Investigation of lithium utilization from a lithium--silicon electrode. [Liâ Si, Liââ Siâ, Liââ Siâ]

A half-cell of the type Li (in solid Li/sub 2/Si or Li/sub 21/Si/sub 8/, or Li/sub 15/Si/sub 4/)/LiCl--KCl eutectic or LiF--LiCl--KCl melt or LiF--LiCl--LiBr melt/Li (in solid Li/sub 2/Si in equilibrium with Si) was used to investigate lithium utilizations (to a 0.5 V cutoff vs. 40 atomic percent Li--Al) from Li/sub 2/Si, Li/sub 21/Si/sub 8/, and Li/sub 15/Si/sub 4/ at current densities between 20 and 1000 mA/cm/sup 2/ and at temperatures between 675/sup 0/ and 750/sup 0/K. The lithium utilizations from these compounds did not appear to be greatly influenced by current density or temperature variations. For example, 60 to 80% of the lithium from the Li/sub 2/Si--Si plateau, >90% of the lithium from the Li/sub 21/Si/sub 8/--Li/sub 2/Si plateau, and 80 to 90% of the lithium from the Li/sub 15/Si/sub 4/--Li/sub 21/Si/sub 8/ plateau were utilized at current densities between 50 and 400 mA/cm/sup 2/. The polarization at current densities up to 500 mA/cm/sup 2/ appeared to be mostly ohmic. 10 figures, 4 tables.