A Novel Phase of Li₁₅Si₄ Synthesized under Pressure

However, in situ X-ray diffraction (XRD) studies on the lithiation /delithiation of Si anodes confi rmed the absence of the above-mentioned stable compounds in the electrochemical reaction in Li-ion batteries at room temperature. [ 12,13 ] The only crystalline lithium silicide formed is Li 15 Si 4 (space group 43 I d), a metastable phase that decomposes to Li 13 Si 4 , Li 17 Si 4 /Li 4.11 Si, or amorphous/weakly crystalline products when annealed at temperatures above 200 °C. [ 12–14 ] In order to optimize the performance of Si anodes, properties of Li 15 Si 4 have been investigated extensively by theoretical simulations. [ 6,15 ] At the same time, experimental study has proven to be diffi cult partially because of the challenges associated with material synthesis and handling due to its high reactivity. [ 7,14 ]