FES Funded ProjectsOutputs
| Title |
Category |
Date |
Authors |
| An Investigation into the Charge Storage Mechanism and Cycling Performance of Mn2O3 as the Cathode Material for Zinc-ion BatteriesHighly crystalline, nanosize Mn 2 O 3 powder is synthesized via a precipitation and calcination method for utilization as the cathode in aqueous zinc-ion batteries (aZIBs). The resultant electrodes are characterized using electrochemical and microstructural methods to determine the mechanisms associated with charge and discharge. In addition, quantitative methods are used to investigate cycling performance stability. A specific capacity of 211 mAh g -1 is retained after 200 cycles at a current density of 500 mA g -1 with 93% capacity retention. Also, 73% capacity retention can be reached after 1100 cycles at a current density of 2000 mA g -1 . The energy storage mechanism associated with Mn 2 O 3 is, for the first time, proposed to be a chemical conversion reaction type with two steps involving the formation/decomposition of ZnMn 2 O 4 (hetaerolite) and zinc sulphate hydroxide (ZHS). Also, capacity fading is directly linked to the incomplete reversibility of the chemical conversion reaction.T06-P03 University of Alberta | Publication | 2022-05-01 | | | An Investigation into the Charge Storage Mechanism for Mn2O3 as the Cathode Material in Zinc-ion Batteries240th Electrochemical Society Meeting, October 10 – 14, 2021 T06-P03 University of Alberta | Activity | 2021-10-10 | | | A Horizontal Zinc-air Battery with Physically Decoupled Oxygen Evolution/Reduction Reaction ElectrodesA horizontal Zn-air battery has been designed to enable the use of physically decoupled and catalytically efficient ORR and OER electrodes for discharge and charge, respectively. The horizontal design features a horizontally positioned ORR electrode and a vertically positioned OER electrode, allowing effective management of oxygen transport and pressure. The ORR catalyst (MnOx) and OER catalyst (Co-Fe alloy) are fabricated via one-step electrodeposition on carbon paper and Ni foam, respectively. MnOx is identified as a combination of Mn3O4 nanorods and α-Mn2O3 spheres. Co-Fe is deposited as a solid solution film with an oxidized surface. Electrochemical tests show that both catalysts have comparable or even better activity than their commercial Pt- Ru catalyst counterpart. The catalysts are cycled at 20 mA cm−2 to examine their durability. Cycling potential affects catalyst durability, with improved lifetime under separate ORR and OER conditions compared with the full ORR-OER voltage range. The fabricated catalysts are assembled into a Zn-air battery for discharge-charge cycling tests and show the same average efficiency (58%) as commercial Pt-Ru catalysts.T06-P03 University of Alberta | Publication | 2018-05-24 | Ming Xiong, Michael Clark, Matthew Labbe, Ivey, D. | | Compositional Effects of Gel Polymer Electrolyte and Battery Design for Zinc\textendash Air BatteriesPoly(acrylic acid) (PAA) is a promising polymer host to support alkaline electrolytes in Zn-air batteries. Herein, precursors containing different concentrations of monomers, crosslinkers and additives such as zinc oxide in alkaline solution are polymerized to fabricate gel polymer electrolytes (GPEs) via one-pot synthesis. The compositional effects of the GPEs on battery performance are evaluated and a more efficient cell design is demonstrated. With a vertical double air electrode configuration, ZABs using PAA-based electrolytes show unprecedented performance including high specific energy (913 Wh kgZn−1), excellent cycling stability (at least 160 cycles at 2×10 mA cm–2) and high power density output (2×135 mW cm−2). The study represents a viable option to replace aqueous electrolytes for high performing ZABs.T06-P03 University of Alberta | Publication | 2020-05-01 | Thuy (Wendy) Nguyen Thanh Tran, Drew Aasen, Dinara Zhalmuratova, Matthew Labbe, Chung, H., Ivey, D. | | Mn3O4 Nanoparticle-Decorated Hollow Mesoporous Carbon Spheres as an Efficient Catalyst for Oxygen Reduction Reaction in Zn-air BatteriesHybrids of Mn3O4 nanoparticles and hollow carbon spheres prepared from templated pyrolysis of polydopamine were assembled via a straightforward sonication procedure. The resulting hybrids exhibit excellent catalytic activity toward the oxygen reduction reaction (ORR) in prototype Zn–air batteries. Impressively, these catalysts exhibit higher discharge potential and exceptional stability when compared to commercial Pt–Ru catalysts while simultaneously showing comparable onset potential and maximum current density.T06-P03 University of Alberta | Publication | 2020-06-19 | Yingjie He, Drew Aasen, Haoyang Yu, Matthew Labbe, Ivey, D., Jonathan GC Veinot | | Hollow Mesoporous Carbon Nanospheres Decorated with Metal Oxide Nanoparticles as Efficient Earth-Abundant Zinc-Air Battery CatalystsHybrids comprising hollow mesoporous nitrogen doped carbon (HMC) nanospheres and metal oxide-nanoparticles were prepared via a hydrothermal synthesis. These materials exhibit excellent bifunctional catalytic activity in the oxygen reduction and evolution reactions (ORR and OER, respectively) that core to the efficient operation of Zn-air batteries. When incorporated into prototype devices, Co3O4 and MnCo2O4 nanoparticle decorated HMC exhibited discharge potentials of 1.26 and 1.28 V at 10 mA cm-2, respectively. ‘CoFeNiO’ decorated HMC exhibited a charging potential of 1.96 V at 10 mA cm-2. These metrics are much superior to benchmark Pt-Ru, which displayed discharge and charging potentials of 1.25 and 2.01 V, respectively, at the same current density. The battery equipped with Co3O4 decorated HMC demonstrated 63% initial efficiency before cycling. After cycling at 10 mA cm-2 for 200 hours, the battery efficiency was maintained at 56.5%, outperforming the battery with Pt-Ru (50.2% after 50 h).T06-P03 University of Alberta | Publication | 2021-01-07 | Yingjie He, Drew Aasen, Alexandra McDougall, Haoyang Yu, Matthew Labbe, Chuyi Ni, Sarah Milliken, Ivey, D., Jonathan GC Veinot | | Atomic Layer Deposition of Iron Oxide on a Porous Carbon Substrate via Ethylferrocene and an Oxygen PlasmaEthylferrocene, a novel precursor for atomic layer deposition (ALD) of iron oxide, was investigated using an oxygen plasma co-reactant. Iron oxide deposition showed a saturating growth rate of 0.1 Å/cycle in the temperature range of 150°C to 250°C. The iron oxide coating was subsequently deposited on a porous gas diffusion layer (GDL) for use as an air electrode in a zinc-air battery. X-ray microanalysis