Practical Zn anodes enabled by a Ti-MOF-derived coating for aqueous batteries

Aqueous Zn-based rechargeable batteries hold great promise for large-scale energy storage systems due to their high safety, environmental benignity, and low cost. However, the active Zn anode suffers from severe dendrite growth and hydrogen gas evolution, which have to be tackled for practical applications. Here, a Ti-MOF derived nanocomposite coating, i.e., mesoporous nitrogen-doped carbon frameworks decorated with TiO₂ nanoparticles (named TiO₂/NC), is prepared to form coatings on Zn foil for improving the anode performance. Compared to the bare Zn anode, the Zn@TiO₂/NC anode exhibits better anti-corrosion performance, much fewer byproducts, and a much longer cycle life in either half or full cells. The symmetric cell using Zn@TiO₂/NC shows a high coulombic efficiency of 99.4% and long cycle life of 1100 h when tested at 5 mA cm⁻². When combined with a MnO₂ cathode, the Zn@TiO₂/NC anode exhibits higher and more stable capacity with cycling. The role of TiO₂/NC in suppressing dendrite growth and reducing hydrogen gas evolution is discussed in detail.