The molten salt the team chose as an electrolyte simply because of its low melting point turned out to have a fortuitous advantage. One of the biggest problems in battery reliability is the formation of dendrites, which are narrow spikes of metal that build up on one electrode and eventually grow across to contact the other electrode, causing a short circuit and hampering efficiency. But this particular salt, it happens, is very good at preventing that malfunction.
Avanti is working on demonstrating that the technology works at scale, including running through hundreds of charging cycles.