Exploring the Effect of TiO 2 Coating on Na 0.85 Li 0.12 Ni 0.22 Mn 0.66 O 2 Cathode Materials for Na-Ion Batteries

Abstract

Layered transition metal oxides have great potential as cathode materials for sodium ion batteries, but some limitations like structural instability and poor rate performance restricts its further application. To overcome the above issues, a simultaneously modified P2-type cathode of Na 0.85 Li 0.12 Ni 0.22 Mn 0.66 O 2 with 1% weight TiO 2 coating (NLNMO-1%wt TiO 2 ) based on doping and coating approaches was prepared by high-temperature solid-state reaction and liquid phase coating. This new strategy reduces the relative content of Mn 3+ , which suppresses the Jahn-Teller effect and enhanes the structural stability. The as-prepared cathode shows improved rate capability, with a high reversible capacity of 111.4 mAh g −1 at 1 C and a capacity retention of 94.5% after 100 cycles. At 5 C, it maintains a capacity of 87.1 mAh g −1 at 5 C with capacity retention of 81.8% after 400 cycles. Additionally, it provides a stable CEI film, reducing side reactions and electrode pulverization. which could be confirmed by scanning electron microscopy and high-resolution transmission electron microscopy. Overall, this synergistic modification strategy provides a pathway for improving the electrochemical performance of layered oxide cathode materials for sodium-ion batteries. A coating strategy increases the performance of cathode for sodium-ion batteries. The pulverization of the cathode is suppressed during charging-discharging cycles. The Jahn-Taller distortion is suppressed with increased structural stability. The cathode possesses superior rate performance and cycling performance.