A facile procedure to improve the performance of food-waste-derived carbons in sodium-ion batteries

The anode of Na-ion batteries under development is dominated by carbon materials, especially hard carbons with poorly organized structures. The production of carbon materials by pyrolysis of food waste is less expensive and more environmentally friendly than from pure organic compounds. In this work, the sulfuric acid pre-treatment of ground coffee grains before carbonization is evaluated as a simple but efficient tool to improve the electro-chemical performance of the resulting carbon for the anode of sustainable Na-ion batteries. The carbon product shows a significant reduction in inorganic impurities and a decrease in crystallinity, which results in a reversible capacity close to 33 % higher, enhanced first-cycle efficiency, and better kinetic response than the non-pre-treated materials. Thus, reversible capacities at C/10 increase from ca. 150 mAhg  1 to 200 mAhg  1 after acid treatment, and the capacity of the non-acid-treated samples falls to negligible values at 2C kinetics, in contrast with significant retention of the acid-treated one.

Automated summary

The sulfuric acid pre-treatment of ground coffee grains before carbonization was evaluated as an efficient method to improve the electrochemical performance of carbon materials for Na-ion batteries, resulting in a significant increase in reversible capacity.