尖晶石锰酸锂的柠檬酸辅助溶胶-凝胶法合成及电化学表征

Synthesis and electrochemical characterizations of spinel LiMn_2O_4 by citric acid-assisted sol-gel method

以醋酸锰、氢氧化锂为原料,以柠檬酸为络合剂,n(柠檬酸):n(锂)=1:1,采用柠檬酸辅助溶胶-凝胶法制备了富锂尖晶石Li1+xMn2O4(x=0,0.02,0.05,0.07),采用TG-DTA、XRD、SEM分别对前驱体和目标材料进行了表征,采用恒流充放电及循环伏安(CV)测试对材料进行了电化学性能表征,考察了不同n(Li):n(Mn)对材料性能的影响。结果表明,材料的最佳烧结温度为750℃,前驱体经750℃煅烧可获得晶体结构完整和形貌规整的尖晶石型锰酸锂,最佳n(Li):n(Mn)=1.05:2,在0.5C和3.4～4.35V电压条件下,Li1.05Mn2O4的初始放电容量达到124.5mAh/g,90次循环后放电容量保持率达到92.5%。显示了良好的综合电化学性能。

The spinel Li1＋xMn2O4（x=0,0.02,0.05,0.07）cathode materials were prepared by a citric acid-assisted sol-gel method using LiOH and Mn（CH3COO）2 as raw materials and citric acid as the chelating agent,the molar ratio of citric acid to Li was 1∶1,and the precursors and resultant materials were characterized by TG-DTA,SEM and XRD,respectively.The electrochemical properties of the materials were investigated by galvanostatic charge and discharge and CV test.The influence of Li/Mn molar ratios on the electrochemical properties of Li1＋xMn2O4 cathode materials was examined.The results revealed that the optimal sintering temperature was 750 ℃,the well-defined pure cubic spinel phase can be obtained by calcining the precursor at 750 ℃.The optimal Li/Mn molar ratio was 1.05∶2,and the initial discharge capacity of Li1.05Mn2O4 was 124.5 mAh/g at 0.5C and 3.4~4.35V range,it remained 92.5% of the initial specific discharge capacity after 90 cycles.The Li1.05Mn2O4 displayed better electrochemical performance.