High K-storage performance based on the synergy of dipotassium terephthalate and ether-based electrolytes

Abstract

Potassium-ion batteries (KIBs) are strongly dependent on the development of anodes with high safety and good electrochemical performance. Here, we achieved excellent anode performance of KIBs based on the synergy of dipotassium terephthalate (K₂TP) and a 1,2-dimethoxyethane (DME)-based electrolyte for the first time. The K₂TP is featured as a typical layered structure with K⁺ transport channels. It delivers a large capacity of 249 mA h g⁻¹ at 200 mA g⁻¹ and a high capacity retention of 94.6% after 500 cycles of discharge and charge at 1000 mA g⁻¹ with a Coulombic efficiency of 100%. This is attributed to the active carboxylate groups and the flexible molecular structure of K₂TP, and the stable solid electrolyte interphase (SEI) formed in the DME-based electrolyte. Furthermore, the redox voltage around 0.6 V of K₂TP favors K⁺ insertion rather than deposition during discharge. These make K₂TP a promising anode material for KIBs, and encourage more investigations into the new system of KIBs.