储能科学与技术 ›› 2019, Vol. 8 ›› Issue (6): 1116-1125.doi: 10.12028/j.issn.2095-4239.2019.0083

• 研究开发 • 上一篇    下一篇

LiFePO4/S复合正极材料的制备及其电化学性能

朱蕾, 江小标, 贾荻, 颜廷房, 吴勇民, 汤卫平   

  1. 上海空间电源研究所空间电源技术国家重点实验室, 上海 200245
  • 收稿日期:2019-05-09 修回日期:2019-05-30 出版日期:2019-11-01 发布日期:2019-06-03
  • 通讯作者: 汤卫平,博士,研究员,主要研究方向为锂离子筛吸附剂及储能电池,E-mail:tangwp@sina.cn。
  • 作者简介:朱蕾(1992-),女,硕士,工程师,主要研究方向为锂离子电池正极材料及固态电池,E-mail:winterzlsi@163.com
  • 基金资助:
    国家重点研发项目计划资助项目(2018YFB0905400)。

Preparation and electrochemical performance of LiFePO4/S composite cathode materials

ZHU Lei, JIANG Xiaobiao, JIA Di, YAN Tingfang, WU Yongmin, TANG Weiping   

  1. State Key Laboratory of Space Power Technology, Shanghai Institute of Space Power-Sources, Shanghai 200245, China
  • Received:2019-05-09 Revised:2019-05-30 Online:2019-11-01 Published:2019-06-03

摘要: 以提高磷酸铁锂体系动力电池的能量密度为目的,在LiFePO4正极材料中加入少量S材料球磨制得LiFePO4/S复合正极材料。使用X射线衍射(XRD)和扫描电子显微镜(SEM)表征了结构和形貌,并分别组装扣式电池和软包电池测试其电化学性能。结果表明,磷酸铁锂纳米颗粒致密均匀附着在硫材料表面,构成具有包覆性结构的复合材料。在不同比例的LiFePO4/S复合材料中,硫的添加量为15%的LiFePO4/S复合正极材料表现出最优异的电化学性能,0.1 C下的初始容量为251.5mA·h/g,循环100周之后容量保持率达94.9%。以该比例的复合材料为正极的0.5A·h软包电池,循环100周后容量保持率为86.7%。LiFePO4作为一种极性载体,对多硫化物有一定的吸附能力,少量硫的加入可以在大幅度提高LiFePO4材料放电容量的同时,维持优异的循环稳定性。LiFePO4/S复合材料可为磷酸铁锂体系动力电池的发展提供新的思路。

关键词: 磷酸铁锂, 硫, 复合材料, 动力电池

Abstract: In order to improve the energy density of LiFePO4 power lithium ion batteries, a small amount of S was introduced to the LiFePO4 cathode materials to obtain the LiFePO4/S composite materials by a ball-milling method. The crystalline structure, morphology and electrochemical performance were characterized by X-ray diffraction, scanning electron microscopy and electrochemical tests by coin cells/pouch cells. The results showed that the sulfur particles were covered with nanosized LiFePO4 nanoparticles on the surface, which is analogous to the core-shell structure. The results of electrochemical tests of coin cells showed that the LiFePO4/S composite with 15% S content had the best electrochemical performance, which exhibited a reversible capacity up to 251.5 mA·h·g-1 at 0.1 C and an excellent long-term cycling stability with 94.9% capacity retention after 100 cycles. Moreover, 0.5A·h pouch cell with LiFePO4/S-85/15 composite as cathode LiFePO4 showed a capacity retention of 80.1% after 100 cycles. As a polar carrier, LiFePO4 has a certain adsorption for polysulfides. The addition of a small amount of sulfur can greatly improve the discharge capacity of LiFePO4 materials, while maintaining excellent cycling stability. The LiFePO4/S composites can provide a new strategy for the development of LiFePO4 power lithium ion batteries.

Key words: lithium iron phosphate, sulfur, composite materials, power lithium ion batteries

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