Materials Chemistry Commons^™

Synthesis And Electrochemical Properties Of Li3V2(Po4)3/C Cathode Materials For Lithium Ion Battery, Li-Ying Liu, Hai-Yan Zhang, Lian Chen, Yu-Chun Zhai

Journal of Electrochemistry

Cathode material Li₃V₂(PO₄) ₃ /C for Lithium-ion battery was synthesized by combination of ball milling and baking. Physical and electrochemical performances of as-prepared materials were characterized through XRD,EIS and galvanostatic cell cycling. The results show that the products were monoclinic Li₃ V₂ (PO₄) ₃ with well-developed crystal structure. At 0. 1C,0. 25C and 0. 5C,the initial discharge capacities were 150. 6,134. 1 and 107. 1 mAh·g^-1 ,respectively. Capacity retention rates were 87. 3% after 130 cycles at 0. 25C and 87. 2% after 105 cycles at 0. 5C. Charge-discharge …

Nano-Sized Au On Nickel Foam As Cathode Of Alkaline Al-H2O2 Semi Fuel Cell, Shu-Li Chen, Bang-An Lu, Yao Liu, Gui-Ling Wang, Dian-Xue Cao

Journal of Electrochemistry

Nano-sized Au particles were deposited on a nickel foam substrate by a fast spontaneous deposition method using AuCl₃ as the source of Au. The effects of AuCl₃ concentration and deposition time on the size and distribution of Au particles,and the performance of the obtained Au/Ni electrode as the cathode of Al-H₂O₂ semi fuel cell were investigated. It was found that after the nickel foam was immersed in a 2 mmol·L^-1 AuCl₃ solution for 60 s,Au particles with diameters smaller than 100 nm were deposited on its surfaces and cover the surface completely. The …

Tuning Quantum Dots Optical Properties By Temperature And Concentration Modulation, Amber Sexton

Renée Crown University Honors Thesis Projects - All

Quantum dots have recently been awarded attention due to their tunable optical and spectroscopic properties. The optical and spectroscopic behavior of quantum dots was investigated as a function of mean particle size. Manipulation of the reaction conditions and constituents impact the controllability of size and surface conditions. Therefore, synthesis of CdSe and CdS semiconductor nanoparticles with tunable particle size were created using temperature, time, and composition as variables. Analytical techniques used to characterize the nanoparticles included fluorescence and electronic absorption. The effect of temperature, aside from changing the size of the particle, also eliminated defects on the surface and caused …

Investigation Of Novel Quasiliving Polyisobutylene Chain-End Functionalization (Quenching) Methods, David Lee Morgan

Dissertations

This volume recounts efforts toward the development and understanding of chain functionalization techniques involving the direct addition of nucleophiles to quasiliving polyisobutylene (PIB). Nucleophiles included in the study were sterically hindered organic bases, (di)sulfides, N-substituted pyrroles, and alkoxybenzenes. A kinetic investigation of the end-quenching of TiCl4-catalyzed quasiliving PIB with sterically hindered amines was used to determine the mode of interaction with TiCl4 and the active species responsible for -proton abstraction. 2,5-disubstituted-N-hydropyrroles formed pyrrole-TiCl3 adducts that were active in formation of exo-olefin chain ends; whereas, with other sterically hindered amines, only an equilibrium fraction of the amine that did not complex …

Nanomaterials From Biologically Active Molecules: Self-Assembly And Molecular Recognition, Min Yu

Dissertations

This dissertation describes the development of molecular assemblies and molecular recognition of phospholipids (PLs) that exhibit potential applications in emerging nanotechnologies. It consists of two parts: (1) structural features of PLs responsible for recognition of synthetic copolymers, and (2) design, synthesis and analysis of magnetic nanotubes obtained from PLs with a common theme of colloidal synthesis served as a platform for film formation and nano-assemblies of nanotubes. Poly(methyl methacrylate/n-butyl acrylate) (p-MMA/nBA) colloidal particles that were stabilized by 1,2-dilauroyl-sn-glycero-3-phosphocholine (DLPC) PLs were synthesized, and upon the particle coalescence, PL stratification resulted in the formation of surface localized ionic clusters (SLICs). These …

Aqueous Raft Synthesis Of Stimuli-Responsive, Amphiphilic Block Copolymers And Self-Assembly Behavior In Solution And Incorporation Into Lbl Films, Matthew Grady Kellum

