Lithium intercalation in thin amorphous-silicon films

Abstract

Electrochemical intercalation of lithium in thin films of amorphous hydrogenated silicon (a-Si:H), deposited at temperatures of 100 and 250°C on stainless-steel substrates, is studied. It is shown that the discharge capacity of films of identical thicknesses manufactured at a temperature of 250°C is greater than that for films produced at of 100°C. Dependence of the discharge capacity of the films manufactured at 250°C on their thickness is examined. It is established that an increase in the film thickness leads to acceleration of the decrease in the discharge capacity in the course of cycling. At a current density of 0.175 mA cm−2, the discharge capacity of films 0.25 and 1.35 μm thick equals nearly 2 Ah g−1 in a third cycle, whereas in a hundredth cycle it amounts to 1.10 and 0.37 Ah g−1, respectively. The diffusion coefficient for lithium in the films is equal to ∼10-13 cm2s−1.