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08/30/2006

Lithium Here and There

I can’t recall the definition of a word making such a splash in the
media. Although I planned to write at length about Pluto’s
demotion, the print and TV media have more than adequately
covered the International Astronomers Union’s fine-tuning of the
definition of “planet”. Besides, Pluto itself isn’t aware that it
ever was a planet, nor is it aware that a NASA spacecraft is
headed its way powered by, of all things, plutonium!

There’s another, more scientifically important astronomical story
that hasn’t received such publicity. I worked on lithium batteries
for 17 years at Bell Labs but I had no idea there was not enough
lithium in the universe. Very soon after the Big Bang, the
elements hydrogen, helium and lithium were formed. What I did
not know was that much of that lithium has been “lost”. When
cosmologists looked at the spectra of very old stars, which would
have formed from those early Big Bang elements, they found less
than half the predicted amount of lithium. Without that lithium,
their Big Bang model for the formation of the elements was in
trouble.

Happily, the missing lithium has been found, as reported in the
August 10 issue of Nature, by Andreas Korn and colleagues at
Uppsala University in Sweden and co-authors in Denmark,
Russia and France. These researchers looked carefully at spectra
from 18 old stars of different ages in a particular cluster of stars.
As a star ages, elements diffuse towards the center of the star and
reappear at the surface thanks to turbulent mixing in the star. But
not lithium. Lithium turns out not to be a very sturdy element
and, as it travels towards the center of a star, it encounters
temperatures of over 2.5 million degrees Kelvin. At those
temperatures, lithium can’t stand the heat and breaks apart – end
of that lithium! So, as a star ages the amount of lithium should
decrease. Looking at the old stars of different ages, the
researchers confirmed this effect and found the decreases in
lithium content were in agreement with a model taking into
account diffusion of lithium into the interior of a star.

With the solution of the case of the missing lithium, all is well
with the Big Bang. Unfortunately, here on Earth, lithium is
causing some unwelcome bangs and fiery incidents. As if we
didn’t have enough to worry about with terrorist plots to blow up
aircraft or pilots on the wrong runway, could danger be lurking
under your fingertips as you sit in your plane with your laptop
computer? I’m referring, of course, to those lithium-ion
batteries that power most laptops, cell phones, digital music
players and the like. Last week’s recall by Apple of 1.8 million
lithium-ion batteries added to the earlier recall by Dell 4.1
million laptop batteries. Sony made all the batteries.

Less than 2 years ago, in my column of 12/1/2004, I wrote about
recalls of a total of roughly a million lithium-ion cell phone
batteries by Verizon and the Japanese company Kyocera. In an
article in the August 14 Wall Street Journal, Corey Dade deals at
length with more recent lithium battery incidents involving
aircraft. One incident occurred in May on a Lufthansa flight
about to take off for Munich from Chicago’s O’Hare when
smoke emerged from an overhead luggage compartment. A
computer case was on fire. After using a fire extinguisher, the
crew threw it out a cabin door onto the ground, where the case
burst into flames. After the fire department and bomb squad put
out the blaze, the culprit turned out to be a laptop with a melted
battery of six lithium-ion cells. The owner of the laptop said that
he had bought the battery on eBay and that it might not have
been built to the laptop’s specifications!

NEVER DO THIS! With any rechargeable battery, especially
lithium batteries, never replace the battery with any other than
the model supplied or recommended by the computer or cell
phone manufacturer. As we’ve discussed before, control of the
charging of lithium-ion batteries is critical. Charge them above a
critical voltage and they become unsafe. Typically, the lithium-
ion battery has a silicon chip in it that limits the voltage and time
of charge. Or the computer may have its own charging program.
If not, and you put in a lithium-ion battery without the silicon
chip, you’re courting an explosion and/or fire.

On the other hand, the Dell and Apple recalls point to another
problem as the cause of the laptop incidents. In an article in the
August 21 issue of Chemical and Engineering News, Alex Tullo
quotes Forrest Norrod of Dell as saying that particles of metal
introduced in crimping operations in Sony’s manufacturing
process are the culprit. The lithium-ion cells with which I’m
familiar are made in a jellyroll fashion. Long strips of a cathode
composite and of an anode composite are enclosed in sleeves (or
equivalent) of a polymer known as a separator. The separators
prevent the anode and cathode from touching each other, which
would short circuit the cell. The sleeves of separator/electrode
composites are then wound together like a jellyroll.