Dissertations

Of all the living radical polymerization techniques, reversible addition– fragmentation chain transfer (RAFT) polymerization is arguably the most versatile in terms of the reaction conditions (e.g. temperature and solvent selection), monomer selection (e.g. neutral, anionic, cationic, and zwitterionic), and purification. Since the introduction of RAFT in 1998, the McCormick research group and others including the Lowe, Sumerlin, and Davis research groups have synthesized a wide range of (co)polymers with predetermined molecular weights, low polydispersities, and advanced architectures utilizing aqueous RAFT (ARAFT) polymerization. These research groups have also studied how various block copolymers exhibit stimuli-responsive behavior due to a change in …

Multi Stimuli-Responsive Copolymers Obtained From Colloidal Dispersions, Fang Liu

Dissertations

This dissertation describes the design, synthesis, and development of multi stimuli-responsive random copolymers that exhibit collective responsiveness to temperature, pH or electromagnetic radiation. New colloidal particles of poly(N-(DL)-(1- Hydroxyymethyl) propylmethacrylamide/n-butyl acrylate) (p(DL-HMPMA/nBA) and poly(2-(N,N′-dimethylamino)ethyl methacrylate/n-butyl acrylate) (p(DMAEMA/nBA)) were synthesized, which upon coalesce to form solid continuous films. The presence of lower glass transition (Tg) nBA components not only facilitate film formation, but also provide sufficient free volume for polymer chain rearrangements. These studies showed that coalesced films exhibit 3D dimensional changes upon external stimuli, which are attributed to the collapse and conformational changes of stimuli-responsive components as well as buckling …

Rational Design Of Self-Assembled Nanostructures Based On Polymers Synthesized Via Aqueous Reversible Addition-Fragmentation Chain Transfer Polymerization, Stacey Kirkland York

Dissertations

Recent advances in reversible addition-fragmentation chain transfer (RAFT) polymerization have allowed the rational, bottom-up design of biorelevant assemblies. Utilizing foresight, polymers can be tailored to self-assemble into nano-, micro-, and macroscopic structures. Given the size scale on which rationally-designed polymers can be tailored, they hold significant promise in the biomedical field. For example, nanoscale materials can be designed to carry small-molecule and gene therapeutics while macroscopic structures can be tailored for cell growth scaffolds. The design process begins by selecting monomers, chain transfer agents, and reaction conditions which will yield the desired polymer architecture and composition.

The work herein builds …

Synthesis, Characterization, And Deuterium Labeling Of Polyamides Studied By Nuclear Magnetic Resonance Spectroscopy, Christopher Allen Lange

Dissertations

The synthesis, characterization, and deuterium labeling of polyamides have been investigated. In Chapter II, selective deuterium labeling of various polyamides was demonstrated via a facile method which does not require organic solvent or catalyst. Quantitative solution-state NMR analysis showed deuterium incorporation at the carbon alpha to the carbonyl ranged from 20-75%. Incorporation in ε-caprolactam increased with repeated treatments. Isotopic shift effects for the deuterated materials were additive for all sites within experimental error.

In Chapter III, the effect of stoichiometric imbalances on the polymerization of poly(dodecamethylene terephthalamide)was investigated. Molecular weight was varied by polymerizing the monomer salt with excess diaminododecane, …

Structure-Property Relationships In The Formation Of Polyphenylsulfone Molecular Composites And Nanocomposites, Paul Joseph Jones

Dissertations

As the constituent phases in a polymer composite approach the molecular level, specific phenomena occur that can lead to significant changes in material properties when only minimal quantities of the additive are incorporated into the polymer matrix. Molecular composite and nanocomposites are state-of-the-art polymeric materials that contain nanostructured additives effectively dispersed within polymer matrices. The properties of molecular composites and nanocomposites are directly related to the interactions of the nanostructured additive and the polymer matrix. Subtle changes to the nanostructured additive can have profound effects on the ultimate properties of the composite material. Therefore, understanding the structure-property relationships in these …

Classification, Synthesis And Characterization Of Pyridyl Porphyrin Frameworks, Lucas D. Devries

