The finding could aid the development of batteries with solid electrolytes, called solid-state batteries, for applications including mobile devices and electric vehicles. The researchers published their study in ACS Energy Letters, where it is featured on the cover of the March issue. The development of solid-state batteries faces challenges, however, because it is more difficult to move ions through solid materials. The researchers studied the performance of the solid-state electrolyte compounds lithium zirconium chloride and lithium yttrium chloride and proposed a theory to explain why mixing the materials increased ionic activity. Su and fellow researchers plan to continue to study how the composition and structure of the interface leads to greater ionic conductivity.