As more wind and solar come online in the U.S. and around the world storing electricity to make sure there’s always power is becoming more of a concern. Battery technology is drawing billions of dollars investment, but now MIT researchers are proposing a new take on an old technology, flow batteries, that relies on gravity to store and discharge energy.
The new approach radically simplifies the concept of a flow battery. “All previous versions of liquid batteries have relied on complex systems of tanks, valves, and pumps, adding to the cost and providing multiple opportunities for possible leaks and failures,” MIT said.
The new approach proposed by MIT researchers in the journal Energy and Environmental Science is a liquid battery that uses a gravity-fed arrangement akin to an hourglass to store and release energy. The researchers say it could offer advantages because of its low cost and simple design and operation. The research was co-authored by MIT Professors Yet-Ming Chiang, Alexander Slocum, Gareth McKinley, W. Craig Carter, postdoc Xinwei Chen, graduate student Brandon Hopkins and four others.
In the design both the positive and negative electrodes are in liquid slurries and are separated by a membrane. “In principle, it functions like an old hourglass or egg timer, with particles flowing through a narrow opening from one tank to another. The flow can then be reversed by turning the device over. In this case, the overall shape looks more like a rectangular window frame, with a narrow slot at the place where two sashes would meet in the middle,” MIT said. In addition the ability to absorb or discharge energy is controlled by the angle of the device.
The researchers produced a device as a concept that has liquid on one side and a sheet of lithium on the other. They plan to create device where the positive and negative electrodes are liquid. They will be separated by a membrane and will flow side by side through an opening.
Chiang said the new battery design has advantages of both a liquid and a solid battery. “The concept here shows that you don’t need to be confined by these two extremes. This is an example of hybrid devices that fall somewhere in the middle,” he says. The battery’s power density and its energy density and can be chosen independently. “In a conventional battery, the power and energy are highly interdependent,” Chiang says. In addition only the center of a flow battery needs a contact whereas each of the cells in a conventional battery need to be connected.
The Department of Energy’s Joint Center for Energy Storage Research funded the research.Tweet