Mechanochemically alloyed Si-TM (TM=Fe, Cr) and Quantitative Composition Determination by Mössbauer Spectroscopy

Abstract

Si as a negative electrode material in Li-on batteries has garnered considerable research interest because of its volumetric capacity, thermal stability, and relative low cost. However, because Si does not store Li via an intercalation mechanism Li storage in Si results in a volume expansion of up to 280%. Such large volume expansions are detrimental to cell cycling, and therefore must be limited to some tolerable amount. One method of limiting volume expansion is by alloying Si with a transition metal (TM) forming an inert TM silicide, effectively reducing the amount of active Si; therefore, reducing the total volume expansion. Fe, because of its abundance in the earth’s crust and relative low cost, is an ideal candidate. Cr was additionally explored as the mechanical properties of Cr are different than those of Fe. SiTM alloys were generated by a commercially relevant mechanochemical synthesis and evaluated in Li metal half cells...