Molecular extension engineering constructing long-chain organic elastomeric interphase towards stable potassium storage

Abstract

Electrolytes are critical for achieving high performance potassium ion batteries (PIBs) because of their ability to modulate the solid electrolyte interphase (SEI). However, the compositions of SEI in conventional electrolytes are either anion-derived inorganic-rich compounds or solvent molecule-derived short-chain organic-rich compounds. These SEI are generally inelastic and cannot effectively relieve the stress changes caused by volume changes during the charge/discharge processes. Here, we constructed long-chain organic-rich SEI (LO-SEI) with high elasticity by introducing a green and harmless long-chain solvent of dicaprylyl carbonate (DCC), thus greatly improving the performance of PIBs. As a result, a long stability of more than 1500 cycles (86.7% capacity retention) for graphite half-cells and more than 3700 hours for K||K symmetric cells are achieved. In addition, the elastomeric LO-SEI-based full cell is capable of stable operating for more than 130 cycles (84.3% capacity retention). This work may open new ideas for constructing long-chain elastic interphases to achieve high-performance batteries.