The title is a bit ambiguous ("Batteries last 400 Times Longer") and could be interpreted that the battery can store 400x more energy. It would be more precise to say that the discovery was for batteries that can last through 400x more discharge/recharge cycles.
There is a part of me that loves these stories about serendipitous discoveries. Of course the trick is to recognize what you have found and to use that information.<p>Some technology/inventions discovered by accident: penicillin, x-rays, post-it notes, pacemakers, ink-jet printers, saccharin, microwave ovens, potato chips/crisps and of course Coca Cola.
Promising! As ever the proof is when they make a working prototype to demonstrate this in an everyday battery, as stories like this abound. Fingers crossed.