At least one of the anode and cathode of a lithium-ion processing electrochemical cell are prepared with a layer of mixed particles of both active lithium battery electrode materials and lithium ion adsorbing capacitor materials, or with co-extensive, contiguous layers of battery electrode particles in one layer and capacitor particles in the adjoining layer. The proportions of active battery electrode particles and active capacitor particles in one or both of the electrodes are predetermined to provide specified energy density (Wh/kg) and power density (W/kg) properties of the cell for its intended application.