Title: High performance Lithium Silicide electrode enable by molecular layer deposition

Abstract

Silicon (Si) has become one of the most investigated materials for LIB negative electrodes because of its ability to accommodate 3.75 moles of Li per mole of Si (Li15Si4), leading to a theoretical capacity of 3,579 mA h g-1 at room temperature1. While 372 mA h g-1 is the theoretical capacity for graphite, the material used as negative in the current Lithium Ion Battereis. Despite Si advantages, progress towards a commercially available Si negative electrode has been impeded by their rapid capacity fade, poor rate capability, and low coulombic efficiency. The cause of electrode degradation is the Si volume change of ~300% upon lithium insertion and extraction, presenting a major problem for electrochemical performance. One of the leading strategies established for the realization of such an approach is coating nano Si particles with flexible materials to attempt to accommodate the volumetric changes of the particles. In this context, we propose to carry out a surface modification, in which Atomic Layer Deposition (ALD) and Molecular Layer Deposition (MLD) is utilized to grow a mechanically robust, flexible coating, to undertake the Si expansion and contraction. the recipe here developed is based on Glycerol and TiCl4 as the titanium precursor. The composition of the films was studied using Fourier-Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscope-Energy dispersive X-ray spectroscopy (SEM-EDX). Cyclic Voltammetry was used to characterize the electrochemical performance of the LixSi negative electrode coated with titanicone. We have successfully shown the deposition of titanicone on LixSi electrode and an initial electrochemical assessment of this electrode. Typical voltammogram shows the formation of the solid electrolyte interface, evident in the first cycle. In the subsequent scans, these peaks disappear. The sample exhibit the regular waves are corresponding to the Si redox reaction.