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THE LATEST RESEARCH AND DEVELOPMENT NEWS IN MANUFACTURING AND TECHNOLOGY
Li-ion Battery Tech Leads to Hydrogen Production
D
evelopers of electric cars that used lithium-ion batter-
metals. The team built a conventional water splitter with one
ies are racing the champions of hydrogen-fueled ve-
platinum and one iridium, Wang said. That device started off
hicles to see which will succeed the greenhouse gas-
well, needing only 1.56 volts to split water initially, but within
producing gasoline-powered internal combustion engine.
They’ve been racing in different directions—until now:
Scientists at Stanford University have created a low-voltage,
30 hours the voltage needed to be increased nearly 40%, “a
significant loss of efficiency,” according to Wang.
In conventional water splitters, the hydrogen and oxygen
low-cost “water splitter” that uses a single catalyst to contin-
catalysts often require different electrolytes with different
uously produce both hydrogen and oxygen from water. That
pH–one acidic, one alkaline–to remain stable and active.
catalyst was created by a team co-led by Yi Cui, an associ-
“For practical water splitting, an expensive barrier is needed
ate professor of materials science and engineering at Stanford and of photon science at
the SLAC National Accelerator Laboratory,
using lithium-ion battery technology.
“Our group has pioneered the idea of using
lithium-ion batteries to search for catalysts,”
Cui said. “Our hope is that this technique will
lead to the discovery of new catalysts for other
reactions beyond water splitting.”
The water-splitting device is described in
Photo courtesy LA Cicero, Stanford News Service
a study published on June 23 in the journal
Nature Communications and was announced
in a Stanford news release the same day.
Despite its sustainable reputation, most
commercial-grade hydrogen is made from
natural gas, a fossil fuel. As a greener alternative, researchers have sought to develop
a cheap and efficient way to extract pure
hydrogen from water. A conventional watersplitting device consists of two electrodes
submerged in a water-based electrolyte.
Stanford University graduate student Haotian Wang examines the novel water
splitter that produces hydrogen and oxygen gas 24 hours a day, seven days a week.
“Our water splitter is unique because we only use one
catalyst, nickel-iron oxide, for both electrodes,” said graduate student Haotian Wang, lead author of the study. “This
to separate the two electrolytes, adding to the cost of the
device,” Wang said.
To find catalytic material suitable for both electrodes,
bi-functional catalyst can split water continuously for more
the Stanford team borrowed a technique used in battery
than a week with a steady input of just 1.5 volts of electricity.
research called lithium-induced electrochemical tuning. The
That’s an unprecedented water-splitting efficiency of 82% at
idea is to use lithium ions to chemically break the metal ox-
room temperature.”
ide catalyst into smaller and smaller pieces. “This process
Wang and his colleagues discovered that nickel-iron
creates tiny particles that are strongly connected, so the
oxide, which is cheap and easy to produce, is actually more
catalyst has very good electrical conductivity and stability,”
stable than some commercial catalysts made of precious
Cui said.
August 2015
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AdvancedManufacturing.org
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tech front
Web Content: Polymer
Fiber Mimics Spider Silk
P
olytechnique Montréal researchers have
produced a biomimetic polymer fiber direct-
ly inspired by the structure of spider silk. They
say that composites made by weaving together
tough fibers of this type could make possible
safer and lighter casings for aircraft engines, as
an example. Or at least that’s their spin.
The university announced that Professors
Frédérick Gosselin and Daniel Therriault, along
with their master’s student Renaud Passieux
have recently published an article about the
project in the journal Advanced Materials.
Spider silk is 3–8 µm in diameter but five to ten times tougher than steel or Kevlar.
Only 3–8 µm in diameter but five to ten times tougher than
ability to absorb a large amount of energy before failing—to
steel or Kevlar, spider silk has remarkable elongation and
the particular molecular structure of the protein chain of
stretch-resistance properties that humans have long sought
which it’s composed. The mechanical origin of its strength
to replicate. Spider silk owes its exceptional strength—its
drew the interest of researchers at the Laboratory for Multi-
scale Mechanics in Polytechnique Montréal’s Department of
when the filament makes a loop and bonds to itself. At that
Mechanical Engineering.
point, it takes a pull with a strong energy output on the
“The silk protein coils upon itself like a spring. Each loop
of the spring is attached to its neighbors with sacrificial
resulting fiber to succeed in breaking the sacrificial bonds, as
they behave like protein-based spider silk.
bonds, chemical connections that break before the main
molecular structural chain tears,” explained Gosselin, who,
along with Therriault, is co-supervising Passieux’s master’s
research work. He added: “To break the protein by stretching it, you need to uncoil the spring and break each of the
sacrificial bonds one by one, which takes a lot of energy. This
is the mechanism we’re seeking to reproduce in laboratory.”
