Regulation of Configurational Entropy to Realize Long Cycle Lifespan of High Entropy Alloy Anodes for Potassium Batteries

Abstract

High entropy alloys (HEAs) with entropy-driven stabilization are attractive in potassium-ion batteries (PIBs); however, they suffer from phase segregation due to the disparity of versatile components. Confining multifarious metals into the same lattice using ligands with full-coordination abilities allows for delicate control at the nanoscale level and thus decreases atom diffusion. This chemical synthesis can suppress phase segregation and realize HEAs for PIB anodes. Herein, a new MnCoNiCuZn-based HEA nanoparticle encapsulated within nitrogen-doped carbon (HEA-NPs@NC) is fabricated for PIB anodes. The flexible chlorhexidine is selected due to its long chain, large steric bulkiness, abundant neutral tetradentate donors, and large coordination ability. The high entropy effect and the “cocktail” effect of HEA-NPs@NC allow for tailoring electrochemical functionalities, including multiple K⁺ transport paths, good conductivity, and entropy stability. The HEA-NPs@NC anode achieves a long lifespan of over 3000 cycles, impressive capacity (513 mAh g⁻¹), and high-rate performance (202 mAh g⁻¹ at 5 A g⁻¹). The ex situ characterizations and density functional theory calculations elucidated the HEA acts as an “atomic composite” and forms interstitial metallic solid solutions with K due to the interaction of constituent elements.