Refurbished carbon materials from waste supercapacitors as industrial-grade electrodes: Empowering electronic waste

Abstract

Reinstallation of industrial-grade electrode materials by recycling waste electrochemical energy storage devices is the best way to achieve excellent economic and environmental benefits. In this study, we repaired active carbon materials from end-of-life supercapacitors using simple thermal activation and back-integrated them into high-voltage and super-stable supercapacitors. The recovered carbon materials retained their excellent surface and structural features, including a large specific surface area (~1716 m2/g) with a surface morphology composed of fine nanoparticles and a high degree of graphitization with well-oriented graphitic layers. The repaired carbon was then re-instated in an innovative water-in-salt electrolyte, which can easily be cycled in an extended working voltage range (2 V). Benefiting from the maintained structural and surface characteristics, the renovated supercapacitor delivered exceptional cycling stability over 300,000 cycles, with 99% capacitance retention, achieving a high capacitance of 57 F/g (0.25 A/g), a specific energy of 32 Wh/kg (0.25 A/g), and a rate capability of 85.90%. This ground-breaking performance of recovered materials from waste supercapacitors will encourage future waste-recovery initiatives, aiding sustainable practices and the circular economy.