confirmed deep penetration of the iron oxide into the porosity of the GDL, with a lower substrate temperature providing deeper coverage. Transmission electron microscopy revealed that a uniform 10 nm thick iron oxide coating encased the GDL particles. Electron diffraction and X-ray photoelectron spectroscopy identified the iron oxide film as -Fe2O3. Electrochemical characterization of the ALD-coated GDL showcased promising catalytic activity towards the oxygen evolution reaction.T06-P03 University of Alberta | Publication | 2021-09-15 | Matthew Labbe, Michael Clark, "Zahra Abedi ", Anqiang He, Ken Cadien, Ivey, D. | | D.B. Robinson Scholarship in Chemical and Materials EngineeringAwarded annually to two students of high academic standing who are registered full time in graduate degree programs in Chemical and Materials Engineering. Preference will be given to students studying in the field of Thermodynamics.T06-P03 | Award | 2020-09-01 | Matthew Labbe | | NSERC Canadian Graduate Scholarship – Doctoral (CGS-D)NSERC PhD ScholarshipT06-P03 | Award | 2022-04-28 | Matthew Labbe | | Atomic Layer Deposition of a Manganese-Iron Mixed Oxide as a Bifunctional Oxygen Catalyst for Zinc-Air BatteriesPRiME 2020, October 4-9, 2020T06-P03 University of Alberta | Activity | 2020-10-04 | | | Front Cover: Hollow Mesoporous Carbon Nanospheres Decorated with Metal Oxide Nanoparticles as Efficient Earth-Abundant Zinc-Air Battery CatalystsThe Front Cover shows an artistic representation of a new class of bifunctional zinc‐air battery catalysts that consist of hollow mesoporous carbon nanospheres decorated with various precious‐metal‐free transition‐metal oxide nanoparticles.T06-P03 University of Alberta | Publication | 2021-03-22 | Yingjie He, Drew Aasen, Alexandra McDougall, Haoyang Yu, Matthew Labbe, Chuyi Ni, Sarah Milliken, Ivey, D., Jonathan GC Veinot | | W. Youdelis Graduate ScholarshipOne year award for September 2021 to August 2022 for "superior academic achievement" in Engineering.T06-P03 | Award | 2021-09-01 | Matthew Labbe | | D.B. Robinson Scholarship in Chemical and Materials EngineeringAwarded annually to two students of high academic standing who are registered full time in graduate degree programs in Chemical and Materials Engineering. Preference will be given to students studying in the field of Thermodynamics.T06-P03 | Award | 2021-09-01 | Matthew Labbe | | President's Doctoral Prize of DistinctionThe President's Doctoral Prize of Distinction (PDPD) is a Top-Up award that may be given to students registered full-time in a doctoral degree program at the University of Alberta who have won one of the eligible major doctoral-level scholarshipsT06-P03 | Award | 2022-05-01 | Matthew Labbe | | Captain Thomas Farrell Greenhalgh Memorial Graduate ScholarshipAwarded to graduate students in Chemical and Materials Engineering.T06-P03 | Award | 2021-09-01 | Matthew Labbe | | Alberta Graduate Excellence ScholarshipThe Alberta Graduate Excellence Scholarship recognizes outstanding academic achievement of students pursuing graduate studies in Alberta.T06-P03 | Award | 2021-09-01 | Matthew Labbe | | Atomic Layer Deposition of Transition Metal Oxide Catalysts for Zinc-Air BatteriesTwitter poster and oral presentation as part of the FES Fall Symposium 2021.T06-P03 University of Alberta | Activity | 2021-09-14 | | | Bringing down the cost of zinc-air batteries could unlock their full potential for storing renewable energyA doctoral candidate in engineering at the U of A is working to improve the affordability and feasibility of a zinc-air battery that could potentially be widely used to store solar energy.T06-P03 | Activity | 2022-05-04 | Matthew Labbe | | Growth of Multiple Island Layers during Iron Oxide Atomic Layer Deposition: An Electron Microscopy and Spectroscopic Ellipsometry InvestigationAtomic layer deposition (ALD) of FeOx thin films, prepared using the air stable and low cost precursor of ethylferrocene, was characterized through electron microscopy and spectroscopic ellipsometry (SE) techniques. To model the growth behavior of the layer on carbon-based air electrodes in metal–air batteries, carbon substrates were employed for electron microscopy. Electron imaging revealed an island morphology for the FeOx deposits, which eventually coalesced into a continuous film with pinholes. Further growth resulted in another layer of islands forming on top of the continuous film, in a process that was repeated throughout deposition. In situ SE exhibited both substrate-enhanced and substrate-inhibited characteristics; the former was due to a MnOx seed layer deposited prior to FeOx ALD, while the latter was a consequence of the island growth mode. After an extended number of ALD cycles, the process entered a linear growth regime, which is typically associated with layer-by-layer growth. The application of an effective medium approximation model to the SE data revealed the nucleation of six different layers of FeOx islands through 650 ALD cycles. This novel work showcases the need for multiple characterization techniques to confirm the growth mode displayed by an ALD process.T06-P03 University of Alberta | Publication | 2022-11-10 | | | Low-Temperature Tolerant Poly(Acrylic Acid) (PAA) Gel Polymer Electrolytes for Rechargeable Zinc-Air BatteriesGel polymer electrolytes (GPEs) are emerging materials for Zn-air batteries (ZABs), since the GPE can act as a combined electrolyte and separator in the battery. GPE-KOH was fabricated through the polymerization of poly(acrylic) acid in the presence of KOH and ZnO. GPE-KOH-KI was fabricated following a similar procedure, followed by immersion in a solution containing KOH, KI and ZnO. The addition of KI to the electrolyte changed the conventional charging reaction to a reaction with a lower thermodynamic barrier, which improved the battery efficiency with a maximum increase of 36% relative to ZABs without KI. This work focused on extending the working temperature range of the ZAB to low temperatures (as low as -41℃) as well as exploring the reaction mechanism for ZABs using KI as an additive. It is proposed that the discharging reaction at the air electrode is a combination of the oxygen reduction reaction and iodate reduction reaction.T06-P03 University of Alberta | Publication | 2023-05-11 | | | Experimental Concerns of Current Collector Interference and Electrolyte Creep During Zinc-Air Battery TestingEvaluating the electrochemical performance of catalysts towards the oxygen reduction and evolution reactions in zinc-air batteries is a routine process often conducted