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| Home > Publications database > Laplace inverted pulsed EPR relaxation to study polymer electrode/conductive carbon contact in lithium-ion battery |
| Home > Publications database > Laplace inverted pulsed EPR relaxation to study polymer electrode/conductive carbon contact in lithium-ion battery |
| Poster (After Call) | FZJ-2022-04765 |
; ;
2022
Abstract: The addition of conductive additives during electrode fabrication is a standard practice tomitigate low intrinsic conductivities of most cathode materials used in Li-ion batteries. Toensure an optimal conduction pathway, these conductive additives (carbon particles) need tobe in good contact with the active material. This aspect is crucial for Organic Polymer Radicalbatteries (ORB) where the insulating polymer backbone could hinder the conductive contactbetween redox-active groups and the carbon particles.Herein, we demonstrate the combined use of Pulsed-EPR relaxometry and Inverse LaplaceTransform (ILT) to study such electronic contact. The investigated system comprises of PTMAnitroxides, a commonly used redox unit in ORBs, and SuperP carbon black as the conductiveadditive. Samples with varying PTMA monomer to SuperP ratios (2:1 to 1:30) were preparedby adding nitroxide solutions to SuperP, followed by drying at 60°C. Pulsed-EPR basedInversion recovery experiments (30K) were conducted to obtain T₁ relaxation curves andILT[1] was used to obtain the corresponding relaxation time distributions. For 1:2, therelaxation distribution consists of three resolved relaxation components corresponding todifferent grades of contact between the carbon particles and the nitroxide radicals. Uponincreasing the SuperP amount in the 1:20 sample, more nitroxide radicals are brought intocontact with SuperP, resulting in a decrease of the slower relaxing component and an increaseof the faster relaxing components. Exchange interactions between the spins lead tocoalescence of spectral features making it difficult to separate these components in the EPRspectrum itself.Our analysis suggests that the composition of the electrode is a key factor in determining thequality of active material/conductive carbon contact and that pulsed EPR relaxometry incombination with ILT may serve as a robust tool to study these interactions.[1] J. Granwehr, P. J. Roberts, J. Chem. Theory Comput. 2012, 8, 3473–3482.
Keyword(s): Energy (1st) ; Materials Science (2nd) ; Chemistry (2nd)
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