Three-dimensional thin-film Li-ion microbatteries for autonomous MEMS |
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Authors: | Nathan M. Golodnitsky D. Yufit V. Strauss E. Ripenbein T. Shechtman I. Menkin S. Peled E. |
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Affiliation: | Dept. of Phys. Electron., Tel Aviv Univ., Israel; |
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Abstract: | Autonomous MEMS require similarly miniaturized power sources. In this paper, we present the first working three-dimensional (3-D) rechargeable Li-ion thin-film microbattery technology that is compatible with MEMS requirements. The technology has been developed, and full 3-D cells have been manufactured on both glass and silicon substrates. Our 3-D microbatteries have a sandwich-like structure of conformal thin-film electrodes, electrolyte and current collectors. The films are deposited sequentially on all available surfaces of a perforated substrate (e.g., silicon or a glass microchannel plate or "MCP") using wet chemistry. The substrate has thousands of high-aspect ratio holes per square cm, thereby providing more than an order of magnitude increase in surface area per given footprint (original 2-D substrate area). The full 3-D cell consists of a Ni cathode current collector, a MoO/sub y/S/sub z/ cathode, a hybrid polymer electrolyte (HPE) and a lithiated graphite anode that also serves as anode current collector. One 3-D cell with a roughly 1-/spl mu/m-thick cathode ran at C/10 to 2C charge/discharge rates and room temperature for 200 cycles with 0.2% per cycle capacity loss and about 100% Faradaic efficiency. The cell exhibited a capacity of 2 mAh/cm/sup 2/, about 30times higher than the capacity of a similarly built planar (2-D) cell with the same footprint and same cathode thickness. |
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