(中南大學(xué) 冶金科學(xué)與工程學(xué)院，長(zhǎng)沙 410083)
摘 要: 以乙酸鹽為原料，采用噴霧干燥法制備層狀α-NaFeO2結(jié)構(gòu)的富鋰正極材料Li[Li0.2Ni0.2Mn0.6]O2及摻雜Cr的Li[Li0.2Ni0.15Cr0.1Mn0.55]O2。采用X射線衍射、掃描電鏡、半電池充放電和電化學(xué)阻抗譜等方法研究材料的物相、結(jié)構(gòu)、形貌及電化學(xué)性能。結(jié)果表明：Cr摻雜使材料的顆粒變粗，但不改變材料的結(jié)構(gòu)，而使材料的層狀特征更為明顯；Cr摻雜后材料的電化學(xué)性能得到明顯改善，電荷轉(zhuǎn)移阻抗Rct從275.0 Ω降低到105.0 Ω，循環(huán)穩(wěn)定性和倍率性能均有所改善，Li[Li0.2Ni0.15Cr0.1Mn0.55]O2材料1C倍率下的放電比容量為140.0 mA?h/g，循環(huán)50次后放電比容量為133.7 mA?h/g，遠(yuǎn)高于未摻雜Cr材料的比容量，未摻雜Cr材料在1C倍率下放電比容量為107.1 mA?h/g，循環(huán)50次后放電比容量為102.1 mA?h/g。
關(guān)鍵字: 富鋰正極材料；Li[Li0.2Ni0.2Mn0.6]O2；噴霧干燥；Cr摻雜；鋰離子電池
（School of Metallurgical Science and Engineering, Central South University, Changsha 410083, China）
Abstract:Layered Li-rich cathode Li[Li0.2Ni0.2Mn0.6]O2 and Li[Li0.2Ni0.15Cr0.1Mn0.55]O2 materials with α-NaFeO2 structure were prepared by spray-drying method using aqueous solutions of corresponding metal acetates as the reactants. The composition, crystalline structure, morphology and electrochemical properties of the as-prepared materials were characterized by XRD, SEM and half cell charge-discharge testing and AC impedance. The results show that Cr-doping increases the particle size, Cr-doping does not change the material structure but leads to a better defined, layered structure. The Cr-doped material Li[Li0.2Ni0.15Cr0.1Mn0.55]O2 shows better electrochemical performance, it has lower impedance value (105.0 Ω) compared with that of the undoped material (275.0 Ω), better cycle performance and superior rate capability. It delivers the first discharge specific capacity of 140.0 mA?h/g at 1C and the capacity retention of this sample after 50 cycles at 1C rate is 133.7 mA?h/g, while the undoped sample delivers the first discharge specific capacity of 107.1 mA?h/g at 1C and remains 102.1 mA?h/g at 1C rate after 50 cycles.
Key words: Li-rich cathode; Li[Li0.2Ni0.2Mn0.6]O2; spray-drying; Cr-doping; Li-ion battery
