Nonfluorinated Antisolvents for Ultrastable Potassium-Ion Batteries

A robust interface between the electrodeand electrolyte is essentialfor the long-term cyclability of potassium-ion batteries (PIBs). Aneffective strategy for achieving this objective is to enhance theformation of an anion-derived, robust, and stable solid-electrolyteinterphase (SEI) via electrolyte structure engineering. Herein, inspiredby the application of antisolvents in recrystallization, we proposea nonfluorinated antisolvent strategy to optimize the electrolytesolvation structure. In contrast to the conventional localized superconcentratedelectrolyte introducing high-fluorinated ether solvent, the anion-cationinteraction is considerably enhanced by introducing a certain amountof nonfluorinated antisolvent into a phosphate-based electrolyte,thereby promoting the formation of a thin and stable SEI to ensureexcellent cycling performance of PIBs. Consequently, the nonfluorinatedantisolvent electrolyte exhibits superior stability in the K||graphitecell (negligible capacity degradation after 1000 cycles) and long-termcycling in the K||K symmetric cell (>2200 h), as well as considerablyimproved oxidation stability. This study demonstrates the feasibilityof optimized electrolyte engineering with a nonfluorinated antisolvent,providing an approach to realizing superior electrochemical energystorage systems in PIBs.

Automated summary

The formation of a stable solid electrolyte interphase (SEI) is crucial for the long-term cyclability of potassium-ion batteries (PIBs). In this study, a nonfluorinated antisolvent strategy was proposed to enhance the formation of a robust SEI by optimizing the solvation structure of the electrolyte. The nonfluorinated antisolvent electrolyte showed superior stability and improved cycling performance in PIBs.