Enhancing high-rate and elevated-temperature properties of Ni-Mg co-doped LiMnO cathodes for Li-ion batteries.

The improvements of cyclability and rate capability of lithium ion batteries with spinel LiMnO as cathode are imperative demands for the large-scale practical applications. Herein, a nickel (Ni) and magnesium (Mg) co-doping strategy was employed to synthesize LiNiMgMnO cathode material via a facile solid-state combustion approach. The effects of the Ni-Mg co-doping on crystalline structure, micromorphology and electrochemical behaviors of the as-prepared LiNiMgMnO are investigated by a series of physico-chemical characterizations and performance tests at high-rate and elevated-temperature. The resultant LiNiMgMnO has the intrinsic spinel structure with no any impurities, and exhibits an elevated average valence of manganese in comparison to the pristine LiMnO. Owing to the Ni and Mg dual-doped merits, the LiNiMgMnO sample demonstrates a robust spinel structure and high first discharge specific capacity of 112.3 mAh g, whilst undergoing a long cycling of 1000 cycles at 1 C. At a high current rate of 20 C, the capacity of 91.2 mAh g with an excellent retention of 77% is obtained after 1000 cycles. Even at 10 C under 55 °C, an excellent capacity of 97.6 mAh g is also delivered. These results offer a new opportunity for developing high-performance lithium ion batteries with respect to the Ni-Mg co-doping strategy.