Self-assembled hydrated copper coordination compounds as ionic conductors for room temperature solid-state batteries.

As the core component of solid-state batteries, neither current inorganic solid-state electrolytes nor solid polymer electrolytes can simultaneously possess satisfactory ionic conductivity, electrode compatibility and processability. By incorporating efficient Li diffusion channels found in inorganic solid-state electrolytes and polar functional groups present in solid polymer electrolytes, it is conceivable to design inorganic-organic hybrid solid-state electrolytes to achieve true fusion and synergy in performance. Herein, we demonstrate that traditional metal coordination compounds can serve as exceptional Li ion conductors at room temperature through rational structural design. Specifically, we synthesize copper maleate hydrate nanoflakes via bottom-up self-assembly featuring highly-ordered 1D channels that are interconnected by Cu/Cu nodes and maleic acid ligands, alongside rich COO groups and structural water within the channels. Benefiting from the combination of ion-hopping and coupling-dissociation mechanisms, Li ions can preferably transport through these channels rapidly. Thus, the Li-implanted copper maleate hydrate solid-state electrolytes shows remarkable ionic conductivity (1.17 × 10 S cm at room temperature), high Li transference number (0.77), and a 4.7 V-wide operating window. More impressively, Li-implanted copper maleate hydrate solid-state electrolytes are demonstrated to have exceptional compatibility with both cathode and Li anode, enabling long-term stability of more than 800 cycles. This work brings new insight on exploring superior room-temperature ionic conductors based on metal coordination compounds.