Cation-exchange-assisted formation of NiS/SnS2 porous nanowalls with ultrahigh energy density for battery-supercapacitor hybrid devices

摘要

As a new type of electrochemical energy storage system, aqueous battery-supercapacitor hybrid (BSH) devices are attracting increasing interest due to their high energy and power density, high security, and low cost. Herein, hierarchical NiS/SnS2 heterogeneous nanowall arrays on carbon cloth (NiS/SnS2@CC) are synthesized via a simple cation-exchange method using SnS2@CC as the precursor. Benefiting from the maximum use ratio of the active materials and the synergistic effects between the SnS2 core and the NiS shell, NiS/SnS2@CC delivered an ultrahigh specific capacity of 430.38 mA h g(-1) at a current density of 2.5 mA cm(-2) (1.16 A g(-1)) with excellent rate capability of 185.08 mA h g(-1) at a very high current density of 40 mA cm(-2) (23.26 A g(-1)) and satisfactory cycling stability (82.6% of capacity retention after 1000 cycles). Moreover, all-solid-state BSH devices could be assembled using NiS/SnS2@CC as the battery-type cathode and Fe2O3/rGO@CC as the supercapacitor-type anode. With a maximum working voltage of 1.6 V, such a device exhibited a very high energy density of 104.23 W h kg(-1) at a power density of 301 W kg(-1) with excellent cycling stability and flexibility. This rational design and preparation strategy may provide new insight into the development of high-performance electrode materials for electrochemical devices.