Synthesis of Iron silicide-based composite particulates and their performance for lithium-ion battery negative electrode

Abstract

We have fabricated the composite particulate aggregates, of which Iron silicides, Ca-Si compound and Si are tightly compounded, and evaluated their performance for the lithium-ion battery negative electrode. The particulates are prepared by the solid-state reaction between the layered CaSi2 and FeCl2 using our proposed 'Solid-State Exfoliation Reaction (SSER)' route. The Ca-Si compound is the material that was expected to have similar crystal structure to the layered CaSi2• The co-existing Iron silicides are the materials with well-known phases (FeSi and Fe3Si), however, they are fine particles. The fabricated composite particulates show a capacity per volume, at first cycle, -6 times larger than that of the artificial graphite, MCF. The particulates with larger amount of Ca-Si compound and Si phases show higher capacity. It is suggested that fine particles of the Ca-Si compound and Si would work as the Li ion storage sites leading to such an excellent capacity values.

Formation of Si-based nanosheets by extraction of Ca from CaSi₂ layers on Si substrates

“…It is considered that exfoliation takes place by the Ca extraction from CaSi 2 powders. 19) In this study, the formation of Si-based nanosheets by extraction of the Ca from CaSi 2 layers on the Si substrates using CrCl 2 is reported. In addition, the structural properties of the products containing the Si-based nanosheets were examined.…”

Synthesis of MnSi1.7 nanosheet bundles from CaSi2 crystal powders using MnCl2 in molten salt

“…In addition, Si-based nanocomposites derived from CaSi 2 were synthesized via a solid-state reaction using NiCl 2 , FeCl 2 , MnCl 2 , and TaCl 5 . [19][20][21][22] In a series of the experiments, Ni or Fe silicide particles were formed. However, Ni, Fe, and Ta atoms were not incorporated into the Si nanosheets, and silicide nanosheet formation was not reported.…”

“…18) Si-based nanosheet bundles were synthesized by extracting Ca from CaSi 2 powders via a solid-state exfoliation reaction using chlorides. [19][20][21][22] In these reactions, metallic atoms were not incorporated into the Si nanosheets; however, silicide particles were formed. In the synthesis technique using CrCl 2 as the Ca extraction agent, Si nanosheets were formed, and Cr atoms were not incorporated into the Si nanosheets.…”