From the Labs: Better Batteries, Smaller Devices?
Even as reports are starting to indicate there’s no cause for concern, one of the most common complaints (or perhaps concerns) raised about Apple’s new Macbook Air is the fact that the battery is not meant to be user-replaceable. A few years from now, however, that design decision may be even less relevant.
Earlier this week, Yahoo and other news sites began to report on work researchers at Stanford’s Materials Science and Engineering department reported in the journal Nature Nanotechnology in mid December. The scientists’ breakthrough discovery could yield batteries that can run for 40 or more hours and be smaller than what we use today. And these high powered wonders could be just a few years from being on the market. The implications for portable gadgets, our entertainment on the go, even electric cars, could be significant.
The principle behind rechargeable battery operation is relatively straight forward. When an appliance calls for power, electrons stored in the battery run from the negative (anode) to the positive (cathode) terminal to supply it. When plugged into a charger, the process is reversed. The energy is taken from the outlet and sent from the positive terminal back to the negative, where it is stored.
Internally, reversible chemical reactions participate in the storage, and different movements of the electrons. In a lithium battery, one of the traditional limiting factors has been how much lithium can be stored in the battery’s anode (which is typically made of carbon). To store a lot of lithium requires a big battery.
The Stanford team, took on 30 years of failed efforts to build an efficient battery with a different material. They focused on a battery made with a silicon anode, a complex approach with a problem other scientists hadn’t been able to crack.
Silicon, it turns out, is great for batteries on one level: it can store more lithium than carbon. And the more lithium, the more powerful the battery. But silicon also expands and contracts during the charging process and the repeated expansion and shrinkage causes it to break down. For decades, nobody could figure out a way to make the process durable enough to be effective.
At Stanford, assistant professor Yi Cui, and a team of researchers, came up with an ultra-modern solution. They created ultra small wires, called Nanowires, out of silicon. These are each about one-thousandth the thickness of a sheet of paper. When attached to the battery’s negative terminal and put in contact with the lithium these wires absorb the lithium until they’re about four times their normal size. When present in large enough numbers, a bundle of these silicon nanowires is far more effective at storing lithium than using carbon.
More importantly, and besting past research, according to their report in the journal, these nanowires also “do not pulverize or break into smaller particles” after charging and discharging.
The new batteries may be able to produce ten times the electricity of today’s batteries. They may also do it in a smaller footprint. Unlike past efforts to use silicon as a solution, they don’t break apart either. The early results suggest they’re durable, and powerful.
Cui has filed a patent and is looking into manufacturing. He’s confident the process will be able to travel effectively from the lab to commercialization. He notes that manufacturing requires “one or two different steps [relative to the lab], but the process can be scaled up. It’s a well understood process.”
If he’s right, and partners and/or investors line up, retail results could be just a few years away. Sure, that won’t improve the battery life of the Macbook Air, or people’s concern about servicing it themselves, but it could mean the cell phone you buy in two years only needs to be charged once a week, or your laptop will fly with you around the globe on a single charge. With this kind of breakthrough, a future version of the Macbook could be even lighter (less battery weight) and still get a longer charge. Your bluetooth headset might only need charging once a month.
If these batteries turn out to work, all the gadgets and gizmo’s we crave could have the juice to run far, far longer. If the Stanford breakthrough proves on track, it could bring more portability too; smaller electronics that last longer.
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