Electrically Insulating Rigid Multi-Channel Electrolyte Container for Customizable Electron Transfer in Zn-Halogen Batteries.

Recent advancements in Zn-halogen batteries have focused on enhancing the adsorptive or catalytic capability of host materials and stabilizing complex intermediates with electrolyte additives, while the halogen-ion electrolyte modifications exhibit strong potential for integrated interfacial regulation. Herein, we design an electrically insulating rigid electrolyte container to immobilize a liquid halogen-ion electrolyte for separator-free Zn-halogen batteries with customizable electron transfer. Robust hydrogen bonding of hydroxyl groups in SiO2 with fluorinated moieties in PVDF-hfp regulates Zn2+ solvation and suppresses H2O activity, while multi-channels formed by microcracks and interparticle gaps not only enhance mass transfer but also buffer interfacial electric field, jointly enabling a durable Zn plating/stripping. Effective confinement of intermediates also ensures the high reversibility across single-(I-/I0), double-(I-/I0/I⁺), and triple-(I-/I0/I⁺, Cl-/Cl0) electron transfer mechanisms at cathode, as evidenced by the double-electron transfer systems exhibiting a low capacity decay rate of 0.02‰ over 4500 cycles at 10 mA cm-2 and a high areal capacity of 11.9 mAh cm-2 at 2 mA cm-2. This work presents a novel "container engineering" approach to halogen-ion electrolyte design and provides fundamental insights into the relationships between redox reversibility and reaction kinetics.