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Zhongwei Chen, a chemical engineering professor at Waterloo, and a team of graduate students have created a low-cost battery using silicon that boosts the performance and life of lithium-ion batteries. Their findings are published in the latest issue of Nature Communications. Waterloo's silicon battery technology promises a 40 to 60 per cent increase in energy density, which is important for consumers with smartphones, smart homes and smart wearables. The environmentally safe technology could also make dramatic improvements for hybrid and electric vehicles. The findings could mean an electric car may be driven up to 500 kilometres between charges and the smaller, lighter batteries may significantly reduce the overall weight of vehicles. Current lithium-ion batteries normally use graphite anodes. The Waterloo engineers found that silicon anode materials have a much higher capacity for lithium and are capable of producing batteries with almost 10 times more energy. "Graphite has long been used to build the negative electrodes in lithium-ion batteries," said Professor Chen, the Canada Research Chair in Advanced Materials for Clean Energy and a member of the Waterloo Institute for Nanotechnology and the Waterloo Institute for Sustainable Energy. "But as batteries improve, graphite is slowly becoming a performance bottleneck because of the limited amount of energy that it can store." The most critical challenge the Waterloo researchers faced when they began producing batteries using silicon was the loss of energy that occurs when silicon contracts and then expands by as much as 300 per cent with each charge cycle. The resulting increase and decrease in silicon volume forms cracks that reduce battery performance, create short circuits, and eventually cause the battery to stop operating. To overcome this problem, Professor Chen's team along with the General Motors Global Research and Development Centre developed a flash heat treatment for fabricated silicon-based lithium-ion electrodes that minimizes volume expansion while boosting the performance and cycle capability of lithium-ion batteries. "The economical flash heat treatment creates uniquely structured silicon anode materials that deliver extended cycle life to more than 2000 cycles with increased energy capacity of the battery," said Professor Chen. Professor Chen expects to commercialize this technology and expects to see new batteries on the market within the next year. Explore further: New battery technologies take on lithium-ion More information: Fathy M. Hassan et al. Evidence of covalent synergy in silicon–sulfur–graphene yielding highly efficient and long-life lithium-ion batteries, Nature Communications (2015). DOI: 10.1038/ncomms9597

News Article | November 9, 2015
Site: www.treehugger.com

While lithium-ion batteries are currently the gold standard for batteries and used in most of our electronics -- smartphones, computers, and more -- they have their short-comings. Compared to other battery technologies being tested in labs, they're not the best when it comes to energy storage capacity and lifetime length. Researchers around the world are looking for the better battery that can store more energy, weigh less and last longer than traditional lithium-ion batteries. While many researchers have been working on entirely different battery technologies, researchers at the University of Waterloo decided to address the shortcomings of the lithium-ion battery head-on. The researchers decided to focus on the negative anode of li-on batteries, usually made from graphite. “Graphite has long been used to build the negative electrodes in lithium-ion batteries,” said Professor Chen, the Canada Research Chair in Advanced Materials for Clean Energy and a member of the Waterloo Institute for Nanotechnology and the Waterloo Institute for Sustainable Energy. “But as batteries improve, graphite is slowly becoming a performance bottleneck because of the limited amount of energy that it can store.” Using graphite, the maximum theoretical capacity of the battery is 370 mAh/g (milliamp hours per gram), but silicon has a theoretical capacity of 4,200 mAh/g. Silicon also has the added benefit of being much cheaper. So, why hasn't silicon been used already? The problem with silicon is that it interacts with the lithium inside the cell during the charge cycle and expands and contracts as much as 300 percent. That expansion causes cracks and ultimately causes the battery to fail. The research team figured out a way to minimize the expansion by using a flash heat treatment for the silicon electrodes that creates a "robust nanostructure." This structure resulted in less contact between the electrode and the lithium which cut out most of the expansion and contraction and made the battery much more stable. The new design had a capacity of than 1,000 mAh/g over 2,275 cycles and the researchers say that the design promises a 40 to 60 percent increase in energy density over traditional lithium-ion batteries. That means that an electric car with this new battery design could have a range of over 300 miles, while the batteries themselves would be lighter, reducing the overall weight of the vehicle. The team is working on commercializing the new design and hope that it will be in new batteries in the next year.

