PrF3 Nanocoatings for Stabilizing Spinel LiNi0.5Mn1.5O4 Cathodes

LiNi0.5Mn1.5O4 (LNMO) has broad application prospects due to its high discharge platform and low cost. However, the side reactions of the electrolyte during high-temperature and high-voltage cycling severely limit its commercial development. In this study, PrF3 nanocoatings were constructed by wet chemistry to stabilize the surface of LNMO electrodes to solve such problems. The electrochemical test results show that the PrF3 nanocoating can effectively improve the electrochemical performance of the LNMO electrode, especially at high temperature. In the voltage range of 3.5–4.9 V, the 1 wt % PrF3-coated electrode exhibited a capacity retention of 91.4% after 100 cycles at a rate of 0.2C and 55 °C, while the pristine LNMO electrode could not release its capacity after 91 cycles. At a rate of 10C, the discharge capacity of pristine LNMO was only 48.2 mAh g–1, while that of LNMO-PF1 was 88.9 mAh g–1. The characterization of the samples before and after coating further indicates that the PrF3 nanocoating can stabilize the LNMO electrode surface, inhibit its side reactions with the electrolyte, enhance the structural stability, and improve the lithium ion diffusion kinetics. Our study provides an effective way to stabilize the energy density and cycling performance of LNMO at high temperature and high voltage and provides an idea for the protection strategy of high-energy-density lithium batteries working at high voltage.