Chris Yuan

A scalable graphene sulfur composite synthesis for rechargeable lithium batteries with good capacity and excellent columbic efficiency.

Sulfur nanoparticles wrapped with a conductive graphene framework was synthesized with a high sulfur loading through a scalable one-step process. The graphene-coated sulfur nanostructured composite, when used as cathode for lithium sulfur battery, shows a reversible capacity of 808 mAh g(-1) at a rate of 210 mA g(-1) and an average columbic efficiency of ∼98.3% over 100 cycles. It is found that graphene oxide (GO) with a porous structure offers flexible confinement function that helps prevent the loss of active materials, thus extending the cycling life of the electrode. Moreover, reduced graphene oxide provides a conductive network surrounding the sulfur particles, which facilitates both electron transport and ion transportation. This novel one-step, all-solution-based process is scalable and provides a promising approach for potential industrial applications.

Life Cycle Environmental Impact of High-Capacity Lithium Ion Battery with Silicon Nanowires Anode for Electric Vehicles

Although silicon nanowires (SiNW) have been widely studied as an ideal material for developing high-capacity lithium ion batteries (LIBs) for electric vehicles (EVs), little is known about the environmental impacts of such a new EV battery pack during its whole life cycle. This paper reports a life cycle assessment (LCA) of a high-capacity LIB pack using SiNW prepared via metal-assisted chemical etching as anode material. The LCA study is conducted based on the average U.S. driving and electricity supply conditions. Nanowastes and nanoparticle emissions from the SiNW synthesis are also characterized and reported. The LCA results show that over 50% of most characterized impacts are generated from the battery operations, while the battery anode with SiNW material contributes to around 15% of global warming potential and 10% of human toxicity potential. Overall the life cycle impacts of this new battery pack are moderately higher than those of conventional LIBs but could be actually comparable when considering the uncertainties and scale-up potential of the technology. These results are encouraging because they not only provide a solid base for sustainable development of next generation LIBs but also confirm that appropriate nanomanufacturing technologies could be used in sustainable product development.

A Multilayered Silicon-Reduced Graphene Oxide Electrode for High Performance Lithium-Ion Batteries

A multilayered structural silicon-reduced graphene oxide electrode with superior electrochemical performance was synthesized from bulk Si particles through inexpensive electroless etching and graphene self-encapsulating approach. The prepared composite electrode presents a stable charge-discharge performance with high rate, showing a reversible capacity of 2787 mAh g(-1) at a charging rate of 100 mA g(-1), and a stable capacity over 1000 mAh g(-1) was retained at 1 A g(-1) after 50 cycles with a high columbic efficiency of 99% during the whole cycling process. This superior performance can be attributed to its novel multilayered structure with porous Si particles encapsulated, which can effectively accommodate the large volume change during the lithiation process and provide increased electrical conductivity. This facile low-cost approach offers a promising route to develop an optimized carbon encapsulated Si electrode for future industrial applications.

Efficient Electrochemical and Photoelectrochemical Water Splitting by a 3D Nanostructured Carbon Supported on Flexible Exfoliated Graphene Foil

A novel 3D Co-Nx |P-complex-doped carbon grown on flexible exfoliated graphene foil is designed and constructed for both electrochemical and photoelectrochemical water splitting. The coordination of Co-Nx active centers hybridized with that of neighboring P atoms enhances the electron transfer and optimizes the charge distribution of the carbon surface, which synergistically promotes reaction kinetics by providing more exposed active sites.

A PCA-based method for construction of composite sustainability indicators

PurposeSustainable manufacturing is practiced globally as a comprehensive strategy for improving the sustainability performance of the manufacturing industry. While sustainability is characterized into such three dimensions as economic, environmental, and social, currently, there is no quantitative method yet to measure the so-called “sustainability” in the manufacturing industry. The objective of this research is to develop a comprehensive and effective quantitative method to measure the overall sustainability performance of manufacturing companies.MethodsIn this paper, an integrated methodology is presented for the development of composite sustainability indicators based on principal component analysis (PCA). In developing this integrated approach, both industry and academia surveys are conducted to identify what sustainability indicators are favored by the sustainable manufacturing community. A unique index is then generated to measure the overall sustainability performance of industrial practices. The methodology can be used for benchmarking the overall sustainability performance of various manufacturing companies.ResultsA case study is conducted on a total of 11 global electronic manufacturing companies. The overall sustainability performance of these companies are measured, benchmarked, and ranked. The results showed that PCA is an effective approach for constructing composite sustainability indicators across environmental, economic, and social dimensions.ConclusionsFrom this research, it is found that industry and academia have different views on the sustainability measurement, evidenced by different weights put on the same indicator in industry and academia. The case study demonstrated that the methodology presented in this paper is an effective tool for comprehensive measurement of sustainability performance of manufacturing companies. Strengths and weaknesses of each company can be identified. Then, the recommended improvements can be suggested based on the study of each of the individual indicators.

A decision-based analysis of compressed air usage patterns in automotive manufacturing

This study is an evaluation of the use and supply of compressed air, which is one of the most expensive energy sources in manufacturing, at Ford Motor Companys Livonia (Mich.) Transmission Plant. The aim of the study is to make recommendations to improve environmental and economic efficiency in future facilities. This paper presents a quantitative analysis of three compressed air supply patterns—plant air, point of use (POU), and local generation—as alternatives for future compressed air usage. Environmental Value systems (EnVS) tools are employed to analyze the economic and environmental performance of the three alternative supply patterns by using cost of ownership and environmental impact matrices. The results favor local generation over the other two alternatives in terms of economic and environmental considerations.