If one or more metal particle gets into the act, a metal particle or
shard can puncture the very thin polymer separator (think Saran
Wrap; the thickness is comparable). If this happens, and the
metal particle touches both anode and cathode, it’s a short circuit
inside the cell. The cell may have a fuse to protect against an
external short circuit but that fuse can’t do anything to shut down
an internal short. An internal short circuit can generate a spark
and/or heat, depending on how “hard” the short is. By “hard” I
mean how solid are the contacts of the metal particle with the
two electrodes. Ironically, at Bell Labs some of our best, longest
cycling lithium batteries had “soft” shorts. A hard short circuit
can cause decomposition of organic solvents in a lithium-ion cell
and/or can also decompose the oxide cathode material, a cobalt
oxide typically. The latter decomposition yields oxygen, great
for combustion! Solvent decomposition can yield gaseous
compounds that build up pressure and/or react with the oxygen.
None of these scenarios is good!

Surprisingly, it’s Sony, the company that introduced lithium-ion
batteries to the market over a decade ago, that is having this
quality control/crimping problem. Sony reportedly owns up to
the problem but is also saying that computer architecture may
play a role. This could be a reference to the placement of the
battery in some computers close to the hot-running silicon
circuitry that drives the computer. Presumably, the heat might
hasten any degradation of the battery. Let’s leave that issue to
the lawyers!

I can empathize with Sony in its current predicament. I can also
feel the satisfaction that the missing lithium researchers must
have felt when they found what happened to it. Lithium is not
easy to deal with. At Bell Labs, my own experience with lithium
was a real roller coaster ride. I’ve probably mentioned in earlier
columns my nearly getting fired in my first year at Bell Labs
when I abandoned a project involving lithium in either silicon or
germanium. I found handling lithium to be too tough, only to
end up my career working on lithium batteries for those 17 years!
Three times during those years, a particular lithium battery that I
co-invented was slated for manufacture, twice by the Western
Electric Company and once by a major battery company. Three
times the manufacture was canceled, twice after investment of
considerable time and money. At the time, it was most
frustrating and disappointing but now, in retrospect, I’m happy.
It could have been our battery in those recalls!

Allen F. Bortrum



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-08/30/2006-      
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Dr. Bortrum

08/30/2006

Lithium Here and There

I can’t recall the definition of a word making such a splash in the
media. Although I planned to write at length about Pluto’s
demotion, the print and TV media have more than adequately
covered the International Astronomers Union’s fine-tuning of the
definition of “planet”. Besides, Pluto itself isn’t aware that it
ever was a planet, nor is it aware that a NASA spacecraft is
headed its way powered by, of all things, plutonium!

There’s another, more scientifically important astronomical story
that hasn’t received such publicity. I worked on lithium batteries
for 17 years at Bell Labs but I had no idea there was not enough
lithium in the universe. Very soon after the Big Bang, the
elements hydrogen, helium and lithium were formed. What I did
not know was that much of that lithium has been “lost”. When
cosmologists looked at the spectra of very old stars, which would
have formed from those early Big Bang elements, they found less
than half the predicted amount of lithium. Without that lithium,
their Big Bang model for the formation of the elements was in
trouble.

Happily, the missing lithium has been found, as reported in the
August 10 issue of Nature, by Andreas Korn and colleagues at
Uppsala University in Sweden and co-authors in Denmark,
Russia and France. These researchers looked carefully at spectra
from 18 old stars of different ages in a particular cluster of stars.
As a star ages, elements diffuse towards the center of the star and
reappear at the surface thanks to turbulent mixing in the star. But
not lithium. Lithium turns out not to be a very sturdy element
and, as it travels towards the center of a star, it encounters
temperatures of over 2.5 million degrees Kelvin. At those
temperatures, lithium can’t stand the heat and breaks apart – end
of that lithium! So, as a star ages the amount of lithium should
decrease. Looking at the old stars of different ages, the
researchers confirmed this effect and found the decreases in
lithium content were in agreement with a model taking into
account diffusion of lithium into the interior of a star.

With the solution of the case of the missing lithium, all is well
with the Big Bang. Unfortunately, here on Earth, lithium is
causing some unwelcome bangs and fiery incidents. As if we
didn’t have enough to worry about with terrorist plots to blow up
aircraft or pilots on the wrong runway, could danger be lurking
under your fingertips as you sit in your plane with your laptop
computer? I’m referring, of course, to those lithium-ion
batteries that power most laptops, cell phones, digital music
players and the like. Last week’s recall by Apple of 1.8 million
lithium-ion batteries added to the earlier recall by Dell 4.1
million laptop batteries. Sony made all the batteries.

