Rationally design nickel sulfide@PEDOT arrays as binder-free cathode for durable asymmetric supercapacitor and aqueous Ni-Zn battery

The practical energy storage applications of metal sulfides are greatly hindered by their unsatisfactory specific capacity, inferior rate capability and poor stability. In this work, monolithic Ni3S2@PEDOT arrays are rationally designed by surface engineering as robust binder-free cathode to boost the electrochemical performances of asymmetric supercapacitor and aqueous Ni-Zn battery. Benefiting from the unique protective and conductive PEDOT shell to accelerate the electron/ion transport and provide a large interfacial area, the monolithic Ni3S2@PEDOT array displays a ultrahigh reversible specific capacitance (1589.3 F g(-1) at 2.0 A g(-1)) and favorable rate capability (75.5% of initial capacity retention under 10 A g(-1)). The assembled Ni3S2@PEDOT//active carbon asymmetric supercapacitor exhibits a remarkable capacity of 243.6 F g(-1) at 0.5 A g(-1) and outstanding cycling durability (only 2.4% decay within 4000 cycles). Moreover, the aqueous Ni3S2@PEDOT//Zn battery reveals an admirable specific capacity 261.9 mAh g(-1) under 3.13 A g(-1) while only reaching 2.7% capacity attenuation within 2000 cycles. Furthermore, the aqueous rechargeable Ni3S2@PEDOT//Zn battery presents an impressive energy density 456.4 Wh kg(-1), together with a peak power density 5.45 kW kg(-1). These encouraging results offer compelling insights for the design of high-performance metal sulfides and numerous electronics, electric vehicle applications in the future. (c) 2020 Elsevier Ltd. All rights reserved.