Funding: This work was partially supported by U.S. Department of Energy’s Office of Energy Efficiency and Renewable Energy under award number DE-EE0008447. Author contributions: S.G. and C.-Y.W. developed the concept and wrote the manuscript. S.G. and R.S.L. designed and built the cells. S.G. built the test stand and carried out the performance characterization. T.L. carried out the nail penetration test. Y.L. performed the impedance analysis. Y.G. and Daiwei Wang carried out the XPS and SEM analysis. All authors contributed to development of the manuscript and to discussions as the project developed. Competing interests: The authors declare that they have no competing interests. Data and materials availability: All data needed to evaluate the conclusions in the paper are present in the paper and/or the Supplementary Materials. Additional data related to this paper may be requested from the authors.