Mark Twain quipped, "It ain't what
you don't know that gets you into trouble. It's what you know for
sure that just ain't so
." Truer words were never spoken,
particularly when it comes to the batteries that most of us use and
curse on a daily basis. If you have a car, you have a lead-acid
starter battery that needs to be replaced every couple years.
Cellphones and laptops offer similar trials and tribulations unless
you upgrade your electronics regularly. When our cars don't start or
our electronics don't work, we invariably blame the batteries first.
While most of us haven't noticed any major change in starter battery
performance over the last couple decades, the utility of electronics
has skyrocketed and many believe the gains come from improved
battery performance. They're dead wrong.
Today's car batteries aren't terribly different from the ones we
bought in the '80s and '90s and they don't perform any better or
worse. We just demand more from them as we add increasingly
sophisticated entertainment, passenger comfort, information and fuel
economy systems to passenger cars. The same is true for the
batteries we use in portable electronics. NiMH batteries performed
better than NiCd batteries that were plagued by memory effects.
Lithium-ion performed even better than NiMH. Within each chemistry
class however, today's batteries aren't terribly different from from
the ones we bought years ago. The only truly major improvements have
been longer cycle-lives – the number of times a battery can be
charged and discharged before it needs to be replaced. When you cut
through the fog of errant assumptions and get down to facts, the
reason electronic devices work better is that clever manufacturers
have found ways to slash energy use by 80 to 90 percent while
increasing functionality. It has absolutely nothing to do with
improving the performance of a particular chemistry.
A popular French phrase aptly describes technical progress in the
battery industry – "plus ça change, plus c'est la même
chose," or the more it changes, the more it’s the same thing. The
following table summarizes the development history and typical
specific energy of today's leading battery chemistries.
Two key takeaways are (1) the long periods between the invention and
the commercialization of new battery chemistries, and (2) the slow
incremental nature of progress in the battery industry. Despite a
never-ending stream of optimistic press releases, no major new
battery chemistry has entered the market since the launch of lithium
iron phosphate in 1996.
For those who've gotten used to Moore's Law, cumulative gains of 1%
a year over 153 years are not impressive. I read the same stories as
everyone else and know all about the researchers who boldly promise
to double or triple energy density by the end of the decade. I also
understand the difference between hope and accomplishment. My inner
geek will wildly cheer new developments if, as and when they prove
their technical and economic merit in a free market. But my inner
investor will never forget that hope is not an investment strategy
and results are the only things that count.
Brief history lesson
Like all mature
technologies, batteries have progressed through several evolutionary
cycles over the last century as users' needs changed. Until the
'60s, the two dominant classes of batteries were rechargeable
lead-acid batteries and disposable dry cells. Lead-acid batteries
did the heavy work like starting cars, powering equipment and
providing emergency backup power while dry cells powered
flashlights, toys and consumer goods, including the first wave of
In the early '70s a variety of low-maintenance flooded lead-acid
batteries and high-performance AGM batteries were introduced. They
rapidly became industry standards. They worked so well that R&D
in the lead-acid battery sector plummeted because there was no need
for better lead-acid batteries and the perceived value of additional
refinements didn't justify the added cost. About the same time,
Japanese manufacturers launched a wave of portable electronic
devices that desperately needed better batteries. So R&D
spending on lightweight rechargeable chemistries soared. That trend
continued through the turn of the millennium because lead-acid
batteries were good enough for the work they performed while
batteries for portable electronics were grossly inadequate.
Since the turn of the millennium, a new market dynamic has emerged
that's driving unprecedented levels of R&D in the fields of
electrochemical and physical energy storage. The primary
requirements of this new dynamic are cost-effective systems that
store massive amounts of energy, need little or no maintenance and
deliver peak performance for a decade or longer. It's a tall order
when you understand that most of the batteries we used in the past
were designed for devices that needed tiny amounts of stored energy
and had short replacement and upgrade cycles.
For lithium-ion battery developers, the principal technical
- Making cells that were designed for short useful lives more durable;
- Making cells that were designed for indoor use
- Making larger cells with stable mechanical, thermal,
electrical and electrochemical behavior;
- Making watt-hour sized cells suitable for use in kilowatt-
and megawatt-hour arrays;
- Developing battery management systems for kilowatt- and
- Increasing specific energy to a point where electric drive can
be economically feasible;
- Improving safety, vibration and impact resistance, and overall
- Building new manufacturing infrastructure and materials supply
- Slashing costs by 75% or more in an industry where raw
materials represent 65% of cell costs; and
- Developing cost-effective recycling technologies and
infrastructure for massive battery packs.
