Laser direct writing of microbatteries for integrated power electronics

A novel laser-based process developed at the Naval Research Laboratory has been used to fabricate pseudocapacitors and microbatteries with tailored capacities for small electronic devices having size and/or weight restrictions. This process, called MAPLE DW (for matrix-assisted pulsed-laser evaporation direct write) can deposit rugged mesoscale (1 gm to 10 mm) electronic components over any type of substrate. A pulsed laser operating at 355 rim is used to forward transfer material from a tape-cast ribbon to a suitable substrate to form a precision design. With MAPLE DW, customized mesoscale electronic components can be produced. eliminating the need for multiple fabrication techniques and surface-mounted components. Direct write processing is especially attractive for the fabrication of micro-power sources and systems. The versatility of laser processing allows battery designs to be easily modified. Batteries and/or pseudocapacitors can be integrated with power management electronics to deliver a wide range of power outputs. By building power sources directly on electronic components, the weight of the power sources is decreased as the electronic substrate becomes part of the battery packaging and the lengths of interconnects are shortened, reducing conductor losses. RuOxHy pseudocapacitors deposited with MAPLE DW show good storage capacities. Pads of hydrous RuO2 having dimensions of 2.2 mm x 1.0 mm x 30 mum have been deposited in a planar configuration on gold current collectors. Rechargeable Zn/MnO2 alkaline microbatteries comprising of MnO2, Zn, an ethyl cellulose separator barrier layer and a KOH electrolyte have also been fabricated by MAPLE DW. The resulting structures with dimensions of 1.5 turn x 1.5 mm x 60 mum represent the first demonstration of a multilayer microbattery made by MAPLE DW. The performance of these prototypes are shown and the potential impact of MAPLE DW for the fabrication of novel microbattery systems for integrated power applications are discussed.