In situ formed LiNi0.8Co0.15Al0.05O2@Li4SiO4 composite cathode material with high rate capability and long cycling stability for lithium-ion batteries

LiNi0.8Co0.15Al0.05O2 (LNCA) is a highly promising cathode material for lithium-ion batteries, but the low-rate capability and poor cycling stability of LNCA limit the expansibility of its commercial applications. Herein, Li4SiO4 with a small amount of Al is introduced to modify LNCA by combined wet-chemical and solid-state methods and improve its rate and cycle performance. X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), High Resolution Transmission Electron Microscope (HRTEM), and Energy Disperse Spectroscopy (EDS) results confirm that a Li4SiO4 coating layer (2-5 nm) is firmly wrapped on the LNCA surface. The modified LNCA shows surprising rate performance and excellent cycle retention. Specifically, the LNCA material coated with 3 mol% Li4SiO4 displays a discharge capacity of 156.5 mAh g(-1) at 10 C and exhibits a capacity retention of 88% after 100 cycles at 1 C rate(2.7-4.3 V). The excellent electrochemical performance of the LNCA@Li4SiO4 is due to the incorporation of the Li4SiO4 layer. This layer enhances the lithium-ion diffusion between electrode and electrolyte and suppresses the side reaction produced by direct contact between the active material and electrolyte during repeated charge-discharge cycles. All these findings indicate the high potential of this material for application in advanced lithium-ion batteries.