Quicker and More Zn²⁺ Storage Predominantly from the Interface

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Aqueous zinc-ion batteries (AZIBs) are attractive for grid-scale energy storage due to their low cost and inherent safety.
• A key challenge in AZIB development is simultaneously achieving high energy and high power densities.
• Conventional cathode materials often face limitations in ion diffusion and electron transport, hindering rate capability.

Purpose of the Study:

• To design and synthesize a novel cathode material for AZIBs that overcomes the limitations of traditional designs.
• To investigate a new ion storage mechanism at the material's interface.
• To demonstrate significantly improved energy and power densities in AZIBs.

Main Methods:

• Artificial construction of a vanadium oxide (VOx) sub-nanometer cluster/reduced graphene oxide (rGO) composite cathode.
• Characterization of interfacial V-O-C bonds and the resulting storage mechanism.
• Electrochemical testing to evaluate capacity, rate capability, and cycling stability.

Main Results:

• A novel interface-dominated Zn2+ storage mechanism was revealed, differing from conventional bulk storage.
• The VOx/rGO cathode exhibited an ultrahigh rate capability (174.4 mAh g-1 at 100 A g-1) and high capacity (443 mAh g-1 at 100 mA g-1).
• Decoupled transport of electrons and Zn2+ ions was achieved, alongside reversible interface destruction/reconstruction.

Conclusions:

• Interface-dominated storage in VOx/rGO composites is a viable strategy for high-energy and high-power AZIBs.
• This approach enables exploitation of the conductive rGO matrix for enhanced ion storage.
• The findings present a new pathway for designing advanced cathode materials for next-generation energy storage devices.