Over the last decade, lithium-ion battery developers have made
significant progress on a number of fronts, although cost
reductions, specific energy gains and cost-effective recycling
remain as elusive as unicorns. Some bright researcher may one day
crack the code and solve all the technical challenges of lithium-ion
batteries, but I'm not holding my breath.
For lead-acid battery developers, the principal technical challenges
were far less daunting and included:
- Making batteries that were designed for short useful lives more durable;
- Making kilowatt-hour sized batteries suitable for use in
- Developing battery management systems for megawatt-hour
- Reducing charging times to permit more frequent and deeper
In a nutshell, the lead-acid sector had a simpler and shorter path.
The industry had been making heavy-duty industrial batteries for
decades. More importantly, researchers had a wider variety of
technology and materials options because of the 30-year hiatus in
lead-acid R&D. It was almost like the researchers returned from a
30-year vacation to find a different toolbox. As they started using
advanced materials and manufacturing processes to improve the
performance, cycle life and charging times of lead-acid batteries,
the results were astonishing.
The thorniest conceptual problem in energy storage is the variable
value of a kilowatt-hour of stored electricity. The two primary
determinants of value are time and place. Each of these
characteristics, in turn, has a value hierarchy that ranges from
very high to merely desirable.
In the simple case of a stationary application where the only
variable is time, it's easy to create a value hierarchy. The three principal types
of high value applications are:
- Off-grid batteries that make renewable power available when
the sun isn't shining or the wind isn't blowing;
- Grid-connected batteries that insure system-wide grid
integrity by smoothing minute-to-minute variation in user demand
and power from variable resources; and
- Commercial and industrial batteries that provide
uninterruptible power for mission critical operations.
While system reliability is the primary requirement for every high
value application, total cost of ownership is a crucial secondary
consideration and users are reluctant to pay a premium price for
attributes they don't need. As you move down the food chain from
critical reliability systems to desirable time-shifting
applications, the economics get more complex and the users get more
particular as they weigh the costs and benefits of energy storage
against available alternatives. The complexities of the calculations
are enormous, but the basic rules are clear.
- Storage systems that cycle dozens of times per day are more
valuable than systems that cycle once or twice;
- Performance features that increase system cost without
increasing end-user value are non-starters; and
- The law of economic gravity is inviolate – the cheapest system
that can do the work will win.
There are only a few cases where size and weight are mission
critical for stationary systems. Examples include installations in
existing buildings that have limited floor space or weight
tolerances. As soon as you start evaluating shipping containers on a
concrete pad, size and weight are irrelevant and the only
features that matter are price and performance.
Portable power is usually more valuable than stationary power
because it offers flexibility in both time and place. The most
valuable batteries I own are in my cellphone and laptop where a few
dozen watt-hours are priceless. Next in line is my starter battery.
Once we move away from priceless applications, every energy storage
decision involves trade-offs. The following simple examples
highlight the economic issues that plague electric drive by assuming
free electricity, a $5 gas price and an average fuel consumption of
400 gallons per year.
- In a Prius-class HEV that cuts fuel use by 25%, a 1.3 kWh
battery will save $500 a year or $385 per kWh;
- In a Volt-class PHEV that cuts fuel use by 75%, a 16 kWh
battery will save $1,500 a year or $94 per kWh;
- In a short range Leaf-class EV that cuts fuel use by 100% but
requires a second car for longer trips, a 24 kWh battery will
save $2,000 a year or $83 per kWh;
- In a short-range Tesla Model S that cuts fuel use by 100% but
doesn't necessarily require a second car, a 45 kWh battery will
save $2,000 a year or $44 per kWh; and
- In a long-range Tesla Model S that cuts fuel use by 100% and
won't require a second car, an 85 kWh battery will save $2,000 a
year or $24 per kWh.
The examples deliberately ignore the question of battery cost
because that fact is irrelevant to the fundamental truth that the
economic value per kWh plummets as battery pack size increases. When
it comes to portable power, small is beautiful but big is grossly
Bill Reinert, Toyota's Advanced Technology group manager, recently
described the problem as follows, "I
used to be a big 100-miles-per-gallon guy. But I realized that
we’re above the level of diminishing returns at 50 miles per
gallon. So why not make a whole bunch of 50-miles-per-gallon cars
and put people who are driving 20-miles-per-gallon cars into them?
