Manganese dioxide nanorod technology could lead to a better capacitor

April 16, 2013 by Marcia Goodrich
Building a better capacitor with custom nanorods
The non-aligned manganese dioxide nanorods on the left were made using conventional methods. The aligned nanorods on the right were grown in Desheng (Dennis) Meng's lab at Michigan Technological University using electrophoretic deposition. Using aligned nanorods, Meng's group was able to build a superior chemical capacitor. Credit: Sunand Santhanagopalan

( —A new process for growing forests of manganese dioxide nanorods may lead to the next generation of high-performance capacitors.

As an energy- for batteries and capacitors, manganese dioxide has a lot going for it: it's cheap, environmentally friendly and abundant. However, chemical capacitors made with manganese dioxide have lacked the power of the typical carbon-based physical capacitor. Michigan Technological University scientist Dennis Desheng Meng theorized that the situation could be improved if the manganese dioxide were made into nanorods, which are like nanotubes, only solid instead of hollow. However, a stumbling block has been making manganese dioxide nanorods with the right set of attributes. Until now, researchers have been able to grow nanorods that either have the best or were aligned, but not both.

Now, Meng's research group has developed a technique to grow manganese dioxide nanorods that are not only straight and tall (at least by nano-standards), but also have the optimal , known as α-MnO2.

This minimizes the internal resistance, allowing the capacitor to charge and discharge repeatedly without wearing out. That's a recipe for a better capacitor: it can store more energy, extract that energy more quickly, and work longer between rechargings. Plus, it can be used over and over again. Even after Meng's group recharged their capacitor more than 2,000 times, it was still able to regain over 90 percent of its original charge.

Meng's device belongs to the family of chemical, or reduction-oxidation, capacitors. They are hybrids between physical supercapacitors, which release a burst of energy and discharge quickly, and batteries, which generally store more energy and release it gradually over a longer period. Typically, chemical capacitors have more energy and less power than the physical ones.

The chemical capacitors made with Meng's manganese dioxide nanorods offer the best of both worlds: they hold more energy, like a battery, plus they yield even more power than a comparable carbon-based physical .

His team was able to grow a nanoforest of manganese dioxide nanorods using electrophoretic deposition, a technique in which small particles are deposited on a substrate under the influence of an electric field. The process is not especially difficult. "We did it in a lab, but this is scalable manufacturing," he says. "We can continuously print it out in a roll-to-roll manner, and you can make the substrate very large if you like."

Capacitors made with manganese dioxide nanorods could help hybrid and electric vehicles accelerate more quickly or could be coupled with solar cells. "The process also opens the door for many other applications, not just ," says Meng.

Explore further: High-performance energy storage

More information: Meng's research is described in the article "Scalable High-Power Redox Capacitors with Aligned Nanoforests of Crystalline MnO2 Nanorods by High-Voltage Electrophoretic Deposition" (, which was published online Feb. 1 in ACS Nano.

Related Stories

High-performance energy storage

July 3, 2007

North Carolina State University physicists have recently deduced a way to improve high-energy-density capacitors so that they can store up to seven times as much energy per unit volume than the common capacitor.

Clothing the body electric

June 29, 2012

( -- Over the years, the telephone has gone mobile, from the house to the car to the pocket. The University of South Carolina's Xiaodong Li envisions even further integration of the cell phone – and just about ...

Recommended for you

Physicists develop new technique to fathom 'smart' materials

November 26, 2015

Physicists from the FOM Foundation and Leiden University have found a way to better understand the properties of manmade 'smart' materials. Their method reveals how stacked layers in such a material work together to bring ...

Mathematicians identify limits to heat flow at the nanoscale

November 24, 2015

How much heat can two bodies exchange without touching? For over a century, scientists have been able to answer this question for virtually any pair of objects in the macroscopic world, from the rate at which a campfire can ...

New sensor sends electronic signal when estrogen is detected

November 24, 2015

Estrogen is a tiny molecule, but it can have big effects on humans and other animals. Estrogen is one of the main hormones that regulates the female reproductive system - it can be monitored to track human fertility and is ...


Adjust slider to filter visible comments by rank

Display comments: newest first

Whydening Gyre
1 / 5 (1) Apr 16, 2013
This article is a little more descriptive than the other one of micro super batteries
not rated yet Apr 17, 2013
I liked the descriptive nature of the article.

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.