Investigation of Structure-Electrochemistry Relationships in Novel Silicon Anodes for Lithium-ion Batteries (Webinar)

The following abstract and accompanying webinar were written and presented by Candace K. Chan, Ph.D., Associate Professor, Materials Science and Engineering School for Engineering of Matter, Transport and Energy, Arizona State University, Tempe, AZ, USA.

Investigation of Structure-Electrochemistry Relationships in Novel Silicon Anodes for Lithium-ion Batteries

Due to its high theoretical specific capacity, silicon has been the subject of intense interest and research as a high energy density electrode material to replace conventional graphite anodes in lithium-ion batteries. However, several challenges remain related to the large stresses and volume changes that accompany the electrochemical reactions associated with the lithiation and delithiation processes in silicon. Nanostructuring has been shown to be very effective for the design of electrodes that can relieve lithiation-induced strain and avoid pulverization of the silicon, which can lead to capacities exceeding 3000 mAh/g, a 10X improvement over the commercially used graphite anodes.  Despite this impressive proof-of-principle, nanostructured silicon can still suffer from degradation over long cycling times due to several reasons, such as the collapse of the nanostructure, increased porosity, and insufficient surface passivation.

As an alternative to modifying the particle morphology or microstructure, our group has been investigating the potential of tuning the atomic-scale structure as a strategy to modulate the electrochemical properties of silicon-based electrodes. The clathrate polymorphs of silicon, which feature cage-like structures that can encapsulate various guest atoms, provide a unique platform for investigating the role of local and long-range structure on several properties relevant to electrochemical energy storage, such as the lithiation potential, lithium reaction mechanism, and phase evolution. Through systematic electroanalytical studies, first-principles density functional theory calculations, and synchrotron X-ray analysis, we have identified the structural origins that correspond to the observed electrochemical properties in clathrates. The cage structure and accompanying defects result in significantly different electrochemical properties for clathrate anodes compared to the well-studied amorphous and diamond cubic forms of silicon, such as in one case, the topotactic, reversible insertion of lithium ions.¹ This talk will summarize our main findings for silicon clathrates and some of the unique electrochemical properties these materials exhibit for potential applications as next-generation anodes for lithium-ion batteries.

¹ Dopilka, A., et al. Structural Origin of Reversible Li Insertion in Guest-Free, Type-II Silicon Clathrates. Adv. Energy Sustainability Res. 2021, DOI: 10.1002/aesr.202000114

Biography

Dr. Candace K. Chan is an Associate Professor of Materials Science and Engineering at Arizona State University (ASU). Her research group works working on critical materials issues mostly in the fields of lithium batteries and energy storage, but with additional efforts in photocatalysis and water treatment using engineered nanomaterials. Notable battery research highlights include the demonstration of foldable lithium-ion batteries, the development of novel synthetic processes for nanostructured solid electrolyte garnet materials for all-solid-state lithium batteries, and investigation of novel clathrate-based anodes and polyanionic cathode materials. She has received an NSF CAREER award, Alexander von Humboldt Research Fellowship, ASU Young Investigator Award, and Fulton Exemplar Faculty Award.

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