News Article | November 10, 2016
Site: www.marketwired.com

OAKVILLE, ONTARIO--(Marketwired - Nov. 10, 2016) - Saint Jean Carbon Inc. ("Saint Jean" or the "Company") (TSX VENTURE:SJL), a carbon science company engaged in the exploration of natural graphite properties and related carbon products, is pleased to announce that the Company has a new Chief Technology Officer (CTO), Dr. Zhongwei Chen PhD, MSChE, BS, Canadian Research Chair and Professor in Advanced Materials for Clean Energy Waterloo Institute for Nanotechnology Department of Chemical Engineering, University of Waterloo. Dr. Zhongwei Chen will lead the technology planning, engineering and implementation of all of the Company's clean energy storage and energy creation initiatives. Dr. Zhongwei Chen's research work covers advanced materials and electrodes for PEM fuel cells, lithium ion batteries and zinc-air batteries. His education; PhD, University of California - Riverside, MSChE, East China University of Science and Technology, China, BS, Nanjing University of Technology, China. His honours and awards; Early Researcher Award, Ministry of Economic Development and Innovation, Ontario, Canada (2012), NSERC Discovery Accelerator Award (2014), Canada Research Chair in Advanced Materials for Clean Energy (2014), and E.W.R Steacie Memorial Fellowship (2016). Please follow the link to the full website for complete in-depth details. http://chemeng.uwaterloo.ca/zchen/index.html Dr. Zhongwei Chen, CTO, commented: "I have had the opportunity to work very closely with Saint Jean Carbon over the last year, specifically with their advanced spherical coated graphite for lithium-ion batteries and the very promising results have me hopeful that we, together with my global partners, will build the best and most advanced graphite electrode materials for the growing electric car and mass energy storage industries. We feel it is imperative to make sure that in every step we take towards future supply, we demonstrate our team strengths and constant superior technological advancements." Paul Ogilvie, CEO, commented: "On behalf of the Board of Directors, Shareholders and Stakeholders, I am honoured that Zhongwei has chosen our Company, over the hundreds of other possible suitors. We feel our working relationship over the last year has proven a very strong bond between our raw material and his engineering excellence. We are in a constant drive to move forward as fast as we can with the very best people, and with this appointment, we have just topped our own expectations." Saint Jean is a publicly traded carbon science company, with interest in graphite mining claims in the province of Quebec in Canada. For the latest information on Saint Jean's properties and news please refer to the website: http://www.saintjeancarbon.com/ On behalf of the Board of Directors Neither TSX Venture Exchange nor its Regulation Services Provider (as that term is defined in the policies of the TSX Venture Exchange) accepts responsibility for the adequacy or accuracy of this release. FORWARD LOOKING STATEMENTS: This news release contains forward-looking statements, within the meaning of applicable securities legislation, concerning Saint Jean's business and affairs. In certain cases, forward-looking statements can be identified by the use of words such as "plans", "expects" or "does not expect", "intends" "budget", "scheduled", "estimates", "forecasts", "intends", "anticipates" or variations of such words and phrases or state that certain actions, events or results "may", "could", "would", "might" or "will be taken", "occur" or "be achieved". These forward-looking statements are based on current expectations, and are naturally subject to uncertainty and changes in circumstances that may cause actual results to differ materially. The forward-looking statements in this news release assume, inter alia, that the conditions for completion of the Transaction, including regulatory and shareholder approvals, if necessary, will be met. Although Saint Jean believes that the expectations represented in such forward-looking statements are reasonable, there can be no assurance that these expectations will prove to be correct. Statements of past performance should not be construed as an indication of future performance. Forward-looking statements involve significant risks and uncertainties, should not be read as guarantees of future performance or results, and will not necessarily be accurate indications of whether or not such results will be achieved. A number of factors, including those discussed above, could cause actual results to differ materially from the results discussed in the forward-looking statements. Any such forward-looking statements are expressly qualified in their entirety by this cautionary statement. All of the forward-looking statements made in this press release are qualified by these cautionary statements. Readers are cautioned not to place undue reliance on such forward-looking statements. Forward-looking information is provided as of the date of this press release, and Saint Jean assumes no obligation to update or revise them to reflect new events or circumstances, except as may be required under applicable securities laws.

