On the electrophoretic and sol–gel deposition of active materials on aluminium rod current collectors for three-dimensional Li-ion micro-batteries

• Electrophoretic deposition of TiO2 particles on Al nanorods is demonstrated.
• TiO2 deposition on 3D Al current collectors by Ti-isopropoxide impregnation.
• Stable 3D TiO2/Al electrode capacities over 100 cycles are shown.
• Capacities of 1.5 μAh/cm2 were obtained for the 3D TiO2 electrodes.
• Sol–gel impregnation is a promising coating method for 3D electrodes.

Electrophoretic deposition of titanium oxide particles, as well as sol–gel synthesis of thin films of TiO2 employing a titanium isopropoxide precursor solution, were studied as possible deposition routes for the coating of aluminium pillar current collectors intended for three-dimensional Li-ion micro-batteries. While electrophoresis of TiO2 particles was homogeneously covering the two-dimensional aluminium substrates, it was difficult to conformally coat the three-dimensional current collectors with this technique. The sol–gel approach, on the other hand, gave rise to thin and amorphous TiO2 layers on the Al rod based current collectors. The latter could be cycled for 100 cycles indicating that such straightforward sol–gel approaches may be used for the manufacturing of 3D electrodes for Li-ion micro-batteries.