Methods-Ampero-Coulometry: a new technique for understanding lithium-sulfur electrochemistry

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Gulzar, Umair
Lonergan, Alex
Egorov, Vladimir
Zhang, Yan
Grant, Alex
Carroll, Aoife
O'Dwyer, Colm
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Despite limited commercial success, lithium sulfur technology (LST) is still far from competing existing Li-ion technology. One of the main reasons hindering the success of LST is the complexity of lithium-sulfur chemistry during electrochemical charging and discharging. Dissolution of sulfur species in the electrolyte solution exacerbates the difficulties of this system. Therefore, a comprehensive understanding of sulfur species and their kinetics during charge/discharge process is paramount for a high-performance lithium-sulfur battery. We present a new technique we refer to as Ampero-Coulometry, which takes the chronoamperometric (galvanostatic) charge-discharge curves and mathematically transforms them to a series of curves that reveal the cation diffusional rate inside carbon-sulfur porous electrodes at different states of charge/capacity. This technique allowed us to track the overall Li+ ion diffusional rate inside a Li-S cell over a complete state of discharge. As dissolution of sulfur species and their interplay inside a porous sulfur electrode has a significant role in limiting Li-S battery capacity, and method allows correlation between the known mechanism of polysulfide dissolution, the kinetics of a sulfur electrode, and its response.
Lithium , Sulfur , Battery , Energy storage , Electrochemistry , Materials
Gulzar, U., Lonergan, A., Egorov, V., Zhang, Y., Grant, A., Carroll, A. and O’Dwyer, C. (2023) ‘Methods—ampero-coulometry: a new technique for understanding lithium-sulfur electrochemistry’, Journal of The Electrochemical Society, 170(3), 030503 (9pp). doi: 10.1149/1945-7111/acbca0