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Active material for batteries from apple leftovers

The waste apple is sliced, dried in the oven and then thoroughly ground. The resulting black-brown powder is treated with acid and pyrolysed (heated in an oven at 1100°C under inert gas) to obtain the hard carbon active material. This latter is coated on an aluminium foil to form a composite electrode which can be used as the negative electrode in sodium-ion batteries. For research purposes, a punched disk electrode is placed in a research cell under inert atmosphere (glove box). Once closed, the small research cell is subjected with the help of a so-called battery cycler to several hundreds charge and discharge cycles under chosen conditions. Further details are available in "Apple Biowaste-Derived Hard Carbon as Powerful Anode Material for Na-Ion Batteries” by L. Wu, D. Buchholz, C. Vaalma, G.A. Giffin, and S. Passerini ChemElectroChem 2016, 3, 292 (DOI: 10.1002/celc201500437)