Apricot shell derived hard carbons and their tin oxide composites as anode materials for sodium-ion batteries

To be used in sodium ion batteries, preparation of the hard carbon anode materials from the bio waste source of apricot shell (AS) via hydrothermal carbonization (HTC) is introduced. Further pyrolysis at different temperature conditions are applied in order to attain sufficient conductivity and higher surface area that are essential for battery applications. With the purpose of increasing the sodium storage capacity values, SnO2 nanoparticles under HTC conditions are also incorporated into the AS derived carbons. The superior capacity values are obtained with 1000 °C temperature treated hard carbon anode materials with 184 mAh/g of capacity over 250 cycles. In-situ preparation method for the SnO2 hard carbon anode results much improved electrochemical properties. In contrast, mechanically mixing of SnO2 with hard carbon results fast capacity fading since SnO2 particles are not coated with AS derived carbon which functions as volume expansion suppressor of the nanoparticles.