Reactivating Li₂O with Nano‐Sn to Achieve Ultrahigh Initial Coulombic Efficiency SiO Anodes for Li‐Ion Batteries

Abstract

The application of SiO anodes in Li‐ion batteries is greatly restricted by its low initial coulombic efficiency (ICE). Usually, a pre‐lithiation procedure is necessary to improve the ICE, but the available technologies are associated with safety issues. Metal (M)‐mixed SiO shows great promise to address these issues by reactivating Li2O through the reaction M+Li2O→MOx+Li+, which is the inverse reaction to that occurring at MOx anodes. Sn is found to be a good choice of metal for this concept. Nanoscale Sn‐mixed SiO composites are prepared by mechanical milling. Sn forms an outstanding conductive phase, which boosts the reaction kinetics and also reactivates the Li2O byproduct. Sn/SiO (1:2 w/w) delivers a significant improvement in ICE from 66.5 % to 85.5 %. A higher ICE value of >90 % is obtained when the Sn content is ≥50 wt %. However, additional electrolyte decomposition occurs, which is catalyzed by Sn. In addition, coarsening of the nano‐Sn material reduces the inverse conversion reactivity of Sn/Li2O and subsequently results in rapid capacity fading. The quantitative analysis indicates that, in contrast to transition metals, the alloying and dealloying nature of Sn gives a 50 % improvement in reversible capacity, attributed to Sn/Li2O. This work gives a general strategy to choose metals for increasing the ICE of SiOx and metal oxides.

Prelithiation/Presodiation Techniques for Advanced Electrochemical Energy Storage Systems: Concepts, Applications, and Perspectives

“…Interestingly, a facile cathode prelithiation method based on the nanoscale mixtures of metal (M) and binary compound has been developed, which manifests high prelithiation efficacy and good compatibility. [127,128] Triggered by the unique characteristics of conversion reactions, high capacity could be donated for anode materials. In consideration of this strategy, M/Li 2 O composite as a kind of cathode prelithiation additive was first exploited.…”

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).…”

“…However, it should be noted that the lithiated materials are not compatible with the current electrode processing technology due to their high chemical reactivity with moisture and air. Owing to the water-based solvent used in the state-of-the-art binders (CMC/SBR or PAA), the requirements for experimental conditions are too strict to achieve. , Second, metal/metal oxide was mixed with SiO to revive Li 2 O to active Li or reduce SiO to generate SiO x . − But the delithiation potential is accordingly elevated. To some extent, a high oxidation potential is invalid for an anode.…”

Revealing the size-dependent electrochemical Li-storage behaviors of SiO-based anodes

“…10,11 There are still some challenges facing SiO anodes, including their low initial coulombic efficiency due to the formation of irreversible products (Li y SiO z and/or Li 2 O), non-negligible volume variation, and low intrinsic conductivity. 10 In this regard, various strategies have been developed to tackle these drawbacks, such as carbon coating, [12][13][14][15] particle downsizing, 16,17 compositing with metal/alloy materials, 18,19 and prelithiation/ magnetization treatments. [20][21][22] For example, Liu demonstrated that graphene-encapsulated SiO can improve the reversible capacity and cycling stability.…”