Tag Archives: Xiaogang Han

‘Beleafing’ in magic; a new type of battery

A Jan. 28, 2016 news item on ScienceDaily announces the ‘beleaf’,

Scientists have a new recipe for batteries: Bake a leaf, and add sodium. They used a carbonized oak leaf, pumped full of sodium, as a demonstration battery’s negative terminal, or anode, according to a paper published yesterday in the journal ACS Applied Materials Interfaces.

Scientists baked a leaf to demonstrate a battery. Credit: Image courtesy of Maryland NanoCenter

Scientists baked a leaf to demonstrate a battery.
Credit: Image courtesy of Maryland NanoCenter

A Jan. ??, 2016 Maryland NanoCenter (University of Maryland) news release, which originated the news item, provides more information about the nature (pun intended) of the research,

“Leaves are so abundant. All we had to do was pick one up off the ground here on campus,” said Hongbian Li, a visiting professor at the University of Maryland’s department of materials science and engineering and one of the main authors of the paper. Li is a member of the faculty at the National Center for Nanoscience and Technology in Beijing, China.

Other studies have shown that melon skin, banana peels and peat moss can be used in this way, but a leaf needs less preparation.

The scientists are trying to make a battery using sodium where most rechargeable batteries sold today use lithium. Sodium would hold more charge, but can’t handle as many charge-and-discharge cycles as lithium can.

One of the roadblocks has been finding an anode material that is compatible with sodium, which is slightly larger than lithium. Some scientists have explored graphene, dotted with various materials to attract and retain the sodium, but these are time consuming and expensive to produce.  In this case, they simply heated the leaf for an hour at 1,000 degrees C (don’t try this at home) to burn off all but the underlying carbon structure.

The lower side of the maple [?] leaf is studded with pores for the leaf to absorb water. In this new design, the pores absorb the sodium electrolyte. At the top, the layers of carbon that made the leaf tough become sheets of nanostructured carbon to absorb the sodium that carries the charge.

“The natural shape of a leaf already matches a battery’s needs: a low surface area, which decreases defects; a lot of small structures packed closely together, which maximizes space; and internal structures of the right size and shape to be used with sodium electrolyte,” said Fei Shen, a visiting student in the department of materials science and engineering and the other main author of the paper.

“We have tried other natural materials, such as wood fiber, to make a battery,” said Liangbing Hu, an assistant professor of materials science and engineering. “A leaf is designed by nature to store energy for later use, and using leaves in this way could make large-scale storage environmentally friendly.”

The next step, Hu said, is “to investigate different types of leaves to find the best thickness, structure and flexibility” for electrical energy storage.  The researchers have no plans to commercialize at this time.

Here’s a link to and a citation for the paper,

Carbonized-leaf Membrane with Anisotropic Surfaces for Sodium-ion Battery by Hongbian Li, Fei Shen, Wei Luo, Jiaqi Dai, Xiaogang Han, Yanan Chen, Yonggang Yao, Hongli Zhu, Kun Fu, Emily Hitz, and Liangbing Hu. ACS Appl. Mater. Interfaces, 2016, 8 (3), pp 2204–2210 DOI: 10.1021/acsami.5b10875 Publication Date (Web): January 4, 2016

Copyright © 2016 American Chemical Society

This paper is behind a paywall.

Wooden batteries in Maryland (US)

There seems to be a gusher of interest in making wooden batteries. Last year, there was news from a joint Polish-Swedish research team (my Aug. 14, 2012 posting) who’d combined lignin with a conductive polymer (polypyrrole) to create a battery cathode. Today, June 19, 2013, Nanowerk featured a news item about a team at the University of Maryland (US) who are also using wood to make battery components (Note: A link has been removed),

A sliver of wood coated with tin could make a tiny, long-lasting, efficient and environmentally friendly battery (“Tin Anode for Sodium-Ion Batteries Using Natural Wood Fiber as a Mechanical Buffer and Electrolyte Reservoir”).

But don’t try it at home yet– the components in the battery tested by scientists at the University of Maryland are a thousand times thinner than a piece of paper. Using sodium instead of lithium, as many rechargeable batteries do, makes the battery environmentally benign. Sodium doesn’t store energy as efficiently as lithium, so you won’t see this battery in your cell phone — instead, its low cost and common materials would make it ideal to store huge amounts of energy at once – such as solar energy at a power plant.

The June 19, 2013 University of Maryland news release, which originated the news item, explains why this work with wood is so exciting (Note: Links have been removed),

Existing batteries are often created on stiff bases, which are too brittle to withstand the swelling and shrinking that happens as electrons are stored in and used up from the battery. Liangbing Hu, Teng Li and their team found that wood fibers are supple enough to let their sodium-ion battery last more than 400 charging cycles, which puts it among the longest lasting nanobatteries.

“The inspiration behind the idea comes from the trees,” said Hu, an assistant professor of materials science. “Wood fibers that make up a tree once held mineral-rich water, and so are ideal for storing liquid electrolytes, making them not only the base but an active part of the battery.”

Lead author Hongli Zhu and other team members noticed that after charging and discharging the battery hundreds of times, the wood ended up wrinkled but intact. Computer models showed that that the wrinkles effectively relax the stress in the battery during charging and recharging, so that the battery can survive many cycles.

Here’s a link to and a citation for the research paper,

Tin Anode for Sodium-Ion Batteries Using Natural Wood Fiber as a Mechanical Buffer and Electrolyte Reservoir by Hongli Zhu, Zheng Jia, Yuchen Chen, Nicholas Weadock, Jiayu Wan, Oeyvind Vaaland, Xiaogang Han, Teng Li, and Liangbing Hu. Nano Lett., Article ASAP DOI: 10.1021/nl400998t Publication Date (Web): May 29, 2013

Copyright © 2013 American Chemical Society

This paper is behind a paywall.