A transition-metal-and-solvent-free dual-graphite battery

Abstract

Conventional grid-scale energy-dense batteries are reliant on transition metal ions, volatile and flammable organic solvents, and are not sustainable or easy to recycle. Here, we present a battery chemistry where graphite serves as both anode and cathode (dual-graphite battery) with no solvents, transition metal ions, or metals as active species. We show that a molten mixture of low-melting alkali cation (Li, K, Cs) bis(fluorosulfonyl)amide (FSA)-based salts can support dual graphite batteries. Using spectroscopic and diffraction techniques, we show conclusively that lithium is the only active species that reversibly (de)intercalates at the graphite anode, while FSA (de)intercalation occurs at the graphite cathode. We find that this molten salt can support graphite/graphite cycling for at least 100 cycles especially when the solid electrolyte interface is carefully pre-formed, demonstrating its promise as a solvent-free, inherently energy-dense next-generation dual-ion battery electrolyte.