NANOTECH LAB | YUSHIN GROUP

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.

News

Publications

Hierarchical Fabric Decorated with Carbon Nanowire/Metal Oxide Nanocomposites for 1.6 V Wearable Aqueous Supercapacitors

2018

Advanced Energy Materials

W Fu, E Zhao, X Ren, A Magasinski, G Yushin

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)

Protons Enhance Conductivities in Lithium Halide Hydroxide/Lithium Oxyhalide Solid Electrolytes by Forming Rotating Hydroxy Groups

2018

Advanced Materials

A.-Y. Song, Y Xiao, K Turcheniuk, P Upadhya, A Ramanujapuram, J Benson, A Magasinski, M Olguin, L Meda, O Borodin, G Yushin

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)

Conversion cathodes for rechargeable lithium and lithium-ion batteries

2017

Energy & Environmental Science

F Wu, G Yushin

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)

Collaborators

Some of the Institutions we’ve collaborated in the past. For collaboration inquiries, contact Professor Gleb Yushin.

Central South University
Xavier University of Louisiana
Technische Universität Dresden
Spanish National Research Council

Contact Us

Get in touch! Send an email to Professor Yushin at yushin@gatech.edu.