Controlled synthesis of spindle-like CoNi2S4 as electrode material for aqueous energy storage application

Rational structural design is an important method to control conductivity and enhance the electrochemical performance. In this work, a spindle-like CoNi2S4 is prepared by a simple hydrothermal technique. XRD and SEM tests indicate the spindle shape of CoNi2S4. TEM measurement further implies the hollow structure, which can effectively shorten electron/ion transfer distance and improve conductivity. Electrochemical analysis demonstrates that the CoNi2S4 exhibits a specific capacitance of 1326.2 F g−1 at 1 A g−1; the CoNi2S4//AC also shows high specific capacitance (96.48 F g−1 at 0.2 A g−1) and cycling durability with nearly no capacitance retention after 10,000 cycles. Furthermore, in Ni–Zn battery application field, the CoNi2S4//Zn also displays satisfying specific capacity (156.7 mAh g−1 at 0.5 A g−1) and cycle durability (∼60.3 % capacity retention after 1500 cycles). The above results imply that CoNi2S4 is a promising electrode candidate in energy storage field.