Fast ion diffusion alloy layer facilitating 3D mesh substrate for dendrite-free zinc-ion hybrid capacitors

Although aqueous zinc ion hybrid capacitors have advantageous integration of batteries and supercapacitors, they still suffer from the inherent problems of dendrite growth and interfacial side reactions on Zn anodes. Herein, a universal fast zinc-ion diffusion layer on a three-dimensional (3D) mesh structure model is demonstrated to effectively improve Zn plating/stripping reversibility. The fast ion diffusion alloy layer accelerates the Zn2+ migration in an orderly manner to homogenize Zn2+ flux and overcomes the defects of the commercial mesh substrate, effectively avoiding dendrite growth and side reactions. Consequently, the proof-of-concept silver-zinc alloy modified stainless steel mesh delivers superb reversibility with the high coulombic efficiency over 99.4% at 4 mA cm−2 after 1600 cycles and excellent reliability of over 830 h at 1 mA cm−2, Its feasibility is also evidenced in commercial zinc ion hybrid capacitors with activated carbon as the cathode. This work enriches the fundamental comprehension of fast zinc-ion diffusion layer combined with a 3D substrate on the Zn deposition and opens a universal approach to design advanced host for Zn electrodes in zinc ion hybrid capacitors.