Tijmen Euser1,2,Ermanno Miele1,2,Wesley Dose3,2,Michael Frosz4,Zach Ruff3,2,Michael De Volder3,2,Clare Grey3,2,Jeremy Baumberg1,2
Cavendish Laboratory, University of Cambridge1,The Faraday Institution2,University of Cambridge3,Max Planck Institute for the Science of Light4
Tijmen Euser1,2,Ermanno Miele1,2,Wesley Dose3,2,Michael Frosz4,Zach Ruff3,2,Michael De Volder3,2,Clare Grey3,2,Jeremy Baumberg1,2
Cavendish Laboratory, University of Cambridge1,The Faraday Institution2,University of Cambridge3,Max Planck Institute for the Science of Light4
Liquid-filled hollow-core fibres (HCF) are excellent sample cells in which light propagates in well-defined modes at the centre of a microchannel. The internal sample volumes in HCF can be as small as a few nL per cm interaction length, while long optical paths enable sensitive absorption, fluorescence, and Raman spectroscopy [1,2]. This talk will introduce optofluidic hollow-core fibres and briefly review their applications as microreactors. It will then demonstrate a new operando Raman spectroscopy method that tracks the chemistry of liquid electrolytes during battery cycling. An optofluidic hollow-core fibre is integrated into a working Li-ion cell and used to analyse sub-microlitre electrolyte samples at different stages of the charge-discharge cycle by background-free Raman spectroscopy. The observed changes in electrolyte composition are related to the solid electrolyte interphase (SEI) formation [2]. In addition, Raman measurements over multiple cycles reveal early signs of battery electrolyte degradation and we demonstrate that lost capcity can be recovered by infiltration of fresh electrolyte into a degraded cell. The new methodology contributes to understanding better the limitations of Li-ion batteries and paves the way for studies of degradation mechanisms in different electrochemical energy storage systems.<br/><br/><b>References</b><br/>[1] A. M. Cubillas <i>et al.</i>, Chem. Soc. Rev. <b>42</b>, 8629 (2013). https://doi.org/10.1039/C3CS60128E<br/>[2] <i>Ermanno Miele et al., Nature Commun. </i><b>13</b>, 1651 (2022). https://doi.org/10.1038/s41467-022-29330-4