A Room-Temperature Chloride-Conducting Metal-Organic Crystal [Al(DMSO)(6)]Cl-3 for Potential Solid-State Chloride-Shuttle Batteries

The growing demand for substitutes of lithium chemistries in battery leads to a surge in budding novel anion-based electrochemical energy storage, where the chloride ion batteries (CIBs) take over the role. The application of CIBs is limited by the dissolution and side reaction of chloride-based electrode materials in a liquid electrolyte. On the flipside, its solid-state electrolytes are scarcely reported due to the challenge in realizing fast Cl- conductivity. The present study reports [Al(DMSO)(6)]Cl-3, a solid-state metal-organic material, allows chloride ion transfer. The strong Al-Cl bonds in AlCl3 are broken down after coordinating of Al3+ by ligand DMSO, and Cl- in the resulting compound is weakly bound to complexions [Al(DMSO)(6)](3+), which may facilitate Cl- migration. By partial replacement of Cl- with PF6-$$ {\mathrm{PF}}_6<^>{-} $$, the room-temperature ionic conductivity of as-prepared electrolyte is increased by one order of magnitude from 2.172 x 10(-5) S cm(-1) to 2.012 x 10(-4) S cm(-1). When they are assembled with Ag (anode)/Ag-AgCl (cathode) electrode system, reversible electrochemical redox reactions occur on both sides, demonstrating its potential for solid-state chloride ion batteries. The strategy by weakening the bonding interaction using organic ligands between Cl- and central metallic ions may provide new ideas for developing solid chloride-ion conductors.