In order to unleash the full potential of renewable energy, scientists are constantly exploring advanced battery technology to solve the intermittent problem of solar and wind power generation. A team at the Pacific Northwest National Laboratory (PNNL) has proposed a new design that meets several important conditions in this field, showing a "hibernating" battery that can store energy for months at a time.
At the heart of the research is an energy storage technology called molten salt batteries. This kind of battery has existed in various forms for more than 50 years and is considered to be a grid-scale renewable energy storage solution because of its low cost and the use of common materials.
It is reported that these devices use molten salt as an electrolyte, which is a solution that carries an electric charge between the two electrodes of the battery (cathode and anode). Keep the electrolyte at high temperature and the salt will melt and see it flow like a liquid, but it will become solid at room temperature. The PNNL team has used these attributes to produce hibernating batteries called temperature-based batteries.
It is understood that the device consists of aluminum anodes and nickel cathodes, which are immersed in molten salt electrolytes mixed with sulfur to increase additional capacity. The battery is charged by heating to 180 °C, and the ions produce chemical energy through the liquid electrolyte. Cooling the battery to room temperature will solidify the electrolyte, freeze the ions, and lock the energy until the battery is heated again, causing the energy to flow again.
For this reason, scientists also call the device a "freeze-thaw battery", and although the prototype is only the size of a hockey puck, they are optimistic about the potential to expand its size. Its theoretical density is 260Wh per kilogram, which is higher than today's lead-acid and liquid-flow batteries, and the material cost for energy storage is about $23 per kilowatt-hour. The team hopes to reduce the material cost to about $6 per kilowatt-hour by adding iron to the design. In the test, the battery maintained 92% capacity in 12 weeks.
The research was recently published in the journal Battery report physical Science (Cell Reports Physical Science). "it's a lot like growing food in your garden in spring, putting excess food in a container in the refrigerator and thawing it out for dinner in winter," the researchers said. "
Eventually, scientists hope the technology will provide a seasonal form of energy storage that collects energy at one time of year for another. And because the battery can be idle while keeping most of its stored energy, it only needs to be recharged and discharged a few times a year.
