Li-ion microbatteries generated by a laser direct-write method

A laser-based direct-write process is demonstrated as a method to fabricate Li-ion microbatteries. The battery electrodes are made by the laser-induced forward transfer of inks of charge-storage materials (composites of carbon/binder and LiCoO₂/carbon/binder) onto micromachined metal-foil current collectors to form 40-60 μm thick electrodes with 16mm² (4 mm × 4 mm) footprints. Both half cells and packaged microbatteries display capacities of approximately 155 μAh or 100 mAh/g, as normalized to the amount of LiCoO₂, and are comparable to the capacities of control electrodes that have been stenciled and pressed. The electrode capacities are not compromised when they are assembled into microbatteries, packaged and tested in air. The density and volumetric capacity of the laser-transferred electrodes are lower than those reported for sputtered thin-film microbatteries, yet the former electrodes can be made thicker and therefore deliver the same amount of charge from a smaller footprint. The data indicate that this laser direct-write method may be a viable approach for developing Li-ion microbattery systems for autonomous microelectronic devices and microsensors.