A week or so ago, I was leading forth in this column about the way technological developments will always assure the longevity of the electronics industry. Coincidently, a recent and very intriguing technical breakthrough by the Rensselaer Polytechnic Institute, America’s oldest technological university, totally endorses that view.
Imagine a sheet of paper that can be rolled, twisted, cut, and shaped to fit just about any contour. So what, you say? Well, this is no ordinary sheet of paper. It is, in reality, a battery, or if need be, a supercapacitor. Add to that the following facts: It can operate in a temperature range of plus 300ºF down to 100º below zero; no harsh chemicals are used in its production; and it’s cheap to make. You have to agree that this is fantastic stuff.
What exactly is this paper battery? The easiest way to grasp this is to imagine carbon nanotubes sitting upright on a silicon wafer, a bit like a microscopic hairbrush. Then, imagine a compound of cellulose (the same plant cells used to make most types of paper) being poured between the nanotubes. Let the whole thing set and peel the sheet of paper away from the wafer.
To activate the battery, the researchers used an ionic liquid as an electrolyte. Because ionic liquid doesn’t contain water, there’s nothing in the batteries to freeze or evaporate.
The nanotubes act as electrodes and the device will function as both a lithium-ion battery and a supercapacitor. It can provide the long, steady power output like a conventional battery, or the quick burst of high energy like a supercapacitor.
Of particular importance was an experiment performed by the Rensselaer team, in which paper batteries were printed without adding any electrolytes. Then they showed that naturally occurring electrolytes in human sweat, blood, and urine can be used to activate the battery device. This has major implications when it comes to powering medical implant devices, such as pacemakers. Also, the paper battery doesn’t use the harsh chemicals associated with conventional battery design.
The researchers now have to look at how they will mass-produce these paper batteries. They’re confident that a method will be found whereby rolls of paper can be used just as they are for the printing of newspapers. Good news indeed!