title: Neutron imaging of ion transport in mesoporous carbon materials.
abstract: Neutron imaging is presented as a tool for quantifying the diffusion of ions inside porous materials, such as carbon electrodes used in the desalination process via capacitive deionization and in electrochemical energy-storage devices. Monolithic mesoporous carbon electrodes of ∼10 nm pore size were synthesized based on a soft-template method. The electrodes were used with an aqueous solution of gadolinium nitrate in an electrochemical flow-through cell designed for neutron imaging studies. Sequences of neutron images were obtained under various conditions of applied potential between the electrodes. The images revealed information on the direction and magnitude of ion transport within the electrodes. From the time-dependent concentration profiles inside the electrodes, the average value of the effective diffusion coefficient for gadolinium ions was estimated to be 2.09 ± 0.17 × 10(-11) m(2) s(-1) at 0 V and 1.42 ± 0.06 × 10(-10) m(2) s(-1) at 1.2 V. The values of the effective diffusion coefficient obtained from neutron imaging experiments can be used to evaluate model predictions of the ion transport rate in capacitive deionization and electrochemical energy-storage devices.
authors.affiliation: Georgia Institute of Technology, Atlanta, GA 30332-0373, USA.
authors.forename: Ketki
authors.initials: K
authors.lastname: Sharma
authors.forename: Hassina Z
authors.initials: HZ
authors.lastname: Bilheux
authors.forename: Lakeisha M H
authors.initials: LM
authors.lastname: Walker
authors.forename: Sophie
authors.initials: S
authors.lastname: Voisin
authors.forename: Richard T
authors.initials: RT
authors.lastname: Mayes
authors.forename: Jim O
authors.initials: JO
authors.lastname: Kiggans
authors.forename: Sotira
authors.initials: S
authors.lastname: Yiacoumi
authors.forename: David W
authors.initials: DW
authors.lastname: DePaoli
authors.forename: Sheng
authors.initials: S
authors.lastname: Dai
authors.forename: Costas
authors.initials: C
authors.lastname: Tsouris