A transition-metal-and-solvent-free dual-graphite battery for grid-scale energy storage

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 new energy-dense 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 mixture of low melting alkali cation (Li, K, Cs)-based bis(fluorosulfonyl)amide (FSA)-based molten salt 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 electrolyte can support graphite/graphite cycling for at least 100 cycles at overall cell upper cutoff potentials of 5.2 V. We change the paradigm of battery design to emphasize the confluence of high energy density, intrinsic safety, earth-abundant materials, sustainability, and recyclability for next-generation grid-scale energy storage.