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EMI-Lab's Research Interests:
EMI-Lab's Research Interests:
Solid State Battery Development
Solid State Battery Development
Atomic/Molecular Layer Deposition
Atomic/Molecular Layer Deposition
Li, Na, Mg Metals-Based High Energy Batteries (Li-S, Na-S Systems)
Li, Na, Mg Metals-Based High Energy Batteries (Li-S, Na-S Systems)
Conversion Materials and Phase Separation
Conversion Materials and Phase Separation
Anti-Corrosion Coating Development
Anti-Corrosion Coating Development
High-Precision, Novel, Conformal Coatings for Energy, Optics and Packaging
High-Precision, Novel, Conformal Coatings for Energy, Optics and Packaging
Hybrid, Flexible Materials Synthesis
Hybrid, Flexible Materials Synthesis
Our research has been supported by Department of Energy (DOE) , National Science Foundation (NSF), and NASA. We greatly appreciate the funding agencies for the generous support!!
Delayed Phase separation of conversion materials via interfacial kinetics
Delayed Phase separation of conversion materials via interfacial kinetics
Our experimental studies on LiPON-coated iron oxyfluoride (FeOF) conversion materials revealed that the “intercalation” lithiation process can be extended further to a large extension of the typical threshold of the conversion reaction of FeOF reported previously. The delay of the onset of the “conversion” reaction process is conjectured to be dominated by kinetic effects (such as interfacial energy, nucleation barriers, and mechanical strains).
One of the essential scientific questions is: Can we control (promote/suppress) the conversion reaction? For example, using the lithium conducting surface coating as the chemical and mechanical constraints to delay the conversion reactions. This finding opens up a promising solution to the degradation and irreversible problems faced by the conversion reaction electrode materials: utilizing the “intercalation” reactions in an extended capacity range by controlling the solid-state phase transformation via interface design, which is illustrated in the figure.
Energy Storage and Sustainability
Energy Storage and Sustainability
We develop energy storage technologies as candidates for beyond Li-ion systems. Li-metal based (including Li-S), Na-ion, Mg-ion, Solid-state batteries are developed in EMI-Lab. We aim on tackling the degradation issues associated with utilizing the metal anodes through interfacial engineering (designed artificial solid-electrolyte interphase (A-SEI) to suppress dendrites formation, electrolyte decomposition and eventually electrode failure. The integrations of the next-generation high-energy electrodes can be realized with smart designs of the interphases/interfaces.
We develop energy storage technologies as candidates for beyond Li-ion systems. Li-metal based (including Li-S), Na-ion, Mg-ion, Solid-state batteries are developed in EMI-Lab. We aim on tackling the degradation issues associated with utilizing the metal anodes through interfacial engineering (designed artificial solid-electrolyte interphase (A-SEI) to suppress dendrites formation, electrolyte decomposition and eventually electrode failure. The integrations of the next-generation high-energy electrodes can be realized with smart designs of the interphases/interfaces.
maintaining structural integrity and electrical connectivity of Conversion Materials
maintaining structural integrity and electrical connectivity of Conversion Materials
ACS Nano 2016, 10, 2, 2693–2701
We fabricate and protect 3D conversion core-shell electrodes by first coating multiwalled carbon nanotubes (MWCNT) with a model conversion material, RuO2, and subsequently protecting them with conformal thin-film LiPON. Interestingly, the capacity retention for the protected-RuO2 (>90%) is much higher than that for the unprotected-RuO2 (~55%) over 50 cycles, shown in (a). As we investigated the hysteresis behavior of both cases plotted in (b), we found that the protected-RuO2 performs smaller voltage hysteresis (overpotential) with the maximum difference Δƞmax ~ 0.65 V, where Δη = ηbare – ηprotected, with the reduction of the voltage hysteresis majorly exhibits in the charging (delithiation) process (oxidation of Ru0): Ru + 2Li2O → RuO2 + 4Li+ + 4e−. Our hypothesis for the observation is that when the unprotected tetragonal RuO2 crystallites (c) were lithiated, the phase separation occurred to form Ru/Li2O composite phase through the reduction of Ru4+ (receiving electrons) in the open space, like the schematic in (d). The domains of the mixtures of reduced metal and lithium compounds (e.g., LiO2) form as conductor-dielectric nanocomposites, which are poorly electrical-conducting matrices.
Flexible Materials | Mechanically Tunable Materials | Composite Materials
Flexible Materials | Mechanically Tunable Materials | Composite Materials
We develop composite materials and organic-inorganic hybrid materials for energy storage application - (1) develop polymer-CNT composite materials to improve the mechanical and chemcial stabilities of current collectors (2) develop flexible solid state electrolytes and the interfaces through "Molecular Layer Deposition (MLD)" and ceramics sintering techniques. The mechanical flexibility can drastically reduce the interfacial strain of the solid-state devices.
We develop composite materials and organic-inorganic hybrid materials for energy storage application - (1) develop polymer-CNT composite materials to improve the mechanical and chemcial stabilities of current collectors (2) develop flexible solid state electrolytes and the interfaces through "Molecular Layer Deposition (MLD)" and ceramics sintering techniques. The mechanical flexibility can drastically reduce the interfacial strain of the solid-state devices.
Atomic Layer Deposition (ALD) and Functional Thin Films and Coatings
Atomic Layer Deposition (ALD) and Functional Thin Films and Coatings
Vapor phase chemical synthesis is crucial for conformal coating of 3D nano/micro structures. We developed non-trivial Li solid electrolytes (LiPON) through vapor phase synthesis, which are demonstrated to mitigate the degradation by incorporating with 3D model electrodes, and to realize the 3D solid-state batteries. (SSBs). Additional, ALD thin films and coatings are widely applied for electronics, and semiconductor industries, and used for packaging, corrosion prevention, and structural protection.
Vapor phase chemical synthesis is crucial for conformal coating of 3D nano/micro structures. We developed non-trivial Li solid electrolytes (LiPON) through vapor phase synthesis, which are demonstrated to mitigate the degradation by incorporating with 3D model electrodes, and to realize the 3D solid-state batteries. (SSBs). Additional, ALD thin films and coatings are widely applied for electronics, and semiconductor industries, and used for packaging, corrosion prevention, and structural protection.
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