Solvent modulation strategy for Sb-based anode to achieve stable potassium storage

Abstract

High-concentration electrolyte (HCE) and localized high-concentration electrolyte (LHCE) strategies have been successfully developed for potassium-ion batteries (PIBs) to address the interface incompatibility issue, especially for the high-theoretical-capacity antimony (Sb)-based alloy-typed anode suffering from the drastic volume expansion problem. However, the high costs along with special solvents for these electrolytes significantly limits their widespread applications in PIBs. Herein, a new dilute electrolyte of 1 M KFSI in a mixed solvent of ethylene carbonate (EC) and 1, 2-dimethoxyethane (DME) (1:1 v/v) is developed to stabilize the K-storage kinetics of Sb anodes. The mixed solvent of common ester and ether promotes the formation of stable K+-EC solvent pair and thus generates a robust solid-electrolyte-interphase (SEI) for stable K-storage. As a result, the fabricated Sb@NC anode exhibits a stable capacity of 376 mAh/g after 100 cycles at 100 mA g−1, which is comparable to that in the HCE of 5 M KFSI/DME. These results demonstrated that low-cost and high-compatibility electrolytes for alloy-typed anodes can be achieved via rational design of the solvation structures for dilute electrolytes, resulting into stable K-storage properties and huge prospects of commercialized applications.