Flash upcycling of waste glass fiber-reinforced plastics to phase-controllable silicon carbide

The increasing use of fiber-reinforced plastic has triggered an urgent demand for its recycling once it reaches its end-of-life. Currently, landfilling and incineration are major disposal methods of fiber-reinforced plastic, which lead to undesirable waste of resources and environmental contamination. To address this issue, we disclose a solvent-free and energy-efficient flash upcycling method to convert the mixture of glass fiber-reinforced plastic and carbon fiber-reinforced plastic into SiC powders within seconds and in yields of >90%. By modulating input pulse voltages and flash times, SiC with two different phases, 3C-SiC and 6H-SiC, can be selectively synthesized, each with phase purity of 90-99%. Theoretical simulations reveal that the increasing content of Si vacancy during flash process dominates the phase transformation from 3C-SiC to 6H-SiC. The SiC powders are further used as the anode material for lithium-ion batteries, which yields a phase-dependent performance. The 3C-SiC anode exhibits superior reversible capacity (741 mAh·g-1 at 0.2 C) and rate performance over the 6H-SiC anode (626 mAh·g-1 at 0.2 C), while both show excellent cycling stability (~95% capacity retention after 200 cycles). Life cycle assessment reveals the flash upcycling process greatly reduces the energy demand, greenhouse gas emission and water consumption over other recycling processes.