An aluminum-doped sodium manganese hexacyano ferrate cathode for high-rate safe Na-ion batteries.

Aluminum (Al) doping in sodium manganese hexa-cyano-ferrate (NMHCF) stabilizes the cubic phase and suppresses multiphase formation. Doping reduces the particle size (∼0.35 μm), catalyzing the rate kinetics. Further Al-doping promotes aluminum-oxy-fluoride formation at the cathode electrolyte interphase for water in salt electrolytes, enabling safer, high-rate Na-ion battery performance.