One-step oil bath preparation of cobalt-doped MnO2/coconut activated carbon composite with superior zinc ion storage performance

Abstract

MnO2 is a prospective cathode material for aqueous zinc ion batteries due to its high theoretical capacity and low cost. However, bare MnO2 usually suffers from large volume change and dissolution problems. In this work, Co-doped MnO2/coconut activated carbon composite (Co-β-MO/CAC) has been successfully synthesized by a one-step oil bath method. The electrochemical impedance spectroscopy (EIS) and galvanostatic intermittent titration technique (GITT) tests demonstrate that both the Co doping and the incorporation of coconut activated carbon can effectively reduce the electrochemical reaction resistance of MnO2 and improve the intercalation and deintercalation abilities of H+ and Zn2+. The combined effect of the Co doping and CAC compositing has resulted in excellent electrochemical property of Co-β-MO/CAC. After 120 cycles at 0.2 A g−1, the capacity of Co-β-MO/CAC increases from 224.7 mAh g−1 to 436.7 mAh g−1. Moreover, the composite can also deliver a high reversible capacity of 233.2 mAh g−1 after 900 cycles at 0.5 A g−1.