Thursday, 2 June 2022: 14:20
West Meeting Room 202 (Vancouver Convention Center)
Y. ben Cherifi (Univ. Grenoble Alpes, CEA, CNRS, IRIG, SyMMES, Grenoble, FR-38000), O. Hassan (Univ. Grenoble Alpes, CEA, CNRS, IRIG, SyMMES, Grenoble, Fr-38000), Y. Chenavier (Univ. Grenoble Alpes, CEA, CNRS, IRIG, SyMMES, Grenoble, FR-38000), P. Simon (CIRIMAT, Université Toulouse 3 - Paul Sabatier , CNRS), P. L. Taberna (Université Toulouse III Paul Sabatier - CIRIMAT, UMR CNRS 5085), L. Dubois (Univ. Grenoble Alpes, CEA, CNRS, IRIG, SyMMES, Grenoble, Fr-38000), S. Pouget (Univ. Grenoble Alpes, CEA, CNRS, IRIG, MEM, Grenoble, Fr-38000), H. Mendil-Jakani (U. Grenoble Alpes, CEA, CNRS, Grenoble SyMMES, 38000 Grenoble/France), and F. Duclairoir (Univ. Grenoble Alpes, CEA, CNRS, IRIG, SyMMES, Grenoble, Fr-38000)
Reduced graphene oxide (RGO) based electrochemical double-layer capacitors (EDLC), have been extensively studied, as they offer good power capability. However they suffer from medium capacitances, as the reduced graphene sheets partially restack through π- π interactions limiting the resulting adsorption active surface area. Different paths have been followed in the literature to circumvent or partially avoid this restacking: using graphene aerogels [1] or expanded graphene structures.[2] In this latter case, an intercalate or pillar (
eg. CNT, AC, diamines...) is used to space out the graphene layers and recover active surface area. Both methodologies lead to graphene sheets assemblies, either at the macroscale for aerogel or at the nanoscale for pillared graphene structures. In the laboratory, we developed pillared graphene and pillared graphene aerogel that were tested as electrode materials for supercapacitors.[3,4]
In this presentation, the preparation of these macro- and nano-scale assemblies (Fig.1a) using hydrothermal or chemical conditions will be explained, and previous electrochemical results will be recalled.[3,4] These storage performances can be correlated to sample physico-chemical, but also structural properties. Hence, the talk will focus on specific sample characterization details. Particular attention will be paid to explain the morphology and multi-scale porosity of the various samples. A focus will be made on the local structure of the expanded graphene, studied with XRD, and on the macroscale morphology, observed with SEM. These porosity- and morphology-related parameters are very important in the final electrode material, so differences between pristine, grinded and pelleted materials will also be shown. These advanced characterization information will give insight on electrolyte accessibility to the adsorption-active surface area, and could be correlated to ions diffusion resistances, that are of great importance in EDLC structures.
References
- Hu et al., Adv. Mater., 25 (2013) 2219.
- Sun et al., Carbon, 120 (2017) 145.
- Banda et al., J. Power Sources, 360 (2017) 538.
- Banda et al., ACS Nano, 13 (2019) 1143.
