Sodium-ion batteries (SIBs) are a plausible alternative to lithium-ion batteries (LIBs) due to their on-par specific energy, better safety and abundance of sodium. However, their performance needs to be improved to make them relevant for practical use [1]. In particular, there is a need to develop high-performance electrode materials for SIBs. Cathode materials studied so far include layered oxides, poly-anion compounds, Prussian blue analogues, etc. Among these cathodes, layered oxides are attractive due to their high specific capacity (260 mAh/g) and ease of synthesis. P2-NaxMnO2 (0.5