Chloride-Bridge Reshaped Electric Double Layer Enables Oriented Deposition for High-Performance Aqueous Aluminum Ion Batteries.

Abstract

Aqueous aluminum-ion batteries (AAIBs) have emerged as a promising candidate for large-scale energy storage. However, the strong solvation of Al³⁺ ions and the formation of passivating oxide layers impede interfacial charge-transfer kinetics, resulting in progressive performance degradation during prolonged cycling. Herein, a chloride-bridge strategy is proposed by employing trichloroethanol (TCE) as an additive that spontaneously self-assembles at the electrolyte/electrode interface to form a chloride-bridge-rich molecular layer. The resulting chloride-bridge framework reorganizes the electric double layer (EDL), accelerates interfacial charge-transfer kinetics, and promotes uniform Al³⁺ deposition with a preferred (111) crystallographic orientation. The tailored interface sustains highly reversible Al deposition/stripping for over 800 h with low polarization and enhances the FeCoPBA full-cell lifetime from fewer than 50 cycles in the OTF electrolyte to 150 at 100 mA g^-1 and 300 cycles at 200 mA g^-1. Furthermore, the PANI cathode delivers 116 mAh g^-1 after 200 cycles at 100 mA g^-1 and remains stable over 350 cycles at 200 mA g^-1, whereas the OTF electrolyte retains only 46 mAh g^-1 after 200 cycles at the same current rate. This work establishes a chloride-bridge-mediated interfacial engineering strategy for accelerating interfacial charge-transfer kinetics and enabling durable AAIBs.