Smart Pillared Carbon Materials for Supercapacitors: from fundamental understanding of ion transport to device testing – SPICS

The 1st tasks of the project will deal with the preparation and characterization of expanded graphene materials made from new pillars, as well as with the development of SECM observation procedures on standard materials.
In a second step, the first materials will be tested electrochemically in aqueous-, CH3CN-based electrolytes, and then in electrolytes based on ionic liquids.
Advanced characterization studies will then be started on reference samples derived from graphene, then on pillared graphenes, and will continue throughout the project, in standard or LI electrolytes.
The physicochemical, morphological and mechanistic information acquired will, in turn, help to optimize further the materials or their formulations.
The electrochemical results enable to select the most efficient material-electrolyte pair, on the basis of the highest capacitance values, ionic and electronic transfer rate constants, etc. This material-electrolyte pair will be used to develop a complete all-solid device consisting of an electrode / electrolyte material embedded in a solid matrix (ionogel).

After 6 months, the scientific part of the project started according to the planned schedule with the following achievements: 1) the first pillared graphene samples were produced, 2) a study on the reduction of graphene oxide is conducted, and will be transferred to the reduction of pillared graphene, and 3) the reference sample SECM observation conditions have been developed.

The perspectives will follow the course defined initially, with in particular in the short term the first electrochemical studies on pillared graphene.

Poster Graphene 2021

The wide goal of SPICS project is to provide enhanced electrode materials for supercapacitor application.
SPICS aims at developing innovative 2D carbon layered materials with enhanced storage capability thanks to the use of redox active pillars. We aim to reach volumetric capacitance of about 400 F/cm3. The original idea of SPICS is to go beyond the use of simple mechanical pillars and to introduce redox functionality to enhance specific interactions with the electrolyte leading to improved charge storage capability. To achieve this goal, an important part of the project will be devoted to an in-depth analysis of the charge compensation mechanisms through the use and development of cutting-edge characterization techniques. Indeed, these fundamental investigations based on ss-NMR and DNP, SECM (Scanning Electrochemical Microscope) and QCM derived techniques (conventional EQCM, QCM coupled with EIS and QCM coupled to electroacoustic impedance) will be undertaken to understand the impact of these active pillars on the dynamics of ion transfer at the electrode/electrolyte interface, on kinetic rate transfer constants and on faradic reactions occurrences, and will also allow to evaluate the electromechanical and structural stress experienced by the material during cycling. For the electrochemical evaluations, different electrolytes will be tested (from ammoniums salt in CH3CN to ionic liquids-based electrolytes). This tight relation between material development, advanced characterization and electrochemical evaluation will lead to the establishment of a virtuous circle resulting in a major breakthrough in correlating electroadsorption/charge transfer phenomena to smart 2D carbon materials properties, enabling the design of refined material and the selection of the most promising ones. The best material will also be tested with a solid-state electrolyte based on the use of ionogel. Supercapacitors with performances at the state of the art are expected to be achieved with these innovative 2D smart carbon materials, capacitances as high as 300 F/g and 400 F/cm3 with 90% charge retention over 10 000 cycles. Hence SPICS bridges fundamental mechanisms understandings efforts to preliminary tests responding to an important societal demand.
The development and optimization of these next generation active pillared graphene materials will be enabled a close partnership between CEA, CIRIMAT and LISE. The expertise and complementarity of the 3 partners - in graphene–based materials developments, ss-NMR analysis of modified samples, electrochemical material characterization, advanced and SECM techniques - are fundamental to the success of the project. Indeed, the skills and know-how of each partners are highly relevant and necessary to address the project WPs inter-connexion, to allow an efficient project progression, to finally achieve the objectives stated above.