Improvement electrochemical performance of Li1.5Ni0.25Mn0.75O2.5 with Li4Ti5O12 coating

Layered cathode Li1.5Ni0.25Mn0.75O2.5 has been synthesized and coated by Li4Ti5O12. The pristine and coated Li1.5Ni0.25Mn0.75O2.5 powders are characterized by X-ray diffraction (XRD), indicating the materials remained the layered structure before and after coating. The coated Li4Ti5O12 has been detected by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and energy-dispersive X-ray spectroscopy (DEX). The electrochemical performance, especially rate performance of Li1.5Ni0.25Mn0.75O2.5 electrode, is improved effectively after Li4Ti5O12 coating. The first discharge capacity, coulombic efficiency, and capacity retention of Li4Ti5O12-coated Li1.5Ni0.25Mn0.75O2.5 electrode are 244 mA h g(-1), 81.5 %, and 98.3 % after 50 cycles, respectively. The Li4Ti5O12-coated Li1.5Ni0.25Mn0.75O2.5 electrode exhibits 108 mA h g(-1) at 10 A degrees C rate. Electrochemical impedance spectroscopy (EIS) results show that the charge transfer resistance (R (ct)) of Li1.5Ni0.25Mn0.75O2.5 electrode decreases after coating, which is due to the existence of Li4Ti5O12 with high lithium ion diffusion coefficient and suppression of the solid electrolyte interfacial (SEI) layer development and is responsible for the excellent rate capability and cyclic performance.