Transforming the energy materials landscape from the nanoscale to the macro
Our research group focuses on finding nanotechnology-driven solutions to enable the next generation of lighter, more energy dense, more cost effective energy storage devices by studying their materials structure-property relationships. We have developed nano-scale synthesis strategies to bypass macro-scale limitations of energy and structural materials with applications in clean tech, electric vehicles, wearable electronics, and more.
Kolby Hanley, a third year undergraduate student in the Yushin lab, has won the 2018 InVenture prize of $20,000, a free patent filing, and a spot in the GT startup accelerator Flashpoint for his company UltraView. Kolby has invented a one-of-a-kind lightweight device to help competitive archers aim and illuminate their targets. Koly himself is a four time national champion in archery, and at one point was the top archer under 21 in the nation. Congratualtions, Kolby! Read more about it in [this article](http://www.news.gatech.edu/2018/03/06/setting-sights-competitive-archery).
The Bavatnik National Awards celebrate young scientists 42 and below in the Life Sciences, Physical Sciences & Engineering, and Chemistry categories. Prof. Yushin was one of the 30 finalists from a pool of over 300 nominees. He was honored at the annual awards ceremony at the American Museum of Natural History in New York City. Congratulations! Read more about it in the [following article.](https://www.materialstoday.com/materials-chemistry/news/mt-editor-finalist-2017-blavatnik-awards/)
In MRS 2017 Fall Meeting in Boston, Kostiantyn received a “Best Poster Award” for his poster titled “Nonporous Copper Synthesized via De-alloying of Copper-Calcium Alloys to Accommodate Lithium Titanate for Asymetric Supercapacitors.” The Yushin group is proud of the superb work of everyone who contributed to this work in the lab. Congratulations!
Materials Today, a peer-reviewed journal in which Professor Yushin is Co-Editor-in-Chief, has released an exclusive interview with Professor Yushin on his lab, his team, and his vision. Read more about it in the [following article](https://www.materialstoday.com/lab-profile-gleb-yushin-georgia-tech).
Supercapacitors, also known as electrochemical capacitors, have witnessed a fast evolution in the recent years, but challenges remain. This review covers the fundamentals and state-of-the-art developments of supercapacitors. Conventional and novel electrode materials, including high surface area porous carbons for electrical double layer capacitors (EDLCs) and transition metal oxides, carbides, nitrides and their various nanocomposites for pseudocapacitors–are described. Latest characterization techniques help to better understand the charge storage mechanisms in such supercapacitors and recognize their current limitations, while recently proposed synthesis approaches enable various breakthroughs in this field. Z. Lin et al., Materials Today 2018 (in press) [https://doi.org/10.1016/j.mattod.2018.01.035](https://doi.org/10.1016/j.mattod.2018.01.035)
Aqueous asymmetric supercapacitors (ASCs) may offer comparable or higher energy density than electric double-layer capacitors (EDLCs) based on organic electrolytes. As such, ASCs may be more suitable for integration into smart textiles, where the use of flammable organic solvents is not acceptable. However, reported ASC devices typically suffer from poor rate capability and low areal loadings. This study demonstrates the development of nitrogen-doped carbon (N-C) nanowire/metal oxide (Fe2O3 and MnO2) nanocomposite electrodes directly produced on the internal surface of a conductive fabric for use as high-rate electrodes for solid-state ASCs. The N-C nanowires provide fast and efficient pathways for electrons, while short diffusion paths within nanosized metal oxides enable fast ion transport, leading to greatly enhanced performance at high rates. The porous structure of the fabric enables high areal capacitance loading in each electrode (≈150 mF cm−2). Both electrodes show high specific capacitance of ≈180 F g−1 (Fe2O3) and ≈250 F g−1 (MnO2) and excellent rate capability. Solid-state ASCs assembled by using an aqueous gel electrolyte operate at 1.6 V and deliver over 60 mF cm−2 during ≈50 s charging/discharging time and over 30 mF cm−2 for ≈5 s discharge. W Fu et al., Adv. Energy Mater. 2018, 1703454 [https://doi.org/10.1002/aenm.201703454](https://doi.org/10.1002/aenm.201703454)
Li-halide hydroxides (Li2OHX) and Li-oxyhalides (Li3OX) have emerged as new classes of low-cost, lightweight solid state electrolytes (SSE) showing promising Li-ion conductivities. The similarity in the lattice parameters between them, careless synthesis, and insufficient rigor in characterization often lead to erroneous interpretations of their compositions. Finally, moisture remaining in the synthesis or cell assembling environment and variability in the equivalent circuit models additionally contribute to significant errors in their properties. Thus, there remains a controversy about the real values of Li-ion conductivities in such SSEs. Here an ultra-fast synthesis and comprehensive material characterization is utilized to report on the ionic conductivities of contaminant-free Li2+xOH1−xCl (x=0-0.7), and Li2OHBr not exceeding 10-4 S cm-1 at 110 °C. Using powerful combination of experimental and numerical approaches, it is demonstrated that the presence of H in these SSEs yields significantly higher Li+ -ionic conductivity. Born-Oppenheimer molecular dynamics simulations show excellent agreement with experimental results and reveal an unexpected mechanism for faster Li+ transport. It involves rotation of a short OH-group in SSEs, which opens lower-energy pathways for the formation of Frenkel defects and highly-correlated Li+ jumps. These findings will reduce the existing confusions and show new avenues for tuning SSE compositions for further improved Li-ion conductivities. A.Y Song et al., Advanced Energy Mat. 2018, [https://doi.org/10.1002/aenm.201700971 ](https://doi.org/10.1002/aenm.201700971)
Commercial lithium-ion (Li-ion) batteries built with Ni- and Co-based intercalation-type cathodes suffer from low specific energy, high toxicity and high cost. A further increase in the energy storage characteristics of such cells is challenging because capacities of such intercalation compounds approach their theoretical values and a further increase in their maximum voltage induces serious safety concerns. The growing market for portable energy storage is undergoing a rapid expansion as new applications demand lighter, smaller, safer and lower cost batteries to enable broader use of plug-in hybrid and pure-electric vehicles (PHEVs and EVs), drones and renewable energy sources, such as solar and wind. Conversion-type cathode materials are some of the key candidates for the next-generation of rechargeable Li and Li-ion batteries. Continuous rapid progress in performance improvements of such cathodes is essential to utilize them in future applications. In this review we consider price, abundance and safety of the elements in the periodic table for their use in conversion cathodes. We further compare specific and volumetric capacities of a broad range of conversion materials. By offering a model for practically achievable volumetric energy density and specific energy of Li cells with graphite, silicon (Si) and lithium (Li) anodes, we observe the impact of cathode chemistry directly. This allows us to estimate potentials of different conversion cathodes for exceeding the energy characteristics of cells built with state of the art intercalation compounds. We additionally review the key challenges faced when using conversion-type active materials in cells and general strategies to overcome them. Finally, we discuss future trends and perspectives for cost reduction and performance enhancement. F Wu et al., Energy & Environmental Science 10 (2), 2017, 435-459 [https://doi.org/10.1039/C6EE02326F](https://doi.org/10.1039/C6EE02326F)
Some of the Institutions we’ve collaborated in the past. For collaboration inquiries, contact Professor Gleb Yushin.
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