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DDC: 620 × Publisher: New York, NY [u.a.] : Elsevier ×

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    Interlaboratory study assessing the analysis of supercapacitor electrochemistry data
    (New York, NY [u.a.] : Elsevier, 2023) Gittins, Jamie W.; Chen, Yuan; Arnold, Stefanie; Augustyn, Veronica; Balducci, Andrea; Brousse, Thierry; Frackowiak, Elzbieta; Gómez-Romero, Pedro; Kanwade, Archana; Köps, Lukas; Jha, Plawan Kumar; Lyu, Dongxun; Meo, Michele; Pandey, Deepak; Pang, Le; Presser, Volker; Rapisarda, Mario; Rueda-García, Daniel; Saeed, Saeed; Shirage, Parasharam M.; Ślesiński, Adam; Soavi, Francesca; Thomas, Jayan; Titirici, Maria-Magdalena; Wang, Hongxia; Xu, Zhen; Yu, Aiping; Zhang, Maiwen; Forse, Alexander C.
    Supercapacitors are fast-charging energy storage devices of great importance for developing robust and climate-friendly energy infrastructures for the future. Research in this field has seen rapid growth in recent years, therefore consistent reporting practices must be implemented to enable reliable comparison of device performance. Although several studies have highlighted the best practices for analysing and reporting data from such energy storage devices, there is yet to be an empirical study investigating whether researchers in the field are correctly implementing these recommendations, and which assesses the variation in reporting between different laboratories. Here we address this deficit by carrying out the first interlaboratory study of the analysis of supercapacitor electrochemistry data. We find that the use of incorrect formulae and researchers having different interpretations of key terminologies are major causes of variability in data reporting. Furthermore we highlight the more significant variation in reported results for electrochemical profiles showing non-ideal capacitive behaviour. From the insights gained through this study, we make additional recommendations to the community to help ensure consistent reporting of performance metrics moving forward.
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    Cracking and associated volumetric expansion of NMC811 secondary particles
    (New York, NY [u.a.] : Elsevier, 2023) Shishvan, S.S.; Fleck, N.A.; McMeeking, R.M.; Deshpande, V.S.
    Secondary particles comprising a large number of nickel-rich single crystal primary particles are extensively used as storage particles in cathodes of lithium-ion batteries. It is well-established that crack formation in secondary particles is an important degradation mode that contributes to decline in battery performance. Recent X-ray tomographic observations suggest that, at very low C-rates, concentration gradients of lithium within an NMC811 secondary particle are negligible yet cracking still occurs. Additionally, during delithiation the primary particles shrink yet a volumetric expansion of the secondary particle occurs. These observations are explained by a numerical model of distributed cracking due to the extreme anisotropy of lithiation strain of primary particles. The incompatible deformation from grain to grain induces large self-stresses even in the absence of spatial gradients in the lithium concentration. The stress state is sufficient to drive a dynamic catastrophic fracture event, and the associated kinetic energy acquired by the primary particles moves them apart (akin to an explosive event) with the carbon and binder domain surrounding each secondary particle restricting the outward motion of the primary particles. It is predicted that a volume expansion of the secondary particles on the order of 20 % accompanies cracking, in agreement with recently reported observations.
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    Supramolecular assemblies of block copolymers as templates for fabrication of nanomaterials
    (New York, NY [u.a.] : Elsevier, 2011) Nandan, B.; Kuila, B.K.; Stamm, M.
    Self-assembled polymeric systems have played an important role as templates for nanofabrication; they offer nanotemplates with different morphologies and tunable sizes, are easily removed after reactions, and could be further modified with different functional groups to enhance the interactions. Among the various self-assembled polymeric systems, block copolymer supramolecular assemblies have received considerable attention because of the inherent processing advantages. These supramolecular assemblies are formed by the non-covalent interactions of one of the blocks of the block copolymer with a low molar-mass additive. Selective extraction of the additive leads to porous membranes or nano-objects which could then be used as templates for nanofabrication leading to a variety of ordered organic/inorganic nanostructures. In this feature article, we present an over-view of the recent developments in this area with a special focus on some examples from our group.