Dual-functional nanoengineering via molecular pillaring and conductive hybridization for high-performance aqueous zinc-ion batteries

Abstract

Aqueous Zn-ion batteries (AZIBs) stand out as exceptionally promising energy storage devices owing to their superior safety, environmental benignity, and excellent electrochemical performance. However, high-performance cathode materials remain a challenge. Ammonium vanadate (NVO) nanosheets have garnered immense attention as potential AZIB cathodes due to their unique layered nanostructure, but repeated intercalation/extraction of ammonium ions induces severe nanoscale structural collapse, whereas the intrinsically low conductivity further hinders their real-world implementation. Herein, we introduce a nanoscale, dual-functional engineering strategy for NVO cathodes. This approach partially replaces interlayer NH₄⁺ in NVO nanosheets with symmetric tetrahedral TMA⁺ cations as “molecular pillars”, and then hybridizes the modified nanosheets with graphene oxide (GO) to form a TNVO@GO nanocomposite. TMA⁺ suppresses interlayer contraction at the nanoscale, alleviating lattice strain. GO hybridization constructs a continuous 2D nanoconductive network, accelerating electron transfer and preventing vanadium dissolution. Thus, TNVO@GO delivers a high specific capacity of 438.2 mAh g⁻¹ at 0.2 A g⁻¹, with a capacity retention rate of 84.6% after 3000 cycles at 6.0 A g⁻¹. In situ and ex situ characterization further verified the reversible H⁺/Zn²⁺ co-intercalation mechanism, in which TMA⁺ and GO synergistically inhibit structural collapse and promote charge transfer. Furthermore, TNVO@GO based pouch cells exhibit stable performance under bending, confirming their practical application potential. This nanoscale dual-strategy engineering provides a feasible approach for optimizing vanadium-based cathodes and offers insights into the development of next-generation high-performance AZIBs.