Molecular firefighting biocomposites for plastic life-cycle management: fabrication, use and upcycling

Abstract

The low degradability and durability of plastics are a double-edged sword: they enable plastics to have versatile applications in the use phase, but pose environmental challenges at the end-of-life of the plastics. This dilemma requires innovative strategies to strike a balance between the plastic performance and recycling to achieve a sustainable ecosystem. To address the challenges, we constructed a hybrid biocomposite (denoted as EVA/MPAPS) made of an ethylene-vinyl acetate (EVA) copolymer and melamine phytate decorated potato starch (MPAPS), which has tailored recyclable properties, via a recycle-by-design strategy. The EVA/MPAPS presented high performance in fire safety and mechanical behavior in its use phase; at the end-of-life, it could be converted into high-value-added carbons via controlled carbonization for versatile electrochemical applications, thus maximizing the valorization of the biocomposites. The electrochemical performances of the recycled carbons could be manipulated by adjusting their porosity and chemical structure through different carbonization temperatures. The recycled carbons carbonized by EVA/MPAPS at 600 °C (denoted as MPAPS600) exhibited a specific capacitance as high as 207 F g⁻¹ at 1 A g⁻¹, which was almost twice that of a commercial supercapacitor (YP-50F), as well as an excellent rate capability of 72% capacitance retention at 20 A g⁻¹. When the carbonization temperature was elevated to 700 °C, the recycled carbons (denoted as MPAPS700) presented high reversible capacity (204.4 mA h g⁻¹ at 500 mA h g⁻¹), good cycling performance (∼79% retention after 450 cycles) and excellent coulombic efficiency. This work provides a new perspective on the prospects for management of the fabrication, use and upcycling of biocomposites efficiently, thus moving forward towards a circular carbon economy.