Dr. Ke An

Strength by cyclic torsion: For most alloys, conventional or high entropy, increasing strength comes at the cost of poor ductility. Although there are many strategies to break this inverse relationship, Pan et al . now show that cyclic torsion on a high-entropy alloy enhances strength without degrading ductility (see the Perspective by Yeh). Cyclic torsion creates a gradient of dislocations and low-angle grain boundaries from the surface to the interior that organize into tiny stacking faults and twin when straining begins. These structures allow for the good ductility while simultaneously helping to work harden the alloy. —BG

1 July 2016 in Nature Communications

Journal Article

Gas–solid interfacial modification of oxygen activity in layered oxide cathodes for lithium-ion batteries

Bao Qiu

Minghao Zhang

Lijun Wu

Jun Wang

Yonggao Xia

Ying Shirley Meng

Lattice oxygen can play an intriguing role in electrochemical processes, not only maintaining structural stability, but also influencing electron and ion transport properties in high-capacity oxide cathode materials for Li-ion batteries. Here, we report the design of a gas–solid interface reaction to achieve delicate control of oxygen activity through uniformly creating oxygen vacancies without affecting structural integrity of Li-rich layered oxides. Theoretical calculations and experimental characterizations demonstrate that oxygen vacancies provide a favourable ionic diffusion environment in the bulk and significantly suppress gas release from the surface. The target material is achievable in delivering a discharge capacity as high as 301 mAh g⁻¹ with initial Coulombic efficiency of 93.2%. After 100 cycles, a reversible capacity of 300 mAh g⁻¹ still remains without any obvious decay in voltage. This study sheds light on the comprehensive design and control of oxygen activity in transition-metal-oxide systems for next-generation Li-ion batteries.

7 June 2017 in Advanced Materials

Journal Article

Phase‐Transformation Ductilization of Brittle High‐Entropy Alloys via Metastability Engineering

Hailong Huang

Yuan Wu

Junyang He

Hui Wang

Xiongjun Liu

Z. P. Lu

About Me

Dr. Ke An received his M.S. from Department of Chemical Engineering, Tianjin University, and Ph.D. from Department of Engineering Science and Mechanics, Virginia Tech. He is the Senior and Lead Scientist of the versatile materials science and engineering diffractometer, the VULCAN beamline, at the world most intense pulsed neutron source Spallation Neutron Source (SNS), funded by Basic Energy of Science, Office of Science, Department of Energy. He also holds an Adjunct Associate Professor position at the Department of Materials Science, the University of Tennessee, Knoxville. Since 2017 he has started leading the Materials and Engineering Initiative of Neutron Science Directorate to promote neutron science in area of M&E. Starting in 2016, he leads the newly formed Industrial Application Program of SNS and HFIR to promote the engagement of industrial users in using neutrons. Since 2007, he has been a major team member of the design and construction of the VULCAN instrument. He leads in commissioning, operation and further upgrade of the VULCAN beamline. The VULCAN beamline started commissioning in 2009 and entered successfully the general user program in 2010. Since then, he and the instrument team have grown a vibrant user program in materials research with neutron diffraction in energy storage and conversion materials (batteries and fuel cells materials), engineering structural materials, and functional materials, etc.

Dr. Ke An

Dr. Ke An

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About Me