High-performance battery-type supercapacitor based on porous biocarbon and biocarbon supported Ni–Co layered double hydroxide

To achieve robust and efficient architecture for supercapacitor electrodes, seeds of Toona sinensis (STS) with honeycomb structure are used as template to obtain STS derived carbon (STSC), which act as substrate for both negative and positive electrodes of a battery-type supercapacitor. When activated by KOH, the as obtained anodic a-STSC-1-600 with a big specific surface area of 1031.6 m g−1 shows a specific capacitance of 210.0 F g−1 at 1 A g−1. After hydrothermally growing Ni–Co layered double hydroxide, the as obtained cathodic Ni–Co LDH/STSC-0-800 exhibits a big specific capacitance of 992.2 F g−1 (1 A g−1). Both electrodes show excellent rate capability due to the stable and unblocked honeycomb structure. When constructing into a battery-type supercapacitor (Ni–Co LDH/STSC-0-800||a-STSC-1-600), a wide working voltage window of 1.5 V is achieved. The device delivers a relatively high energy density of 23.5 Wh kg−1 and a power density of 959.7 W kg−1, with decent rate capability and cycling stability. This work explores a simple way to fabricate highly-interconnected carbon substrate and its further processing on fabricating efficient anodic and cathodic materials for battery-type supercapacitors.