The Li Insertion-Extraction Characteristics of Amorphous Silicon Thin FilmsReport as inadecuate

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Chemical and biochemical engineering quarterly, Vol.21 No.1 March 2007. -

Amorphous hydrogenated silicon a-Si:H is known to be a perspective material for negative electrodes of modern lithium-ion batteries. The electrochemical lithium insertion into thin-film a-Si:H electrodes is studied using chronopotentiometry, cyclic

voltammetry CV, and electrochemical impedance spectroscopy EIS. The electrodes were grown on stainless-steel substrates by glow discharge at the temperature of T = 100 and 250 oC. The insertion capacity of the films deposited at 250 oC is higher than

that of the equally thick films deposited at 100 oC. The increase in the film thickness involves the drastic decrease of the insertion capacity during the potential cycling. An equivalent circuit is suggested for the lithium insertion to the electrodes, which comprises electrolyte resistance and three RC-chains in series, each chain being a parallel

connection of a resistance and a constant-phase element, which relate to charge transfer at the silicon-electrolyte interface, charge transport in the passive film on silicon, and the lithium diffusion into the silicon bulk. With the potential cycling in progress, the most significant changes are observed in the chain relating to the passive film. The Li diffusion coefficient in a-Si:H is estimated from data of CV and EIS. It equals D = 4 ·10–13 and 10–13 cm2 s–1 for electrodes synthesized at a temperature of 100 and 250 oC, respectively.

Amorphous silicon; thin films; lithium insertion; diffusion coefficient; chronopotentiometry; electrochemical impedance spectroscopy

Author: T.L. Kulova - A.M. Skundin - Yu. V. Pleskov - O.I. Konkov - E.I. Terukov - I.N. Trapeznikova -



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