using a two-electrode cell. At the air electrode, a current collector is necessary if a carbon paper-based gas diffusion layer (GDL) is employed. The catalytic properties of the current collector may interfere with the studied catalyst on the GDL if flaws in cell design allow electrolyte contact to be made with the current collector. At the zinc electrode, highly alkaline electrolytes (e.g., KOH), with high surface tension, can easily climb up the electrode and accumulate at the interface between the cell and the surrounding atmosphere. An oxygen concentration cell is then enabled by the deposited electrolyte and the zinc electrode is rapidly corroded until failure, prematurely ending a long-term cycling test.T06-P03 University of Alberta | Publication | 2023-05-06 | | | Zinc-Air Batteries: The Search for Better RustPresentation to the University of Alberta Senate on the use of iron oxide as a catalyst for the air electrode in zinc-air batteries. T06-P03 | Activity | 2023-03-03 | Matthew Labbe | | Zinc-Air Battery Advances: Efficiency, Stability, and Low Temperature OperationPoster presentation on progress in Ivey Group on zinc-air batteries.T06-P03 University of Alberta | Activity | 2023-04-28 | | | Growth Behaviour of Iron Oxide using Atomic Layer DepositionPresentation dealing with modelling of atomic layer deposition of iron oxide for use as a catalyst for the air electrode in zinc-air batteries. T06-P03 University of Alberta | Activity | 2022-06-14 | | | Atomic Layer Deposition of Highly Stable Manganese-Iron Oxide Bifunctional Catalysts for Zinc-Air BatteriesAtomic layer deposition of manganese-iron oxide bifunctional catalysts for the air electrode for zinc-air batteriesT06-P03 University of Alberta | Activity | 2022-05-31 | | | President's Doctoral Prize of Distinction (PDPD)The PDPD is a top-up award that may be given to students registered full-time in a doctoral degree program at the UofA who have won one of the eligible major doctoral-level scholarships. T06-P03 | Award | 2023-05-01 | Matthew Labbe | | Alberta Graduate Excellence ScholarshipThe Alberta Graduate Excellence Scholarship recognizes outstanding academic achievement of students pursuing graduate studies in Alberta.T06-P03 | Award | 2022-09-01 | Matthew Labbe | | D.B. Robinson Scholarship in Chemical and Materials EngineeringAwarded annually to two students of high academic standing who are registered full time in graduate degree programs in Chemical and Materials Engineering. Preference will be given to students studying in the field of Thermodynamics.T06-P03 | Award | 2022-09-01 | Matthew Labbe | | Challenges in Zn-Air Battery Cell DesignConference presentation dealing will issues associated with design zinc-air batteriesT06-P03 University of Alberta | Activity | 2024-05-24 | | | Catalyst Integration within the Air Electrode in Secondary Zn-air BatteriesThe air electrode of a Zn-air battery facilitates the O2 reduction and evolution reactions during battery discharge and charge, respectively. These reactions are kinetically sluggish and appropriate catalysts are essential at the air electrode to increase battery efficiency. Precious metals are traditionally used, but increasingly attention has shifted towards non-precious metal catalysts to decrease the cost and increase the practicality of Zn-air batteries. However, loading of the catalyst onto the air electrode is equally as important as catalyst selection. Several methods can be used to deposit catalysts, each with their own advantages and disadvantages. Example methods include spray-coating, electrodeposition, and impregnation. These can be categorized as indirect, direct, and hybrid catalyst loading techniques, respectively. Direct and hybrid loading methods generally provide better depth of loading than indirect methods, which is an important consideration for the porous, air-breathing electrode of a Zn-air battery. Furthermore, direct methods are free from ancillary materials such as a binder, required by indirect and hybrid methods, which translates into better cycling stability. This review examines the various techniques for fabricating catalyst-enhanced air electrodes with an emphasis on their contributions to battery performance and durability. More durable Zn-air battery air electrodes directly translate to longer operational lifetimes for practical Zn-air batteries, which is an important consideration for the future implementation of electrochemical energy storage in energy systems and technologies. Generally, direct catalyst loading techniques, which integrate catalyst material directly onto the air electrode structure, provide superior cycling performance to indirect catalyst loading techniques, which distribute an ex-situ synthesized material onto the top layer of the air electrode. Hybrid catalyst loading techniques, which grow catalyst material directly onto nanostructured supports and then integrate them throughout the air electrode architecture, offer a compromise between direct and indirect methods.T06-P03 University of Alberta | Publication | 2024-05-22 | | | Bifunctional Mn-Fe Oxide Catalysts for Zn-Air Battery Air Electrodes Fabricated Through Atomic Layer DepositionZinc-air batteries (ZABs) are one of many energy storage technologies that can help integrate renewable energy into the power grid. A key developmental goal for ZABs is replacing the precious metal catalysts at the air electrode with more abundant and inexpensive materials. In this work, a MnFexOy bifunctional catalyst is directly deposited on a ZAB air electrode using atomic layer deposition (ALD). With ALD, the atomic composition of the air electrode coating can be finely tuned based on catalytic activity. Characterization through electron microscopy, photoelectron spectroscopy and diffraction techniques indicate that the novel ALD film deposits as a nanocrystalline (Mn,Fe)3O4 cubic spinel. The mixed oxide catalyst outperforms its individual binary MnOx or FeOx constituents, operating at 50.7% bifunctional efficiency at 20 mA cm-2. Moreover, the long term stability of the ALD catalyst is showcased by 600 h (1565 cycles) of ZAB cycling at 10 mA cm-2. The efficiency retention of the bifunctional transition metal oxide catalyst is superior to a precious metal benchmark of Pt-Ru-C, with 84.7% efficiency retention after more than 1500 cycles versus only 66.2% retention for the precious metal catalyst. The ALD technique enables deep penetration of catalyst material into the air electrode structure, improving the cycling behaviour. T06-P03 University of Alberta | Publication | 