Silicon (Si) is the one of the most abundant element found in the earth crust, which has essential role for the production of semiconductors, solar cells, and electrodes for lithium ion batteries. Moreover, silicon nanoparticles (with a diameter in the range of 1 to 20 nm) have quantum confinement effect that may make these nanoparticles useful in nanotechnology. It is expected that silicon will play a greater role in the near future. However, presently several hurdles associated with silicon nanomaterials based device fabrication which includes high costs, large material consumption, and rather complex processes of film deposition, such as chemical vapor deposition (CVD) and plasma-enhanced chemical vapor deposition (PE-CVD). In order to meet the high demand in the future, it will be necessary to develop cost-effective, straightforward, and high-rate depositing methodologies. To accomplish all this requirement, electrodeposition technique can offer the opportunity for creating Si thin films in an elegant manner. This technique has ability to deposit any semiconductor on any conducting surface with a low consumption of the target material when compared to others. Additionally, in this technique parameters such as potential, current density, and concentration could be easily manipulated to control the desired structure and size. However, a large-scale application of Si anodes is being slowed down due to mainly two factors: (a) a huge volume change (approximately 300%) during discharging and (b) the fading of silicon after several cycles of charging and discharging. These detriments can be resolved by coating of silicon nanostructures with carbon nanomaterials that also enhance the LIBs' electrochemical performance.

Our work has examined the electrochemical behavior of electrodeposited Si on copper substrates coated with Graphene nanoplatelets (Grn) using ionic liquids that were contaminated with water (3000−8000 ppm). The ionic liquids were selected based on their water content at a relative humidity of 90%. At -1.2 V, Si was deposited using 1M SiCl₄ in a 1-Butyl-3-methylimidazolium-bis (trifluoromethylsulfonyl) imide (BMImTf2N) ionic liquid. The silicon deposition is confirmed by Field Emission Scanning Electron Microscopy (FE-SEM) with average particle size 88 nm. Electrochemical tests were also carried out to see how well the active material performed as a negative electrode in Li-ion batteries.

Conclusion

We have used a water-contaminated ionic liquid at room temperature to show an effective approach for electrodepositing of Si nanospheres on Grn coated Cu substrates. The ionic liquid's accessible potential window has not been impacted by the presence of water. The electrodeposition of Si Nano spheres from SiCl₄ was aided by the fact that water remained in bound form in the water contaminated ionic liquid. The Grn on the Cu substrate avoids oxidation and aids Si electrodeposition nucleation. At a current density of 0.6 A g^-1, the specific discharge and charge capacities were 2000 and 1700 mAh g^-1, respectively. Between the 1^st and 100^th cycles, the columbic efficiency reached up to 95%. By tolerating volume expansion and enhancing the conductivity of the Si Nano spheres is expected to improve cycle life.