Antibonding orbital tailor and stress relief engineering for FeS 2 complex toward superior sodium storage

Abstract The sluggish kinetics behaviors and vast volume variations of Na + hosts to FeS 2 anode involved intercalation, and conversion reactions plague its applicability of sodium‐ion batteries (SIBs). Here, a significantly expedited kinetics via cation intercalation and considerably relieved stress accumulation by constructing the concave scaffold protector are approached for FeS 2 complex. Upon Mn 2+ intercalation into FeS 2 , a new stable Mn–FeS 2 was generated with distorted coordination; elevated antibonding orbital occupancy and lowed d band center to the release of more free Na + were achieved, which was further encapsulated by hollow bowl‐like carbon spheres (BC). This cation intercalation and concave morphology strategies confer Mn–FeS 2 @BC significantly enhanced electron/ion transport kinetics via reversed electron transfer to FeS 2 , fast desolvation kinetics, and evidently depressed structural deformation during Na + insertion and extraction. Consequently, Mn–FeS 2 @BC delivers the longevity and stable Na + storage capacity in both half and full cell device. Moreover, Mn–FeS 2 @BC also displays excellent adaptability in a wider temperature range. This work proposes new views into the deep regulation of electrochemical performance of transition metal anodes via intercalation chemistry and concave engineering.