NanoEngineers at the University of California, San Diego are
designing new types of lithium-ion (Li-ion) batteries that could be
used in a variety of NASA space exploration projects – and in
a wide range of transportation and consumer applications. NEI
Corporation and UC San Diego recently won a Phase II Small Business
Technology Transfer contract from NASA to develop and implement
high energy density cathode materials for lithium batteries.
NEI is the prime contractor on the NASA contract and Shirley
Meng, a professor in the Department of NanoEngineering at the UC
San Diego Jacobs School of Engineering, is a subcontractor. The
nearly $600,000 program builds upon expertise in the UC San Diego
Department of NanoEngineering in modeling new nanocomposite
structures for next generation electrode materials, and NEI’s
capability to reproducibly synthesize electrode materials at the
nanoscale.
Battery Applications
Advanced Li-ion battery systems with high energy and power
densities – and the ability to operate at low temperatures
– are required for NASA’s exploration missions. The James
Webb Space Telescope (JWST), Mars Atmospheric and Volatile
Evolution (MAVEN), deep drilling equipment and Astrobiology Field
Laboratory on Mars, International X-ray Observatory (IXO), and
extravehicular activities are potential space applications.
Advanced lithium-ion battery packs could also be used in hybrid
electric vehicles, consumer electronics, medical devices, electric
scooters, and a variety of military applications.
Designing Batteries from the Atom Up
The UC San Diego NanoEngineers will help guide development of
the new batteries using advanced modeling techniques. “We will give
NEI candidate materials that we think will have optimal battery
properties, and they will make the materials using their
proprietary technology,” said professor Shirley Meng, who leads the
Laboratory for Energy Storage and Conversion in the Department of
NanoEngineering at the UC San Diego Jacobs School of Engineering.
https://ne.ucsd.edu/smeng/
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The outcome of the program will be a commercially useable
cathode material with exceptionally high capacity – more than
250 milliAmp-Hours per gram (250 mAh/g) at about 4V, which
translates to an energy density of more than 1000 Watt-hours per
kilogram (Wh/kg). This represents a factor of two enhancement in
energy density over lithium cobalt oxide, which is the most
commonly used cathode material at the present time. NEI expects to
have sample cathode materials for testing by interested end-users
by the middle of 2011.
The UC San Diego NanoEngineers will design the candidate cathode
materials using “first principles calculations” – a
quantum-mechanical based calculation method that enables the
engineers to predict electrochemical properties of the batteries
prior to synthesis.
One aspect of the batteries the engineers will predict is the
structural stability of the electrode materials as the lithium
concentration fluctuates during charge and discharge. Enhancing
structural stability is critical for extending the life of
rechargeable batteries.
“We are pleased to be working closely with Shirley Meng on this
exciting materials manufacturing project. The shortest path to
developing new materials and implementing them in practical
applications is for materials manufacturers to work synergistically
with researchers like Prof. Meng, who can create new structures
through computation and modeling,” said Dr. Ganesh Skandan, CEO NEI
Corporation.
“This work, which could lead to new batteries for space
exploration and beyond, is just one example of the high impact
research being done in the Department of NanoEngineering,” said
Kenneth Vecchio, Professor and Chair of the Department of
NanoEngineering at the UC San Diego Jacobs School of
Engineering.
Batteries for hybrid electric vehicles or full electric
cars
Work in the Meng lab on next-generation batteries extends beyond
the collaboration with NEI.
“In my group, we are very interested in batteries that will be
used in future transportation systems. Lithium batteries for
plug-in hybrid electric vehicles or full electric cars have a lot
of potential, but we have to work very hard to decrease the dollar
per kilowatt hour numbers,” said Meng, whose research group at UC
San Diego is funded through grants from the U.S. Department of
Energy (DOE) and other government and industry sources.
The new Phase II Small Business Technology Transfer contract
follows a similar Phase I contract awarded to the same
industry-university team.
“If we are going to use large scale batteries for applications
such as electric cars, it is not acceptable to replace batteries
every three years. The cycle life of the batteries becomes very
important and this is a challenge to address. How do we make
batteries last for ten years instead of three years? We have to
look for other options for the structure of the battery materials
that are more robust,” said Meng.
The Cathode Bottleneck
The positive electrode in lithium-ion batteries – the
cathode – is one battery component ripe for additional
improvements.
“The cathode is a performance bottleneck for modern lithium
batteries that power consumer electronics like PDAs, mp3 players
and laptops,” said Meng. “There is plenty of room for improving
energy density in lithium batteries by at least another 50 percent.
The problem is making these improvements under the constraints of
cost. That is the main obstacle. We are looking at dollars per
kilowatt hour. We need to make sure the raw materials are low cost,
the synthesis process is low cost, and the packaging of the battery
is low cost,” said Meng.
Moving to Manganese
The lithium ion batteries Meng’s group is working on are
primarily manganese based, while most of the lithium batteries in
the marketplace today are cobalt based.
“Manganese is much cheaper than cobalt, and manganese is more
abundant,” said Meng. “Also, we are focusing on a different
material structure for the batteries, one that is easier to make
and could lead to cheaper synthesis.”
The nanoengineers in the Meng lab will be using first principles
to model new nanocomposite structures for the generation of cathode
materials with exceptionally high energy density.
“We explore the electrochemical properties of the batteries we
design and develop to see if the experimentally measured properties
match with our predictions,” said Meng. “We use this feedback
mechanism to improve our computational modeling.”