炭材料在低温型磷酸铁锂材料中的应用分析及展望

Application and prospects for using carbon materials to modify lithium iron phosphate materials used at low temperatures

  • 摘要: 磷酸铁锂为正极的锂离子电池是目前电动汽车和储能领域应用最为广泛的电池体系之一,具有成本低廉、循环寿命长、安全性好等特点。但磷酸铁锂为正极的锂离子电池在低温下的容量和循环寿命衰减问题一直制约了其在寒冷地区的推广和应用。因此磷酸铁锂材料本身低温放电性能的提高,对于改善磷酸铁锂为正极的锂离子电池体系的低温放电特性具有重要意义。本文首先分析了磷酸铁锂为正极的锂离子电池的低温衰减机制,从炭材料作用的角度评述了低温型磷酸铁锂材料的研究进展,同时也关注了高倍率型磷酸铁锂材料。因磷酸铁锂的高倍率性能与低温特性具有很大的相似之处,两者对材料的要求基本接近,材料的设计原则和方法也基本相同。本文也重点分析了纳米炭材料,如碳纳米管和石墨烯等在低温型磷酸铁锂材料领域的应用。

     

    Abstract: LiFePO4, one of the most widely used cathode materials in Li -ion batteries, has many excellent properties, such as low-cost, long life and excellent safety. Unfortunately, its poor performance at low temperature hinders its use in cold regions of the world. The incorporation of carbon materials, which also have excellent electronic and ionic conductivity, in LiFePO4 offers a promising way to solve this problem. We first briefly introduce the fade mechanism of LiFePO4 cells at low temperature, and the preparation methods, structure, and electrochemical performance of carbon-modified LiFePO4 materials are then summarized with a focus on carbon coatings, various carbon conductive fillers and nano-carbon modification. A combination of compositing the LiFePO4 with carbon, followed by carbon coating is a promising way of fabricating a material for use at low-temperatures. Besides conventional carbon black, other conductive additives such as graphene and carbon nanotubes also have great potential for use in LiFePO4 batteries at low temperatures. The problems encountered and the future development of these composites are also discussed.

     

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