Effects of equimolar Mg (II) and Si (IV) co-doping on the electrochemical properties of spinel LiMn2−2xMgxSixO4 prepared by citric acid assisted sol–gel method. (1st January 2015)

• Record Type: Journal Article
• Authors: Zhao, Hongyuan; Li, Fang; Liu, Xingquan; Cheng, Cai; Zhang, Zheng; Wu, Yue; Xiong, Weiqiang; Chen, Bing
• Is Part Of: Electrochimica acta. Volume 151(2015)
• Page Start: 263
• Page End: 269
• Publication Date: 2015-01-01
• Subjects: Lithium-ion battery -- Cathode material -- Spinel LiMn2O4 -- Equimolar Mg -- Si co-doping -- Sol–gel method; Electrochemistry -- Periodicals; Electrochemistry, Industrial -- Periodicals; 541.37
• DOI: 10.1016/j.electacta.2014.11.095
• Languages: English
• ISSNs: 0013-4686

Abstract

Abstract: The spinel LiMn2−2x Mgx Six O4 (x = 0, 0.01, 0.03, 0.05 and 0.07) cathode materials were successfully synthesized by a citric acid assisted sol-gel process with LiOH · H2 O, Mn(CH3 COO)2 · 4H2 O, Mg(NO3 )2 · 6H2 O and C8 H20 O4 Si as raw materials. The crystal structures and morphologies of LiMn2−2x Mgx Six O4 were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively. All the obtained samples with good crystallinity were identified as the cubic spinel structure of LiMn2 O4 and no impurity peaks were observed. Equimolar Mg 2+ and Si 4+ ions could completely occupy the octahedral (16d) sites to substitute Mn 3+ and Mn 4+ ions, respectively, which significantly improved the structural stabilization and suppressed the Jahn–Teller distortion. The effects of equimolar Mg 2+ and Si 4+ ions co-doping on the electrochemical properties of LiMn2−2x Mgx Six O4 were investigated by galvanostatic charge–discharge test, cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The results showed that the equimolar Mg 2+ and Si 4+ ions co-doped LiMn2 O4 presented better cycling retention and rate performance. For the optimal LiMn1.90 Mg0.05 Si0.05 O4, the initial discharge capacity was 126.9 mAh g −1 and remained 123.5 mAh g −1 after 100 cycles at 0.5 C in the voltage range of 3.20 ∼ 4.35 V. The capacity retention could reach 97.3%, which was far higher than that of the undoped LiMn2 O4 .