Molybdenum Incorporated O3‐type Sodium Layered Oxide Cathodes for High‐Performance Sodium‐Ion Batteries

Transition metal layered oxide materials with a general formula NaxMO2 (M=Ni, Mn, Co, Fe) are widely researched with various possible electrode configurations. A significant improvement in structural and electrochemical performance is required to broaden the future applications of sodium‐based layered oxide materials for Na‐ion batteries. In this work, O3‐type NaNi(1‐x)/2Mn(1‐x)/2MoxO2 (x=0, 0.05,0.1) layered oxide cathode materials were synthesized by solid‐state reaction method, and its structural, thermal and electrochemical performance in Sodium (Na) ion battery was investigated. The structural analysis reveals that a single phase highly crystalline O3‐type cathode material with irregular particle shape was formed. The introduction of molybdenum (Mo) improves the thermal stability of cathode materials, which can be attributed to the improved TMO2 layers that provide stability to the material. The addition of Mo to Na layered oxide cathode materials influences their electrochemical performance. In comparison, the developed cathode materials, the NaNi0.475Mn0.475Mo0.05O2, exhibited excellent specific discharge capacity (∽154mAh/g) at C/20 rate, (an increase of ∽20% when compared to the NaNi0.5Mn0.5O2) which can be attributed to the increased capacitance effect by the addition of Mo. The EIS study reveals that the diffusion of Na+ into/from the host structure is rapid during the first cycle and then gradually reduces with subsequent cycling due to the formation of the SEI layer, which hinders Na+ migration. This has a potential effect on the improved electrochemical performance of the material.This article is protected by copyright. All rights reserved.