2024-05-22 | Matthew Labbe, Michael Clark, Ken Cadien, Ivey, D. | | Gel Polymer Electrolyte for Zinc-Air Batteries Operating at Low TemperaturesPoster presentation for FES Fall Symposium 2021T06-P03 University of Alberta | Activity | 2021-09-17 | | | Efficient Low Temperature Performance of All Solid-State Zinc-air Batteries with MnCo2O4/Carbon Fiber Bifunctional Electrocatalyst and Poly(acrylic Acid) (PAA) Polymer ElectrolyteSpinel type MnCo2O4 coated on asphaltene based carbon fibers (MnCo2O4/CF) was used as the electrode material/electrocatalyst for air electrodes for zinc‐air batteries (ZABs). The batteries were assembled using an alkaline poly(acrylic acid) hydrogel electrolyte. The low temperature battery performance of the prepared ZAB cells was studied in terms of charge/discharge voltage and efficiency at different current densities, cycle life, power density, and cell voltage at temperatures between −45 °C and 21 °C. At all temperatures, the ZABs successfully completed 200 cycles of charge/discharge (100 h) at 2 mA cm−2 which is double the current density reported in the recent literature. The maximum power densities at 0 and −45 °C were 75 and 12 mW cm−2, respectively. The good performance is attributed to the porous design of the air electrode and the use of an efficient electrocatalyst and an optimized gel polymer electrolyte.T06-P03 University of Alberta | Publication | 2023-02-02 | | | Zinc-Air Batteries with Efficient and Stable MnCo2O4/Carbon Fiber Bifunctional Electrocatalyst and Poly(acrylic Acid) (PAA) Based Gel ElectrolyteEfficient and high-performance zinc–air batteries (ZABs) with gel polymer electrolytes (GPEs) were prepared. Cubic spinel-type MnCo2O4-coated carbon fibers (MnCo2O4/CF) were used to prepare air electrodes, and poly(acrylic acid) was used to prepare alkaline GPEs. Materials characterization, including electron microscopy and X-ray photoelectron spectroscopy, confirmed the formation of MnCo2O4 on the CFs. The optimum composition of the GPE was determined by rheological measurements and battery testing; using GPE with a crosslinker concentration of 30 mM led to the best performing battery. Full-cell battery tests and cycling tests showed that this ZAB cell had outstanding performance with an initial efficiency of 62.6% at 10 mA cm–2, which degraded by only 6.5% after 200 cycles (100 h). The power output of this cell was 240 mW cm–2, which is superior to the power outputs reported in the recent literature for ZABs.T06-P03 University of Alberta | Publication | 2022-11-04 | | | Modified Gel Polymer Electrolytes for Zinc-Air Batteries Operating at Various TemperaturesPresentation dealing with gel polymers for application as the electrolyte in zinc-air batteries.T06-P03 University of Alberta | Activity | 2022-06-14 | | | Gel Polymer Electrolytes for Zinc-air Batteries Operating at Low TemperaturesGel polymers for use as the electrolyte for zinc-air batteries in applications at low temperatures. T06-P03 University of Alberta | Activity | 2022-05-24 | | | ECS Travel Grant for 241st ECS MeetingCompetitive award to help fund travel to ECS conference. T06-P03 University of Alberta | Award | 2022-05-29 | | | Low-Temperature Tolerant Gel Polymer Electrolytes for Rechargeable Zn-Air BatteriesMSc thesisT06-P03 University of Alberta | Publication | 2022-12-22 | | | O, N-Enriched, Self-Activated, Holey Carbon Sheets for High-Loading Zinc-Ion SupercapacitorsT06-Q03 University of Alberta | Publication | 2023-12-27 | Zhixiao Xu, "Zhe Sun ", "Janay Shan ", "Song Jin ", Cui, J., Zhiping Deng, Min Ho Seo, Wang, X. | | Functional Electrolyte Additives for Zinc-Ion BatteriesT06-P03 University of Alberta | Activity | 2024-05-24 | | | Zinc-philic Electrolyte Additives for Zinc-Ion BatteriesT06-P03 University of Alberta | Activity | 2024-05-22 | | | Microstructural Characterization of Nickel-Coated Anodes for Zinc-Air Flow BatteriesPresentation dealing with characterization of anodes for zinc-air reflow batteries. T06-P03 University of Alberta | Activity | 2022-06-14 | Hang Hu, Anqiang He, Drew Aasen, "Sheida Arfania ", "Shatanu Shukla ", Ivey, D. | | Failure Analysis of Nickel-Coated Anodes in Zinc-Air Flow BatteriesAnalysis of failure of anodes for zinc-air reflow batteries.T06-P03 University of Alberta | Activity | 2022-05-29 | Hang Hu, Anqiang He, Drew Aasen, "Sheida Arfania ", "Shantanu Shukla ", Ivey, D. | | Dimple Grinding Coupled with Optical Microscopy for Porosity Analysis of Metallic CoatingsDimple grinding is one of the steps used in a common method of preparing samples for transmission electron microscopy (TEM); the TEM sample preparation process also involves ion beam sputtering after the dimpling stage. During dimpling, a spherical depression is machined into the sample, leaving a thicker rim to support and facilitate sample handling. In this paper, an alternative application for dimple grinding is developed; dimple grinding combined with optical microscopy is utilized to quantify internal porosity present within coatings. This technique essentially permits three dimensional porosity quantification across the coating thickness using a simple polishing method which provides analysis of areas larger than those observed during standard cross sectional microscopy. The application of this technique to nine electroless nickel-phosphorus (Ni-P) coatings deposited on Mg substrates is demonstrated.T06-P03 University of Alberta | Publication | 2024-03-01 | Hang Hu, Anqiang He, Drew Aasen, "Shantanu Shukla ", Ivey, D. | | The Corrosion Behavior of Electroless Ni-P Coatings in Concentrated KOH ElectrolyteNi-P has been widely used as a protective coating for many substrates. The corrosion resistance of Ni-P in neutral solutions such as NaCl, or acidic electrolytes such as HCl and H2SO4, has been extensively studied. However, the corrosion behavior of Ni-P coatings in caustic media, such as KOH, has received much less attention. Typically, corrosion behavior is studied through the use of electrochemical methods with corrosion rates determined from corrosion currents and potentials measured from Tafel curves. In this work, the corrosion rates of Ni-P coatings, with P concentrations varying from 2 to 11 wt%, in highly alkaline KOH (11 M) are obtained directly through electron microscopy measurements of cross sections and subsequent correlation with electrochemical data. Phosphorus concentration affects the corrosion rate; corrosion rate increases with increasing P content, peaks out at about 6-8 wt% P, and then decreases with any further increase in P content. This behavior is