Li_(1.02)Mn_(1.92)Al_(0.02)Cr_(0.02)Mg_(0.02)O_(4-x)F_x尖晶石正极材料的研究

采用溶胶-凝胶法合成了复合离子掺杂的尖晶石型锰酸锂Li1.02Mn1.92Al0.02Cr0.02Mg0.02O4-xFx(x=0,0.06)正极材料,并用XRD、CV、EIS和充放电测试等研究了其结构和电化学性能。结果表明,F与金属离子(Li、Al、Cr、Mg)的复合掺杂不仅提高了材料的比容量,还增加了尖晶石结构的稳定性,改善了材料的循环性能和可逆性能;充放电测试结果表明,Li1.02Mn1.92Al0.02Cr0.02Mg0.02O3.94F0.06具有优越的循环性能,常温下,以1/3C充放电的首次放电容量及50个循环后的容量保持率分别为117.9 mAh/g,96.9%。

An investigation of the spinel materials Li1.02 Mn1.92 Al0.02 Cr0.02 Mg0.02 O4-xFx

To improve the cycle performance of spinel LiMn2O4 as the cathode of 4-V-class lithium secondary batteries,spinel phases Li1.02Mn1.92Al0.02Cr0.02Mg0.02O4-xFx(x=0,0.06) have been successfully prepared through so-gel method.The structure and physicochemical properties of this as-prepared powder were investigated by powder X-ray diffraction(XRD),electrochemical impedance spectroscopy(EIS),and galvanostatic charge-discharge test in detail.Results showed that the specific capacity of the material was increased,the stability of spinel structure and cycle performance were improved by F,Li,Al,Cr and Mg multiplex doping.The charge-discharge tests revealed that Li1.02Mn1.92Al0.02Cr0.02Mg0.02O3.94F0.06 has the best cycling performance.At 1/3C rate and 25 ℃,its first specific discharge capacity was 117.9 mAh/g and the capacity retention ratio was 96.9% after 50 cycles.