New study suggests model preserves non-peak energy better
New research is constantly trying to address energy efficiency, including the advancement of battery storage by testing its viability. According to a new study from Pacific Northwest National Laboratory (published in Cell Reports Physical Science), new "freeze-thaw" batteries—despite sounding like an instant coffee item—can store charged energy for months. Here's how it works:
Solidified molten salt stops self-discharge during ambient storage. Active when heated, 90% of stored charge can then be recovered, PNNL says. Next, sulfur doping helps to activate nickel cathode and preserve capacity.
Grid-level storage of seasonal excess can be an important asset to renewable electricity, as many operators see the value of energy storage infrastructure only if it can outweigh the losses of off-peak seasons or periods.
"By applying the freeze-thaw thermal cycling strategy, here, we report Al-Ni molten salt batteries with effective capacity recovery over 90% after a period of 1–8 weeks as a proof-of-concept," the PNNL abstract reads. "We explore three activation methods of the nickel cathode in a molten-salt battery: (1) heat treating the cathode granules under H2/N2, (2) incorporating a partially charged NiCl2/Ni cathode, and (3) doping the molten salt electrolyte with sulfur."
In particular, sulfur doping, a cost-efficient method suitable for large-scale applications, was deemed "not only effective in activating the Ni cathode initially but also invaluable for energy retention during thermal cycling." Overall, these Al-Ni molten salt batteries under thermal cycling showed high retention in cell capacity over weeks, setting a direction for scalable seasonal storage.