Effects of Cr3+ Doping on Spinel LiMn2O4 Morphology and Electrochemical Performance

LiMn2O4, a significant cathode material for lithium-ion batteries, has garnered considerable attention due to its low cost and environmental friendliness. However, its widespread application is constrained by its rapid capacity degradation and short cycle life at elevated temperatures. To enhance the electrochemical performance of LiMn2O4, we employed a liquid-phase co-precipitation and calcination method to incorporate Cr3+ into the LiMn2O4 cathode material, successfully synthesizing a series of LiCrxMn2-xO4 (x = 0~0.06). The prepared Cr-doped samples exhibited an excellent spinel structure and a unique truncated octahedral morphology. Additionally, the substitution of Mn3+ in LiMn2O4 by Cr3+, coupled with the significantly higher Cr-O bond energy compared to Mn-O bond energy, enhanced the stability of the crystal structure and inhibited the Jahn-Teller effect. Experimental results demonstrated that the optimized LiCr0.04Mn1.96O4 displayed superior electrochemical performance, with a capacity retention rate of 93.24% after 500 cycles under a 0.5C current density; even at 50 °C, the capacity retention rate remained at 86.46% after 350 cycles under a 0.5C current density. The polyhedral morphology formed by Cr doping in LiMn2O4 offers an effective approach to achieving high-performance LiMn2O4 cathode materials.