Anion‐cation double‐substitution endows iron sulfide with remarkably enhanced specific capacity and rate performance as anode for supercapacitors

Abstract

Metal sulfides have shown great potential as the anodes of the asymmetric supercapacitors ascribed to their superior theoretical specific capacitance. However, their specific capacitance and rate performances are still far from the expectation due to the intrinsic poor electronic conductivity and sluggish kinetics. Herein, we employ the anion and cation double‐substitution strategy to prepare iron sulfide nanoparticles on graphene composite (denoted as NiFeSP/G) to improve the electronic conductivity of FeS2. The NiFeSP/G composite exhibits greatly improved electrochemical performances with a high specific capacity of 765 C g−1 (765 F g−1) at 5 A g−1 and a remarkable rate capability of 65% at 100 A g−1. Moreover, an aqueous asymmetric supercapacitor is fabricated with the NiFeSP/G as anode and NiCo‐LDH/graphene as cathode presents an impressively high energy density up to 109 Wh kg−1 at 1591 W kg−1 and cycling performance (89% of the initial capacity retained after 8000 cycles).

Shape controlled growth of hierarchical NixSy on stainless steel by solution processing with enhanced electrochemical energy storage performance

“…The electrodes displayed similar redox behavior, with well-defined redox peaks within the range of applied potential, indicating the faradaic battery-type behavior of Ni x S y /SS electrodes. 24,47 The strong redox peaks in the potential sweeps, without a proper rectangular shape of the CVs, indicate that the charge storage is mainly due to the faradaic process between Ni 2+ and Ni 3+ species of the electrodes. Moreover, the anodic sweeps are not symmetric compared to their corresponding cathodic sweeps in CVs, which corresponds to the kinetic irreversibility in the redox process.…”

“…The relative contribution for surface-controlled faradaic (capacitive) and diffusion-controlled battery type charge storage behavior was estimated by using the following equation: 24 i ( v ) = k 1 v + k 2 v 1/2 here i ( v ) is the current in CV curves, k 1 and k 2 are constants, and v is the scan rate. Eqn (7) can be rearranged as follows:by plotting eqn (8), k 1 and k 2 can be calculated from the slope and intercept, respectively.…”

“…For instance, iron sulfide with anion-cation double substitution demonstrated excellent specific capacity and rate performance as an anode supercapacitive material. 24 Similarly, the NiS/rGO composite prepared using a facile solid-phase route displayed high energy and charge density along with a remarkable capacity retention of over 30 000 charge/ discharge cycles. 25 Nickel sulfides have received recent attention as electrode materials for SCs due to their high redox activity, low cost, ecofriendliness, diverse stoichiometric combinations such as NiS, NiS 2 , Ni 7 S 6 , Ni 3 S 4 , Ni 3 S 2 , etc., and ease of fabrication in various shapes.…”

“…For instance, iron sulfide with anion–cation double substitution demonstrated excellent specific capacity and rate performance as an anode supercapacitive material. 24 Similarly, the NiS/rGO composite prepared using a facile solid-phase route displayed high energy and charge density along with a remarkable capacity retention of over 30 000 charge/discharge cycles. 25…”

Rational design of CoP@Ni(OH)2 bilayer nanosheets for high-performance supercapacitors

“…1,2 Supercapacitors (SCs), a type of electric power storage technology, have received a great deal of focus from researchers due to their large cycle lifespan, rapid charging/discharging cycles, and high power densities. [3][4][5] Nevertheless, the limited energy density hinders the practical application of SCs. Generally, SCs include electric double-layer supercapacitors (EDLCs) and pseudocapacitors (PCs).…”