correlated to internal stress levels developed in the coatings.T06-P03 University of Alberta | Publication | 2024-05-18 | Anqiang He, Hang Hu, Drew Aasen, Ivey, D. | | ECS Travel Grant for 241st ECS MeetingCompetitive travel award to attend and present at the ECS conference.T06-P03 | Award | 2022-05-29 | Hang Hu | | Characterization of Electroless Ni-P Coatings and Electrodeposition of Ni Coatings for Electrodes in Zinc-Air Flow BatteriesMSc thesisT06-P03 | Publication | 2023-05-08 | Hang Hu | | Composition effects of electrodeposited Co-Fe as electrocatalysts for the oxygen evolution reactionCobalt and Fe were co-electrodeposited as single crystal, faceted particles onto carbon paper to produce Co/Fe-oxyhydroxide oxygen evolution reaction (OER) catalysts with various Co/Fe ratios. Electron microscopy and Auger electron spectroscopy were used to investigate the morphology and composition of the electrodeposits. Iron content in the deposits increased with increasing Fe concentration in the electrolyte and Fe segregated to the particle surfaces. Electrochemical tests demonstrated that the deposit Co/Fe ratio influences OER activity by altering the electrochemically active surface area (ECSA) and charge transfer resistance. The OER activity increased with increasing Fe content up to ∼65 at% Fe, with a minimum overpotential of 0.33 V at 10 mA cm−2 in 1 M KOH. The fabricated OER catalysts were assembled into a Zn-air battery for discharge-charge cycling tests and showed lower charge potentials compared with bare carbon paper.T06-P03 University of Alberta | Publication | 2017-12-09 | | | Sequentially Electrodeposited MnOX/Co-Fe as Bifunctional Electrocatalysts for Rechargeable Zinc-Air BatteriesManganese oxide (MnOx) and cobalt-iron (Co-Fe) were sequentially electrodeposited onto a gas diffusion layer (GDL) as bifunctional electrocatalysts for rechargeable zinc-air batteries. The fabricated material was characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The sequentially deposited MnOx/Co-Fe catalysts, tested using cyclic voltammetry (CV), showed activity for both the oxygen reduction and oxygen evolution reactions (ORR and OER), with better performance than either MnOx or Co-Fe alone. The fabricated material was assembled into a zinc-air battery as the air electrode component for battery cycling tests. The zinc-air battery using MnOx/Co-Fe catalysts exhibited good discharge-recharge performance and a cycling efficiency of 59.6% at 5 mA cm−2, which is comparable to Pt/C catalysts. In addition, the electrodeposited MnOx/Co-Fe layer showed strong adhesion to the gas diffusion layer (GDL) and was structurally stable throughout 40 h of battery cycling.T06-P03 University of Alberta | Publication | 2017-03-17 | | | Electrodeposited Co-Fe as an Oxygen Evolution Catalyst for Rechargeable Zinc-air BatteriesCobalt-iron (Co-Fe) nanocubes were directly electrodeposited onto carbon paper and utilized as efficient oxygen evolution reaction catalysts for rechargeable zinc-air batteries. The morphology and mass loading were directly controlled by adjusting deposition time and the deposits evolved from single crystal nanocubes into a continuous film. Co-Fe catalysts exhibited low overpotential, small Tafel slopes and high durability during testing. A zinc-air battery using Co-Fe showed the same cycling efficiency as one using commercial Pt/Ru catalysts.T06-P03 University of Alberta | Publication | 2017-02-01 | | | Synthesis of Bifunctional Catalysts for Metal-Air Batteries Through Direct Deposition MethodsRechargeable metal-air batteries, such as Li-air and Zn-air batteries, have gained renewed interest because of their high theoretical energy density, safety and low cost. The air electrode, with bifunctional electrocatalysts for the oxygen reduction reaction (ORR) and the oxygen evolution reaction (OER), plays the most important role in determining battery performance. Direct deposition of catalysts on the air electrode, using methods such as electrodeposition, electroless deposition, chemical vapor deposition (CVD) and physical vapor deposition (PVD), is shown to be a viable way to fabricate durable and active catalysts with high efficiency and low cost. This review examines recent research activities which apply direct deposi- tion methods to prepare bifunctional catalysts. The benefits and drawbacks of these methods are compared to provide guide- lines for their application.T06-P03 University of Alberta | Publication | 2018-09-06 | | | Saturation Behaviour of Atomic Layer Deposition MnOx from Bis (Ethylcyclopentadienyl) Manganese and Water: Saturation Effect on Coverage of Porous Oxygen Reduction ElectrodesMnOx deposits on porous gas diffusion layer (GDL) substrates for application as catalysts for the oxygen
reduction reaction (ORR) in metal−air batteries have been prepared using atomic layer deposition (ALD). The saturation behavior of the bis(ethylcyclopentiadienyl) manganese ((EtCp)2Mn) and H2O ALD system has been investigated. The observed saturation behavior is in disagreement with previous reports in literature. (EtCp)2Mn + H2O depositions exhibited non-ALD behavior, as demonstrated by a high growth per cycle (GPC) at substrate temperatures (Tsub) = 40−50 °C and nonsaturating reactions at Tsub ≥ 60 °C. The introduction of a forming gas (FG) (95% N2 + 5% H2) plasma between the (EtCp)2Mn and H2O doses promoted precursor saturation with a constant GPC (1.15 Å/cy) in the Tsub range of 100−200 °C. The effect of saturation behavior on porosity coverage was investigated by coating porous carbon electrodes with ALD MnOx. Energy dispersive X-ray (EDX) spectroscopy, electrochemical surface area measurements, and oxygen reduction activity all indicate that the saturating behavior of the (EtCp)2Mn + FG + H2O deposition resulted in superior coverage compared with the (EtCp)2Mn + H2O depositions.T06-P03 University of Alberta | Publication | 2018-12-19 | Michael Clark, Ming Xiong, Ken Cadien, Ivey, D. | | A Study of Alkaline Gel Polymer Electrolytes for Rechargeable Zinc-Air BatteriesIn this report, hydrated hydrogels are investigated for application in rechargeable zinc-air batteries (ZABs) based on their ionic conductivities, chemical stability, electrochemical windows and mechanical properties. Three different hydrogel networks, i.e., poly(vinyl alcohol) (PVA), poly(acrylic acid) (PAA) and poly(4- vinylbenzenesulfonate-co-[3-(methacryloylamino)propyl]trimethylammonium chloride) (PAM), were chosen based on their chemical composition and network electrical charge difference. Since the hydrogel network affects