氧化铝包覆量对锰酸锂正极材料电化学性能的影响

Effect on Electrochemical Performance of Different Ratio of Al₂O₃ Coating LiMn₂O₄ Cathode Material

摘要: 针对锰酸锂正极材料存在循环性能差的问题，以九水硝酸铝(Al(NO₃)₃∙9H₂O)和尖晶石锰酸锂(LiMn₂O₄)为原料，采用溶胶–凝胶法制备氧化铝包覆锰酸锂正极材料，研究氧化铝包覆量(氧化铝与锰酸锂的质量比)对锰酸锂正极材料的结构及其电化学性能的影响。采用XRD和SEM等手段研究合成材料的晶体结构和微观形貌；通过循环充放电测试和循环伏安法等方法研究其电化学性能。XRD和SEM结果表明：氧化铝的包覆并没有改变锰酸锂的晶体结构，只是包覆在锰酸锂的表面。电化学性能测试结果表明，当氧化铝包覆量为1.0%时，材料具有较好的循环性能，1 C条件下，循环200周容量保持率为96.96%，锰酸锂为52.78%。

Abstract: In order to improve the cycle performance of LiMn₂O₄ cathode materials, we synthesize Al₂O₃ coating LiMn₂O₄ cathode materials by sol-gel method using Al (NO₃)₃•9H₂O and LiMn₂O₄ as starting materials. Effects on structure and electrochemical performance of Al₂O₃ coating LiMn₂O₄ cathode materials at different ratio have been researched. The crystal structure and morphology of mate-rials were characterized using X-ray diffraction (XRD) and scanning electron microscope (SEM); And the electrochemical performance was tested by cyclic voltammetry and cycling experiment. XRD and SEM results show that the coating is only on the surface of LiMn₂O₄ and it does not affect crystal structure of LiMn₂O₄. Electrochemical tests show that 1% Al₂O₃coating sample has an excellent electrochemical performance; the capacity retention is 96.96% at 1 C rate after 200 cycles when capacity retention of the uncoated LiMn₂O₄ is 52.78%.