Enhanced high-rate and long-cycle performance of Mg2+-Al3+ co-doped spinel LiMn2O4 cathode materials for Li-ion batteries

Abstract

Spinel LiMn2O4 has the potential to be used as a cathode material in lithium-ion batteries because of its affordability, low toxicity, and excellent charge/discharge capability. However, severe capacity attenuation results from the degradation of its long-cycle and high-rate performance caused by the Jahn-Teller distortion and Mn dissolution. Herein, a simple solid-state combustion process is used to successfully prepare the Mg2+-Al3+ co-doped LiMn2O4 with truncated octahedral morphology. The Jahn-Teller distortion is inhibited by the stable Mn-O framework and the decreased lattice constant, which in turn lowers the dissolution of Mn. Moreover, Mg2+-Al3+ co-doped LiMn2O4 have lower activation energy and greater Li+ diffusion coefficient. As a result, the optimized LiMg0.03Al0.10Mn1.87O4 delivers satisfied initial capacity of 102.1 mAh‧g−1 with a capacity retention of 76.2 % after 1000 cycles at 10 C. Even at the ultra-high rate of 15 C and 20 C, Mg2+-Al3+ co-doped sample also remain desired structure stability and cycling performance, which remains 73.8 % of its original capacity after 1000 cycles at 20 C. This work provides a reference for developing high-performance and stability cathode materials for lithium-ion battery.