Ultra-long cycle life flexible quasi-solid-state alkaline zinc batteries enabled by PEDOT:PSS encapsulated Ni3S2 nanorods

Abstract

Alkaline nickel-zinc (Ni-Zn) batteries are considered as one of the most promising rechargeable battery systems. However, the poor cycling stability of the Ni cathode limit their service life. Herein, a conductive polymer (PEDOT:PSS) encapsulated Ni3S2 hollow nanorod structure via facile immersion is proposed. PEDOT:PSS coating layer can not only provide adhesion for Ni3S2 nanorods to prevent Ni3S2 from falling off the substrate during cycling, but also facilitate electron transfer via the complete conductive pathway. The hollow nanorods structure of Ni3S2 is beneficial to mitigate the volume change and accelerate the rapid transport of ions. Besides, a gel electrolyte with double network porous structure in our battery system is well designed. The ionic association of sodium alginate on Zn2+ can effectively reduce the activity of bound water molecules in the solvation sheath of Zn2+, inhibit the side reaction and dendrite generation through the ion-confinement effect, to achieve uniform deposition of zinc ions. As a consequence, the as-designed quasi-solid-state flexible Ni-Zn battery demonstrates a high specific capacity of 1.06 mAh cm−2 (276.04 mAh g−1) at 8 mA cm−2 and an ultra-long cycle stability over 10,000 cycles with a capacity retention of 88.96% at 30 mA cm−2.