Adjustment of zinc ion storage performance by the synergetic effect of P/S heteroatoms, pore engineering and additive

The P/S doped carbon nanosheets (PSCN) were prepared by one-step method. • PSCN exhibits uniform N, S doped, porous structures and abundant defect sites. • The PSCN presents large Zn 2+ ion diffusion coefficient of 1.07 × 10 −6  cm 2  s −1 . • PSCN cathode displays long cycle life with capacity increase of 0.29% after 50,000 cycles. Aqueous zinc-ion hybrid capacitors have become an attractive option in the fields of energy storage on account of their inherent affordability and enhanced safety features. However, there is room for significant improvement in terms of energy density and specific capacity in current state. To solve this problem, we propose a strategy to improve the surface characteristics of carbon nanosheets (CNs) by synergistically incorporating P/S heteroatoms and pore engineering. The doping of P/S heteroatoms not only furnish defect sites, but also facilitates the redox reaction between Zn 2+ and oxygen functionalities. Additionally, the pore engineering enables the formation of multiple ion adsorption sites and transport channels in the CNs. Meanwhile, the KI additive introduces reversible I − /I 3 − redox reactions on the cathode, contributing extra faradaic capacity, and stabilizes the Zn anode by regulating Zn 2+ deposition and suppressing side reactions. Therefore, the PSCN cathode displays interesting zinc ion storage merits, e.g. large discharge capacity of 284.29 mAh g −1 at 0.1 A g −1 , excellent energy density of 240.72 Wh kg −1 and long cycle life with capacity increase of 0.29% after 50,000 cycles. This study affords a route to boost Zn 2+ storage performance by the synergetic effect of heteroatoms, pore engineering and ion additives. Download: Download high-res image (79KB) Download: Download full-size image