Area-selective atomic layer deposition of titanium oxide and nitride on vertically aligned carbon nanotubes patterned by Aerosol Jet Printing for 3D Microsupercapacitors

Abstract

This article demonstrates novel fabrication of the first interdigital 3D microsupercapacitors (MSC) using area-selective atomic layer deposition (ASALD). A unique ASALD process was developed to selectively deposit pseudocapacitive titanium oxide and nitride layers on one or both interdigitated vertically aligned carbon nanotube (VACNT) electrodes to form asymmetric or symmetric 3D MSC devices. This work compliments and expands on our previously published article exploring ALD of thin conformal coatings of TiO2 and TiN on VACNTs for 3D MSCs. Further, we demonstrate the first use of Aerosol Jet Printing, a recently developed additive manufacturing technique, to enable ASALD patterning of 3D MSC devices by direct writing of PMMA inhibitors on and adjacent to relatively thick nanostructured electrodes. The synthesis, characterization, and performance evaluation of ASALD TiN-TiO2-VACNT 3D MSCs described herein provides a novel approach for manufacturing of new nanocomposite based electrochemical energy storage microdevices that could be integrated as an on-chip power source for portable electronics. Results indicated the symmetric ASALD TiN(100)-TiO2(100)-VACNT MSC (6.55 mF cm−2) exhibited nearly two orders of magnitude (94×) improvement in specific capacitance compared to the uncoated VACNT MSC (0.07 mF cm−2), significantly improving energy density (3.28 mWhr cm−2) while maintaining high power density (2.34 mW cm−2).