The Battery: How Portable Power Sparked a Technological Revolution - Henry Schlesinger (2010)


Bring on the Future

“Prediction is very hard, especially when it’s about the future.”

—Yogi Berra

Predictions far into the future are always dangerous. This is painfully evidenced by the legions of baby boomers who have grown to middle age and beyond still waiting for the arrival of flying cars and personal jet packs promised in the magazines of their youth.

In the more distant future are ultracapacitors or double-layer capacitors or electric double-layer capacitors. A major technological leap forward from standard batteries, ultracapacitors work not by generating a charge through a chemical reaction but by holding an electrical charge in much the same way as a Leyden jar. In their most common form, ultracapacitors are made up of two nonreactive plates coated with carbon mounted in an electrolyte. The trick is that the surface area of each porous plate is enormous, so it’s able to hold a large charge.

Technically, the Leyden jar was a capacitor, though ultracapacitors first arrived on the scene in the late 1950s with a somewhat uneven improvement rate over the years and are today used in a variety of applications, such as supplying backup power for electronic devices. However, what’s changed is experiments in materials that supply an enormous amount of surface area, hence more electricity than standard capacitors, but still significantly less than a typical Li-ion battery. The surface area just isn’t there yet, but they’re getting close. In theory, there are huge advantages to this kind of technology, at least with a few more product generations. For one thing, because there isn’t a chemical reaction, ultracapacitors are less susceptible to environmental factors. They can also deliver more power more quickly than batteries and, since they don’t depend on a chemical reaction to recharge, they recharge quickly, within seconds. In theory, you could fully charge your iPod while waiting for an elevator or in line at the bank. They can also be recharged more often without losing their efficiency, say 50,000 times or more.

In the vanguard of the research effort are Professor Joel E. Schindall and a team at MIT’s Laboratory for Electromagnetic and Electronic Systems (LEES). What they’ve done is replace the activated carbon of ultracapacitors with carbon nanotubes that are 1/30,000 of a human hair. The tubes are actually “grown” on the surface. Once a plate’s surface is prepared with a catalyst, it’s then exposed to a hydrocarbon gas at a high temperature. As the gas fills the closed chamber, the catalyst captures the carbon atoms to build up or self-assemble a fuzzy layer of tiny regularly spaced nanotubes vertically aligned on the plate’s surface within minutes to grow a little nanotube forest. “What we’re trying to do is grow an array of nanotubes on a conducting electrode, like tin foil, for example,” Schindall explained. “We believe a nanotube could operate at three to four volts, about five times as much storage capacity as a commercial ultracap.”

This is the kind of technology that could not only find use in small, portable devices, but also in autos and storage for alternate energy generators, such as wind power. If all goes well, commercial products could be ready within as decade. However, more than a decade has passed since the introduction of Toyota’s Prius, the first mass-produced hybrid car with only incremental improvements to the original concept. Compared to the technological enhancements the iPod has undergone since its introduction a few years after the Prius, the electric car appears to be standing still.

The comparison, of course, is not a fair one. However, it is those very elements that make it unfair—all those differences between the hybrid apples and the iPod oranges—that need to be addressed. To make alternate energy a reality by adapting existing technology or developing new technology will require the kind of technological well-funded push afforded reluctantly to Samuel Morse for his electromagnetic telegraph, advocated by Vannevar Bush in his “Endless Frontier” essay, or promised by President Kennedy through NASA.

ON A MUCH SMALLER SCALE, MIT researchers are experimenting with microbatteries about half the size of a human cell. However, it isn’t the size of the battery that has generated interest, it is the assembly process. A genetically altered virus called M13 is set loose on a specially prepared surface to build up material for the anode. This is the kind of research that could lead to incredibly small self-powered ICs for implantable sensors.

And then there are so-called bio-batteries. As early as 2003, students at St. Louis University in Missouri developed a battery that ran on alcohol, specifically vodka and gin, using a catalyst to break down the components into enzymes. Sony followed suit with a battery that runs on sugar. Like the vodka-gin battery, enzymes break down or digest the sugar (glucose) while a specially designed anode extracts the electrons and hydrogen ions from the sugar. Not long ago in Singapore, a scientist unveiled a small bio-battery that uses urine as an electrolyte. Although it garnered a fair share of jokes in the media, the so-called pee battery essentially runs on the same principle as the power source in the proximity fuse—just add electrolyte—and could find applications in powering low-energy medical tests—for example, a diabetes or pregnancy test.

At Rensselaer Polytechnic Institute, scientists have come up with a somewhat similar concept, a battery that uses bodily fluids as an electrolyte. Paper-thin, the battery is comprised primarily of cellulose with nanotubes printed on it. The advantage, the researchers pointed out, is that it’s easily cut to size to fit comfortably under the skin for a device such as a pacemaker.

BATTERY DEVELOPMENT IS, AT LONG last, catching up to related fields. Today, the basic chemical principles that generate power for a vast range of devices are more alike than they are different. Tomorrow, they will likely become as different as the devices they power. Science and technology adapt, change, and interact in often surprising ways. More than two centuries ago, a dead frog’s leg unexpectedly twitched. The debate that followed has long been settled, but the science that emerged continues today and will no doubt continue far into the future.