November 19, 2014, by Peter Brewitt
Concrete Progress is an ongoing series of columns by Peter Brewitt devoted to exploring America’s infrastructure. It is part of Orion’s Reimagining Infrastructure project. Above: An enlarged image of wood splinters, which are pliable enough to be used as a key component of longer-lasting, more sustainable batteries.
This is not some sort of steampunk innovation. This is, quite literally, the power for a better tomorrow. To understand why this is a big deal, cast your mind back thirty years, and think about technology. It was an era of audiotapes and rotary phones, Apple IIE computers and black and white TVs and hand-cranked car windows. The hot new video game was Tetris. But batteries? Batteries were pretty much the same as we have now. Our failure to develop efficient power storage at the same rate as we’ve developed other kinds of technology has been a huge problem for energy progress as a whole—if you can’t store energy, you’ll lose it, as anyone who has vainly whimpered as their phone died in their hand knows. But wood, the oldest technological material, may provide a way to hold lots of energy cheaply.
In an engineering lab at the University of Maryland, a team led by Drs. Liangbing Hu, Teng Li, and Hongli Zhu (the lead author on the group’s publication) has built a timber battery. Their batteries are not made entirely of wood—you still need metal components to take an electric charge—but the wooden part is replacing the metal through which ions pop. Over time, this popping (between the anode and the cathode, for those who remember ninth grade) wears down the material in between. The engineers had been hoping to replace the lithium ions that batteries often use with sodium, which is much more abundant and therefore cheaper. The problem is that sodium ions, while chemically similar to lithium, are larger and unwieldy, deforming the rigid tin material that the engineers had hoped to use to shuttle them back and forth. Wood, though, is pliable enough to maintain its strength as ions pass through. The team tried tiny slivers of yellow pine, to great success. The result is an economical, and more sustainable, battery.