| Autor: |
Shanbhag S; Department of Civil and Environmental Engineering, ‡Department of Materials Science and Engineering, §Department of Engineering and Public Policy, and ∥The Scott Institute for Energy Innovation, Carnegie Mellon University , 5000 Forbes Ave, Pittsburgh, Pennsylvania 15213, United States., Bootwala Y; Department of Civil and Environmental Engineering, ‡Department of Materials Science and Engineering, §Department of Engineering and Public Policy, and ∥The Scott Institute for Energy Innovation, Carnegie Mellon University , 5000 Forbes Ave, Pittsburgh, Pennsylvania 15213, United States., Whitacre JF; Department of Civil and Environmental Engineering, ‡Department of Materials Science and Engineering, §Department of Engineering and Public Policy, and ∥The Scott Institute for Energy Innovation, Carnegie Mellon University , 5000 Forbes Ave, Pittsburgh, Pennsylvania 15213, United States., Mauter MS; Department of Civil and Environmental Engineering, ‡Department of Materials Science and Engineering, §Department of Engineering and Public Policy, and ∥The Scott Institute for Energy Innovation, Carnegie Mellon University , 5000 Forbes Ave, Pittsburgh, Pennsylvania 15213, United States. |
| Abstrakt: |
We evaluate the efficiency and capacity of electrochemically reversible insertion electrodes for use in targeted ion removal applications in aqueous solutions. The relative attributes of insertion material chemistry are evaluated by comparing the performance of two different sodium insertion materials, NaTi 2 (PO 4 ) 3 and Na 4 Mn 9 O 18 , in different electrolyte environments. We performed experiments over a range of solution compositions containing both sodium and other non-inserting ions, and we then developed mechanistic insight into the effects of solution concentration and composition on overpotential losses and round trip Coulombic efficiency. In dilute aqueous streams, performance was limited by the rate of ion transport from the bulk electrolyte region to the electrode interface. This leads to slow rates of ion removal, large overpotentials for ion insertion, parasitic charge loss due to water electrolysis, and lower round trip Coulombic efficiencies. This effect is particularly large for insertion electrodes with redox potentials exceeding the water stability window. In solutions with high background concentrations of non-inserting ions, the accumulation of non-inserting ions at the electrode interface limits inserting ion flux and leads to low ion removal capacity and round trip Coulombic efficiency. |
