P2-Type Na0.67Mn0.5Fe0.5O2 Synthesized by Solution Combustion Method as an Efficient Cathode Material for Sodium-Ion Batteries

Abstract

P2-type sodium transition metal oxide materials have a high theoretical capacity (∼170–210 mAh g−1) and exhibit high sodium-ion diffusion rates. In the present work, we report P2-type Sodium layered transition metal oxide Na0.67Mn0.5Fe0.5O2 material prepared by the simple solution combustion method followed by thermal treatment is studied as a promising cathode for Sodium-ion Batteries (SIBs). The formation of a pure hexagonal crystal system P2- Na0.67Mn0.5Fe0.5O2 with P63/mmc phase having plate-like morphology is confirmed. The electrochemical performance of the P2- Na0.67Mn0.5Fe0.5O2 as cathode for Sodium-ion Batteries shows an initial discharge capacity of ∼166 mAh g−1 with a moderate capacity retention of ∼111 mAh g−1 at a 0.1 C rate for 100 cycles. Further, the C rate performance of the material shows a reasonable capacity of >95 mAh g−1 at a 1 C rate. The slow decrease in performance during cycling of Na0.67Mn0.5Fe0.5O2 cathode is due to surface reconstruction, intragranular cracks, transition metal reduction and dissolution, and electrolyte decomposition which is evident from various surface studies. The P2-Na0.67Mn0.5Fe0.5O2 exhibits stable cycling and C-rate performance between 0.1C–1C which is superior to many of the literature results.