"The freeze-thaw phenomenon is possible because the battery’s electrolyte is molten salt - a molecular cousin of ordinary table salt. The material is liquid at higher temperatures but solid at room temperature. The freeze-thaw battery was shown to retain 92 per cent of its capacity over 12 weeks."

Any relation between this and 'sodium-ion' battery companies like the recently acquired Faradion? (see https://www.youtube.com/watch?v=W2PmRT3akGk )