Redox-flow batteries have been perking the interest of researchers for some time now, as they could present an effective alternative to lead acid and lithium batteries for the storage of energy produced by renewable sources, especially solar. A team from Harvard University is one group that has been tinkering with the technology to try and reduce costs and increase its energy storage capacity, most recently added a vitamin B2-inspired molecule to the battery, which has been able to achieve both of those things.
Flow batteries work using two separate tanks that exchange fluids that react with electrodes to store electricity. The electronics of the systems are separate from the tanks, which means that it is possible to scale up the capacity of the system without increasing the expensive electronics of the system. Due to the nature of the technology, it is also possible to store energy for a long time with much loss, making it, in theory, possible to store electricity from summer to winter. This is particularly attractive for solar PV.
However, as the technology is still relatively new, it is expensive, and the systems need a lot of space, meaning that it would be better suited to utility-scale PV. On top of this, its discharge is slower that lithium batteries, meaning that it would be less effective for grid stabilization. What has been suggested is that it would be most effective in a system that incorporates lithium batteries as well.
The team from Harvard was focusing on increasing the energy storage capacity per unit of volume of the redox-flow batteries, which in turn should reduce the cost of the technology. To do this, the team added an electrolyte based on alloxazine, which is the component of vitamin B2 that enables it to store energy in the human body.
The results of the research, published in the Nature Energy journal, were open-circuit voltage approaching 1.2V and current efficiency and capacity retention exceeding 99.7% and 99.98% per cycle. Additionally, the team believes that the electrolyte can be produced on an industrial scale at a relatively low cost.