Document Type: Research Paper
Nano-fabricated Energy Devices Laboratory, School of Electrical and Computer Engineering, College of Engineering, University of Tehran, Tehran, Iran.
Lithium ion batteries are among the most used rechargeable batteries in the world. Carbon nanostructures including carbon nanotubes (CNTs) are considered as important electrode materials for this kind of batteries. Therefore improving the performance of these carbon based electrodes in Lithium ion batteries is an important issue and attracts much attention in the battery community. In this manuscript, a new method for high content Nitrogen doping on CNTs is reported as an efficient approach for enhancing the battery performance. Direct current-plasma enhanced chemical vapor deposition (DC-PECVD) system was used for nitrogen doping. Annealing with Nitrogen during CNT growth and plasma exposure after the growth has been used for Nitrogen doping of the CNTs. The growth was performed on an Indium Tin oxide (ITO) covered Silicon substrate. Implementation of Silicon substrate enables the possibility of future integration of other electronic circuits with the fabricated Lithium ion battery. Vertically aligned CNTs with an average diameter of around 150 nm and 4 um height has been obtained on this substrate. The synthesized CNTs was subsequently used as the electrode of Lithium ion battery in a half cell configuration. The results show a significant improvement of about 400% in the specific capacity of the battery as a result of Nitrogen doping. For Nitrogen doped CNT based battery, specific capacity of around 0.4 mAh/cm2 and coulombic efficiency of 97% were achieved after 28 cycles of charge/discharge with C rate of 2.5. This Nitrogen doping method is propped as an efficient technique for enhancing the performance of Lithium ion batteries with carbon based electrodes.