Electrophoretic Deposition of Lithium Titanium Oxide (LTO) Anode at AC, PDC and DC Mode for 3D Microbatteries

The three-dimensional battery architecture is a promising concept for increasing the power capability, while producing high capacity per battery footprint. Most of the thin-film electrode materials used in current commercial variations of thin-film batteries are deposited in vacuum chambers by RF and DC magnetron sputtering, and by thermal or chemical evaporation. However, these methods are inapplicable for the fabrication of high-aspect-ratio, complex-shape 3D electrodes and electrolytes. We have recently presented the feasibility study of the preparation of all the thin-film active-material layers of the microbattery by simple and inexpensive electrophoretic-deposition routes [1].

In the current research, the focus has been made on the determination of the effects of solvents, polymers and charging agents in the electrolytic bath, voltage and deposition protocol (AC, continuous or pulse DC) with the aim of obtaining highly adhesive, compact pristine and composite LTO films. The samples were investigated by scanning electron microscopy (SEM) and TOFSIMS. These methods confirmed the presence of a polymer binder and its homogeneous lateral distribution in the composite EPD-LTO anode. With the advantage of thin films, which conformally follow all the contours of the 3D-substrate and are composed of nanosize lithium titanate and quasi-solid electrolyte, our 3D microbatteries enable the maintenance of high reversible specific capacity, long cycle life, and intrinsic safety of microbattery.