CoNi2S4 Electrode with High Mass‐Loading for High‐Energy‐Density Supercapacitor: Role of S‐Containing Anions Exchange

Abstract

AbstractAnion exchange is recognized as an effective method to regulate the composition, electronic conductivity, and electrochemical behavior of the transition metal‐based compounds. In this work, anion exchange is adopted as a rational post‐treatment route to facilitate the capacitive activity of CoNi2S4 nanoparticle arrays grown on carbon cloth (CC) with high mass‐loading. As soaked in saturated Na2S solution, the CoNi2S4/CC electrode showed an increased capacity from 483 C g−1 to 841 C g−1 at 10 mA cm−2 with excellent rate performance and stable cycling performance, which was superior to the CoNi2S4/CC electrode activated by NaBH4 reduction. Anion exchange was beneficial for enhancing the crystallinity, retaining the adhesion of nanoarrays, and realizing low resistance nature in a mild route. The as‐assembled CoNi2S4/CC//activated CC hybrid supercapacitor delivered a high areal capacitance of 1.28 F cm−2 at 5 mA cm−2, and achieved an energy density of 0.58 mWh cm−2 at a power density of 4.5 mW cm−2 with excellent cycle stability with 90.6 % capacity retention after 10000 cycles.