Introduction to Green Manufacturing

This chapter has as its objective a basic introduction to the topic to set the stage for the rest of the book. It introduces first the importance of this topic now and then the motivation, basics, and definitions associated with green manufacturing and sustainability. It describes some of the drivers that are causing governments and industry to take steps to green their processes, machines, systems, and enterprises. A discussion about the distinction between green and sustainable is introduced with respect to incremental improvements, greening and achieving overall sustainability. Strategies for achieving green manufacturing are presented. Barriers and obstacles to greening manufacturing are presented along with examples from industrial practice.

Ternary Porous Cobalt Phosphoselenide Nanosheets: An Efficient Electrocatalyst for Electrocatalytic and Photoelectrochemical Water Splitting

Exploring efficient and earth-abundant electrocatalysts is of great importance for electrocatalytic and photoelectrochemical hydrogen production. This study demonstrates a novel ternary electrocatalyst of porous cobalt phosphoselenide nanosheets prepared by a combined hydrogenation and phosphation strategy. Benefiting from the enhanced electric conductivity and large surface area, the ternary nanosheets supported on electrochemically exfoliated graphene electrodes exhibit excellent catalytic activity and durability toward hydrogen evolution in alkali, achieving current densities of 10 and 20 mA cm-2 at overpotentials of 150 and 180 mV, respectively, outperforming those reported for transition metal dichalcogenides and first-row transition metal pyrites catalysts. Theoretical calculations reveal that the synergistic effects of Se vacancies and subsequent P displacements of Se atoms around the vacancies in the resulting cobalt phosphoselenide favorably change the electronic structure of cobalt selenide, assuring a rapid charge transfer and optimal energy barrier of hydrogen desorption, and thus promoting the proton kinetics. The overall-water-splitting with 10 mA cm-2 at a low voltage of 1.64 V is achieved using the ternary electrode as both the anode and cathode, and the performance surpasses that of the Ir/C-Pt/C couple for sufficiently high overpotentials. Moreover, the integration of ternary nanosheets with macroporous silicon enables highly efficient solar-driven photoelectrochemical hydrogen production.

Integrated Hierarchical Cobalt Sulfide/Nickel Selenide Hybrid Nanosheets as an Efficient Three-dimensional Electrode for Electrochemical and Photoelectrochemical Water Splitting

Developing highly active electrocatalysts for photoelectrochemical water splitting is critical to bring solar/electrical-to-hydrogen energy conversion processes into reality. Herein, we report a three-dimensional (3D) hybrid electrocatalyst that is constructed through in situ anchoring of Co9S8 nanosheets onto the surface of Ni3Se2 nanosheets vertically aligned on an electrochemically exfoliated graphene foil. Benefiting from the synergistic effects between Ni3Se2 and Co9S8, the highly conductive graphene support, and large surface area, the novel 3D hybrid electrode delivers superior electrocatalytic activity toward water reduction in alkaline media, featuring overpotentials of -0.17 and -0.23 V to achieve current densities of 20 and 50 mA cm-2, respectively, demonstrating an electrocatalytic performance on the top of the Ni3Se2- and Co9S8-based electrocatalysts as reported in literature. Experimental investigations and theoretical calculations confirm that the remarkable activity of the obtained material results from the unique 3D hierarchical architecture and interface reconstruction between Ni3Se2 and Co9S8 through Ni-S bonding, which leads to charge redistribution and thus lowers the energy barrier of hydrogen desorption in the water splitting process. Further integration of the 3D hybrid electrode with a macroporous silicon photocathode enables highly active and sustainable sunlight-driven water splitting in both basic media and real river water. The overall water splitting with 10 mA cm-2 at a low voltage of 1.62 V is achieved using our hybrid as both anode and cathode catalysts, which surpasses that of the Ir/C-Pt/C couple (1.60 V) for sufficiently high overpotentials.

Life Cycle Assessment of Titania Perovskite Solar Cell Technology for Sustainable Design and Manufacturing

Perovskite solar cells have attracted enormous attention in recent years due to their low cost and superior technical performance. However, the use of toxic metals, such as lead, in the perovskite dye and toxic chemicals in perovskite solar cell manufacturing causes grave concerns for its environmental performance. To understand and facilitate the sustainable development of perovskite solar cell technology from its design to manufacturing, a comprehensive environmental impact assessment has been conducted on titanium dioxide nanotube based perovskite solar cells by using an attributional life cycle assessment approach, from cradle to gate, with manufacturing data from our laboratory-scale experiments and upstream data collected from professional databases and the literature. The results indicate that the perovskite dye is the primary source of environmental impact, associated with 64.77% total embodied energy and 31.38% embodied materials consumption, contributing to more than 50% of the life cycle impact in almost all impact categories, although lead used in the perovskite dye only contributes to about 1.14% of the human toxicity potential. A comparison of perovskite solar cells with commercial silicon and cadmium-tellurium solar cells reveals that perovskite solar cells could be a promising alternative technology for future large-scale industrial applications.