Behavior of electrodeposited silicon film on glassy carbon during lithiation and delithiation

Silicon is one of the promising anode materials for lithium-ion batteries with enhanced performance. However, the degradation of silicon during lithiation/delithiation is still the main problem that prevents it commercial use as electrodes. In this work the behavior of a silicon film of about 5–6 µm thick electrodeposited from LiCl-KCl-CsCl-K2SiF6 melt on glassy carbon was studied during its lithiation and delithiation, the film being a part of the anode half-cell of a lithium-ion battery. For this purpose, the methods of cycling in galvanostatic mode, electrochemical impedance, and scanning electron microscopy were used. The principal possibility of lithiation/delithiation of the film was shown and its energy characteristics during multiple cycling were determined. However, during 714 charge-discharge cycles with the current being 0.84 A/g the discharge capacity decreased from 723 to 58 mA·h/g. It was noted that the cause of degradation of the investigated sample was the detachment of the film from the glassy carbon substrate and its cracking.