Composites Li2MnO3·LiMn1/3Ni1/3Co1/3O2: Optimized synthesis and applications as advanced high-voltage cathode for batteries working at elevated temperatures

• DOI: 10.1016/j.electacta.2012.06.084
• Publication Date: 2012-07-02T08:31:42Z
• Authors: Chuang Yu; Guangshe Li; Xiangfeng Guan; Jing Zheng; Liping Li; Tianwen Chen
• Keywords: 01 natural sciences; 7. Clean energy; 0104 chemical sciences

Abstract This work reports on the optimized preparation of a series of composites x Li 2 MnO 3 ·(1 − x )LiMn 1/3 Ni 1/3 Co 1/3 O 2 ( x = 0.1–0.4) with an aim to find an advanced high-voltage cathode for lithium-ion batteries that can work at elevated temperatures. Developing a two-step molten-salt method leads to composites with a layered-type structure, showing a particle size distribution ranging from 350 to 450 nm. The composites are featured by oxidation states stabilized as Mn 4+ , Ni 2+ , and Co 3+ , and by lattice occupation of Li + in both transition-metal layers and lithium layer of LiMn 1/3 Ni 1/3 Co 1/3 O 2 . When acting as a cathode of lithium-ion batteries, the composite at x = 0.3 shows an optimum electrochemical performance as characterized by a discharge capacity of 120 mAh g −1 at a high current density of 500 mA g −1 and a capacity retention of 64% after 20 cycles. Surprisingly, this electrochemical performance is significantly improved at elevated temperatures. Namely, discharge capacity is increased to 140.4 mAh g −1 at a high current density of 500 mA g −1 , while average capacity decay rate becomes very small to 0.76%. These excellent performance is explained in terms of the dramatically improved lithium-ion diffusions in both electrode and surface films at elevated temperatures.