In Situ Construction of Inorganics‐Rich Cathode‐Electrolyte Interface toward Long‐Life Prussian White Cathode

Abstract Prussian white (PW) is one of the most promising candidates as a cathode for sodium‐ion batteries (SIBs) because of its high theoretical capacity, excellent rate performance, and low production cost. However, PW materials suffer severe capacity decay during long‐term cycling. In this work, a robust cathode electrolyte interface (CEI) is designed on the PW cathode by employing cresyl diphenyl phosphate (CDP) and adiponitrile (ADN) as electrolyte additives. CDP and ADN possess higher highest occupied molecular orbital energy levels (HOMO) than other solvents, leading to the preferential decomposition of CDP and ADN to construct an inorganics‐rich CEI layer in situ on the PW cathode. Benefiting from this CEI layer, the degradation of PW is effectively inhibited during the long cycling. The Na||PW cell achieves an excellent cycling performance with a capacity retention of 85.62% after 1400 cycles. This work presented here provides a feasible strategy for improving the cycling performance of PW by electrolyte modification.