Facile synthesis of ultrathin ZnCo2O4 nanosheets/carbon cloth composite electrode for hybrid supercapacitors with high-rate and excellent reversibility

Abstract

Supercapacitors (SC) are considered to be a promising energy storage device due to their series of advantages. However, preparation of electrode materials with controllable morphology is still a challenge for SC. In this work, ultrathin ZnCo2O4 nanosheets were prepared on the carbon cloth (CC) substrate (ZCO/CC) by regulating electrochemical deposition with a bidirectional pulse current method in an organic system. The ultrathin nanosheets with the thickness of 3 ~ 4 nm possess a larger specific surface area and increasing reactive active sites, shortening the electron transmission path during the electrochemical reactions. Comparing the samples deposited for 15 min (ZCO/CC-15), 30 min (ZCO/CC-30), and 60 min (ZCO/CC-60), the results prove that ZCO/CC-30 has the best electrochemical performance with a specific capacitance of 149.8 F g−1 at the current density of 1 A g−1, a good rate capability (93% capacitance retention at 10 A g−1) and excellent reliability with a retaining capacitance of 135F g−1 after 10,000 cycles. Using ZCO/CC as cathode and CC as anode, the as-prepared hybrid SC also shows a good electrochemical performance.