Novel zinc-iodine hybrid supercapacitors with boosted energy density using redox iodide ion electrolyte and B, N dual doped carbon electrode

With the development of modern society, energy storage gradually becomes a crucial issue for portable device and electric vehicle. Recently, zinc-ion hybrid supercapacitors (ZHS), as a new type of energy storage device, have received great attention, mainly because zinc possesses many advantages, such as natural abundance, low cost, non-toxicity and high safety. However, the limited energy density of currently reported ZHS should be further promoted for their large-scale applications. Herein, we designed novel zinc-iodine hybrid supercapacitors (Z-IHS) via introducing redox iodide ion in ZnSO4 electrolyte to improve the energy density and employing B, N dual doped porous carbon microtubes (BN-CMT) as cathode to facilitate the faradaic reaction on the electrode surface by changing the electronic structure and density state of carbon. BN-CMT based Z-IHS exhibits an amazingly high capacity of 416.6 mAh g-1, high energy density (472.6 Wh kg-1) at the power density of 1600 W kg-1 in a voltage range of 0.2-1.8 V and excellent cycling stability with a capacity retention of 99.1% over 10000 cycles at 10 A g-1. The strategy in this work should provide a new insight in exploring high energy density storage device.