Their project involves making micron-sized microstruc-
Biofuel Research Broke the Mold
S
cientists at the Manchester Institute of Biotechnology
(MIB) at UK’s University of Manchester have identified the
exact mechanism and structure of two key enzymes isolated
from yeast molds that together provide a new, cleaner route
to the production of hydrocarbons. The university announced
tured fibers that have mechanical properties similar to those
the discovery in a June news release, saying that the dis-
of spider silk. “The filament forms a series of loops or coils,
covery will lead to the development of new applications in
kind of like when you pour a thread of honey onto a piece
biofuels and sustainable chemical manufacturing.
of toast,” said Passieux. “It forms regular periodic patterns,
which we call instability patterns.”
The fiber then solidifies as the solvent evaporates. Some
instability patterns feature the formation of sacrificial bonds
Published in the science journal Nature, the research
offers the possibility of replacing the need for oil in current
industrial processes with a greener and more sustainable
natural process.
tech front
Lead investigator Professor David Leys, noting the finite
currently not one that is well understood, and although the
and dwindling level of oil reserves used for fuels, plastics and
potential for large-scale biological hydrocarbon production
petrochemicals, said, “While the direct production of fuel
exists, in its current form it would not support industrial ap-
compounds by living organisms is an attractive process, it is
plication, let alone provide a valid alternative to fossil fuels.”
Leys and his team investigated in
detail the mechanism whereby common yeast mold can produce kerosene-like odors when grown on food
containing the preservative sorbic acid.
They found that these organisms use
a previously unknown modified form
of vitamin B2 (flavin) to support the
production of volatile hydrocarbons that
caused the kerosene smell. Their findings also revealed the same process
is used to support synthesis of vitamin
Q10 (ubiquinone).
Using the Diamond synchrotron
source at Harwell in Britain, they analyzed this bio catalytic process at the
atomic level and found it shares similarities with procedures commonly used
in chemical synthesis but previously
thought not to occur in nature.
Leys said: “Now that we understand
how yeast and other microbes can produce very modest amounts of fuel-like
compounds through this modified vitamin B2-dependent process, we are in
a much better position to try to improve
the yield and nature of the compounds
produced.”
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August 2015
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Friction Stir Lap Joining
of Aluminum-Lithium
Alloy for Aerospace
F
riction Stir Welding (FSW) is a relatively recent joining process that uses
friction to heat adjoining metal structures
enough to plasticize and ‘stir’—intermix—them without actually melting them
as in traditional welding. First proven out
by UK’s The Welding Institute (TWI) in
1991, it’s been beneficial to the production of metallic wings, fuselages and
™
other aerostructures. At Vanderbilt University, four Dept. of
Mechanical Engineering researchers—BT Gibson, MC Ballun,
GE Cook and AM Strauss—took a look at the weld strengths
of conventional FSW compared to weaved FSW and pulsed
FSW. They shared their results in “Friction stir lap joining of
2198 aluminum–lithium alloy with weaving and pulsing variants,” published in the April 2015 edition of SME’s Journal of
Manufacturing Processes.
Lap joints of 2198-T8 Al–Li alloy in 1.6-mm sheet thickness were friction stir welded to investigate the combination
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materials
Carmex’s specially engineered combination of
carbide substrates and advanced multi-layer
coatings deliver higher production, improved
finish, and longer tool life.
of this material and assembly method for the manufacturing
of aerospace structures, they write. They also looked at tool
geometry variables, comparing a more traditional flat shoulder
Developed for medium to high cutting speeds
in conventional materials including stainless,
Carmex BMA inserts are available in a wide
range of sizes.
Photo courtesy TWI
Carmex recently introduced BLU combines
high strength and high wear resistance in stainless
and hard-to-machine metals including Inconel
and Titanium.
Friction Stir Welding, first invented by TWI in 1991, is becoming
a joining method of importance in aerospace.
tool geometry operated with a tilt angle to a tapered shoulder
tool geometry operated at a 0° tilt angle, which offers the
possibility of simplifying robotic welding operations. Another
variable examined was the use of faying surface sealant, “the
use of which is critical in aerospace applications, to determine
its impact on weld strength and to characterize its interactions
with welding parameters and process variants,” they wrote.
Their conclusions—and a wealth of current process research
and how to submit your own research—can be accessed via
the journal’s Web site at http://www.journals.elsevier.com/
journal-of-manufacturing-processes/.
Tech Front is edited by Senior Editor Michael C. Anderson
Tech Front welcomes your manufacturing research-related news
releases: Please email them to Tech Front editor Michael Anderson
at manderson@sme.org.
SME’s authoritative peer-reviewed research journals, Journal of
Manufacturing Processes, Journal of Manufacturing Systems, and
Manufacturing Letters, and technical papers may be reached via
www.sme.org/publications. The journals welcome submissions:
Information available at www.sciencedirect.com/sme.
August 2015
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AdvancedManufacturing.org
37
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