物理化学学报 >> 2015, Vol. 31 >> Issue (8): 1513-1520.doi: 10.3866/PKU.WHXB201506082

电化学和新能源 上一篇    下一篇

三元掺杂改性锂离子电池正极材料Li3V2(PO4)3

孙孝飞1,2,*(),徐友龙1,2,郑晓玉1,2,孟祥飞1,2,丁朋1,2,3,任航1,2,李龙1,2   

  1. 1 西安交通大学电子陶瓷与器件教育部重点实验室,西安710049
    2 西安交通大学国际电介质研究中心,西安710049
    3 武汉军械士官学校电源教研室,武汉430075
  • 收稿日期:2015-02-03 发布日期:2015-08-12
  • 通讯作者: 孙孝飞 E-mail:xfsunxjtu@mail.xjtu.edu.cn
  • 基金资助:
    国家自然科学基金(21343011);陕西省自然科学基金(2014JQ2-2007);111引智计划(B14040);中央高校基本科研业务费专项资金(xjj2014044)

Triple-Cation-Doped Li3V2(PO4)3 Cathode Material for Lithium Ion Batteries

Xiao-Fei. SUN1,2,*(),You-Long. XU1,2,Xiao-Yu. ZHENG1,2,Xiang-Fei. MENG1,2,Peng. DING1,2,3,Hang. REN1,2,Long. LI1,2   

  1. 1 Electronic Materials Research Laboratory, Key Laboratory of the Ministry of Education, Xi'an Jiaotong University, Xi'an 710049, P. R. China
    2 International Center for Dielectric Research, Xi'an Jiaotong University, Xi'an 710049, P. R. China
    3 Staff Room of Power, Wuhan Ordnance Non-Commissioned Officer Academy, Wuhan 430075, P. R. China
  • Received:2015-02-03 Published:2015-08-12
  • Contact: Xiao-Fei. SUN E-mail:xfsunxjtu@mail.xjtu.edu.cn
  • Supported by:
    the Natural Science Foundation of China(21343011);Natural Science Foundation of Shaanxi Province, China(2014JQ2-2007);111 Project(B14040);Fundamental Research Funds for the Central Universities of China(xjj2014044)

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摘要：

以柠檬酸为螯合剂和还原剂, NH4VO3为钒源,通过溶胶-凝胶法制备了锂离子电池正极材料Li3V2(PO4)3及其三元掺杂体系Li2.85Na0.15V1.9Al0.1(PO4)2.9F0.1.分别采用X射线衍射(XRD)、高分辨透射电子显微镜(HRTEM)、能量损失谱(EELS)、拉曼(Raman)光谱、扫描电子显微镜(SEM)、X射线能谱(EDS)、恒流充放电、循环伏安(CV)和交流阻抗谱(EIS)等技术对材料的微观结构、颗粒形貌和电化学性能进行分析.结果表明:在残余碳包覆的基础上, Na、Al、F三元掺杂有利于稳定Li3V2(PO4)3的晶体结构,进一步减少颗粒团聚和提升材料导电特性,促进第三个锂离子的脱出和嵌入,从而显著改善Li3V2(PO4)3的实用电化学性能.未经掺杂的Li3V2(PO4)3原粉在1/9C、1C和6C倍率下的可逆比容量分别为141、119和98 mAh·g-1,而三元掺杂改性材料在1/9C、1C、8C和14C倍率下的比容量分别为172、139、119和115 mAh·g-1.在1C倍率下循环300圈后,掺杂体系的比容量依然高达118 mAh·g-1,比原粉高出32.6%.值得注意的是,这种三元掺杂还使Li3V2(PO4)3的多平台放电曲线近似转变为一条斜线,显示出可能不同的储锂机制.

关键词: 磷酸钒锂, 掺杂, 溶胶-凝胶, 正极材料, 锂离子电池, 能量存储

Abstract:

Li3V2(PO4)3 and its triple-cation-doped counterpart Li2.85Na0.15V1.9Al0.1(PO4)2.9F0.1 were prepared by a conventional sol-gel method. The effect of Na-Al-F co-doping on the physicochemical properties, especially the electrochemical performance of Li3V2(PO4)3, were investigated by X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), electron energy loss spectroscopy (EELS), Raman spectroscopy, scanning electron microscopy (SEM), X-ray energy dispersive spectroscopy (EDS), galvanostatic charge/discharge, cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS). It was found that combined with surface coating from residual carbon, this triple-cation co-doping stabilizes the crystalline structure of Li3V2(PO4)3, suppresses secondary particle agglomeration, and improves the electric conductivity. Moreover, reversible deinsertion/insertion of the third lithium ion at deeper charge/discharge is enabled by such doping. As a consequence, the practical electrochemical performance of Li3V2(PO4)3 is significantly improved. The specific capacity of the doped material at a low rate of 1/9C is 172 mAh·g-1 and it maintains 115 mAh·g-1 at a rate of 14C, while the specific capacities of the undoped sample at 1/9C and 6C are only 141 and 98 mAh·g-1, respectively. After 300 cycles at 1C rate, the doped material has a capacity of 118 mAh·g-1, which is 32.6% higher than that of the undoped counterpart. It is also noteworthy that the multiplateau discharge curve of Li3V2(PO4)3 transforms to a slope-like curve, indicating the possibility of a different lithium intercalation mechanism after this co-doping.

Key words: Lithium vanadium phosphate, Doping, Sol-gel, Cathode material, Lithiumion battery, E nergy storage