共沉淀法合成Li1-2xNixFePO4正极材料的研究  

Study on Li_(1-2x)Ni_xFePO_4 Synthesized by Co-precipitation Method

作　　者：成定波[1] 习小明[2] 李运姣[1] 邱文顺[1] 陈盼盼[1] 

机构地区：[1]中南大学冶金科学与工程学院,湖南长沙410083 [2]长沙矿冶研究院,湖南长沙410012

出　　处：《矿冶工程》2008年第4期91-93,97,共4页Mining and Metallurgical Engineering

基　　金：国家自然科学基金(50474048);教育部新世纪优秀人才支持计划资助

摘　　要：利用共沉淀法合成了Ni2+掺杂量x=0.00,0.005,0.01和0.03的Li1-2xNixFePO4。通过对合成材料的XRD、元素组成及其电化学性能研究表明,少量Ni2+的掺杂并未影响材料晶体结构,但对材料的电化学性能却有着非常积极的影响:0.1C放电时,掺杂量x=0.01样品的首次放电比容量可达143.2mA.h/g,20次循环后放电比容量为131.2mA.h/g,容量衰减仅为8.4%。分别从荷锂状态(Li1-2xNixFePO4)和缺锂状态(FePO4)两方面对Ni2+掺杂改性的原理进行了简单的探讨:材料处于荷锂状态时,Ni2+掺入形成的锂空位与镍取代有利于提高锂离子于晶体中的扩散速率以及材料的电子导电能力;材料处于缺锂状态时,Ni2+掺入使得材料形成了Fe2+/Fe3+共存的状态,从而提高了其电子导电能力。The cathode material of Li1-2xNixFePO4 （ with Ni^2＋ doping amount x = 0,0.005,0.01,0.03 ） was synthesized by co-precipitation method. The results of XRD, elemental composition and electrochemical performance analyses indicated that a little of Ni^2＋ doped had no influence on the crystal structure but a positive influence on the electrochemical performance of LiFePO4. At the discharge percentage of 0.1 C, the first discharge specific capacity of the sample （with x =0.01 ） was 143.2 mA · h/g, which reduced to 131.2 mA · h/g after recharging/discharging 20 times, with a capacity fading rate of only 8.4%. The mechanism of modifying LiFePO4 by Ni^2＋ doping was discussed in terms of two conditions ： with lithium（Li1-2xNixFePO4） and without lithium（ FePO4 ）. When the material is in the first condition, the replacement of lithium vacancy by nickel resulted from Ni^2＋ doping is useful for enhancing lithium diffusion speed in the crystal and the electron conductivity of the material. When in the second condition, Ni^2＋ doping makes coexistence of Fe^2＋/Fe^3＋ formed in the material and the electron conductivity improved.

关 键 词：锂离子电池 正极材料 LIFEPO4 共沉淀 NI^2+ 掺杂 

分 类 号：TM912[电气工程—电力电子与电力传动]