Upcycling of Packing-Peanuts into Carbon Microsheet Anodes for Lithium-Ion Batteries.

Porous carbon microsheet anodes with Li-ion storage capacity exceeding the theoretical limit are for the first time derived from waste packing-peanuts. Crystallinity, surface area, and porosity of these 1 μm thick carbon sheets were tuned by varying the processing temperature. Anodes composed of the carbon sheets outperformed the electrochemical properties of commercial graphitic anode in Li-ion batteries. At a current density of 0.1 C, carbon microsheet anodes exhibited a specific capacity of 420 mAh/g, which is slightly higher than the theoretical capacity of graphite (372 mAh/g) in Li-ion half-cell configurations. At a higher rate of 1 C, carbon sheets retained 4-fold higher specific capacity (220 mAh/g) compared to those of commercial graphitic anode. After 100 charge-discharge cycles at current densities of 0.1 and 0.2 C, optimized carbon sheet anodes retained stable specific capacities of 460 and 370 mAh/g, respectively. Spectroscopic and microscopic investigations proved the structural integrity of these high-performance carbon anodes during numerous charge-discharge cycles. Considerably higher electrochemical performance of the porous carbon microsheets are endorsed to their disorderness that facilitate to store more Li-ions than the theoretical limit, and porous 2-D microstructure enabling fast solid-state Li-ion diffusion and superior interfacial kinetics. The work demonstrated here illustrates an inexpensive and environmentally benign method for the upcycling of packaging materials into functional carbon materials for electrochemical energy storage.