Zhang X.,Waterloo Institute for Nanotechnology | Zhang X.,University of Waterloo | Servos M.R.,University of Waterloo | Liu J.,Waterloo Institute for Nanotechnology
Langmuir | Year: 2012

Single-stranded DNA can be adsorbed by citrate capped gold nanoparticles (AuNPs), resulting in increased AuNP stability, which forms the basis of a number of biochemical and analytical applications, but the fundamental interaction of this adsorption reaction remains unclear. In this study, we measured DNA adsorption kinetics, capacity, and isotherms, demonstrating that the adsorption process is governed by electrostatic forces. The charge repulsion among DNA strands and between DNA and AuNPs can be reduced by adding salt, reducing pH or by using noncharged peptide nucleic acid (PNA). Langmuir adsorption isotherms are obtained, indicating the presence of both adsorption and desorption of DNA from AuNPs. While increasing salt concentration facilitates DNA adsorption, the desorption rate is also enhanced in higher salt due to DNA compaction. DNA adsorption capacity is determined by DNA oligomer length, DNA concentration, and salt. Previous studies indicated faster adsorption of short DNA oligomers by AuNPs, we find that once adsorbed, longer DNAs are much more effective in protecting AuNPs from aggregation. DNA adsorption is also facilitated by using low pH buffers and high alcohol concentrations. A model based on electrostatic repulsion on AuNPs is proposed to rationalize the DNA adsorption/desorption behavior. © 2012 American Chemical Society.

Saran R.,Waterloo Institute for Nanotechnology | Liu J.,Waterloo Institute for Nanotechnology
Inorganic Chemistry Frontiers | Year: 2016

Pb2+ is a very important metal cofactor in DNAzyme catalysis. GR5 is the first reported DNAzyme, and 17E is the most thoroughly studied. Both have the highest activity with Pb2+ and are by far the fastest RNA-cleaving DNAzymes. GR5 reacts only with Pb2+ while 17E is also active with a number of other divalent metal ions. It is also interesting to note that Pb2+ shows activity with most RNA-cleaving DNAzymes. To understand these Pb2+-dependent DNAzymes and the occurrence of DNAzyme sequences, herein systematic mutation studies are performed on GR5. A comparison with 17E is also made. The A6, G7, C13, and G14 positions in 17E have been previously established to be crucial and we report A6, G7, C14, and G15 in GR5 to have the same role. The guanine at the cleavage site dinucleotide junction of the substrate strand is also mutated to hypoxanthine, 2-aminopurine, and adenine. Again, both enzymes show the same trend of activity change. Our results suggest that both DNAzymes have a similar binding pocket for Pb2+. The reason for Pb2+ being active in many DNAzymes is attributed to its simple binding motif requirement. Finally, we propose that 17E is a special form of GR5. They both have the simple sequence requirements needed for Pb2+-dependent activity, but 17E has additional motifs making it active also with other divalent metal ions. © the Partner Organisations 2016.

Chen Z.,Waterloo Institute for Nanotechnology | Higgins D.,Waterloo Institute for Nanotechnology | Lee D.U.,Waterloo Institute for Nanotechnology
Journal of Materials Chemistry A | Year: 2013

Capitalizing on the immense theoretical energy storage densities of metal-air batteries requires the development of high performance air electrode materials. These materials must simultaneously meet the criteria of high surface areas, excellent oxygen reduction reaction activity and low cost. Herein, catalyst materials with exemplary surface areas (2980 m2 g -1) and ORR activity were developed by innovatively coupling KOH activation of exfoliated graphene with ammonia induced nitrogen doping (N-a-ex-G). Specifically, ORR activity approaching that of commercial platinum based catalysts was observed (ca. 45 mV lower onset potential), and these unique materials were found to provide excellent practical metal-air battery performance. In particular, N-a-ex-G provided a 60% higher discharge current (on a catalyst mass basis at a cell voltage of 1.0 V) in a zinc-air battery single cell, along with higher discharge voltages and a 42% capacitance increase in comparison with pure carbon black based electrodes in a Li-oxygen battery single cell. These promising results, attributed to the favourable properties of N-a-ex-G, including high surface areas and inherent ORR activity indicate their practicality as air cathode electrocatalysts. © 2013 The Royal Society of Chemistry.

Park H.W.,Waterloo Institute for Nanotechnology | Lee D.U.,Waterloo Institute for Nanotechnology | Liu Y.,Waterloo Institute for Nanotechnology | Wu J.,Waterloo Institute for Nanotechnology | And 2 more authors.
Journal of the Electrochemical Society | Year: 2013

Ethylene diamine-based nitrogen doped carbon nanotube (NCNT) was successfully synthesized on thermally reduced graphene oxide (TRGO) by an injection chemical vapor deposition method and its electrocatalytic activities for oxygen reduction and evolution reactions (ORR and OER, respectively) were investigated for metal air battery applications. The TRGO/NCNT composite with a novel bridged planes morphology does not only exhibits ORR performance similar to that of commercial Pt/C catalyst, but also demonstrates a superior OER activity. Furthermore, the composite exhibits an excellent electrochemical durability confirmed by full range cyclic voltammetry (CV) cycling. This study highlights an approach to prepare highly active and durable metal free catalysts as a highly efficient electrode material for rechargeable metal air battery applications. © 2013 The Electrochemical Society.

