Effective enhancement of the electrochemical performance of layered li-rich cathode Li_1.5Ni_0.25Mn_0.75O_2.5 by a facile molten salt method for Lithium-ion batteries

A Li-rich Mn-based Li_1.5Ni_0.25Mn_0.75O_2.5 cathode material with excellent electrochemical performance is prepared using a combination of hydroxide co-precipitation and molten salt method. Powder X-ray diffraction (XRD), scanning electron microscopy (SEM), inductively coupled plasma-atomic emission spectrometer (ICP-AES), X-ray photoelectron spectroscopy (XPS), electrochemical impedance spectroscopy (EIS) and galvanostatic charge-discharge tests are employed to analyze the particle morphology, crystal structure, and electrochemical properties of the as-prepared material. XRD results indicate that this sample has a more ordered α-NaFeO₂ structure (space group R3m), and reduced Li⁺/Ni²⁺ cation mixing. Electrochemical results confirm that this sample has a dramatically decreased initial irreversible capacity loss, and excellent rate performance and cycling stability. Specifically, it delivers a small initial irreversible capacity loss of 50 mAh·g^-1 (the first coulombic efficiency is 84%) between 2.0 and 4.8 V at 0.1C. At 10C rate, it can still exhibit a high discharge capacity of 102 mAh·g^-1. After 100 cycles at 0.5C, the cathode also shows a discharge capacity of 205 mAh·g^-1 with capacity retention of 90%.