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Insights into the electrochemical reduction products and processes in silica anodes for next‐generation lithium‐ion batteries

DOI: 10.1002/aenm.202001826 DOI Help

Authors: Jake E. Entwistle (The University of Sheffield) , Samuel G. Booth (The University of Sheffield) , Dean S. Keeble (Diamond Light Source) , Faisal Ayub (The University of Sheffield) , Maximilian Yan (The University of Sheffield) , Serena A. Corr (The University of Sheffield) , Denis J. Cumming (The University of Sheffield) , Siddharth V. Patwardhan (The University of Sheffield)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Advanced Energy Materials , VOL 278

State: Published (Approved)
Published: September 2020
Diamond Proposal Number(s): 2257

Open Access Open Access

Abstract: The use of silica as a lithium‐ion battery anode material requires a pretreatment step to induce electrochemical activity. The partially reversible electrochemical reduction reaction between silica and lithium has been postulated to produce silicon, which can subsequently reversibly react with lithium, providing stable capacities higher than graphite materials. Up to now, the electrochemical reduction pathway and the nature of the products were unknown, thereby hampering the design, optimization, and wider uptake of silica‐based anodes. Here, the electrochemical reduction pathway is uncovered and, for the first time, elemental silicon is identified as a reduction product. These insights, gleaned from analysis of the current response and capacity increase during reduction, conclusively demonstrated that silica must be reduced to introduce reversible capacity and the highest capacities of 600 mAh g−1 are achieved by using a constant load discharge at elevated temperature. Characterization via total scattering X‐ray pair distribution function analysis reveal the reduction products are amorphous in nature, highlighting the need for local structural methods to uncover vital information often inaccessible by traditional diffraction. These insights contribute toward understanding the electrochemical reduction of silica and can inform the development of pretreatment processes to enable their incorporation into next‐generation lithium‐ion batteries.

Journal Keywords: green chemistry; silicon; sustainability

Subject Areas: Materials, Chemistry, Energy

Instruments: I15-1-X-ray Pair Distribution Function (XPDF)