Emerging Technologies
Emerging Technologies #13
A Way To Boost Lithium-Air Battery Performance, With Help Of Modified
Viruses
Emerging Technologies
Table of Contents
Section 1 – Executive Summary ........................................................................................................................ 3
Section 2 – Related News & Articles ................................................................................................................ 4
Article 1.
Researchers find way to boost lithium-air battery performance, with help of
modified viruses
4
Article 2.
Viruses assemble key components for the lithium-air batteries of the future
6
Article 3.
Lithium-air batteries go viral for greater durability and performance
7
Emerging Technologies
Section 1 – Executive Summary
A Way To Boost Lithium-Air Battery Performance, With Help Of Modified Viruses

Lithium-oxygen batteries have a great potential to enhance the gravimetric energy density of fully
packaged batteries by two to three times that of lithium ion cells. MIT researchers have found that
adding genetically modified viruses to the production of nanowires will boost the performance of
lithium-air battery used in electric cars.

The key to their work was to increase the surface area of the wire, thus increasing the area where
electrochemical activity takes place during charging or discharging of the battery. The increase in surface
area produced by their method can provide a big advantage in lithium-air batteries' rate of charging and
discharging. Unlike conventional fabrication methods, which involve energy-intensive high temperatures
and hazardous chemicals, this process can be carried out at room temperature using a water-based
process.

By using a genetically modified version of the M13 virus, the MIT team was able to increase the surface
area of a nanowire array, which is about 80 nm across. The virus has the ability to “capture molecules of
metals from water and bind them into structural shapes,” says to Angela Belcher, the W.M. Keck Professor
of Energy and a member of MIT’s Koch Institute for Integrative Cancer Research. "Similar to how an
abalone grows its shell.”

The viruses built wires of manganese oxide, a material often used for the cathode of lithium-air batteries,
that had a rough, spiked surface. Having spikes, rather than a flatter surface as results when wires are
“grown” through conventional chemical methods, creates more surface area for the chemical reaction to
occur. This process also creates a cross-linked 3D structure, rather than isolated wires, making for a more
stable electrode. Adding to its advantages, the viral process is water-based and done at room
temperature.
Emerging Technologies
Section 2 – Related News & Articles
Article 1.
Researchers find way to boost lithium-air battery performance, with help of
modified viruses
Source: http://phys.org/news/2013-11-boost-lithium-air-battery-viruses.html (13/11/2013)
Video URL: http://www.youtube.com/watch?feature=player_embedded&v=pUVrUIV4xu4

Lithium-air batteries have become a hot research area in recent years: They hold the promise of
drastically increasing power per battery weight, which could lead, for example, to electric cars with a
much greater driving range. But bringing that promise to reality has faced a number of challenges,
including the need to develop better, more durable materials for the batteries' electrodes and improving
the number of charging-discharging cycles the batteries can withstand.

Now, MIT researchers have found that adding genetically modified viruses to the production of
nanowires—wires that are about the width of a red blood cell, and which can serve as one of a battery's
electrodes—could help solve some of these problems.

The new work is described in a paper published in the journal Nature Communications, co-authored by
graduate student Dahyun Oh, professors Angela Belcher and Yang Shao-Horn, and three others. The key
to their work was to increase the surface area of the wire, thus increasing the area where electrochemical
activity takes place during charging or discharging of the battery.

The researchers produced an array of nanowires, each about 80 nanometers across, using a genetically
modified virus called M13, which can capture molecules of metals from water and bind them into
structural shapes. In this case, wires of manganese oxide—a "favorite material" for a lithium-air battery's
cathode, Belcher says—were actually made by the viruses. But unlike wires "grown" through
conventional chemical methods, these virus-built nanowires have a rough, spiky surface, which
dramatically increases their surface area.
Emerging Technologies

Belcher, the W.M. Keck Professor of Energy and an affiliate of MIT's Koch Institute for Integrative Cancer
Research, explains that this process of biosynthesis is "really similar to how an abalone grows its shell"—
in that case, by collecting calcium from seawater and depositing it into a solid, linked structure.

The increase in surface area produced by this method can provide "a big advantage," Belcher says, in
lithium-air batteries' rate of charging and discharging. But the process also has other potential
advantages, she says: Unlike conventional fabrication methods, which involve energy-intensive high
temperatures and hazardous chemicals, this process can be carried out at room temperature using a
water-based process.

Also, rather than isolated wires, the viruses naturally produce a three-dimensional structure of crosslinked wires, which provides greater stability for an electrode.

A final part of the process is the addition of a small amount of a metal, such as palladium, which greatly
increases the electrical conductivity of the nanowires and allows them to catalyze reactions that take
place during charging and discharging. Other groups have tried to produce such batteries using pure or
highly concentrated metals as the electrodes, but this new process drastically lowers how much of the
expensive material is needed.

Altogether, these modifications have the potential to produce a battery that could provide two to three
times greater energy density—the amount of energy that can be stored for a given weight—than today's
best lithium-ion batteries, a closely related technology that is today's top contender, the researchers say.

