A multifunctional MXene-porous polydopamine interface for stable and dendrite-free zinc metal batteries

Aqueous zinc ion batteries are regarded one of the most promising next generation battery technologies for safe and low-cost energy storage applications. However, the inevitable dendrites growth and detrimental side reactions for Zn metal anodes in aqueous electrolytes induce short cycle life, low coulombic efficiencies, and cell failure. Here we propose to construct a MXene-porous polydopamine (MPP) interfacial layer on the Zn metal surface. The abundant functional groups in MPP can effectively trap water molecules to suppress their corrosion to Zn metal, indicating the desolvation and anticorrosion functions. Combined experimental and simulation results show that MPP layers can also lower the nucleation overpotentials and homogenize the electric field distribution and Zn ion flux, which ensure the horizontal and dendrite-free Zn metal deposition. The MPP-Zn electrodes exhibit an exceptionally long cycle life of over 1000 h (10 times that of bare Zn) and excellent high-rate capabilities in (a)symmetric cells. When the optimal Zn anodes were coupled with NH4V4O10 cathodes, the Zn metal full cells presented a remarkable capacity of 368 mAh g−1 and negligible capacity degradations after 300 cycles, which rivals the state-of-the-art performance in literature. The multifunction-in-one concept in this work would spur the development of practical Zn metal batteries.