Unveiling the Effect of Surface and Bulk Structure on Electrochemical Properties of Disproportionated SiO_x Anodes

Abstract

As a promising lithium‐ion battery anode materials, silicon suboxides (SiOx) exhibit elusive microstructure with atomic‐scale disproportionation which reveals a strong relation to performance. Generally, the structure of SiOx could be tuned via high‐temperature treatment. In this work, disproportionated SiOx are prepared to systematically discuss the internal relationship among microstructure, physicochemical properties and electrochemical performance. After annealing, amorphous SiO2 and nanocrystalline Si appear, and the SiO2 accumulating on the surface results in large resistance and low Li‐ion diffusivity, which leads to large overpotential and poor performance. If mechanical milling is employed followed by annealing, the SiO2 layer can be crushed, SiOx and Si with electrochemical activity are uncovered. Further research on the SiOx with diverse degrees of disproportionation indicates that proper amount of Si and SiO2 determines the optimal electrochemical performance. This result gives an in‐depth understanding and probable guidance to the modification investigation of SiOx anode for Li‐ion batteries.

In Situ Mesopore Formation in SiOx Nanoparticles by Chemically Reinforced Heterointerface and Use of Chemical Prelithiation for Highly Reversible Lithium‐Ion Battery Anode

“…In general, the SiO 2 phase is not reduced even at temperatures as high as 800 °C under H 2 atmosphere because of the highly stable covalent bonds between silicon and oxygen atoms. [ 34 ] The reduced nonstoichiometric SiO x phase has a much higher electrochemical activity as an anode material for lithium‐ion batteries. The electrochemical activity of the SiO x phase varies as a function of the degree of the reduction reaction.…”

Insights into the Effect of Heat Treatment and Carbon Coating on the Electrochemical Behaviors of SiO Anodes for Li‐Ion Batteries

“…Higher heating temperatures and longer heating times facilitate the formation of a thicker and denser SiO 2 shell, making it more resistant to electrochemical reactions. [21,29] The shell with high electrical resistance and low Li + transport acts as a barrier, preventing the migration of Li-ions through the surface of the particles, causing the maximum resistance overpotential (orange arrow, Figure 3b). When the heat treatment is performed at 1000 °C for 20 h, the exterior SiO 2 shell is thick enough to completely prevent Li-ions from passing through, making the lithiation potential drop to 0 V versus the counter electrode (lithium metal), which indicates that Li-ions begin to deposit on the surface of the D-SiO particles, resulting in the capacity dive of D-SiO-1000-20.…”

Mg2SiO4/Si-Coated Disproportionated SiO Composite Anodes with High Initial Coulombic Efficiency for Lithium Ion Batteries

“…Figure a shows the initial galvanostatic charge/discharge curves of MSO ( n = 4) at 0.05C (1C = 1200 mAh g –1 ) in the voltage range of 0.005–2.0 V (vs Li/Li + ). The pristine SiO shows a typical charge–discharge curve of commercially available SiO , (Figure S3a), and the charging capacity and ICE are 1688.8 mAh g –1 and 67.7%, respectively. Compared with SiO, the specific capacities of MSO ( n = 4) synthesized at different temperatures decrease, while the ICE increases significantly (Table S1).…”