From Clusters to Crystals: A Bottom-up Design of Energy Materials

Clean, abundant, and sustainable energy is undoubtedly one of the greatest challenges in the 21st century. Fossil fuels that account for more than 80% of the current world’s need are not only limited but also are harmful to the environment. While solar, wind, and hydrogen together can meet the world’s energy needs, considerable material challenges remain before they can replace our dependence on fossil fuels. I will outline some of the material challenges in energy storage and conversion with particular emphasis on hydrogen storage [1], Li-ion batteries [2-4], and perovskite solar cells [5]. A common feature of all these materials is that they are complex salts whose negative ion components can be identified as superhalogen clusters that mimic the chemistry of halogens. This realization has made it possible to use the vast advances in cluster science to design novel materials for energy applications. I will discuss how superhalogens can help us synthesize halogen-free electrolytes for Li, Na, and Mg-ion batteries [2-4], enable focused discovery of durable hybrid perovskite solar cells [5], understand the intermediate phases [6] during de-hydrogenation of complex metal borohydrides, and design safer materials capable of storing large amounts of hydrogen [7]. These results based on density functional theory have predictive capability. Examples of experimental verification of some of the predicted results will be presented. * P. Jena: “Materials for Hydrogen Storage: Past, Present, and Future”, J. Phys. Chem. Letters 2, 206 (2011). * S. Giri, S. Behera, and P. Jena: “Superhalogens as Building Blocks of Halogen-free Electrolytes in Li-ion Batteries”, Angew. Chem. Int. Ed. 53, 13916 (2014); * Zhao, J. Zhou, and P. Jena, “Stability of B12(CN)122-: Implications for Lithium and Magnesium Ion Batteries”, Angew. Chem. Int. Ed. (VIP) 55, 3704 (2016) * P. Jena, Superhalogens: A Bridge between Complex Metal Hydrides and Li-ion Batteries. J. Phys. Chem. Letters 6, 1119 (2015). * H. Fang and P. Jena, “Super-ion Inspired Colorful Hybrid Perovskite Solar Cells”, J. Mat. Chem. A 4, 4728 (2016); Fang, H. and Jena, P.: “Molecular Origin of the properties of organic-inorganic hybrid perovskites: The Big Picture from Small Clusters”, J. Phys. Chem. Lett. 7, 1596−1603 (2016) * Y. Liu, S. Giri, J. Zhou, and P. Jena: “Intermediate phases during decomposition of metal borohydrides, M(BH4)n (M=Na, Mg, Y)”, J. Phys. Chem. C 118, 28456 (2014) * D. A. Knight, R., Zidan, R. Lascola, R. Mohtadi, C. Ling, P. K. Sivasubramaniam, J. A. Kaduk, S. -J. , Hwang, D. Samanta, and P. Jena.: “Stabilization of Hydrogen Rich, Yet Highly Pyrophoric Al(BH4)3 via the Synthesis of the Hypersalt K[Al(BH4)4]”, J. Phys. Chem. C 117, 19905 (2013)