tocThree-Dimensional Thin-Film Li-Ion Microbatteries for AutonomousMenachem Nathan, Diana Golodnitsky, Vladimir Yufit, Ela Strauss,I. I NTRODUCTIONFig.€1. (a) Schematic description of a 3-D thin-film battery on Fig.€2. (a) Schematic isometric view of the 3-D thin-film microbII. E XPERIMENTALFig.€3. (a) Top SEM view of the Ni-plated MCP substrate. (b) CroFig.€4. SEM image of the Ni-plated MCP substrate tilted at 45 $^A. Ni Current CollectorB. CathodeC. Polymer Electrolyte MembraneFig.€5. Cross-sectional SEM view of the MCP coated by nickel curFig.€6. SEM micrograph of the polymer electrolyte membrane.Fig. 7. SEM micrograph of the PVDF- ${\rm SiO}_{2}$ membrane on D. AnodeIII. R ESULTS A ND D ISCUSSIONA. Battery TestingFig.€8. Top view SEM micrograph of the full 3-D-MCP cell filled Fig.€9. Typical charge/discharge curves of the 3-D-MCP cell.Fig.€10. Curves of the 3-D-MCP cell at different current densitiFig.€11. (a) Cycle life of the 3-D-MCP cell. (b) Comparison of tFig.€12. Plot of charge/discharge capacities versus cycle numberIV. C ONCLUSIONJ. W. Long, B. Dunn, D. R. Rolison, and H. S. White, Three-dimenM. Nathan, D. Haronian, and E. Peled, Micro Electrochemical EnerV. Yufit, M. Nathan, D. Golodnitsky, and E. Peled, J. Power SourV. Yufit, K. Freedman, M. Nathan, L. Burstein, D. Golodnitsky, aD. Golodnitsky, V. Yufit, M. Nathan, I. Shechtman, T. Ripenbein,M. Nathan, E. Peled, D. Golodnitsky, V. Yufit, Y. Lavi, M. KastnV. Yufit, M. Nathan, E. Peled, D. Golodnitsky, Y. Lavi, and E. SD. Golodnitsky, V. Yufit, M. Nathan, I. Shechtman, T. Ripenbein,R. Wartena, A. E. Curtright, C. B. Arnold, A. Pique, and K. E. SP. H. Humble and J. N. Harb, Optimization of nickel-zinc microbaJ. B. Bates, N. J. Dudney, B. Neudecker, A. Ueda, and C. D. EvanG. Nagasubramanian and D. H. Doughty, Electrical characterizatioI. Rodriguez, P. Spicar-Mihalic, C. L. Kuyper, G. S. Fiorini, anM. Carbonnier and M. Romand, Tin-free electroless metallization F. A. Lowenheim, Ed., Modern Electroplating, 3rd ed: John Wiley G. O. Mallory and J. B. Hajdu, Eds., Electroless Plating FundameJ. B. Wang, L. Taherabadi, G. Jia, M. Madou, Y. Yeh, and B. DunnJ. L. Souquet and M. Duclot, Thin-film lithium batteries, Solid D. A. LaVan, T. McGuire, and R. Langer, Small scale systems for D. Golodnitsky, V. Yufit, M. Nathan, and E. Peled, Development oJOURNAL OF MICROELECTROMECHANICAL SYSTEMS, VOL. 14, NO. 5, OCTOBER 2005 879Three-Dimensional Thin-Film Li-Ion Microbatteriesfor Autonomous MEMSMenachem Nathan, Diana Golodnitsky, Vladimir Yufit, Ela Strauss, Tania Ripenbein, Inna Shechtman,Svetlana Menkin, and Emanuel PeledAbstract—Autonomous MEMS require similarly miniatur-ized power sources. In this paper, we present the first workingthree-dimensional (3-D) rechargeable Li-ion thin-film microbat-tery technology that is compatible with MEMS requirements.The technology has been developed, and full 3-D cells have beenmanufactured on both glass and silicon substrates. Our 3-D mi-crobatteries have a sandwich-like structure of conformal thin-filmelectrodes, electrolyte and current collectors. The films are de-posited sequentially on all available surfaces of a perforatedsubstrate (e.g., silicon or a glass microchannel plate or “MCP”)using wet chemistry. The substrate has thousands of high-aspectratio holes per square cm, thereby providing more than an order ofmagnitude increase in surface area per given footprint (original 2-Dsubstrate area). The full 3-D cell consists of a Ni cathode currentcollector, aMoOySzcathode, a hybrid polymer electrolyte (HPE)and a lithiated graphite anode that also serves as anode currentcollector. One 3-D cell with a roughly 1-m-thick cathode ran atC/10 to 2C charge/discharge rates and room temperature for 200cycles with 0.2% per cycle capacity loss and about 100% Faradaicefficiency. The cell exhibited a capacity of 2mAhcm2, about30 times higher than the capacity of a similarly built planar (2-D)cell with the same footprint and same cathode thickness. [1461]Index Terms—Li-ion 3-D thin-film microbattery, lithium 3-Dthin-film microbattery, MEMS, microchannel plate.I. INTRODUCTIONTHE miniaturization of electrical, mechanical, and opticalsystems using MEMS technologies has provided systemsand devices with a total volume on the order of at most a few tensof. The recognition that such miniaturized systems anddevices need similarly miniaturized power sources has led to aquest for true three-dimensional (3–D) microbatteries (MBs). Arecent review of the field [1] presents a wide array of ideas forvarious architectures and technologies, but states that the con-struction of an operational, fully 3-D microbattery “has yet tobe achieved.” In fact, a realistic technology of such a microbat-tery based on conformal thin-film structures that follow a 3-Dsurface was suggested already in 1998 [2], and its developmenthas continued since [3]–[8], [20], culminating in the fabrica-tion of working prototypes, one of which is described in de-Manuscript received November 12, 2004; revised March 3, 2005. The finan-cial support for this project was provided by RAMOT—Tel Aviv UniversityAuthority for Applied Research and Industrial Development, Ltd. Subject Ed-itor O. Tabata.M. Nathan, V. Yufit, and T. Ripenbein are with the Department of PhysicalElectronics, School of Electrical Engineering, Tel Aviv University, Tel Aviv69978, Israel (e-mail: [email protected]).D. Golodnitsky is with the School of Chemistry and Wolfson Applied Mate-rials Research Center, Tel Aviv University, Tel Aviv 69978, Israel.E. Strauss, I. Shechtman, S. Menkin, and E. Peled are with the School ofChemistry, Tel Aviv University, Tel Aviv 69978, Israel.Digital Object Identifier 10.1109/JMEMS.2005.851860tail in this paper. The thin-film aspect is important, because itprovides distinct advantages over conventional bulk MB’s [9],[10], which essentially miniaturize the geometry of standardbatteries. The correct frame of reference for comparison of our3-D thin-film MB’s are planar (2-D) thin-film batteries, bestrepresented by the Li and Li-ion technology developed at OakRidge National Laboratories (ONRL) by Bates and coworkers[11]. 2-D thin-film batteries cannot be considered “microbat-teries” since they require relatively large footprints of at least afewin order to provide reasonable capacity and energy.The basic proposition behind the architecture of our 3-Dmicrobatteries is that the main disadvantage (i.e., large