electrolyte uptake, which in turn may influence conductivity, understanding the correlation between hydrogel species and ionic conductivity provides insight into designing an appropriate gel polymer electrolyte (GPE) for ZABs. The relationship between ionic conductivity, water uptake and temperature are discussed. In ZAB cycling tests, although GPEs have a higher bulk resistance than aqueous electrolytes, they have lower interfacial and charge transfer resistances. The total resistance values for PVA and PAA, with 6 M KOH, vary from 4 - 6 Ω, which are lower than the values for KOH solution (~11 Ω) and PAM with 6 M KOH (~14 Ω). As such, this study demonstrates that GPEs show considerable promise for use as electrolytes in ZABs.T06-P03 University of Alberta | Publication | 2019-12-10 | | | A Gas Diffusion Layer Impregnated with Mn3O4 Decorated, Nitrogen-Doped Carbon Nanotubes for High Performance Zinc-Air BatteriesMn3O4 decorated N-CNTs are synthesized and impregnated into porous carbon paper (gas diffusion layer or GDL) to form a composite catalyst-GDL material in a simple and novel one-pot process. The impregnated electrode features high active surface area, improved discharge performance and reduced vulnerability to flooding when compared with other electrode preparation techniques for similar catalysts. Electrochemical and battery testing show catalytic activity and a maximum discharge potential superior to other CNT supported Mn3O4 catalysts, and comparable to commercially used Pt-Ru (1.21 V at 20 mA cm-2). The composite is cycled at 10 mA cm-2 and 20 mA cm-2 as a bifunctional catalyst and as an ORR exclusive catalyst, respectively. Discharge performance is stable over 200 cycles at 20 mA cm-2 when used exclusively for ORR with a discharge-charge efficiency superior to Pt-Ru when coupled with electrodeposited Co-Fe as the OER catalyst (efficiency of 59% after cycling). T06-P03 University of Alberta | Publication | 2019-11-05 | | | Current Distribution Investigation and Structure Optimization of Zn-air Batteries3-D Modeling of a Zn-air battery was performed, using COMSOL Multiphysics software, to simulate its discharge and charge processes. The modeling was validated by comparing simulated electrochemical performance with experimental test results. The model was then used to investigate the current distribution across Zn electrode surface and to help explain its thickness change after cycling tests. The structure of the Zn-air battery was optimized to increase spatial utility and efficiency. Finally, a flowing electrolyte was simulated to facilitate uniform Zn electrodeposition.T06-P03 University of Alberta | Publication | 2018-08-07 | | | Colorimetric Voltmeter Using Colloidal Fe3O4@SiO2 Nanoparticles as an Overpotential Alarm System for Zinc-air BatteriesT06-P03 University of Alberta | Publication | 2019-10-20 | "Lelin Zheng ", Thuy (Wendy) Nguyen Thanh Tran, "Dinara Zhalmuratova ", Ivey, D., Chung, H. | | High Performance Oxygen Reduction/Evolution Electrodes for Zinc-Air Batteries Prepared by Atomic Layer Deposition of MnOxOxygen reduction electrodes for zinc–air batteries (ZAB) have been prepared by depositing conformal films of MnOx directly onto high surface area gas diffusion layers (GDL) via atomic layer deposition (ALD). MnOx films were prepared by means of two deposition conditions: one using a forming gas (95% N2, 5% H2) plasma (FG-MnOx) and one using an O2 plasma (O2-MnOx). A composite electrode of FG-MnOx + CoOx was also examined. The conformal nature of ALD films allowed for MnOx to be deposited within the porosity of the GDL, as confirmed by X-ray microanalysis. Full cell ZAB tests showed excellent performance for MnOx-coated electrodes, outperforming Pt/Ru–C at current densities larger than 100 mA cm–2. Annealed FG-MnOx and O2-MnOx electrodes had maximum power densities of 170 and 184 mW cm–2, respectively. With the catalyst distributed within the structure of the GDL, performance limitations associated with electrolyte flooding and air diffusion are reduced, improving discharge potential and cycling behavior. FG-MnOx + CoOx electrodes showed good cycling stability, both in a trielectrode configuration and bifunctionally. When cycled at 20 mA cm–2 for 100 h (200 cycles), FG-MnOx + CoOx had initial and final discharge potentials of 1.18 and 1.15 V, respectively.T06-P03 University of Alberta | Publication | 2020-04-01 | Michael Clark, Ming Xiong, Ken Cadien, Ivey, D. | | (Co,Fe)3O4 Decorated Nitrogen‐Doped Carbon Nanotubes in Nano‐Composite Gas Diffusion Layers as Highly Stable Bifunctional Catalysts for Rechargeable Zinc‐Air Batteries(Co,Fe)3O4 nanoparticles are decorated onto N‐doped carbon nanotubes at room temperature through a simple mixing process and are simultaneously deposited within a porous gas diffusion layer (GDL) by an impregnation technique. The (Co,Fe)3O4 nanoparticles are identified as the spinel phase through transmission electron microscopy (TEM) and X‐ray photoelectron spectroscopy (XPS) analysis. The composite GDL is used as the air electrode for Zn‐air batteries and shows excellent performance as a bifunctional catalyst with initial discharge and charge potentials of 1.19 V and 2.00 V, respectively, at 20 mA cm−2. Cycling performance of the impregnated electrode compares favourably with benchmark Pt‐RuO2 catalysts at both 10 mA cm−2 and 20 mA cm−2. The (Co,Fe)3O4/N‐CNT impregnated GDL had a final discharge/charge efficiency of 58.5 % after 100 h (200 cycles) of bifunctional cycling at 10 mA cm−2, which is superior to that of Pt‐RuO2 (55.3 % efficiency). The cycling efficiency for (Co,Fe)3O4/N‐CNT impregnated GDL at 20 mA cm−2 is also better than that for Pt−Ru (53.5 % vs 41.3 % after 50 h (100 cycles)). The result is a simple and easily scalable one‐pot electrode synthesis method for high performing bi‐functional air electrodes for Zn‐air batteries.T06-P03 University of Alberta | Publication | 2019-11-19 | | | Investigation of Transition Metal-Based (Mn, Co, Ni, Fe) Trimetallic Oxide Nanoparticles on N-doped Carbon Nanotubes as Bifunctional Catalysts for Zn-Air BatteriesVarious transition metal-based bimetallic and trimetallic oxides on N-CNTs were successfully synthesized in a one-pot process. Porous gas diffusion layers (GDLs) were simultaneously impregnated with the catalysts during synthesis, resulting in an efficient and scalable preparation technique for nano-composite air electrodes. NiMnOx/N-CNT, NiFeOx/N-CNT, and (Co,Fe)3O4/N-CNT catalysts were the highest performing bimetallic oxides based on battery rate test results. Therefore, Ni-Co-Fe, Ni-Mn-Fe, and