Manufacture of mesoscale energy storage systems by laser-direct write

The development of micro power systems, on the mm size scale, is necessary for emerging technologies in small, portable micro-electronic device applications. Direct-write processes are used to produce the high-power, low-power, and recharging elements of such mesoscale micro power systems. Successful fabrication of alkaline and lithium based micro-batteries, micro-ultracapacitors, and dye-sensitized micro-solar cells are possible on various low processing temperature and flexible substrates using laser direct-write approaches that are ideally suited for the many different structurally complex electrochemical materials used in these systems. Increased areal energy density is realized by depositing thick layers > 10 μm, while maintaining patterns as small as 2 mm². Micro-ultracapacitors exhibit high power densities > 250 mW/cm², while primary alkaline microbatteries exhibit open circuit potentials of 1.5 V with high capacities and discharge currents up to 1 mA. Secondary LiCoO₂ and LiMn ₂O₄ based microbatteries employing a novel nanocomposite solid-state electrolyte exhibit open circuit potentials > 4 V and have shown multiple recharging cycles without loss of capacity. Results of the different systems will be discussed with particular emphasis on the combination of elements to produce hybrid micro power systems.