Fast interfacial electrocatalytic desolvation enabling low-temperature and long-cycle-life aqueous Zn batteries

Abstract

Low-temperature zinc batteries (LT-ZIBs) based on aqueous electrolytes show great promise for practical applications owing to their natural resource abundance and low cost. However, they suffer from sluggish kinetics with elevated energy barriers due to the dissociation of bulky Zn(H₂O)₆²⁺ solvation structure and free Zn²⁺ diffusion, resulting in unsatisfactory lifespan and performance. Herein, dissimilar to solvation shell tuning or layer spacing enlargement engineering, delocalized electrons in cathode through constructing intrinsic defect engineering is proposed to achieve a rapid electrocatalytic desolvation to obtain free Zn²⁺ for insertion/extraction. As revealed by density functional theory calculations and interfacial spectroscopic characterizations, the intrinsic delocalized electron distribution propels the Zn(H₂O)₆²⁺ dissociation, forming a reversible interphase and facilitating Zn²⁺ diffusion across the electrolyte/cathode interface. The as-fabricated oxygen defect-rich V₂O₅ on hierarchical porous carbon (ODVO@HPC) electrode exhibits high capacity robustness from 25 to −20°C. Operating at −20°C, the ODVO@HPC delivers 191 mAh g⁻¹ at 50 A g⁻¹ and lasts for 50 000 cycles at 10 A g⁻¹, significantly enhancing the power density and lifespan under low-temperature environments in comparison to previous reports. Even with areal mass loading of ~13 mg cm⁻², both coin cells and pouch batteries maintain excellent stability and areal capacities, realizing practical high-performance LT-ZIBs.