Construction of Si Anode Half Cell. Experimental Method. Si wafer samples with native SiOx surface layer were used in this study. All of the silicon electrodes (1 cm × 1 cm squares) were cleaned with an established multi step cleaning protocol to remove surface contamination.33 Silicon wafers (Czochralski process, boron-doped to 0.001−0.005 Ω cm, (100) orientation, 700 μm thick, purchased from Addison Engineering) were used as anodes. They were laser cut to an area of 1 × 1cm2 and then received an RCA clean.33 The RCA clean was completed without HF acid etching steps in order to preserve the original native SiOx film.

After cleaning, the electrodes were dried in a vacuum oven at 100 °C prior to cell fabrication. The electrolytes selected for this research are 1.2 mol/L LiPF6 dissolved in a solution of ethylene carbonate (EC):ethyl methyl carbonate (EMC) with ratio of 3:7 by weight, respectively. All of the Si electrodes were used as working electrodes in the coin cells, where lithium

metal was used as a counter electrode.In every cell, 4.3 μL of the electrolyte was used; glass microfiber filters (Whatman, GE Healthcare Life Sciences) with a thickness of 260 μm with Celgard 2325 separators were used in cell assembly. Coin cells containing the aforementioned components were assembled in an Ar-filled glovebox. To maintain cells at a constant internal pressure, 0.5 mm thick stainless-steel spacers and 0.3 mm thick stainless-steel springs were used . An coin cell crimper (Xiamen Tmaxcn Inc.) was utilized to complete assembly with 4 s of applied pressure.