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.
Dr. Yushin was recently recognized by NC State, his alma mater, for his accomplishments in the space of nanotechnology research, his co-founding of Sila Nanotechnologies, and the strides he has made for Materials Today as editor-in-chief.
Three of our PhD students Ani, Enbo, Dan, and DongChan matriculated this past spring/summer semester.
Reserves of cobalt and nickel used in electric-vehicle cells will not meet future demand.
Improving efficiency of an adjuvant, material that enhances the body’s immune response to an antigen, has become vital for the development of safer, cheaper, and more effective next-generation vaccines. Commercial vaccines typically use aluminum salt-based adjuvant particles, most commonly aluminum oxyhydroxide (AlOOH) and aluminum hydroxide (Al(OH)3) based, often referred to as “alum”. Despite their broad use, their adjuvant properties are rather moderate. This is even worse in the case of aluminum oxide (Al2O3)-based adjuvant. While being more robust and less cytotoxic, Al2O3 is a significantly less effective adjuvant than above-mentioned Al compounds and is consequently not commonly used. Here, we report on the remarkably enhanced adjuvant properties of Al2O3 when produced in the form of nanowires (NWs). Based on recent advances in understanding neutrophil activation by inert nanoscaffolds, we have created ultra-long Al2O3 NWs with a high aspect ratio of ∼1000. These NWs showed strong humoral immune response with no damaging effect on the microvasculature. Since only the change of shape of Al adjuvants is responsible for the excellent adjuvant properties, our finding holds great promise for rapid implementation as safer and more effective adjuvant alternative for human vaccines. The mechanism behind human blood-derived neutrophil activation with Al2O3 NWs was found to be sequestering of Al2O3 NWs by neutrophils via formation of neutrophil extracellular traps (NETs).
Robust and flexible micro‐supercapacitors based upon a graphene oxide–silk layered bionanocomposite is reported. Generation of micropatterned electrodes with sub‐micrometer spatial resolution is accomplished using a novel resist‐stenciling technique, enabling the transfer of complex microcircuit designs to a graphene oxide–silk layered substrate as chemically reduced features microfeatures across wafer‐length scales. Resist‐stenciling can produce micropatterned reduction features with over ten times the feature density compared to techniques such as laser‐scribing or screen printing. As a proof‐of‐concept, resist‐stenciling is used to fabricate the first 2D micro‐supercapacitors integrated into a layered graphene bionanocomposite. These demonstrate a specific capacitance of ≈128 F g−1, good capacitance retention under charge cycling (87.5% after 2000 cycles), and repeated mechanical bending without failure. Resist‐stenciling leverages tools currently in use by the microelectronics industry to enable the scalable, high‐resolution conversion of layered nanocomposites into microelectronic circuit, storage, and sensing elements.
Rechargeable alkaline batteries may become attractive nonflammable alternatives to lithium-ion (Li-ion) batteries for applications where achieving the highest energy density is less critical than safety, environmental friendliness, and low cost of energy storage. The broad abundance and low price of iron (Fe) make it attractive as a rechargeable anode material for aqueous batteries. Through cyclic voltammetry and post-mortem analysis, we revealed four distinct stages of Fe anode evolution: development, retention, fading, and failure, where each stage is associated with very specific changes in the morphology and phase of Fe anodes. We observed the Fe particle fragmentation resulted in the capacity increase during the initial cycles of charge−discharge. Most importantly, we discovered the irreversible formation of maghemite (γ-Fe2O3) with low reactivity is responsible for the eventual Fe anode capacity fading. This unexpected discovery changes the paradigm on possible routes to stabilize Fe anodes and contributes to future development of low-cost alkaline cells.
Fabrication and applications of lightweight, high load-bearing, thermally stable composite materials would benefit greatly from leveraging the high mechanical strength of ceramic nanowires (NWs) over conventional particles or micrometer-scale fibers. However, conventional synthesis routes to produce NWs are rather expensive. Recently we discovered a novel method to directly convert certain bulk bimetallic alloys to metal–organic NWs at ambient temperature and pressure. This method was demonstrated by a facile transformation of polycrystalline aluminum–lithium (AlLi) alloy particles to aluminum alkoxide NWs, which can be further transformed to mechanically robust aluminum oxide (Al2O3) NWs. However, the transformation mechanisms have not been clearly understood. Here, we conducted advanced materials characterization (via electron microscopy and nuclear magnetic resonance spectroscopies) and chemo-mechanical modeling to elucidate key physical and chemical mechanisms responsible for NWs formation. We further demonstrated that the content of Li metal in the AlLi alloy could be reduced to about 4 wt % without compromising the success of the NWs synthesis. This new mechanistic understanding may open new avenues for large-scale, low-cost manufacturing of NWs and nanofibers for a broad range of composites and flexible ceramic membranes.
Some of the Institutions we’ve collaborated in the past. For collaboration inquiries, contact Professor Gleb Yushin.
Get in touch! Send an email to Professor Yushin at email@example.com.