Electrochemical energy conversion and storage is important for developing an energy-sustainable society.1 Our group focuses on (electro)catalysis and rechargeable batteries. The research starts with materials synthesis, chemical/structural characterization, and performance assessments. This talk will consist of two topics: noble metal nanostructures for (electro)catalysis and electrode materials for advanced rechargeable batteries.

Highly dispersed noble metal nanostructures (such as Pd and Au), a group of important catalysts for many applications, are typically synthesized via top-down or bottom-up methods. Not many syntheses integrate the advantages of both strategies. Recently, we have developed such an unconventional method,2,3 which is entitled “alternating voltage induced electrochemical synthesis (AVIES)”. This method enables a simultaneous synthesis of both colloidal nanoparticles and nanostructured electrodes.4 I will discuss the synthesis, characterization, formation mechanism, and (electro)catalytitic performance of a few noble metals.

Lithium ion batteries (LIBs), the most advanced rechargeable batteries, are currently ubiquitous in portable devices and will be popular in large-scale applications (such as electric vehicles) in the future.5 We are interested in both anode and cathode materials made of earth-abundant elements. This presentation will focus on alkali sulfide (M2S, M = Li and Na) cathodes.6,7 M2S cathodes are attractive for developing M-S batteries, because they can circumvent many issues associated with the direct use of metal anodes and sulfur cathodes.8 However, one big challenge towards realizing practical M2S cathodes, which require both high specific capacity and capacity density, is the lack of an efficient method to produce M2S secondary clusters – the entities of assembled M2S nanoparticles.6 In this talk, I will demonstrate our progress towards this ultimate goal.

References:
(1) Whittingham, M. S. "History, Evolution, and Future Status of Energy Storage", Proceedings of the IEEE, 2012, 100, 1518-1534.
(2) Cloud, J. E.; McCann, K.; Perera, P. A. K.; Yang, Y. "A Simple Method for Producing Colloidal Palladium Nanocrystals: Alternating Voltage Induced Electrochemical Synthesis", Small, 2013, 9, 2532-2536.
(3) Cloud, J. E.; Yoder, T. S.; Harvey, N. K.; Snow, K.; Yang, Y. "A Simple and Generic Approach for Synthesizing Colloidal Metal and Metal Oxide Nanocrystals", Nanoscale, 2013, 5, 7368-7378.
(4) Zhao, Y.; Li, X.; Schechter, J. M.; Yang, Y. "Revisit of the Oxidation Peak in the Cathodic Scan of Cyclic Voltammogram of Alcohol Oxidation on Noble Metal Electrodes", RSC Advances, 2016, 6, 5384-5390.
(5) Goodenough, J. B. "Evolution of Strategies for Modern Rechargeable Batteries", Accounts of Chemical Research, 2013, 46, 1053-1061.
(6) Li, W.; Liang, Z.; Lu, Z.; Yao, H.; Seh, Z. W.; Yan, K.; Zheng, G.; Cui, Y. "A Sulfur Cathode with Pomegranate-Like Cluster Structure", Advanced Energy Materials, 2015, 5, 1500211.
(7) Li, X.; Wolden, C. A.; Ban, C.; Yang, Y. "Facile Synthesis of Lithium Sulfide Nanocrystals for Use in Advanced Rechargeable Batteries", ACS Applied Materials and Interfaces, 2015, 51, 28444–28451.
(8) Yang, Y.; Zheng, G. Y.; Cui, Y. "Nanostructured Sulfur Cathodes", Chemical Society Reviews, 2013, 42, 3018-3032.


Yongan Yang, Colorado School of Mines