While these experiments used viruses for the molecular assembly, Belcher says that once the best
materials for such batteries are found and tested, actual manufacturing might be done in a different way.
This has happened with past materials developed in her lab, she says: The chemistry was initially
developed using biological methods, but then alternative means that were more easily scalable for
industrial-scale production were substituted in the actual manufacturing.
Emerging Technologies
Article 2.
Viruses assemble key components for the lithium-air batteries of the future
Source:
http://www.zmescience.com/research/virus-cathode-nanowires-lithium-air-battery-053534/
(14/11/2013)

In a synergy between biology and electrochemistry, researchers at MIT cleverly exploited
genetically modified viruses to assemble metal molecules into extremely thin nanowires that can
be used as cathodes in a lithium-air battery. This type of battery has been thoroughly researched in
the past few years and has sparked the interest of scientists because of its tremendous potential to store
high amounts of energy per unit size. For instance, such batteries can carry as much as three times the
amount of energy per area than a lithium-ion battery, currently the de facto mobile energy storage
medium used for everything from mobile phones to notebooks to electric cars.

The MIT researchers specifically genetically designed a virus called M13 which has an inherent
affinity for capturing metal molecules from water and binding them together to form structures –
he’s quite the nifty builder, too. The team demonstrated that the virus could assemble manganese oxide
molecules (a favored material for lithium-air battery cathode) into nanowires as thin as 80 nanometers
or about the width of a blood cell.

The process doesn’t construct perfectly smooth wires, which in our case is a good thing. The rougher the
surface, the better, since you want as many lithium molecules to come into contact with the cathode
material as possible – this way you don’t just have an almost 2D surface for molecules to cling on, but a 3D one. Also, the viruses naturally produce a three-dimensional structure of cross-linked wires, which
provides greater stability for an electrode. Another positive point going to the virus generation method is
that unlike conventional chemical manganese oxide assembly methods, which are extremely energy
intensive requiring a high temperature environment, the present process can be run at room
temperature.

To make the nanowires more electrically conductive and of course provide the cathode with catalysis
capabilities, the wires are doped with palladium nanoparticles. Other methods involve making cathode
nanowires in bulk materials which translates in a lot of palladium being used, and as you may know it’s a
very expensive material.

One of the lead authors of the paper, MIT Professor Angela Belcher, envisions the whole process akin to
how an abalone grows its shell by collecting calcium from seawater and depositing it into a solid, linked
structure.
Emerging Technologies

Belcher stresses, however, that their work only details how a cathode could be made for a lithium-air
battery. It still remains to be seen how the anode or the electrolyte (the material or solution that allows
lithium ions to pass to the anode and complete the electrochemical reaction) will be assembled. A big
questions arises, as well. Can this method be scaled? Well, it might be difficult to grow millions of cathode
nanowires using viruses alone, but it’s possible that actual manufacturing might be done in a different
way. This has happened with past materials developed in her lab, she says: The chemistry was initially
developed using biological methods, but then alternative means that were more easily scalable for
industrial-scale production were substituted in the actual manufacturing.
Article 3.
Lithium-air batteries go viral for greater durability and performance
Source: http://www.gizmag.com/m13-virus-electrode-lithium-air-battery/29791/ (14/11/2013)

In recent years, lithium-air batteries that
promise improved power density per
pound over lithium-ion batteries have been
the subject of much research in the quest to
give electronic vehicles greater range. By
enlisting the help of a genetically-modified
virus, researchers at MIT have found a way
to improve the performance and durability
of lithium-air batteries, which offer the
potential of two to three times the energy density of current lithium-ion batteries.

The main reason lithium-air batteries boast higher energy density than lithium-ion batteries is because,
in place of the heavy conventional compounds used in lithium-ion batteries, they use oxygen from the air
to react with a lithium anode through a carbon-based air cathode. Nanowires used as one of the
electrodes for these batteries are typically created through a high-energy chemical process, which
produces electrodes with a flat surface area.

By using a genetically modified version of the M13 virus, the MIT team was able to increase the surface
area of a nanowire array, which is about 80 nm across. The virus has the ability to “capture molecules of
metals from water and bind them into structural shapes,” says to Angela Belcher, the W.M. Keck Professor
of Energy and a member of MIT’s Koch Institute for Integrative Cancer Research. "Similar to how an
abalone grows its shell.”
Emerging Technologies

The viruses built wires of manganese oxide, a material often used for the cathode of lithium-air batteries,
that had a rough, spiked surface. Having spikes, rather than a flatter surface as results when wires are
“grown” through conventional chemical methods, creates more surface area for the chemical reaction to
occur. This process also creates a cross-linked 3D structure, rather than isolated wires, making for a more
stable electrode. Adding to its advantages, the viral process is water-based and done at room
temperature.

This doesn’t mean that our battery-making facilities will become industrial virus churns, as Belcher
expects the manufacturing process to evolve, as it has with other materials developed in her lab in the
past. “The chemistry was initially developed using biological methods, but then alternative means that
were more easily scalable for industrial-scale production were substituted in the actual manufacturing.”

The researchers only produced a cathode using the viral process and the produced material was tested
through 50 cycles of charging and discharging, which is a drop in the bucket compared to the thousands
of cycles electric vehicle batteries would endure. According to the team, more research is needed,
specifically in the area of the electrolyte of the battery, to make lithium-air batteries commercially viable.