Preparation of Ni–Zn dual-doped polyhedral LiMn2O4 for endurable cycling lithium ion batteries at high rate

Abstract

Jahn-Teller distortion and manganese dissolution are always the dominant problem of attenuating long cyclic performance and rate capacity of spinel LiMn2O4 cathode materials. Herein, a Ni–Zn dual-doping strategy is proposed to synthesize various LiNi0.05ZnxMn1.95-xO4 (x = 0–0.05) materials via a solid phase combustion method. All the as-prepared Ni–Zn co-doping materials have a good spinel structure with Fd3m space group and present unique polyhedron morphology with exposed (111) facets, which is conductive to relieving the manganese dissolution and Jahn-Teller effect. Moreover, the Ni–Zn co-doping gives rise to the extended Li–O bond and increased cell volume, hence boosting the favorable intercalation and deintercalation kinetics of Li+ ions. Consequently, the optimized LiNi0·05Zn0·02Mn1·93O4 cathode exhibits good electrochemical performance with the initial discharge capacity of 127.30 mAh g−1 and capacity retention of 70% after 1000 cycles at 1 C. At 5 C, an ultra-long cycle stability with a capacity retention of 61% is obtained up to 1800 cycles. Even at the high current rates of 10 C and 20 C, the relatively high first discharge capacities of 106.50 mAh g−1 and 99.40 mAh g−1 are also delivered, respectively. The Ni–Zn co-doping polyhedral LiMn2O4 will provide a solution for developing high-performance cathode materials in lithium ion battery.