purity＞99.9% of NiO, purity＞99% of carbon dust; SnO ₂, the NiO granularity is micron order, submicron order or nanoscale.