Mn-Co-Fe systems were investigated as combined trimetallic oxide/N-CNT catalysts for Zn-air batteries. Trimetallic oxides on N-CNTs exhibited improved OER activity and comparable ORR activity relative to the bimetallic oxide catalysts in linear sweep voltammetry (LSV) tests. Discharge/charge efficiencies for tri-metallic oxides on N-CNTs calculated from battery rate test measurements at a current density of 20 mA cm−2 were 60.5%, 60.7%, and 60.0% for NCFO/N-CNT, NMFO/N-CNTs and MCFO/N-CNT, respectively. Bifunctional cycling of all trimetallic oxide/N-CNT electrodes at 10 mA cm−2 for 100 h showed excellent stability, particularly the NCFO/N-CNT catalyst. Additionally, the efficiencies for NCFO/N-CNT, NMFO/N-CNT and MCFO/N-CNT samples were 58.5%, 57.9% and 57.2%, respectively, after cycling, which compare favorably with that of Pt-Ru/C (55.3%). Trimetallic oxides on N-CNTs are, therefore, excellent candidates as high performing, non-precious metal catalysts for Zn-air batteries.T06-P03 University of Alberta | Publication | 2020-02-11 | | | Effects of Crosslinker Concentration in Poly(Acrylic Acid)–KOH Gel Electrolyte on Performance of Zinc–Air BatteriesZinc–air batteries (ZABs) using gel polymer electrolytes suffer from low energy efficiency and poor cyclability. This issue is not only associated with the air electrode, as early failure of the battery is often due to the Zn electrode. Here, the cycle life of ZABs using alkaline poly(acrylic acid) (PAA–KOH) as the electrolyte is shown to vary by changing its crosslinking density. For ZABs using hydrogel electrolytes, understanding the failure mechanism and optimization of the hydrogel composition are key to achieving better utilization of the Zn electrode and battery rechargeability. In addition, the effects of crosslinker concentration on rheological properties, sol–gel fraction, ionic conductivity and water retention ability of the hydrogel are discussed. PAA–KOH gels with lower crosslinking concentrations are weaker, but they have higher conductivity and better water retention, whereas gels with higher crosslinking concentrations affect the diffusion of zincate ions and facilitate passivation of the Zn electrode, resulting in early failure of the battery.T06-P03 University of Alberta | Publication | 2020-04-01 | | | A Tri–Electrode Configuration for Zinc–Air Batteries Using Gel Polymer ElectrolytesTo increase the cyclability of rechargeable zinc–air batteries (ZABs) using gel polymer electrolytes (GPEs), battery design and structure need to be optimized. Two different configurations for a tri–electrode battery have been developed in this work; i.e., a planar cell and a sandwich cell. Discharge–recharge cycling tests at 5 mA cm–2 show that the sandwich cell is more suitable for ZABs than the planar cell. Various additives for the GPEs, such as cross linking agents and ZnO, have also been evaluated using the tri–electrode design. Cross linking density affects the physical state of GPEs, which in turn affects the oxygen evolution reaction as there is an adverse effect of excessive GPE/Ni foam electrode contact area because oxygen bubble may be trapped in the GPE. The addition of ZnO to the oxygen reduction reaction side of the battery enhances the cycling performance of ZABs; i.e., the battery can withstand at least 100 cycles at 5 mA cm–2 with an efficiency of 62% during the first cycle.T06-P03 University of Alberta | Publication | 2020-01-24 | | | Electrodeposited and Oxidized Mn/Co-Fe As Bi-Functional Electrocatalysts for Rechargeable Zinc-Air BatteriesIn this study, MnOX and CoFe were sequentially electrodeposited onto a gas diffusion layer (GDL) as bifunctional electrocatalysts for rechargeable zinc-air batteries. The fabricated material was then assembled into a zinc-air battery as the air electrode component to run battery cycling tests. The sequentially deposited MnOX-CoFe catalysts showed activities for both ORR and OER, better than either MnOX or CoFe alone. The zinc-air battery using MnOX-CoFe catalysts exhibited good discharge-recharge performance and an efficiency comparable to Pt/C catalysts. In addition, the electrodeposited MnOX-CoFe layer showed strong adhesion to GDL and was stable throughout battery cycling.T06-P03 University of Alberta | Publication | 2017-01-05 | | | In-situ Transformation of Electrodeposited W-Co Oxide to ZnCo2O4 Nanoparticles as Effective Bifunctional Catalysts in ZABsW-Co was cathodically electrodeposited on gas diffusion layer (GDL) electrodes for application as a bifunctional catalyst for Zn air batteries. The electrodes were synthesized galvanostatically at various pH values (4.5 and 7.5) and deposition times (5, 15 and 25 min). Transmission electron microscopy (TEM) analysis showed that the deposits oxidized in contact with air, forming a conformal layer of W-Co oxide with a thickness of ~10 nm. During battery cycling, most of the W dissolved in the electrolyte. The remaining Co oxide agglomerated, forming nanoparticles less than 100 nm in size. Zinc (present in the electrolyte as ZnO) was incorporated into the Co oxide nanoparticles. As such, the conformal layer of W-Co oxide transformed into cubic spinel ZnCo2O4 nanoparticles which provided excellent bifunctional catalytic activity. The W in the original deposit acted as a conduit to facilitate formation of the ZnCo2O4 nanoparticles. The ZnCo2O4 catalyst demonstrated good performance in two-electrode and three-electrode full-cell Zn-air battery tests. In three-electrode tests at 10 mA cm-2, a round trip efficiency of 62% was achieved, exceeding the efficiency of Pt/Ru-C (61%). In two-electrode tests at 10 mA cm-2, an initial efficiency of 61% was obtained and the stability exceeded that of Pt/Ru-C. The final efficiencies were 59% for the three-electrode and 56% for the two-electrode configuration (after 100 cycles). A high maximum power density of 216 mW cm-2 was also achieved.T06-P03 University of Alberta | Publication | 2020-04-07 | "Josiel Costa ", Michael Clark, Ambrosio F de Almeida Neto, Ivey, D. | | Zn-Based Oxides Anchored to Nitrogen-Doped Carbon Nanotubes as Efficient Bifunctional Catalysts for Zn-Air BatteriesZn-Co oxide (ZnCoOx), Zn-Mn oxide (ZnMnOx), Zn-Mn-Co oxide (ZMCO), and Zn-Co-Fe oxide (ZCFO) nanoparticles were successfully synthesized on nitrogen-doped carbon nanotubes in a one-pot process. Porous carbon paper was simultaneously impregnated with the catalysts during synthesis and used as air electrodes for Zn-air batteries. ZnMnOx/N-CNT catalysts had the best ORR performance in half-cell LSV experiments