Direct and Rapid High-Temperature Upcycling of Degraded Graphite

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Li, Tangyuan
Tao, Lei
Xu, Lin
Meng, Taotao
Clifford, Bryson Callie
Li, Shuke
Zhao, Xinpeng
Rao, Jiancun
Lin, Feng
Hu, Liangbing
Li, T., Tao, L., Xu, L., Meng, T., Clifford, B. C., Li, S., Zhao, X., Rao, J., Lin, F., Hu, L., Direct and Rapid High-Temperature Upcycling of Degraded Graphite. Adv. Funct. Mater. 2023, 2302951.
Recycling the degraded graphite is becoming increasingly important, which can helped conserve natural resources, reduce waste, and provide economic and environmental benefits. However, current regeneration methods usually suffer from the use of harmful chemicals, high energy and time consumption, and poor scalability. Herein, we report a continuously high-temperature heating (≈2000 K) process to directly and rapidly upcycle degraded graphite containing impurities. A sloped carbon heater is designed to provide the continuous heating source, which enables robust control over the temperature profile, eliminating thermal barrier for heat transfer compared to conventional furnace heating. The upcycling process can be completed within 0.1 s when the degraded graphite rolls down the sloped heater, allowing us to produce the upcycled graphite on a large scale. High-temperature heating removes impurities and enhances the graphitization degree and (002) interlayer spacing, making the upcycled graphite more suitable for lithium intercalation and deintercalation. The assembled upcycled graphite||Li cell displays a high reversible capacity of ≈320 mAh g−1 at 1 C with a capacity retention of 96% after 500 cycles, comparable to current state-of-the-art recycled graphite. The method is a chemical-free, rapid, and scalable way to upcycle degraded graphite, and is adaptable to recycle other electrode materials.