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

LiNi 0.8 Co 0.15 Al 0.05 O 2 (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, Li 4 SiO 4 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 Li 4 SiO 4 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% Li 4 SiO 4 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@Li 4 SiO 4 is due to the incorporation of the Li 4 SiO 4 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.