Advanced materials for the 3D microbattery

Out recent achievements in the development of three-dimensional (3D) thin film microbatteries on silicon and on microchannel plates (MCP) are presented. In such 3D microbatteries, the battery sandwich-like structure, including electrodes, electrolyte and current collectors, is deposited conformally on all available surfaces, thereby utilizing the dead volume of the substrate. Thin-film molybdenum oxysulfide and iron sulfide cathodes were deposited galvanostatically. XRD, XPS and TOF–SIMS characterizations indicated that the submicron thick MoOySz films were amorphous, with the stoichiometry of the films varying with depth. Electrodeposited FeSx films have an amorphous, network-like porous structure with nanosize particles. A special flow cell for conformal coating of the perforated substrates was designed. A Li/hybrid polymer electrolyte (HPE)/MoOySz-on-Si 3D half cell ran at id = ich = 10 μA cm−2 and room temperature for 100 charge/discharge cycles with 0.1%/cycle capacity loss and 100% Faradaic efficiency. A 3D half cell on MCP exhibited 20 times higher capacity than that of a planar half cell with the same footprint.