ALD titanium nitride on vertically aligned carbon nanotube forests for electrochemical supercapacitors

Titanium nitride (TiN) coating on vertically aligned carbon nanotube (VACNT) forest electrodes by means of atomic layer deposition (ALD) to store charge in electrochemical supercapacitors has been demonstrated. Experimental results show that after 400 cycles of ALD process, a roughly 20 nm-thick TiN layer is coated uniformly on individual CNTs in the forest electrodes. The electrochemical characterizations show 2000 times higher capacitance of the ALD TiN-CNT device as compared to that of a flat-shape TiN electrode. Furthermore, over 500% enhancement of electrochemical capacitance of the ALD TiN-CNT device (81 mF/cm2) as compared to bare CNT forest electrodes (14 mF/cm2) has been accomplished due to the increased oxygen vacancies on the TiN surfaces. As such, this work presents a new path to increase energy density of supercapacitors using TiN-based porous electrode materials.