Liquid-Phase Integrated Surface Modification to Construct Stable Interfaces and Superior Performance of High-Voltage LiNi0.5Mn1.5O4 Cathode Materials

Spinel LiNi0.5Mn1.5O4 (LNMO) is regarded as the next potential generation of highly competitive cathode material for high-energy-density lithium-ion batteries due to its cobalt-free and high energy density merits. Nevertheless, the unstable surface structure and severe side reactions during cycling lead to poor electrochemical stability, limiting its commercial-scale development. Herein, a comprehensive strategy of high ionic conductivity CeF3 (CF) coating and Ce doping was achieved on an LNMO surface by a liquid-phase method to enhance its interfacial stability and electrochemical properties. The results show that the capacity retention of 1 wt %-CF-modified LNMO is 87.01% after 400 cycles at 1C and room temperature and is 83.98% after 200 cycles at 55 degrees C. The assembled 1 wt %-coated LNMO/Li4Ti5O12 full cell exhibited an initial discharge capacity of 99.0 mAh g(-1) and capacity retention of 90.1% for 100 cycles at 0.5C. Further studies revealed that the CeF3 layer alleviated the dissolution of transition-metal ions and the side reaction between the LNMO surface and electrolyte, resulting in better structural stability, and superficial Ce doping induced an increase in Mn3+ to improve the electronic conductivity. More importantly, the CeF3 modification effectively improves its electrochemical kinetic behavior, and the fast Li+ diffusion and ideal pseudocapacitance behavior make the 1 wt %-CF electrode have optimal performance.

Automated summary

Spinel LiNi0.5Mn1.5O4 (LNMO) with CeF3 coating and Ce doping on the surface shows improved interfacial stability and electrochemical properties. CeF3 coating alleviates the dissolution of transition-metal ions and the side reaction between LNMO and electrolyte, resulting in better structural stability and improved electronic conductivity. CeF3 modification also improves the electrochemical kinetic behavior and leads to optimal performance for LNMO electrode.