>Cui estimated that, given the water-based battery’s expected lifespan, it would cost a penny to store enough electricity to power a 100-watt lightbulb for twelve hours.
Oh dear, I hate university news "journalism" with a passion. For the life of me I cannot understand why they feel the need to dumb down parts of the content while other parts remain decidedly technical. Is it to have something that laymen can quote? In this example, it's not clear how long the storage would be, but presumably overnight? It would make much more sense to compare the expected price to existing solutions, and/or the current price of electricity.