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06/13/2000
Labels, Lithium and Overfueling
After last week''s rerun column, I''m back again live after a trip to
Amsterdam to give a 3-day short course on batteries with my
colleague Al. After that my wife and I spent three days in Milan,
followed by a week in Como, Italy for the 10th International
Meeting on Lithium Batteries, IMLB10 for short. This week I''ll
discuss how simple things can complicate one''s life and, from
IMLB10, how a simple label can make a big difference in battery
safety.
A simple misplaced decimal point provided unwanted pre- and
post-trip diversions. If you are of the old school, taught that the
written-out-in-words value on a check is the defining indication of
the monetary value of the check, forget it! My bank''s
representative (referred to henceforth as MBR) made it clear to
me that an "encoder", the person who enters the values of checks
into the bank''s records, relies strictly on the number itself. Of
course, it had to be a check to the IRS on which, probably the
only time in my life, I neglected to add two little superscript
zeroes to an even dollar amount. As a result, my December
estimated tax payment of $2500 was entered as $25.00, with a
nonexistent decimal point inserted courtesy of the encoder!
Spotting the error on my January statement, MBR seemed duly
grateful for my calling attention to a $2475 error in my favor.
Sure enough, my February statement contained an "encoding
error adjustment" in that amount. Being nanve enough to assume
that the IRS had been duly reimbursed, it came as a surprise that,
about 15 hours before our scheduled departure for our trip, I
received a letter from the IRS stating that I owed them $2475
plus penalties. About three of the remaining 15 hours were
employed (a) reaching a human being at the IRS 800 number and
(b) convincing MBR that the bank owed the IRS some money.
Another post-trip 3 hours were spent following up on this decimal
point affair, which still remains somewhat in limbo.
Our actual trip began quite smoothly. We arrived at Newark
airport two and a half hours ahead of our 10 AM flight departure
time and were checked in less than 5 minutes later. Boarding of
the Continental flight to Gatwick (where we stayed overnight en
route to Amsterdam) proceeded so smoothly it looked like we
might actually leave the gate before 10 AM.
Has the thought ever entered your mind that they might not put
enough fuel in the gas tank to carry you to your destination? Not
to worry! The captain came on the intercom with the good news
that we had plenty of fuel on board. The bad news was that we
had so much fuel that the excess had to be sucked out. A
passenger reported that she had overheard that the reason for the
oversupply was, like my decimal point, a simple thing. She said
that the fueling personnel rely on some kind of dipstick or float to
monitor the fuel level. She understood that the stick had simply
stuck, unobserved by the fueling crew. Inasmuch as a special
defueling truck was required and defueling takes longer than
fueling, we sat in the plane for three hours before leaving the
gate. (See note at end for more info on fueling.)
After less than 5 hours sleep in the Gatwick Hilton it was off to
Amsterdam. Saturday night on the Rembrandtsplein (Rembrandt
Square) in Amsterdam is quite a swinging place. Those of you
who frequent Europe may recall that roving groups of young
people tend to burst into what we were told were soccer club
songs and chants at any hour of the day or night, notably 3, 4 or 5
AM. After about two hours sleep that night, I discovered for the
first time the effectiveness of a simple invention, the earplug. I
slept like a baby the next night and managed to stay awake during
my lectures to the participants in our course. Continental had
provided my earplugs on the overseas flight, helping to
compensate for the overfueling incident.
The selection of Como as the site for IMLB10 was particularly
appropriate, this year being the 200th anniversary of the invention
of the battery by Volta. Alessandro Volta was born and died in
Como and his image adorns the Italian 10,000 lire banknote,
roughly equivalent to $5 in U.S. currency. IMLB10 was also
overfueled, with battery papers. There were over 50 invited
lectures and some 350 poster papers. I must admit that, after a
couple days, all the posters looked the same to me.
In general, the papers dealt with various aspects of the electrode,
separator and electrolyte materials. Many of the papers were
rather complex, with emphasis on results obtained by very
sophisticated techniques. As in any field of endeavor, there are
certain workers in the field that stand out as "superstars". One
such superstar in the lithium battery field is Jeff Dahn, a professor
at Dalhousie University in Nova Scotia, Canada. Jeff is a
physicist who is at home with advanced experimental techniques,
complicated crystal structures and theoretical concepts. I tell the
participants in our courses that they can never go wrong reading
one of Dahn''s papers or listening to one of his talks. Indeed,
almost every lecturer at the meeting referred to Jeff''s work in his
or her talk.
