Optimization Of Zinc Anodes Via Interface Regulation Strategy For Aqueous Zinc-Iodine Batteries

Aqueous rechargeable zinc-iodine batteries(ARZIBs)as a promising new type of energy storage equipment have the advantages of high theoretical specific capacity(211 mAh g-1),low cost,and good safety.However,the dendrites growth caused by uneven Zn deposition and side reactions seriously endanger the cycling stability and lifespan of ARZIBs.Interfacial coating modification,gel electrolyte and other strategies were adopted to regulate Zn deposition process and inhibit corrosion reactions,thus improving the performance of aqueous zinc-iodine batteries.The main research results are summarized below:(1)On the basis of the chemical inertness of metallic tin(Sn)and good compatibility with Zn anode,the tin functional layer was constructed on the surface of Zn anode(Zn|Sn)via the spontaneous displacement reaction.The tin functional layer not only provides abundant nucleation sites for lowing the nucleation overpotential of Zn deposition,but also can inhibit the growth of Zn dendrites via the induced deposition effect,realizing a highly reversible Zn plating/stripping process.Furthermore,the corrosion reaction is effectively inhibited due to the inherent chemical inertness and isolation of tin coating.Therefore,Zn|Sn anodes exhibited ultra-low overpotential(13.9 mV)and good stability for more than 900 h in symmetric cells.(2)A highly conductive gel electrolyte(IC-Zn)with ion transfer channels was fabricated via the cold-set mechanism and cation bridging effect,which can achieve rapid ion transfer.Its unique double helix structure with good mechanical properties provides the rapid zinc ion channels guided by sulfate groups,thus confining and guiding the order Zn deposition process.Therefore,the zinc-iodine batteries fabricated with IC-Zn gel electrolyte exhibited the remarkable reversibility and stability with an impressive capacity retention(91.9%)and a high average coulombic efficiency(99.8%)over 5000 cycles.(3)A uniform organic-metal functional film(PAA-Zn)was coated on the surface of Zn foil via the coordination of polyacrylic acid and divalent metal ions.The carboxyl groups uniformly distributed in PAA-Zn film can not only adjust the uniform distribution of the interfacial electric field,inhibiting the growth of zinc dendrites,but also significantly enhance the interfacial hydrophilicity,thus improving the electrolyte/electrode interface contact.Furthermore,the PAA-Zn film can reduce the free water molecules reaching to the zinc surface,thus inhibiting corrosion and hydrogen evolution side reactions.Therefore,PAA-Zn electrodes in symmetrical cells showed a cycling lifespan of more than 1000 h and excellent stability.