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Edison's Nickel-Iron Battery Modernized
July 9, 2012
Electrochemistry shows that there are
many possible battery systems. All you need are a reasonable pair of
half-reactions, and a suitable
electrolyte.
Science is one thing, but
technology is another. There are qualities required for a viable
storage battery (rechargeable battery, or secondary cell), such as charging rate and the number of recharges allowed.
The charging rate depends on such factors as the
surface area of the
electrodes and the
mobility of ions in the electrolyte. The number of charging/discharging cycles allowed depends on the ability of the electrodes to hold themselves together as they transform from one
chemical compound to another. For the
lead-acid battery commonly used in conventional,
internal combustion automobiles, this involves transformations of
lead dioxide (PbO
2) to
lead sulfate (PbSO
4), and
lead to lead sulfate, in the presence of
sulfuric acid.
Since rechargeable batteries are an important part of
mobile devices, there has been much
research and development in battery systems that allow a high
energy density along with a fast charging rate. The following figure shows the currently preeminent secondary battery systems and their energy densities in terms of both
weight and
volume.
Secondary cell energy density, in terms of both weight and volume. Research helps us to go farther to the upper right hand corner. (Via Wikimedia Commons))
It's possible to make a
nickel–iron battery using a
cathode of
nickel oxide-hydroxide and an
iron anode. One interesting thing is that the electrolyte, a mixture of
potassium hydroxide and
lithium hydroxide, is not part of the
reaction. It just acts as a reservoir of mobile
hydroxide ions.
Cathode: 2NiOOH + 2H2O + 2e− <--> 2Ni(OH)2 + 2OH−
Anode: Fe + 2OH− <--> Fe(OH)2 + 2e−
This is not a very good storage battery by today's standard, since it has an energy density of just 50
Wh/kg, far towards the lower left quadrant of the figure. There's the further problem that
nickel has become an expensive
metal, costing about seven dollars a pound, as compared to the $0.80 per pound cost of
lead. However, a century ago, when nickel wasn't too expensive and storage batteries were generally lead-acid, this battery type caught the interest of
Thomas Edison.
I wrote about Edison in a few previous articles (
"His Master's Voice," August 15, 2011,
"People Who Live in Concrete Houses...," June 30, 2011, and
"Edison's Iron Mine," September 20, 2010). Edison's forte was not in
invention,
per se, but in improving and commercializing other's inventions. Edison didn't invent the
incandescent light bulb, as commonly believed; instead, he perfected an inexpensive, long-lived version of it using a
carbon filament derived from carbonized
bamboo.
The nickel–iron battery was invented by
Swedish inventor,
Waldemar Jungner, while conducting
experiments on the
nickel–cadmium battery he had invented in 1899. As most
materials scientists would do, Jungner alloyed the
cadmium with other metals, including
iron, and showed that a nickel-iron rechargeable battery was possible. Edison took the idea to production in 1901 as a power source, superior to lead-acid, for
electric automobiles.
Fig. 4 of US Patent No. 692,507, "Reversible Galvanic Battery," by Thomas Alva Edison, February 4, 1902.
(Google Patents)[1]
Edison created the
Edison Storage Battery Company in
East Orange, New Jersey, just a short drive from my house, to manufacture these nickel-iron batteries. The factory functioned from 1903 to 1975, having been sold to
Exide in 1972. Although not made at Edison's plant, a nickel-iron battery powered the
electronics of the
German V-1 flying bomb, and the
V-2 rocket during
World War II.
Workers producing Edison storage batteries.
Note how all machine power is derived from overhead drive shafts.
(Edison Archive of the National Park Service))
Edison's nickel-iron batteries had a somewhat higher energy density than lead-acid batteries, and they could be charged twice as fast. The hydroxide electrolyte was less responsive than sulfuric acid at low
temperatures; and, because of the nickel content, the batteries were more expensive. However, they were extremely rugged and used in many industrial applications. They did prove suitable for electric vehicles, as a thousand mile endurance test in 1910 proved.[2]
A woman using a washing machine powered by Edison storage batteries.
(Edison Archive of the National Park Service))
A large team of
scientists from the
Department of Chemistry,
Stanford University (Stanford, California),
Canadian Light Source Inc. (Saskatoon, Saskatchewan, Canada), and the Department of
Chemical Engineering,
Tsinghua University (Beijing, China) have brought Edison's battery into the modern age by using
graphene and
carbon nanotubes.[3-5] In a recent article in
Nature Communications,[4] they report on a nickel-iron battery that uses carbon nanotube and graphene hybrid materials as electrodes.
In Edison's battery, the iron electrode was a
composite of
graphite and iron powder.[3] In the nanoscale version, the nickel oxide-hydroxide and iron exist as nanoparticles that sit on either graphene or carbon nanotubes, so they have a larger area. As a consequence, these novel batteries have a thousand-fold faster charging and discharging rate than their conventional counterparts. they also have a high energy density.[5]
The batteries could be charged in about two minutes, and discharged within thirty seconds. Their energy density of 120
Wh/kg and
specific power of 15 kW/kg put them at the same performance level as other rechargeable batteries, and much higher than conventional nickel-iron batteries.[5] Unlike its
lithium-ion battery competitors, this battery uses a
non-flammable electrolyte of water and potassium hydroxide.[3]
In theory, this new battery has the same per weight energy density as the lithium-ion battery in the
Nissan Leaf, an all-electric car.[4] There's a potential for cost savings, since iron and nickel are more abundant than
lithium, and thereby less expensive. The caveats are that the lab-scale cell has only powered a
flashlight,[3] and the capacity is reduced by 20% after 800 discharge/charge cycles.[3]
One naysayer,
M. Stanley Whittingham, a
professor of
chemistry and director of the
Institute for Materials Research at
Binghamton University, registered this criticism in
Science News,
"Quoting power and energy density from small lab cells is not realistic... Real cells typically have capacities of only 20 percent of the numbers calculated in the lab."[4]
References:
- Thomas Alva Edison, "Reversible Galvanic Battery," US Patent No. 692,507, February 4, 1902
- A Bailey electric automobile, equipped with Edison storage batteries, and driven in a thousand mile endurance run in 1910.
- Mark Shwartz, "Stanford scientists develop ultrafast nickel-iron battery," Stanford University Press Release, June 26, 2012.
- Devin Powell, "Old battery gets a high-tech makeover," Science News, June 26, 2012.
- Hailiang Wang, Yongye Liang, Ming Gong, Yanguang Li, Wesley Chang, Tyler Mefford, Jigang Zhou, Jian Wang, Tom Regier, Fei Wei and Hongjie Dai, "An ultrafast nickel–iron battery from strongly coupled inorganic nanoparticle/nanocarbon hybrid materials," Nature Communications, vol. 3, Article No. 917, June 26, 2012 .
Permanent Link to this article
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