Current laptop and mobile phone batteries last about two years before they become useless. One reason for this is the short life of silicon dioxide used as electrodes in the batteries. The silicon rods have a short life because every time they are charged, they expand beyond their normal size but upon discharge they shrink way too much. After several discharge-re-charge cycles the silicon rods lose material strength and develop cracks. The cracks start as microscopic disjoints between molecules but increase both in number and size to render the electrode completely useless.
To work around cracks such as these scientists have been working on how to develop self healing materials. A similar technology has been employed in LG’s curved phone (read: G Flex: Self healing curved LG phone) where minor scratches on the phone’s cover heals themselves. The same technique is being used by Researchers at Stanford and the SLAC National Accelerator Laboratory to protect the Lithium-ion batteries with silicon dioxide electrodes against the cracks. To do this, the researchers have coated the electrodes with a light polymer material that when the electrodes expand, the polymer expands likewise and even cracks. But upon discharging and as the electrodes contract, the polymer bonds are able to rejoin back to compactness. The image below illustrates:
So far the researchers have been able to have their prototype batteries go through 100 discharge-recharge cycles without losing the ability to store energy. This is however is still way below the researchers’ target as normally typical car batteries go through 3000 cycles while phone batteries have an average of 500 cycles.
The research if successful will solve a big problem not only to consumers who have to buy new batteries every so often but also the environment that has to contend with the billions of battery waste annually.