Bipolar electrochemical capacitors using double-sided carbon nanotubes on graphite electrodes
Journal article, 2020

The electrochemical capacitor (EC) is a key enabler for the miniaturized self-powered systems expected to become ubiquitous with the advent of the internet-of-things (IoT). Vertically aligned carbon nanotubes (VACNTs) on graphite holds promise as electrodes for compact and low-loss ECs. However, as with all ECs, the operating voltage is low, and miniaturization of higher voltage devices necessitates a bipolar design. In this paper, we demonstrate a bipolar EC using graphite/VACNTs electrodes fabricated using a joule heating chemical vapor deposition (CVD) setup. The constructed EC contains one layer of double-sided VACNTs on graphite as bipolar electrode. Compared to a series connection of two individual devices, the bipolar EC has 22% boost in volumetric energy density. More significant boost is envisaged for stacking more bipolar electrode layers. The energy enhancement is achieved without aggravating self-discharge (71.2% retention after 1 h), and at no sacrifice of cycling stability (96.7% over 50000 cycles) owing to uniform growth of VACNTs and thus eliminating cell imbalance problems.

Miniaturized self-powered systems

Self-joule heating

Self-discharge

Series connection

Volumetric

CVD

Supercapacitor

Bipolar

Author

Josef Hansson

Chalmers, Microtechnology and Nanoscience (MC2), Electronics Material and Systems Laboratory

Qi Li

Chalmers, Microtechnology and Nanoscience (MC2), Electronics Material and Systems Laboratory

Anderson David Smith

Chalmers, Microtechnology and Nanoscience (MC2), Electronics Material and Systems Laboratory

Isaac Zakaria

University of California

Torbjörn Nilsson

Chalmers, Microtechnology and Nanoscience (MC2), Electronics Material and Systems Laboratory

Andreas Nylander

Chalmers, Microtechnology and Nanoscience (MC2), Electronics Material and Systems Laboratory

L. Ye

SHT Smart High-Tech

Per Lundgren

Chalmers, Microtechnology and Nanoscience (MC2), Electronics Material and Systems Laboratory

Johan Liu

Chalmers, Microtechnology and Nanoscience (MC2), Electronics Material and Systems Laboratory

Peter Enoksson

Chalmers, Microtechnology and Nanoscience (MC2), Electronics Material and Systems Laboratory

Journal of Power Sources

0378-7753 (ISSN)

Vol. 451 227765

Subject Categories

Energy Engineering

Materials Chemistry

Other Electrical Engineering, Electronic Engineering, Information Engineering

DOI

10.1016/j.jpowsour.2020.227765

More information

Latest update

2/12/2020