Unlocking high volumetric energy storage for zinc-ion batteries using a composite protective layer-coated anode

Challenges including the disintegration and corrosion of the zinc (Zn) anode, poor wettability, and a scarcity of nucleation points for Zn deposition have impeded progress in the advancement of Zn-ion batteries (ZIBs). To address these issues, this study introduced a composite protective layer consisting of TiO₂ nanoparticles and carbon nanotubes (CNTs) onto the surface of the anode to protect it and enhance its electrochemical behavior. The TiO₂ nanoparticles acted as a barrier, which simultaneously effectively inhibited the dissolution and corrosion of Zn and provided numerous nucleation sites for Zn plating, whereas the CNTs played a crucial role in reducing the interfacial resistance of the electrode owing to their network structure and high electrical conductivity. The ZIBs with a surface-modified Zn anode demonstrated a high energy density of 267 and 91 Wh kg⁻¹ over a power density range of 300 to 2000 W kg⁻¹. Additionally, the TiO₂ nanoparticles and CNT protective layer induced a flatter and denser growth of dendrites, enabling the utilization of a thinner separator. This design enabled a higher volumetric energy storage capacity (24.6 mAh cm⁻³). The suggested approach offers considerable potential to enhance the energy storage capabilities of ZIBs significantly, while also diminishing their cell size.