(中南大學(xué) 冶金科學(xué)與工程學(xué)院，長(zhǎng)沙 410083)
摘 要: 采用草酸鹽前驅(qū)體合成Ti4+、Mg2+摻雜正極材料Li(Nil/3Col/3−xMnl/3)MxO2(M=Ti, Mg)。利用XRD和SEM對(duì)其結(jié)構(gòu)和形貌進(jìn)行表征，并采用循環(huán)伏安、交流阻抗、恒流/恒壓充放電測(cè)試其電化學(xué)性能。結(jié)果表明：Ti4+、Mg2+摻雜后晶胞體積增大，大倍率充放電時(shí)LiNil/3Col/3Mnl/3O2的電化學(xué)反應(yīng)阻抗Rct降低，其大倍率充放電性能得到改善，Ti4+摻雜效果更好；當(dāng)摻雜量x＝0.025時(shí)，材料晶型完整，具有單一的a-NaFeO2層狀結(jié)構(gòu)；1C倍率時(shí)Li(Nil/3Col/3−0.025Mnl/3)Ti0.025O2的第二循環(huán)放電容量為143.2 mA∙h/g，2C時(shí)為128.0 mA∙h/g，經(jīng)100次循環(huán)后容量分別為132.5和115.8 mA∙h/g，容量保持率為92.53%和90.47%。
關(guān)鍵字: LiNi1/3Co1/3 Mn1/3O2；鋰離子電池；正極材料；電化學(xué)性能
（School of Metallurgical Science and Engineering, Central South University, Changsha 410083, China）
Abstract:Cathode materials of Li(Nil/3Col/3−xMnl/3)MxO2(M=Ti, Mg) were prepared from oxalate precursor. The structures and morphologies of the synthesized samples were characterized by XRD and SEM. The electrochemical performance were tested by cyclic volt-ampere (CV), AC impedance and constant current/constant voltage charge-discharge measurement. The results show that the crystal volume of sample increases with the doping of Ti4+ or Mg2+. The electrochemical reaction resistant Rct decreases at high rates, thus improving the high rate charge-discharge properties of the materials. The effect of Ti4+ doped is better than that of Mg2+ doped. The sample is well crystallized and simple pure phase with a-NaFeO2 layered structure when doping quantity x=0.025. The second specific discharge capacity of Li(Nil/3Col/3−0.025Mnl/3)Ti0.025O2 is 143.2 mA∙h/g at 1C, 128.0 mA∙h/g at 2C, and still remains 132.5 and 115.8 mA∙h/g after 100 cycles, respectively, keeping capacity of 92.53% and 90.47%.
Key words: LiNi1/3Co1/3Mn1/3O2; lithium-ion batteries; cathode materials; electrochemical performance
