Stable Solid-State Zinc-Iodine Batteries Enabled by an Inorganic ZnPS3 Solid Electrolyte with Interconnected Zn2+ Migration Channels

Aqueous zinc-iodine (Zn-I-2) batteries, with their outstanding merits in safety, cost, and environmental friendliness, have received extensive attention. However, the unstable electrochemistry at the electrode-electrolyte interface originating from free water results in zinc dendrite growth, hydrogen evolution reaction (HER), and polyiodide ions shuttle, hindering their practical applications. Herein, solid-state Zn-I-2 batteries based on an inorganic ZnPS3 (ZPS) electrolyte are developed to overcome inherent interfacial issues associated with aqueous electrolytes. The inorganic ZnPS3 electrolyte, with a low Zn2+ diffusion energy barrier of approximate to 0.3 eV, demonstrates an exceptional ion conductivity of 2.0 x 10(-3) S cm(-1) (30 degrees C), which also satisfies high chemical/electrochemical stability and mechanical strength. The solid Zn2+ conduction mechanism, facilitated by bounded water only on grains, effectively suppresses HER and polyiodide ions shuttling. During cycling, a ZnS functional layer is spontaneously formed on the anode/electrolyte interphase, promoting dendrite-free Zn deposition behavior with a more stable (002) crystal orientation. Consequently, the solid-state configuration of Zn-I-2 battery enables an impressive reversible capacity of 154.2 mAh g(-1) after 400 cycles at 0.1 A g(-1). Importantly, the compatibility of the solid-state ZnPS3 electrolyte is also confirmed in the Zn||CuS cell, indicating its potential as a versatile platform for developing inorganic solid-state zinc-ion batteries (ZIBs).