Three-dimensional (3-D) Thin-Film Microbattery
The Invention The 3-D Thin-film Microbattery is a, lithium or lithium-ion battery conformally formed on all exposed surfaces of a perforated substrate. The extended area provides an increase of 1-2 orders of magnitude in specific energy (per volume and weight) and capacity vs. conventional planar thin-film microbatteries. 3-D Microbatteries will be of great importance to self powered semiconductor devices, autonomous MEMS, nanosystems, and implantable micro-medical devices requiring energy in limited spaces.
The Technological Innovation A 3-D Thin-film Microbattery is formed by depositing conformal battery layers on all available surfaces of a perforated substrate, as shown schematically in Fig. 1. Such substrates may be formed by either subtractive processes (etched silicon) or additive processes (multi-channel plates or MCPs). A hole array as shown may increase the surface area per original unit area by a factor of up to ca. 50. The battery capacity is directly proportional to active film volumes (anode and cathode), i.e. to film thickness x surface area.
Accordingly, for an equivalent total cathode/electrolyte/anode thickness as found in a typical 15 micron-thick 2-D structure, this 3-D microbattery provides an increase of up to 50 times in capacity and energy. Moreover, since the perforated substrate has only a small fraction of the full substrate weight (typically 10-20%) the specific gravimetric capacity and energy are further increased by a factor of 5-10 times. Yet another major advantage over conventional microbatteries is expressed by the much larger currents provided by this 3-D microbattery, which result from the extremely large contact areas between the active layers and the central electrolyte layer.
Commercial Applications Microsystems and nanosystems of the future will require miniaturized independent power sources. The development of such sources lags far behind that of active and passive components of the systems themselves. The 3-D Thin-film Microbattery offers an immense improvement in terms of specific capacity and energy, and solves the problem of size and weight additions to autonomous microsystems.
Implementation The manufacturing processes of the 3-D Thin-film Microbattery are based on chemical and electrochemical methods, and therefore only simple and inexpensive equipment is required. The processes may be made compatible with CMOS processes. Therefore, this microbattery may be integrated into silicon microelectronic chips.
Menachem Nathan, Emanuel Peled, Diana Golodnitzky
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