It's a classic conflict where the technically possible is
diametrically opposed to the economically sensible.
The last decade has been an exciting time in the lead-acid battery
industry as manufacturers respond to changing market dynamics. The
first major technology transition was increased reliance on
maintenance-free AGM batteries that are more robust and abuse
tolerant than first-generation flooded batteries. The second major
technology transition is the integration of varying amounts of
carbon to reduce charging times and increase cycle-life. In a
presentation at last September's Asian Battery Conference, the
Advanced Lead Acid Battery Consortium offered an exhaustive
on the use of carbon in lead-acid batteries
and the approaches the principal manufacturers are taking.
The simplest, cheapest and most direct approach is adding fine
carbon powders to the sponge lead pastes used in the negative
electrodes of first- and second-generation lead-acid batteries.
Extensive testing over the last decade has shown that changing the
paste formulation to include up to 6% carbon by weight (±30%
by volume) offers excellent cycleability and power while
significantly reducing charging times. Johnson Controls (JCI
Exide Technologies (XIDE
and several other companies are already using carbon paste additives
in enhanced versions of their flooded and AGM batteries with notable
success. Others will follow. While carbon enhanced batteries have
slightly lower specific energy than their predecessors, their 100 to
200 percent increase in cycle-life reduces the cost of energy
storage by 30 to 50 percent.
A more complex approach is the Ultrabattery from CSIRO, Furukawa
Battery and East Penn Manufacturing. It divides each negative
electrode into two parts, a lead half and a carbon half. The end
result is superior cyclability and power with even shorter charging
times. The Ultrabattery is being tested in a variety of stationary
and micro-hybrid applications and shows significant promise,
including the potential to reduce the cost of energy storage by 50
to 70 percent.
The third and most sophisticated approach is the PbC battery from
Axion Power International (AXPW.OB
that replaces the lead-based negative electrodes used in
conventional batteries with a carbon electrode assembly. The
resulting device is an "asymmetric lead-carbon capacitor" that
offers the energy storage of a battery and the power and
cycleability of a capacitor in a single hybrid device. The PbC has
the lowest specific energy of all the emerging lead-carbon
technologies, but it offers the cycleability and charge acceptance
of the best lithium-ion batteries at a fraction of the cost. The PbC
has been extensively tested for stationary, railroad, micro-hybrid
and military applications and shows great promise, including the
potential to slash the cost of energy storage by 80 percent or more.
The road forward
Lead-acid battery chemistry is one of the oldest, safest, most
widely used and most environmentally benign technologies known to
man. While lead-acid batteries can cause grave health problems if
they're not manufactured, used and recycled in compliance with
applicable regulations, the lead-acid battery industry has a stellar
track record in the US and Europe where over 98% of used batteries
are recycled to make new ones. According to USGS
reports, over 95%
of the lead used by US battery manufacturers
in 2011 came from recycled batteries. No other closed-loop recycling
ecosystem even comes close. When it comes to other types of
batteries, similar closed-loop recycling ecosystems don't even
The lead-acid battery sector has a massive global footprint with
robust supply chains, distribution systems and recycling
infrastructure. The new lead-carbon technologies have
been developed to integrate seamlessly into the existing
infrastructure and leverage the manufacturing base instead of displacing it.
The commercial lead-carbon batteries that are rolling off the assembly lines
today already offer 200 to 1,000 percent better performance than the batteries
you think you know.
Lead-carbon batteries are heavy and bulky. They'll never be small or
light enough for portable electronics or electric cars that need to
travel long distances at highway speeds. As soon as you move away
from these niche applications where size and weight are mission
critical and money is no object, the advantages of lead-carbon
batteries become overwhelming. Shakespeare said,
"Nothing is so commonplace as to
wish to be remarkable
." When it comes to energy storage, however, most of our needs are
fairly mundane and there's no sense paying for extreme performance
when adequate performance can do the necessary work for a fraction
of the cost.
The first commercial products based on R&D conducted since the
turn of the millennium are being launched today. The new products
use cheap classic chemistry, but offer 21st century performance that
many thought was the exclusive province of lithium-ion batteries.
Over the next few years, these innovations will re-energize the lead
acid battery sector with products that are vastly superior to their
predecessors and competitors for applications where size and weight are not mission critical
Author is a
former director of Axion Power International (AXPW.OB
and holds a substantial long position in its common stock.