A novel redox bromide-ion additive hydrogel electrolyte for flexible Zn-ion hybrid supercapacitors with boosted energy density and controllable zinc deposition. Issue 30 (21st July 2020) - Han, Lu
Abstract : A novel redox bromide-ion additive hydrogel electrolyte was designed for flexible Zn-ion hybrid supercapacitors to improve their energy density. Abstract : With the rapid development of flexible wearable electronic devices and the growing energy demands of modern society, flexible energy storage equipment is attracting increasing attention. Recently, flexible Zn-ion hybrid supercapacitors (ZHSs), as a new type of flexible energy storage device, have been reported. However, the limited energy density of the currently reported flexible ZHSs should be further improved to realize their large-scale applications. Herein, we designed a novel redox bromide-ion additive hydrogel electrolyte (SA–Zn–Br) for flexible Zn-ion hybrid supercapacitors (BH-ZHSs) via the introduction of extra faradaic contributions (3Br − /Br3 − ) into the hydrogel electrolyte to improve their energy density. Additionally, the assembled flexible BH-ZHS displays a maximum energy density of 605 W h kg −1 at a power density of 1848 W kg −1 at an amazing voltage of 2.6 V, which is better than that of most reported flexible ZHSs. After a 5000 cycle charge/discharge cycling test, capacity retention of 87.7% is retained. Interestingly, the strong interactions between the charged groups and Zn 2+ ion in the SA–Zn–Br hydrogel electrolyte can harmonize Zn 2+ migration with uniform nucleation on a Zn foil surface, leading to layered zinc deposition. Additionally, the SA–Zn–Br hydrogel electrolyte can also serve as an inhibitor of water/oxygen, resulting in the mitigation of corrosion and highly reversible zinc stripping/depositing. The strategy described in this study should provide a new insight for exploring flexible ZHSs with boosted energy density and controllable zinc deposition.