An electrode is provided having a front region adjacent to a separator and a back region adjacent to a current collector. The electrode includes an anion-absorbing material and a cation-absorbing material. The electrode exhibits a compositional profile such that the anion-absorbing material is present at a higher volume percent at the back region than at the front region. Also provided are electrochemical cells that employ such an electrode as a positive electrode. Optionally, the cells include an electrolyte comprised of a solution of a solvent and a salt dissolved therein at a concentration of at least about 2M when the cell is in a fully discharged state.