Rational Assembly of CoAl‐Layered Double Hydroxide on Reduced Graphene Oxide with Enhanced Electrochemical Performance for Energy Storage

Abstract

AbstractIn this paper, we designed and synthesized composites of CoAl‐layered double hydroxide on reduced graphene oxide (CoAl‐LDH@rGO/NF) via a facile approach. The Co‐Al layered double hydroxide (CoAl‐LDH) nanosheets were grown onto the skeleton of reduced graphene oxide on Ni foam (rGO/NF). The as‐synthesized CoAl‐LDH@rGO/NF composites exhibited a superior electrochemical behavior, attributed to the coupling effect of homogeneous CoAl‐LDH nanosheets and high conductivity of rGO. In addition, the different morphologies of the CoAl‐LDH@rGO/NF composites can be controlled by adjusting the amount of NH4F. The optimum electrochemical performance of the CoAl‐LDH@rGO/NF hybrid electrode was obtained when the amount of NH4F was 6 mmol. The largest specific capacitance of 1671.4 F g−1 (1 A g−1) and the ultra‐high cycling performance with 97 % retention of the original value were achieved even after 5000 charge‐discharge cycles. A remarkable energy density value of 41.3 Wh kg−1 at a power density of 408.9 W kg−1 was achieved in the asymmetric supercapacitor (ASC) using CoAl‐LDH@rGO‐6/NF and activated carbon (AC) for positive and negative materials. Furthermore, the ASC retained 100 % of its original energy density value even after 5000 cycles. In addition, a design method for preparing high performance electrode materials with ideal morphology is proposed in this paper, which might be helpful to the future study of morphology and electrochemical properties.