Stabilizing zinc metal anodes with MXene-derived electrospun titanium dioxide/carbon nanofiber protective layers

Aqueous zinc-ion batteries (ZIBs) have garnered significant attention due to their high theoretical capacity, high safety, and low cost. However, issues such as dendrite growth, anode corrosion, and by-product formation during the Zn²⁺ stripping/plating process severely hinder their cycle life. To address these challenges, we propose a TiO₂/carbon nanofiber (TiO₂/CF) artificial protective layer, denoted as PT-700, which is obtained by heat treatment of electrospun MXene/PAN-derived nanofibers at 700 °C. The highly conductive carbon nanofiber, featuring a three-dimensional (3D) porous structure, along with zincophilic TiO₂ nanoparticles, guides Zn²⁺ flux and regulates Zn²⁺ nucleation sites, resulting in uniform zinc anode deposition. Consequently, the composite protective layer enables the symmetrical battery to achieve an ultra-long cycle life of 2000 h (5.0 mA cm^-2 and 1.0 mAh cm^-2) and high rate capability (15 mA cm^-2). Furthermore, Zn//VO₂ full batteries deliver a high capacity of 262 mAh g^-1 at 0.5 A g^-1, excellent rate capability with 100 mAh g^-1 retained at 20 A g^-1, and outstanding cycling stability with 93.14 % capacity retention after 3000 cycles at 5 A g^-1. Meanwhile, Zn-ion capacitors (Zn//AC) exhibit a capacitance of 91.5 F g^-1 at 1 A g^-1 and remarkable durability, maintaining stable operation for over 40,000 cycles at 2 A g^-1 and more than 50,000 cycles at 4 A g^-1. These results highlight the innovative design and practical promise of the PT-700 artificial protective layer for stable Zn metal anodes.