A dynamic amphiphilic additive with dual solubility modulates Zn2+ solvation and in situ SEI for a dendrite-free zinc anode

Abstract

Aqueous zinc-ion batteries (AZIBs) have garnered significant attention due to their inherent safety and cost-effectiveness, with electrolyte additives playing a pivotal role in enhancing their electrochemical performance. However, the current research landscape reveals a notable gap in the exploration of colloidal additives for AZIB electrolyte systems. This study addresses this limitation by introducing a novel colloidal electrolyte system comprising two synergistic components: a dissolved fraction that modulates the Zn²⁺ solvation structure through small molecules, and an insoluble colloidal fraction that facilitates the formation of a robust solid-electrolyte interphase (SEI) at the anode surface. We propose the innovative use of perylene-3,4,9,10-tetracarboxylic acid diimide (PTCDI) as a multifunctional colloidal additive to engineer a hybrid electrolyte with weak solvation effects. The PTCDI additive demonstrates unique multisite zincophilicity and hydrophobicity, effectively reducing free water content and nucleation potential within the hydrogen bonding network, thereby promoting uniform zinc nucleation. This innovative approach yields remarkable electrochemical performance, achieving stable zinc stripping/plating for 2800 hours with a minimal overpotential of 58.4 mV and an exceptional coulombic efficiency of 99.94%. Zn‖MnO₂ full cells with a low negative/positive electrode capacity ratio of 9.5 exhibit stable cycling performance, maintaining functionality over 500 cycles at a current density of 1 A g⁻¹ at −30 °C. These findings establish colloidal additives as a promising paradigm for advancing AZIB electrolyte design, offering new insights into the development of high-performance zinc-ion battery systems.