Aluminum doped Sodium manganese hexa cyano ferrate cathode for high-rate safe Na-ion battery

Abstract

Despite the high discharge capacity, sodium manganese hexa-cyano-ferrate (NMHCF) cathode remains limited due to the inevitable phase transition, i.e., monoclinic-cubic-tetragonal. The present work demonstrates, Aluminum (Al) doping in NMHCF prevent the multiple-phase formation of the NMHCF and facilitates the formation of the cubic phase. Furthermore, Al doping influences the formation of smaller particle sizes (~0.35 µm) and hence higher surface area than pristine NMHCF (~0.75 µm) which enhances the rate kinetics. Besides stabilizing the cubic phase, the Al doping promotes the formation of aluminum-oxy-fluoride (AlOFx) cathode electrolyte inter-phase (CEI) on the Al-doped NMHCF (Al-NMHCF) cathode for Water In Salt (WIS) electrolyte and believe that the Al-NMHCF cathode paves the way for safe and high-rate applications of Na-ion batteries.