Water-based battery holds promise for solar, wind energy storage
Despite the low output, the team believe they can create an industrial-grade system that could charge and recharge up to 10,000 times for a grid-scale battery with a lifespan of over a decade.
“What we’ve done is thrown a special salt into water, dropped in an electrode, and created a reversible chemical reaction that stores electrons in the form of hydrogen gas,” said Yi Cui, a professor of materials science at Stanford.
Attaching a renewable power source to the prototype, the electrons flowing in reacted with the manganese sulfate dissolved in the water to leave particles of manganese dioxide on the electrodes. Excess electrons bubbled off as hydrogen gas, storing that energy for future use.
Recharging the prototype meant inducing the manganese dioxide particles clinging to the electrode to combine with water, replenishing the manganese sulfate salt. Once this salt was restored, incoming electrons became surplus, and excess power could again bubble off as hydrogen gas.
“We believe this prototype technology will be able to meet Department of Energy (DOE) goals for utility-scale electrical storage practical,” said Cui. This requires batteries for grid-scale storage that store and then discharge at least 20 kilowatts of power over a period of an hour, be capable of at least 5,000 recharges, and have a useful lifespan of 10 years or more. To make it practical such a battery system should cost $2,000 or less, or $100 per kilowatt hour.
The prototype needs more deverlopment as it uses platinum as a catalyst, which would be prohibitive for large-scale deployment. “We have identified catalysts that could bring us below the $100 per kilowatt hour DOE target,” said Cui. The researchers reported 10,000 recharges of the prototypes, but it will be necessary to test the manganese-hydrogen battery under actual electric grid storage conditions.
Cui is patenting the technology through the Stanford Office of Technology Licensing, and plans to form a company to commercialize the system.