Low-crystalline urchin-like CuCo2O4/rGO composite for high-performance supercapacitor

Abstract

Abstract To meet the excellent capacity, power density and long lifespan for supercapacitors, de-veloping advanced transition-metal oxide (TMO) electrode materials is an important topic. Herein, we explored the effect of alkali source hydrolysis on the structural feature of CuCo2O4 during the growing process. It is found that urea with stronger hydrolysis ability leads to better morphology but larger crystalline grain size. Further, the grain size is decreased by introducing reduced graphene oxide (rGO). Consequently, the urea-derived CuCo2O4/rGO (UCG) composite with urchin-like hierarchy configuration and small crystalline grain size provides a specific capacity of 1664 C g−1 at current density of 1 A g−1, and remains 65.3% of initial capacity when the current density increases to 30 A g−1. The symmetric supercapacitor achieves a high energy density (16 Wh kg−1 at 7200 W kg−1) and cycle stability (93.2% capacity retention after 10,000 cycles at 10 A g−1). This study highlights the inherent relation between the structural feature and syn-thesis condition.