Carbon material produced by hydrothermal carbonisation of food waste as an electrode material for supercapacitor application: A circular economy approach

This study aims to use landfill leachate (LL) as an aqueous medium during hydrothermal carbonisation (HTC) of food waste to produce hydrochar (FWH-LL-C), which could be used as an electrode material in energy storage devices. The structural properties and electrochemical performance of the hydrochar were compared to that obtained using distilled water as a reaction medium (FWH-DW-C). The results showed that there is a difference in Brunauer-Emmett-Teller (BET) surface area of FWH-LL-C (220 m(2) gm(-1)) and FWH-DW-C (319 m(2) gm(-1)). The electrochemical properties were comparable, with FWH-LL-C having 227 F g(-1) specific capacitance at 1 A g(-1) current density and FWH-DW-C having 235 F g(-1) specific capacitance at 1 A g(-1) current density. Furthermore, at a power density of 634 W kg(-1), FWH-DW-C achieved the highest energy density of 14.4 Wh kg(-1). The energy retention capacity of the electrode was 98% which indicate that the material has an excellent energy storage capacity. The findings suggested that LL could be used as an alternative source of aqueous media during the HTC of food waste to produce hydrochar which could be used as an effective electrode material in supercapacitors.

Automated summary

This study investigates the use of landfill leachate as a medium in the hydrothermal carbonisation process of food waste to produce hydrochar. The hydrochar's structural and electrochemical properties were compared to those produced using distilled water. The results show that while there is a difference in surface area, the electrochemical performances of the two are comparable. This suggests that landfill leachate can be used as an alternative aqueous medium to produce hydrochar for use in supercapacitors.