A SAXS outlook on disordered carbonaceous materials for electrochemical energy storage

Saurel, Damien; Ségalini, Julie; Jáuregui, María; Pendashteh, Afshin; Daffos, Barbara; Simon, Patrice; Casas‐Cabañas, Montse

doi:10.1016/j.ensm.2019.05.007

Cited by 115 publications

(127 citation statements)

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“…2e). The scattering intensity of the nanoporous carbon can be split into three additive terms: one accounting for spatial correlations on the molecular level, called structure factor, a second one accounting for the spatial correlations of the nanopores, which we refer to as nanopore scattering, and a third one accounting for the scattering contribution of the AC particles (with a size around 1 µm) 31,43,44 . Given the reciprocal relationship between the size of real-space objects and their appearance on the scattering curve, the structure factor contribution is most prominent at large scattering vectors q (large scattering angles).…”

Section: Resultsmentioning

confidence: 99%

Persistent and reversible solid iodine electrodeposition in nanoporous carbons

et al. 2020

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Aqueous iodine based electrochemical energy storage is considered a potential candidate to improve sustainability and performance of current battery and supercapacitor technology. It harnesses the redox activity of iodide, iodine, and polyiodide species in the confined geometry of nanoporous carbon electrodes. However, current descriptions of the electrochemical reaction mechanism to interconvert these species are elusive. Here we show that electrochemical oxidation of iodide in nanoporous carbons forms persistent solid iodine deposits. Confinement slows down dissolution into triiodide and pentaiodide, responsible for otherwise significant self-discharge via shuttling. The main tools for these insights are in situ Raman spectroscopy and in situ small and wide-angle X-ray scattering (in situ SAXS/WAXS). In situ Raman confirms the reversible formation of triiodide and pentaiodide. In situ SAXS/WAXS indicates remarkable amounts of solid iodine deposited in the carbon nanopores. Combined with stochastic modeling, in situ SAXS allows quantifying the solid iodine volume fraction and visualizing the iodine structure on 3D lattice models at the sub-nanometer scale. Based on the derived mechanism, we demonstrate strategies for improved iodine pore filling capacity and prevention of self-discharge, applicable to hybrid supercapacitors and batteries.

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Section: Resultsmentioning

confidence: 99%

Persistent and reversible solid iodine electrodeposition in nanoporous carbons

et al. 2020

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“…The SAXS technique has also been useful to study the influence of the porous carbon texture and structure on the capacitive performance, especially the volume fraction of inaccessible pores, the shape of pores and the pore organization, which are key parameters controlling the ion confinement in nanopores. 209 In addition, Koczwara et al proposed an advanced SAXS technique called in situ anomalous small angle X-ray scattering (ASAXS), for characterizing both the structural change of pores and the concentration change of the in-pore ions at the same time. 210 However, more equipment and theory are required to develop this technique for further electrolyte systems.…”

Section: Small Angle Scattering (Sas) Techniquesmentioning

confidence: 99%

Nanoporous carbon for electrochemical capacitive energy storage

et al. 2020

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“…The use of intensity calibrated smallangle X-ray scattering (SAXS) has recently shown that HC having a low surface area as detected by gas adsorption (which is required to ensure high Coulombic efficiency) [87,108], can at the same time exhibit a high concentration of closed micropores (ca. 25% in volume) [124]. Such studies open the door for potential increase of the capacity by fine-tuning of the closed microporosity without affecting the Fig.…”

Section: Carbonaceous Materialsmentioning

confidence: 90%