Harnessing Berthollide Configuration Entropy for Expedited K+ Storages

Abstract

AbstractVariations in configurational entropy greatly influence the electrochemical behavior of materials; those featuring expanded surface areas, numerous active sites, and accelerated reaction kinetics are highly valued for their superior electrocatalytic properties. In this study, a Berthollide compound is introduced, designated as Cu3Sb0.93Bi0.06Sn0.01S2Se2 (C(ABT)(SSe)). This material, cations, and anions co‐doped Cu3SbS4 (CAS), exhibit significantly enhanced storage performance in potassium‐ion batteries (PIBs). The introduction of foreign elements improved conductivity, while dual‐site conversion and alloying elements enhanced ion diffusion, charge transfer, and electrode kinetics. Regulating configurational entropy created more active sites for Sb. Using high‐capacity Sb and S as primary components, material's configurational entropy is precisely adjusted through active element doping, forming a non‐stoichiometric structure with thermodynamically stable defect active sites. The synergistic effect of trivalent active metals, particularly high‐valence Sb5+, demonstrated superior electrochemical performance compared to materials with unregulated entropy values. Compared to CAS, with the increase in configurational entropy to 0.975 R, the K+ diffusion energy is reduced by 40% and increasing electronic conductivity by 2.6 times, boosting high rate performance (10 A g−1), and showing 49.5% higher capacity after 700 cycles. This novel entropy regulation strategy offers new insights into the design of multi‐element configurational entropy PIBs.