with a more positive onset potential than that of Pt-Ru/C (-0.067 V and -0.078 V vs Hg/HgO, respectively). ZCFO/N-CNT catalysts had the best activity towards OER among the Zn-based oxide catalysts in half-cell linear sweep voltammetry (LSV) testing with an onset potential of 0.63 V vs Hg/HgO. Round-trip efficiencies from battery rate tests at a current density of 20 mA cm-2 were 55.3%, 57.5%, 58.7%, and 58.3% for ZnCoOx/N-CNT, ZnMnOx/N-CNT, ZMCO/N-CNT, and ZCFO/N-CNT, respectively. Bifunctional cycling of the catalysts was done in a homemade Zn-air battery at a current density of 10 mA cm-2 for 200 cycles. The final round trip efficiencies for ZnCoOx/N-CNT, ZnMnOx/N-CNT, ZMCO/N-CNT, and ZCFO/N-CNT were 55.8%, 56.6%, 54.2%, and 55.0%, respectively. All catalysts except ZCFO/N-CNT compared favorably with Pt-Ru/C in terms of round-trip efficiency after cycling (55.3%). Incorporation of Zn into the metal oxide particles showed improved catalytic activity for ZnCoOx/N-CNT and ZnMnOx/N-CNT compared with MnOx/N-CNT and CoOx/N-CNT catalysts prepared via the same technique. T06-P03 University of Alberta | Publication | 2020-05-05 | | | Electrodeposited Manganese Oxide on Carbon Paper for Zinc-Ion Battery CathodesNano-crystalline, flake-like Mn oxide was electrodeposited onto carbon paper (CP) using a pulsed electrodeposition technique. The electrodeposited Mn oxide was identified as Mn3O4 through a combination of X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and Raman spectroscopy. The Mn3O4 on CP was used as a cathode for Zn-ion batteries (ZIBs) and showed excellent cyclability at a current density of 1AgT06-P03 University of Alberta | Publication | 2020-03-30 | | | Ethylene Glycol as an Antifreeze Additive and Corrosion Inhibitor for Aqueous Zinc-Ion BatteriesAqueous zinc-ion batteries are promising candidates for port- able and large-scale applications because of their intrinsically high safety, low cost and high theoretical energy density. However, existing aqueous zinc-ion batteries usually suffer from zinc corrosion and poor performance at subzero temperatures. Herein, to address these problems, the electrolyte in aqueous zinc-ion batteries (1 M ZnSO4) is optimized by adding suitable amounts of ethylene glycol. The addition of ethylene glycol improves the antifreezing ability of the aqueous electrolyte and increases the conductivity of electrolyte at low temperatures. Ethylene glycol serves two purposes, as an antifreeze additive to significantly enhance the capacity of batteries at low temperatures and as a corrosion inhibitor to suppress zinc corrosion and byproduct precipitation. This work offers a facile strategy to realize aqueous zinc-ion batteries with good performance at low temperatures.T06-P03 University of Alberta | Publication | 2022-05-01 | Thuy (Wendy) Nguyen Thanh Tran, Maosen Zhao, "Shujiang Geng ", Ivey, D. | | Tri- and Tetra-Metallic Oxides Anchored to Heteroatom Doped Carbon Nanotubes as Bifunctional Electrocatalysts for Rechargeable Zinc-Air BatteriesElectrochemical catalysts for the air electrode of Zn-air rechargeable batteries were fabricated from nitrogen-doped carbon nanotubes (N-CNTs), combined with either tri-metallic (Ni–Mn–Co) or tetra-metallic (Zn–Ni–Mn–Co) oxides, through a simple impregnation method into carbon-based, gas diffusion layers (GDL). Metal oxide compositions were selected based on previous results, preliminary electrochemical testing, and statistical design of experiments. Microstructural characterization was done using electron microscopy and X-ray photoelectron spectroscopy. Samples were electrochemically tested and the best candidates were subjected to full cell testing and bifunctional cycling for 200 charge/discharge cycles at 10 mA cm−2. The overall bifunctional efficiency, after cycling, of the best NiMnCoOx/N-CNT and ZnNiMnCoOx/N-CNT catalysts was 53.3% and 56.4%, respectively; both outperformed Pt–Ru/C in both overall bifunctional efficiency (38%) and cycling stability. The maximum power density of one of the tetra-metallic oxides exceeded that of Pt–Ru/C (110 mW cm−2) at 134 mW cm−2. The addition of Zn with Ni–Mn–Co oxide particles showed improved cycling stability and overall bifunctional efficiency.T06-P03 University of Alberta | Publication | 2021-11-09 | Alexandra McDougall, "Zahra Abedi ", Ivey, D. | | Dip-Coating Synthesis of rGO/α-Ni(OH)2@Nickel Foam with Layer-by-Layer Structure for High Performance Binder-Free SupercapacitorsThe conventional fabrication of composite electrodes often requires extraordinarily complex electrode preparation steps. We provide here a separate dip-coating method for ultrasmall α-Ni(OH)2 nanoparticles grown between reduced graphene oxide (rGO) sheets on nickel foam, forming a direct binder-free elec- trode of 3D rGO/α-Ni(OH)2@nickel foam (GNH@NF-n, layer number n= 5, 8, 10, 15, 20) with a layer-by- layer structure. At a charge and discharge current density of 1 A/g, the specific capacitance of GNH@NF-5 reaches 2118 F/g (capacity: 323.5 mAh/g). When the current density is changed from 1 to 10 A/g, the specific capacitance retains 74.8% of the maximum value (capacity retains 88.4%). Changes in structure and electrochemical performance are analyzed as the number of layers increases, i.e., as the mass load- ing increases. When the mass loading increases by a factor of 5.2 from 1.4 to 7.3 mg/cm2, the GNH@NF-n electrode maintains a very high specific capacitance, with a value as high as 89% of the capacitance (or capacity) for the lowest mass loading. Dipping separately in nickel-based and rGO solutions (separate dip-coating method) is more effective in achieving the layer-by-layer structure and high electrochemi- cal performance than dipping in a mixed solution (mixed dip-coating method). Furthermore, asymmetric GNH@NF-5//rGO supercapacitors are assembled and exhibit a high specific energy of 109.9 Wh/kg at a specific power of 1.3 kW/kg and a high cyclic stability with capacitance retention of 86.1% after 10,000 charge and discharge cycles.T06-P03 University of Alberta | Publication | 2020-12-01 | Michael Clark, "Liuqin Lai ", "Siyu Su ", "Rong Li ", Ivey, D., "Xiaohong Zhu " | | Transition Metal Oxides Anchored Onto Co-Doped Carbon Nanotubes As Bifunctional Electrocatalysts239th Electrochemical Society Meeting, May 30 – June 3, 2021T06-P03 University of Alberta | Activity | 2021-05-30 | | | Zinc and Nickel Based Oxides Anchored Onto Nitrogen-Doped Nanotubes As Bifunctional Catalysts for Zinc-Air BatteriesPRiME 2020, October 4-9, 2020T06-P03 University of Alberta | Activity | 2020-10-04 | |
|
|
