Engineering topics

Huang, Jian Yu

Publications and source records attributed to Huang, Jian Yu.

At least 19 records

DOE OSTI2017

Compressed glassy carbon: An ultrastrong and elastic interpenetrating graphene network

Carbon’s unique ability to have both sp 2 and sp 3 bonding states gives rise to a range of physical attributes, including excellent mechanical and electrical properties. We show that a series of lightweight, ultrastrong, hard, elastic, and conductive carbons are recovered after compressing sp 2 -hybridized glassy carbon at various temperatures. Compression induces the local buckling of graphene sheets through sp 3 nodes to form interpenetrating graphene networks with long-range disorder and short-range order on the nanometer scale. The compressed glassy carbons have extraordinary specific compressive strengths—more than two times that of commonly used ceramics—and simultaneously exhibit robust elastic recovery in response to local deformations. Finally, this type of carbon is an optimal ultralight, ultrastrong material for a wide range of multifunctional applications, and the synthesis methodology demonstrates potential to access entirely new metastable materials with exceptional properties.

36 MATERIALS SCIENCE↗

DOE OSTI2017

In Situ Observation of Single-Phase Lithium Intercalation in Sub-25-nm Nanoparticles

Although a non-equilibrium single-phase reaction, with the absence of nucleation and growth of a second phase, is believed to be a key factor for high-rate performance of lithium-ion batteries, it is thermodynamically unfavorable and usually proceeds in electrode materials with small particle sizes (tens of nanometers). Unfortunately, the phase evolutions inside such small particles are often shrouded by the macroscopic inhomogeneous reactions of electrodes containing millions of particles, leading to intensive debate over the size-dependent microscopic reaction mechanisms. Here, we provide a generally applicable methodology based on in-situ electron diffraction study on a multi-particle system to track the lithiation pathways in individual nanoparticles, and unambiguously reveal that lithiation of anatase TiO 2 , previously long believed to be biphasic, converts to a single-phase reaction when the particle size is below ~25 nm. Our results imply the prevalence of such a size-dependent transition in lithiation mechanism among intercalation compounds whose lithium miscibility gaps are associated with a prominent size effect, and therefore provide important guidelines for designing high-power electrodes, especially cathodes.

36 MATERIALS SCIENCE↗

DOE OSTI2013