2, Brookhaven National Laboratory, Upton, New York, United States
Lithium based battery systems are attractive due to their higher energy densities, however, safety issues resulting from use of organic electrolytes and formation of Li dendrites remain major concerns. Solid state electrolytes provide an alternative to organic electrolyte, but present their own challenges, including limits in ionic conductivity and the lithium/solid-state electrolyte interface. Self forming batteries, where the anode and cathode are formed upon charge from a single solid electrolyte, can be a promising avenue to address and reduce interfacial resistance. The Li/I2 couple is an attractive target due to its high energy density (1536 Wh/L, 560 Wh/kg) and opportunity to self-heal. Notably, the primary Li/I2 battery has been a successful technology as the power source for pacemakers.
Herein, we describe a fully self-forming solid state rechargeable battery based on the Li/I2 couple using LiI rich lithium iodide-(3-hydroxyproprionitrile)2 electrolyte. To our knowledge, this is the first demonstration of a rechargeable fully self-forming solid state lithium battery with the inclusion of LiI(HPN)2. Characterization to verify the formation of the self-forming active battery will be discussed. The impact of variables such as LiI and LiI(HPN)2 ratio and charging condition on the resulting impedance of the battery system will also be described. These results show promise for the future development of high energy density solid state self-forming self-healing batteries.