采用复合锂源制备的LiFePO4/C材料及其碳含量优化

采用Li_2CO_3与Li OH·H_2O为复合锂源制备LiFePO_4/C材料,同时优化了材料中的碳含量。由于氢氧化锂的熔点低于碳酸锂,在同样的烧结温度下,采用复合锂源可以获得更佳的熔融状态,在高温合成过程中使锂离子具有更高的扩散性,能够更顺利地得到高纯度的LiFePO_4晶相。通过优化碳包覆量达到提高导电性与控制晶粒尺寸的目的,使材料晶相结构完整,纯度高,表现出优秀的加工性能与电化学性能。所制得的LiFePO_4/C材料放电克容量达到158.2 m Ah·g~(-1),在全电池中经过100 d存储后容量保持率仍然高于94.0%,具有优异的长期可靠性。

Preparation by Employing Mixed Lithium Source and Carbon Content Optimization of LiFePO4/C Materials

The LiFePO₄/C composites have been successfully synthesized by adopted Li₂CO₃ and LiOH·H₂O as mixed lithium source, the carbon content of the as-prepared LiFePO₄/C materials have been optimized. Since the melting point of LiOH is lower than that of Li₂CO₃, adopt mixed lithium source can achieve better melting state at the same temperature, and favors the conductivity of lithium ions during the high temperature synthetic process to obtain pure LiFePO₄ structure. The carbon content of LiFePO₄/C composites were optimized to improve the electroconductivity and control the particle size. The LiFePO₄/C cathode displayed excellent crystal structure, processability and electrochemical performances. The discharge capacity of the as-obtained LiFePO₄/C composites is as high as 158.2 mAh·g^-1, after 100 days storage, the capacity retention of full cells is still maintained higher than 94.0%, representing the superior long-term reliability of the optimized LiFePO₄/C material.