A team at the Pacific Northwest National Laboratory (PNNL) has developed a “sleep” battery that can store its energy for several months. When cooled to room temperature, the electrolyte charged in it solidifies, “conserving” energy in itself until the moment the battery is reheated.
The device consists of an aluminum anode, a nickel cathode, and a molten salt electrolyte alloyed with sulfur to further increase the capacity. The battery is charged by heating it to 180°C, where the ions pass through the liquid electrolyte to generate power. When cooled, the ions in the electrolyte “fall into hibernation.”
The first prototype is no larger than a hockey puck and has a density of 260 Wh per kilogram, which is greater than today’s lead-acid and flow batteries. In testing, the battery retained 92% of its capacity for 12 weeks. At the moment, the cost of 1 kWh in such a battery is $23, and due to the use of iron, it can be reduced to $6.
“Imagine a big battery on a 40-foot tractor-trailer parked at a wind farm. The battery is charged in the spring and then the truck drives down the road to the substation where it can be used in the heat of the summer,” said Vince Sprenkle, one of the developers.
Scientists have already patented the technology and published their study in the journal Cell Reports Physical Science.