All-solid-state batteries are safe and viable approaches to energy storage. Detailed understanding of solid-solid interface structure-function relations is critical for the improvement and wide deployment of such batteries. The interfaces between lithium phosphorous oxynitride ("LiPON") solid electrolyte material, and lithium metal anode and Li(x)CoO(2) cathode surfaces, have been reported to generate solid electrolyte interphase ("SEI")-like products and/or disordered regions. Using electronic structure calculations, we predict that "defective" P-O-P sequences in disordered LiPON regions react with Li metal in battery operational timescales, but in general LiPON is kinetically inert towards lithium at room temperature. In contrast, transfer of oxygen atoms from low-energy Li(x)CoO(2) (104) surfaces to LiPON is much faster under ambient conditions. The mechanisms of the primary reaction steps, experimental results to partially corroborate these predictions, and possible mitigation strategies to reduce degradations are discussed. LiPON interfaces are found to be useful case studies in terms of addressing challenges in modeling redox-active oxide interfaces; differentiating electrochemical from interfacial chemical reactions; and highlighting the importance of kinetics-controlled processes during battery assembly, which often involves moderate processing temperatures.

This work was supported by Nanostructures for Electrical Energy Storage (NEES), an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences under Award Number DESC0001160. Sandia National Laboratories is a multimission laboratory managed and operated by National Technology and Engineering Solutions of Sandia, LLC, a wholly owned subsidiary of Honeywell International, Inc., for the U.S. Department of EnergyâNational Nuclear Security Administration under contract DE-NA0003525.