Less than 2 years ago, in my column of 12/1/2004, I wrote about
recalls of a total of roughly a million lithium-ion cell phone
batteries by Verizon and the Japanese company Kyocera. In an
article in the August 14 Wall Street Journal, Corey Dade deals at
length with more recent lithium battery incidents involving
aircraft. One incident occurred in May on a Lufthansa flight
about to take off for Munich from Chicago’s O’Hare when
smoke emerged from an overhead luggage compartment. A
computer case was on fire. After using a fire extinguisher, the
crew threw it out a cabin door onto the ground, where the case
burst into flames. After the fire department and bomb squad put
out the blaze, the culprit turned out to be a laptop with a melted
battery of six lithium-ion cells. The owner of the laptop said that
he had bought the battery on eBay and that it might not have
been built to the laptop’s specifications!

NEVER DO THIS! With any rechargeable battery, especially
lithium batteries, never replace the battery with any other than
the model supplied or recommended by the computer or cell
phone manufacturer. As we’ve discussed before, control of the
charging of lithium-ion batteries is critical. Charge them above a
critical voltage and they become unsafe. Typically, the lithium-
ion battery has a silicon chip in it that limits the voltage and time
of charge. Or the computer may have its own charging program.
If not, and you put in a lithium-ion battery without the silicon
chip, you’re courting an explosion and/or fire.

On the other hand, the Dell and Apple recalls point to another
problem as the cause of the laptop incidents. In an article in the
August 21 issue of Chemical and Engineering News, Alex Tullo
quotes Forrest Norrod of Dell as saying that particles of metal
introduced in crimping operations in Sony’s manufacturing
process are the culprit. The lithium-ion cells with which I’m
familiar are made in a jellyroll fashion. Long strips of a cathode
composite and of an anode composite are enclosed in sleeves (or
equivalent) of a polymer known as a separator. The separators
prevent the anode and cathode from touching each other, which
would short circuit the cell. The sleeves of separator/electrode
composites are then wound together like a jellyroll.

If one or more metal particle gets into the act, a metal particle or
shard can puncture the very thin polymer separator (think Saran
Wrap; the thickness is comparable). If this happens, and the
metal particle touches both anode and cathode, it’s a short circuit
inside the cell. The cell may have a fuse to protect against an
external short circuit but that fuse can’t do anything to shut down
an internal short. An internal short circuit can generate a spark
and/or heat, depending on how “hard” the short is. By “hard” I
mean how solid are the contacts of the metal particle with the
two electrodes. Ironically, at Bell Labs some of our best, longest
cycling lithium batteries had “soft” shorts. A hard short circuit
can cause decomposition of organic solvents in a lithium-ion cell
and/or can also decompose the oxide cathode material, a cobalt
oxide typically. The latter decomposition yields oxygen, great
for combustion! Solvent decomposition can yield gaseous
compounds that build up pressure and/or react with the oxygen.
None of these scenarios is good!

Surprisingly, it’s Sony, the company that introduced lithium-ion
batteries to the market over a decade ago, that is having this
quality control/crimping problem. Sony reportedly owns up to
the problem but is also saying that computer architecture may
play a role. This could be a reference to the placement of the
battery in some computers close to the hot-running silicon
circuitry that drives the computer. Presumably, the heat might
hasten any degradation of the battery. Let’s leave that issue to
the lawyers!

I can empathize with Sony in its current predicament. I can also
feel the satisfaction that the missing lithium researchers must
have felt when they found what happened to it. Lithium is not
easy to deal with. At Bell Labs, my own experience with lithium
was a real roller coaster ride. I’ve probably mentioned in earlier
columns my nearly getting fired in my first year at Bell Labs
when I abandoned a project involving lithium in either silicon or
germanium. I found handling lithium to be too tough, only to
end up my career working on lithium batteries for those 17 years!
Three times during those years, a particular lithium battery that I
co-invented was slated for manufacture, twice by the Western
Electric Company and once by a major battery company. Three
times the manufacture was canceled, twice after investment of
considerable time and money. At the time, it was most
frustrating and disappointing but now, in retrospect, I’m happy.
It could have been our battery in those recalls!

Allen F. Bortrum