When it came time for his own talk, Jeff did not disappoint.
However, his talk was not about some sophisticated results or a
new explanation or refutation of someone else''s work. No, it was
about something quite simple - the battery label. Now, in our
battery course, we always mention the label as being important
for a number of reasons, identifying the type of battery, the
voltage, etc. In our litigious society, the label should also specify
certain precautions such as not throwing the battery in a fire or
not trying to charge a nonrechargeable battery like those AA
alkaline cells you''re always having to replace. But Dahn''s "label"
talk surprised everyone by claiming the safety of a lithium battery
can depend critically on the nature of the label.
As background, we''ve discussed in earlier columns some of the
hazards associated with batteries in general and lithium batteries
in particular. The lithium-ion battery is the one used in most
laptop computers and many cellular phones these days. Under
certain circumstances such as overcharging or short-circuiting,
significant amounts of heat can be generated. If this heat is not
dissipated, a condition known as thermal runaway can result. In
thermal runaway, the cell heats up rapidly and can explode or
catch fire, not a good thing! Jeff Dahn and his students reported
results of experiments in which lithium-ion cells were placed in an
oven at different temperatures and just allowed to sit there and
the temperature of the cells recorded.
The results were startling. When a bare cell was placed in the
oven at 140 degrees Centigrade without its label, there was
thermal runaway. When the cell was placed in the oven with its
label on, there was no thermal runaway. Indeed, in some cases a
labeled cell could be heated 15 to 20 degrees Centigrade higher
before runaway set in. The result was surprising because one
normally would expect the label would tend to hold the heat in,
not help to dissipate it. Dahn''s answer was emissivity. If the label
has a high emissivity, the heat is emitted to a large degree by
radiation, not by convection or conduction.
If you''re not familiar with the concept of emissivity, it''s the
relative ability of a surface to radiate energy (heat) as compared
to that of an ideally black surface under the same conditions.
The best emitter is a truly black surface while a shiny polished
metal surface is generally a much poorer emitter of radiant
energy. A black label will radiate heat much faster than the can
of a bare cell or battery. Therefore, the labeled cell dissipates
heat faster than an unlabeled cell or a cell with a nonblack label. If
you see only black labels on batteries in the future you''ll know the
battery industry has heard about Jeff Dahn''s paper.
Incidentally, the Villa D''Este, one of the world''s premier hotels,
just up the street a few blocks, catered all the lunches, receptions
and the banquet for this meeting in Como. One night my wife and
I dined outdoors at this hotel and I would rate the food and
service on a par with that at Jean Georges, the Trump restaurant
critiqued in an earlier column. My dessert of a tulip- shaped shell
filled with wild strawberries, red raspberries and three huge
blackberries, all picked at their peak of succulence, and
immersed in a to-die-for orange custard sauce, is a memory I''ll
always treasure. At Bell Labs we used to go blackberry picking
and it was a challenge not only to avoid the thorns and ticks, but
also to compete with fellow pickers for the somewhat limited
supply of berries. This competition generally resulted in most of
the berries being picked before their prime. We connoisseurs
knew that the best blackberries were found at the end of the
season, having had time to fully ripen to the point that they
dissolved in your mouth with exquisite flavor. The Villa D''Este
berries had that flavor.
It is hard adjusting to my usual luncheon fare of tuna on whole
wheat and no wine accompaniment. The latter was not designed
to promote alertness during the afternoon sessions. In fact, my
wife attended the afternoon lectures the last day of the meeting
and was shocked to see a number of attendees sound asleep and
snoring. Your ever-alert Bortrum was not one of them!
However, it did seem that my wife understood one of the talks
that a colleague and I found totally perplexing!
Forgive my going on at such length about that dessert but I have
just learned the results of some blood work that indicate I''ll be
going on one of those statin drugs to bring down my cholesterol.
Accordingly, I may never be allowed another such dessert, limited
to angel food cake and no-fat frozen yogurt!
Allen F. Bortrum
Note: Not being content to rely on a passenger''s view of the
overfueling, I talked to an airline pilot and found that there is a
"dripstick" (not a dipstick) with a float that provides a mechanical
check on the fuel level. This mechanically determined level is
checked against the electronic fuel gage reading. Our passenger
had reported that the concern of overfilling was in landing but my
pilot source seemed to think a greater concern would be taking
off or rather, not taking off!
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