Nearly all of our favorite gadgets require batteries. Electronics are always getting smaller and more efficient, but battery technology has lagged behind. Take apart your toys, and you’ll probably find that half the size and more than half the weight of most of them is consumed by the battery. Recent developments may improve on that situation.
Batteries convert stored chemical energy into electrical energy. Regardless of components or chemistry, all storage batteries consist of an anode and a cathode in an electrolyte solution. The element or compound at the cathode is full of negatively-charged anions. When the cathode and anode are connected electrically, anions flow from the cathode to the anode, giving up energy in the form of electrons. When the supply of anions falls below a certain threshold, the battery is exhausted. Primary or non-rechargeable batteries won’t allow the electron flow to be reversed, but secondary or rechargeable batteries will, replenishing the anions on the cathode side and removing them from the anode.
The charge-discharge process is considerably less than 100 percent efficient, and the waste energy is given off as heat. Heat can crystallize the compounds in the battery, making them useless for energy storage and slowly decreasing the storage capacity of the battery. With Li-Ion batteries, you can expect 300-500 charge-discharge cycles with around 50 percent loss of capacity as the battery ages. Sometimes the problem is worse than just loss of capacity. Lithium-Ion (Li-Ion) batteries generate moisture when they heat up, which reacts with the salts in the electrolyte to create hydrochloric acid. The acid eats through the aluminum anode and cathode sheets in the battery, causing a build-up of gases that include hydrogen. You remember hydrogen — that’s what made the Hindenburg explode, and it’s caused a few Li-Ion batteries to do the same thing. Most people view this as undesirable.
A new formulation of lithium battery from Leyden Energy called Lithium-Imide uses a patented salt (in chemist’s terms, a salt is a compound formed from an acid and a base) that doesn’t produce as much heat, doesn’t react with moisture, and uses a conducting graphite compound instead of aluminum for its cathode. The new batteries last over three years, through 1000+ charge-discharge cycles, and maintain close to their full capacity to the end of their service life.
You’ll see the new Li-Imide batteries coming online in the next year, probably first in cell phones and then in other electronics. Cell phones are a very rich market, and devices like the iPhone have to be dismantled to replace the battery, so an extended-life power source is especially valuable.
This doesn’t mean that Li-Ion batteries are all done. Technology developed at the University of Leeds provides for production of a thin, flexible Li-Ion battery that would expand the design capabilities of portable electronics. A typical Li-Ion battery has sealed cells of liquid electrolyte and a porous film separator. The pores allow lithium ions to flow from the anode to the cathode and back again during charge-discharge cycles.
The new design places a thin electrolytic gel between sheets of highly conductive anode and cathode materials. The gel sandwich can be produced rapidly and cheaply, is only a few nanometers thick, can be cut to any size, and is tolerant to damage. Instead of having the battery assume the shape of a brick, it could line the component shell of a device and double as shock-cushioning, or become part of a case or carrying strap.
The new flexible Li-Ion technology has been licensed to the Polystor Energy Corp., a U.S. company. Polystor is working on commercial applications for the new batteries.
