Improved long cycle performance of LiMn2O4 cathode material by Ni-B co-doping combined with truncated octahedron morphology

Abstract

The rapid capacity fading of spinel LiMn2O4 cathode materials still suffers from Jahn-Teller effect and Mn dissolution. Herein, various spinel LiMn1.90-xNi0.10BxO4 cathode materials with truncated octahedron morphology are obtained by a solid-state combustion method. Owing to the substitution of Ni-B dual-doping for Mn, the MnO6 octahedron in the LiMn2O4 generates a contraction that leads to the increased average Mn oxidation state and the suppressed Jahn-Teller effect. Simultaneously, the expansive LiO4 tetrahedron is conducive to boosting the fast Li+ diffusion. Moreover, the growth of {110} crystal planes in the LiMn1.90-xNi0.10BxO4 (x = 0.02–0.15) is also restrained by the Ni-B co-doping, hence alleviating the Mn dissolution. So the Ni-B co-doping accompanied with truncated octahedron morphology presents the preferential growth of {111} and {100} planes. Among the various counterparts of Ni-B co-doping, the optimized LiMn1.84Ni0.10B0.06O4 exhibits the optimal rate performance and cycle life. At 5 C, a capacity retention of 73.5% with an initial discharge capacity of 101.8 mAh g−1 is achieved after ultra-long 2000 cycles. Even at 10 C, the capacity retention of 62.2% is also maintained after 2000 cycles. This combination of element doping and morphology regulation will provide a feasible strategy to synthesize high-performance spinel LiMn2O4 cathode materials for lithium-ion batteries.