High performance flexible quasi-solid-state zinc-ion hybrid supercapacitors enable by electrode potential adjustment

Rechargeable zinc-ion batteries have received increasing attention because of their cost effectiveness, eco-friendliness, and high capacity. However, they suffer from poor rate capacities and low lifespans because of the uncontrolled formation of zinc dendrite on the zinc metal anode. Although replacing the zinc metal negative electrode could fundamentally solve the dendritic problem, it may lead to the lack of anodic Zn2+ source to sustain the charge carriers during charge-discharge. Here, by adopting a pre-zincation electrode treatment, we demonstrate a novel zinc-ion hybrid supercapacitor (ZIS) by using GNS/CNT@MnO2 electrode and activated carbon electrode as the positive and negative electrode, respectively. The ZIS exhibits a high specific energy of 41.5 Wh kg−1 and excellent cycle stability. It retains over 81% of its initial capacitance and near 100% coulombic efficiency after 10000 cycles at 2 A g−1. We also create a Flexible Quasi-Solid-State Zinc-ion Hybrid Supercapacitor (FQSSZIS) by using a ZnSO4/MnSO4-xanthan gel electrolyte and cheap graphite paper current collectors. The obtained device exhibits excellent flexibility, good cycling stability, and a high energy density of 3.13 mWh cm−3 with a power density of 7 mW cm−3. The pre-zincation approach exhibits great potential for exploring zinc-ion energy storage devices without zinc metal electrodes.