Zhang X.,Waterloo Institute for Nanotechnology | Zhang X.,University of Waterloo | Gouriye T.,Saxion University | Goeken K.,University of Twente | And 3 more authors.
Journal of Physical Chemistry C | Year: 2013

We have recently reported on the fast and quantitative adsorption of DNA to 13 nm gold nanoparticles (AuNPs) at pH 3. This is in contrast to most traditional methods at neutral pH, where the adsorption is both slow and requires high excess of DNA. Direct application of our protocol to large particles in many cases did not result in particles that are stable at high (0.3 M) salt, and high excess of DNA was still required for the formation of stable particles. In this work, we investigate the reasons for this limitation on the basis of kinetics and colloidal stability. On the basis of our investigation, fast and quantitative modification of large AuNPs is still possible, either by working at high particle concentration, or by using sonication. As we have shown that fast quantitative modification of large particles is possible, the preparation step of reduction and purification of the thiolated DNA becomes the rate limiting step in the whole AuNP-DNA conjugate protocol. However, we show that this step is unnecessary when using our current protocol. © 2013 American Chemical Society.

Liu B.,Waterloo Institute for Nanotechnology | Sun Z.,Waterloo Institute for Nanotechnology | Huang P.-J.J.,Waterloo Institute for Nanotechnology | Liu J.,Waterloo Institute for Nanotechnology
Journal of the American Chemical Society | Year: 2015

Hydrogen peroxide (H2O2) is a key molecule in biology. As a byproduct of many enzymatic reactions, H2O2 is also a popular biosensor target. Recently, interfacing H2O2 with inorganic nanoparticles has produced a number of nanozymes showing peroxidase or catalase activities. CeO2 nanoparticle (nanoceria) is a classical nanozyme. Herein, a fluorescently labeled DNA is used as a probe, and H2O2 can readily displace adsorbed DNA from nanoceria, resulting in over 20-fold fluorescence enhancement. The displacement mechanism instead of oxidative DNA cleavage is confirmed by denaturing gel electrophoresis and surface group pKa measurement. This system can sensitively detect H2O2 down to 130 nM (4.4 parts-per-billion). When coupled with glucose oxidase, glucose is detected down to 8.9 μM in buffer. Detection in serum is also achieved with results comparable with that from a commercial glucose meter. With an understanding of the ligand role of H2O2, new applications in rational materials design, sensor development, and drug delivery can be further exploited. (Figure Presented). © 2015 American Chemical Society.

Park H.W.,Waterloo Institute for Nanotechnology | Lee D.U.,Waterloo Institute for Nanotechnology | Zamani P.,Waterloo Institute for Nanotechnology | Seo M.H.,Waterloo Institute for Nanotechnology | And 2 more authors.
Nano Energy | Year: 2014

The current generation is not only facing the shortage of fossil fuels in the near future, but also is responsible for preserving the environment for future generations. As a result, the development of clean energy systems is becoming an urgent focus for the research community. Metal air batteries have attracted much attention due to their extremely high energy density, and the rechargeability which is directly governed by the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). Herein, we present a new class of hybrid bi-functional catalyst consisting of porous nanorod perovskite La0.5Sr0.5Co0.8Fe0.2O3 (LSCF-PR) combined with nitrogen-doped reduced graphene oxide (NRGO) active towards both ORR and OER. The novel morphology of LSCF-PR is prepared by an electrospinning method, and incorporated into NRGO sheets. Electron microscopy reveals interesting composite morphology in which LSCF-PR is embedded between the sheets of NRGO, forming an efficient LSCF-PR/NRGO composite morphology for the electrochemical oxygen reactions. Electrochemical testing of the LSCF-PR/NRGO composite in alkaline medium results in excellent ORR and OER catalytic activities, verifying the effective combination for bi-functionality. LSCF-PR/NRGO presents not only a comparable or superior performance to state-of-the-art Pt/C catalyst for ORR or OER, respectively, but also better durability. These results highlight the applicability of LSCF-PR/NRGO composite having unique and efficient morphology as a promising bi-functional catalyst for metal air battery applications. © 2014 Elsevier Ltd.

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