A modification engineering to form two kinds of truncated octahedrons by in situ LaBO3 coating for high-performance LiMn2O4 cathode material

Abstract

Rapid capacity fade of spinel LiMn2O4 cathode material limits the application of lithium-ion batteries. Herein, the introduction of La/B elements achieves the dual-modification of surface coating and single-crystal truncated morphology, ensuring the compatibility of rate capability and cycling stability. The La and B introduction enables the in situ formation of LaBO3 coating layer. Both the LaBO3 coating and truncated morphology prevent the direct exposure of the cathode to the electrolyte, decreasing the Mn dissolution and providing the additional Li+ diffusion channels. The increase of La and B modification partially restrains the development of {110} crystal planes. The refinement manifests that the La3+/B3+ doping partially replaces Mn3+ of the LiMn2O4, inhibiting the Jahn-Teller effect and stabilizing the [MnO6] skeleton. Consequently, the optimized LiMn2O4@0.04LaBO3 with the favorable LaBO3 coating thickness and two truncated octahedrons exhibits the excellent electrochemical properties at high current rate. The first discharge capacities of 109.1, 104.2 and 96.9 mAh⋅g−1 are obtained, whilst the capacity retentions of 64.8 % (after 2000 cycles), 65.8 % (after 2000 cycles) and 80.5 % (after 1000 cycles) can be maintained at 5 C, 10 C and 20 C, respectively. Even at 5 C and 55 °C, the high initial discharge capacity of 113.6 mAh⋅g−1 and good cycling lifespans can be achieved. This modification strategy provides valuable insight for preparing the advanced LiMn2O4 cathode materials for lithium-ion batteries.