Battery energy density too low to power cars

Despite billions of dollars spent on battery since the first battery was created in 1800, there is still no battery in sight that could power cars because batteries depend on electro-chemical processes, resulting in little power density and short life expectancy.

The absolutely insoluble problem, because of the laws of physics, is that even if you made a perfect, 100% efficient battery, it would still deliver very little power compared to gasoline, or even ethanol:

batterry power vs gasolineSource: energy density comparisons in MJ/kg. David Fridley at Lawrence Berkeley National Laboratory.

As Kurt Zenz House, Chief Executive of C12 Energy explains it, “Fossil carbon has dominated the energy market for many reasons–not the least of which is its intrinsic mass and volume energy densities. Today’s lead acid batteries can store about 0.1 mega-joules per kilogram, or about 500 times less than crude oil (50 MJ/k).  Lithium ion batteries are able to deliver .5 mega-joules per kilogram, 100 times less than oil”.  The theoretical maximum a battery could ever deliver is 5 mega-joules per kilogram, 10 times less energy than oil.

Lithium ion car batteries were invented 25 years ago, and the best battery we’ve yet discovered, but they have 3 big problems:

  1. They’re expensive
  2. Cars can’t go far enough between recharges – at most 100 miles.
  3. Half of a lithium-ion battery controls the chemical reactions inside to charge and discharge safely, rather than storing and delivering electricity.
  4. David Fridley, a scientist at Lawrence Berkeley National Laboratory, said “Consider that the largest remaining reserves of lithium are in the brine flats of Bolivia, which nationalized its oil and gas industries two years ago. Is it conceivable that corporations will be able to just come and extract lithium to their needs to provide for Norteamericano driving?”

A breakthrough requires new understanding of very complicated chemistry, lowering expensive manufacturing costs, making a lot of different materials work well together, lengthy testing to see if the new battery can last a long enough time, and safety issues (i.e. lithium batteries can easily catch on fire).

What looks like a simple black box to you is an insanely complicated stew inside of metals, liquids, solids, chemicals, and other substances.  Every time you tweak one or more of these components, the battery may stop working — it won’t recharge, or burns out after just a few recharges, or catches fire easily, and so on.  All of the parts have to be optimized at the same time, and testing takes a long time — too many combinations of factors make finding the miracle batter more like winning a lottery.

On top of that, you’re trying to make the battery into a one-man band, it’s expected to do too many things — store energy quickly, release energy quickly — these tasks are at odds with each other.

Car makers who try to string a lot of small lithium batteries together increase the odds that one of them will catch on fire — they’re crammed with flammable liquids.

George Blomgren, formerly at Eveready and now a battery consultant said that only five new rechargeable batteries have been invented the past 200 years — big advances happen rarely.  Even the lead-acid battery in all our cars hasn’t changed much the past 150 years.

While some are optimistic more energy could be wrung out of better lithium ion batteries, other engineers are more pessimistic, and see a need for something else to replace them.

Although may kinds of new batteries are being researched, there isn’t a single one of them that isn’t stymied by major problems.

The Department of Energy says battery costs need to fall to $250 per kilowatt-hour (kWh)– now batteries are $600-700/kWh, and realistically, closer to $1250-$1700 when you take into account the usable energy output being less than advertised according to a study by the National Research Council.   Way too much to spur the large-scale manufacture of electric cars.

In addition, vehicle batteries must be safe and vibration-resistant, must work over a wide range of temperatures, and must be capable of being recharged at least 1000 times while retaining 80% of their storage capacity. “For a less than $250 a kilowatt-hour system, those are very tough goals,” says Trygve Burchardt, chief scientific officer of ReVolt Technology, an advanced battery maker in Portland, Oregon (Service).

Tesla has made zero new battery technology discoveries, they just strung together 8,000 batteries weighing 1,300 pounds that will have half the power after 5 years as they did originally.  Musk is trying to hide this by offering to exchange batteries on the freeway and other schemes, or is multi-billion dollar factory in Nevada will never get built when investors realize the false promises of battery energy density can never be met due to the laws of physics.

Cars are toys!  Who cares about cars?  It’s tractors/harvesters, mining equipment, freight trucks, trains, ships, and barges that do the actual work of society that delivers food and goods and keeps us alive. They can’t possibly operate on batteries for long-distance travel because the battery would both weigh more and take up more space than the cargo itself.

Battery history

In 1859, a French physicist named Gaston Planté invented the rechargeable lead-acid battery. Planté’s battery used a cathode made of lead oxide and an anode of electron-heavy metallic lead. When his battery discharged electricity, the electrodes reacted with a sulfuric acid electrolyte, creating lead sulfate and producing electric current. But Planté’s structure went back to the very beginning—it was Volta’s pile, merely turned on its side, with plates stacked next to rather than atop one another. The Energizer, commercialized in 1980, was a remarkably close descendant of Planté’s invention. In more than a century, the science hadn’t changed.

In 1966, Ford Motor tried to bring back the electric car. It announced a battery that used liquid electrodes and a solid electrolyte, the opposite of Planté’s configuration. It was a new way of thinking, with electrodes—one sulfur and the other sodium—that were light and could store fifteen times more energy than lead-acid in the same space. There were disadvantages, of course. The Ford battery did not operate at room temperature but at about 300 degrees Celsius. The internal combustion engine operates at an optimal temperature of about 90 degrees Celsius. Driving around with much hotter, explosive molten metals under your hood was risky. Realistically speaking, that would confine the battery’s practical use to stationary storage, such as at electric power stations. Yet at first, both Ford and the public disregarded prudence. With its promise of clean-operating electric cars, Ford captured the imagination of a 1960s population suddenly conscious of the smog engulfing its cities. Popular Science described an initial stage at which electric Fords using lead-acid batteries could travel forty miles at a top speed of forty miles an hour. As the new sulfur-sodium batteries came into use, cars would travel two hundred miles at highway speeds, Ford claimed. You would recharge for an hour, and then drive another two hundred miles. A pair of rival reporters who were briefed along with the Popular Science man were less impressed—despite Ford’s claims, one remarked within earshot of the Popular Science man that electrics would “never” be ready for use. The Popular Science writer went on: They walked out to their cars, started, and drove away, leaving two trains of unburned hydrocarbons, carbon monoxide, and other pollution to add to the growing murkiness of the Detroit atmosphere. Source: The Powerhouse: Inside the Invention of a Battery to Save the World by Steve LeVine


Battery University.

Borenstein, Seth.  Jan 22, 2013. What holds energy tech back? The infernal battery.  Associated Press.–finance.html

The best, but most technical, discussion of where we stand now with battery research is this document:

DOE annual progress report 2008 Energy Storage Research and Development

House, Kurt Zenz. 20 Jan 2009. The limits of energy storage technology. Bulletin of the Atomic Scientists.

Service, Robert. 24 Jun 2011. Getting there. Better batteries paved the way for half-decent electric cars. Making improved versions viable for the mass market will depend on a suite of advanced battery technologies now in labs around the globe.  Science Vol 332 1494-1496.

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