Weakening electrostatic effect and strengthening couple with crystal lattice in vanadium oxide for enhanced Zn2+ storage

Vanadium oxides (VOs) have been widely explored as cathode materials for aqueous zinc ion batteries (AZIBs). However, their practical application is hindered by sluggish Zn2+ transport kinetics and poor structural stability arising from strong electrostatic interactions. To address these issues, potassium tartrate (PT) is introduced into the layered V2O5 framework to construct a hybrid material (VO–PT) featuring C4H4O62− anions and K+ pillars. In this architecture, the polar functional groups (–COO−) of tartrate anions effectively weaken the electrostatic interaction between Zn2+ and lattice oxygen while simultaneously providing additional Zn2+ storage sites. Meanwhile, the –OH groups interact with V centers, strengthening the coupling between the organic species and the host framework. Concurrently, K+ ions act as interlayer pillars, together enhancing structural integrity. Comprehensive characterizations combined with theoretical calculations reveal that this synergistic modulation not only reduces the energy barriers for Zn2+ insertion/extraction but also facilitates ion diffusion kinetics. As a result, the VO–PT||Zn full cell delivers a high specific capacity of 415.3 mAh g−1 at 0.2 A g−1 and maintains a capacity retention of 84.9% after 5000 cycles at high current density. This work provides a viable strategy for designing stable and high-performance vanadium-based cathodes for AZIBs.