Anode performance of lithium-silicon alloy prepared by mechanical alloying for use in all-solid-state lithium secondary batteries

Li22Si5 alloy powder was synthesized by mechanical alloying and its electrochemical performance was investigated for use in solid-state battery anodes. Two types of anode powder were prepared: 1) Li-Si alloy powder after mechanical alloying with Li-granules and Si-powder, and 2) Li-Si alloy powder from the first process followed by additional ball milling for reduction of particle size. Using these anode materials, all-solid-state lithium batteries were assembled with Li4Ti5O12 (LTO) as cathode and Li2S-P2S5 as electrolyte. Impedance spectra of the two types of cells were measured, and the results showed that the non-ohmic resistance was less in the case of the cell with the secondary ball-milled, fine anode powder. Galvanostatic charge/discharge tests were also performed, and capacity was increased about two times by the additional powder milling process; which is consistent with the impedance results. Thus, the results from the present work indicate that using the secondary milling process to refine the electrode powder is an effective way to increase the kinetics of alloying and de-alloying with improvement in interfacial properties in all-solid-state lithium secondary batteries. (C) 2014 The Japan Society of Applied Physics