Pyrolysis of spent coffee grounds dispersed clay in N2: Production of type-II conductive ceramics with electrochemical performance

Pyrolysis of spent coffee grounds dispersed clay in N2 produces type-II conductive ceramics with electrochemical performance. Protective atmosphere and surface screening play important roles in converting spent coffee grounds into carbon coatings on ceramic surfaces; the former prevents oxidation of organic ingredients and confinement of pyrolysis in clay for the latter. Selective-area electrical measurements indicate resultant ceramics to be conductive and interconnected carbon coatings are further verified by SEM inspections and consistency between thermal conductivity and diffusivity. Conductive ceramics show a high usage of surface area by electric double layer charging mechanism thus giving an excellent electrochemical performance. •Spent coffee grounds dispersed clay is converted into conductive ceramics in N2.•Protective atmosphere and surface screening are key in converting spent coffee grounds into carbon coatings on ceramics.•Interconnected carbon coatings enhance electrical conductivity and thermal conductivity.•Conductive ceramics show a high usage of surface area by electric double layer charging mechanism.•The capacitance retention is 94.53 % at 2000 charge-discharge cycles.