Salt-tolerance training enabled flexible molten hydrate gel electrolytes for energy-dense and stable zinc storage

Molten hydrate electrolytes are promising in tackling severe issues facing aqueous zinc-metal batteries (ZMBs), but their flexible equivalents commensurate with the full “flexible vision” of emerging electronics are still lacking. Here, we advance a general salt-tolerance training strategy to fabricate such electrolytes simply by induction of water molecules and ion migration in rationalized hydrogels. Combined characterizations and simulations verify that there are no free water molecules within the electrolyte. This unique flexible electrolyte features desirable mechanical and electrochemical properties and enables exceptional stability of both the cathode and the Zn anode. Warranted by these features of the electrolytes, the assembled flexible ZMBs deliver an unprecedented cumulative areal capacity of 10.3 Ah cm⁻², and pouch cells with practical areal capacities are realized. Solid-state batteries also demonstrate great potential as reliable flexible power sources. This work opens up an avenue for leveraging flexible molten hydrate electrolytes for energy-dense and stable ZMBs.