Solid state batteries are receiving attention due to the possibility of the incorporation of the high energy density of lithium metal coupled with increased safety due to the elimination of flammable organic electrolytes. The lithium/iodine (Li/I₂) solid electrolyte battery system has been used successfully for decades as a primary battery to power implantable cardiac pacemakers and has demonstrated an exceptional record of predictability and reliability with high energy density (1536 Wh/L, 560 Wh/kg).

This presentation describes the demonstration of a lithium/iodine rechargeable battery based on the use of LiI rich lithium iodide-(3-hydroxyproprionitrile)₂ solid state electrolyte. The battery is first assembled fully discharged using only the solid state electrolyte. The LiI is transformed into the active material where, on charge, lithium metal forms at the negative side of the battery and iodine forms at the positive side. To our knowledge, this is the first demonstration of a rechargeable self-forming solid state lithium battery with electrolyte including LiI(HPN)₂. Results on cell formation, cycling, Coulombic efficiency as well as electrochemical impedance spectroscopy will be presented. The results show promise for this conceptual approach for achieving high energy density solid state rechargeable batteries.