Department of Chemistry: Dissertations, Theses, and Student Research

Structural analysis of a solid-state material is vital because the structure often determines the physical (or chemical) properties of the material. An understanding of the relationship between structural components and bulk properties can be used to design materials with specific properties. To achieve such understanding, two things are required: a rigorous structural analysis method and a study of the properties of materials with noteworthy structural features. In this thesis, the author reviews 44 pyridyl porphyrin frameworks in an effort to determine how these framework structures are formed, and if any overreaching trends can be observed. The observed trends are used …

Palm Oil-Based Polyester Binder For Making Fiberboards., Wong Yew Chuan

Student Works (2010-2019)

Palm kernel oil was used as a raw material for the synthesis of polyester polyol.The palm oil based polyester polyol was synthesized using glycerol, phthalic anhydride and fumaric acid. Palm oil based polyester polyol combines with methylene diphenyl diisocyanate (MDI) to form the polyurethane binder. The fibers are derived from empty fruit bunch (EFB) of the palm tree and have the acceptable mechanical properties. In this project, palm fibers were converted into palm fiberboards by using polyurethane (PU) binder under specified pressure and temperature. The binder to fiber ratio was varied from 10% to 30 % by dried weight of …

Effects Of Different Carbon Sources On Performance Of Li3V2(Po4)3/C Composite Cathode Materials, Kai-Yuan Liu, Jian-Shu Huang, Li Yang

Journal of Electrochemistry

The monoclinic Li₃V₂(PO₄)₃ cathode materials were prepared by carbothermal reduction method,with methyl cellulose, chitosan(crab shells) or glucose anhydrous as carbon sources, respectively.The crystal structures, morphologies and the electrochemical performances were characterized by XRD, SEM and electrochemical measurement. The XRD patterns show that the samples obtained at 800 ℃ for 6 h have a pure monoclinic structure,which indicates that the carbon exists in amorphous phase. Electrochemical measurements show that the difference of carbon sources has a significant influence on the electrochemical properties of the materials. The Li₃V₂(PO₄)_{3 …}

Applications Of Block Copolymer Films In The Field Of Electrochemical Energy Systems, Jing-Ze Li, Guo-Guang Chen, Di Mei, Wei Zou, Jian-Wen Li, Motonori Komura, Tomokazu Iyoda

Journal of Electrochemistry

A new series of amphiphilic liquid crystalline block copolymer thin films,having normally aligned and highly ordered nanocylinder array,were functionalized as anisotropic ion conducting materials by selectively infiltration.These ion-active nanocylinders are coaxially aligned and hexagonally arranged in a large area,which might be used as novel types of electrolyte films for electrochemical energy systems such as lithium ion battery,fuel cell,etc.Since the ordered cylinders can carry on and store the ions,the block copolymer films can be utilized as the advanced template to fabricate the ordered array of nanoporous,nanoparticles,and nanowires for the potential application in lithium ion battery as three dimensional electrode materials.

Preparation And Characterization Of Sulfur/Mesoprous Carbon Composite Cathodes, Wen-Hua Zhang, Yao Chen, Xin-Ping Ai, Yu-Liang Cao

Journal of Electrochemistry

A sulfur/mesoporous carbon composite was prepared by thermally treating a mixture of sublimed sulfur and mesoporous carbon. The microstructure of the mesoporous carbon was characterized by BET analysis and X-ray diffraction(XRD). The electrochemical performance of the S/C composite as cathode materials was evaluated by the galvanostatic method. The results confirmed that the mesoporous carbon could not only greatly enhance the electrochemical activity of sulfur electrode, but also effectively confine the diffusion of dissolved polysulfides in organic electrolyte. As a result,the S/C composites showed high capacity, good cycle performance and excellent rate capability. The specific capacity of the S/C composite was …

The Synthesise Of Electron-Conducting Redox Hydrogel And Its Application In Microbial Fuel Cell, Kai-Peng Wang, Sheng-Li Chen

Journal of Electrochemistry

Efficient electron transfer between the microbe and the anode is key for the electricity generation in Microbial fuel cell(MFC).Through the modification of anode,the rate of electron transfer can be accelerated,therefore the performance of MFC can be enhanced.In this paper,we report the synthesis of a type of electronconducting and bio-compatible redox hydrogel and its application.The hydrogel consists of poly(4-vinylpyridine) as backbone and neutral red as the redox center.By immobiliazing neutral red on the backbone through covalent bond,the secondary contamination due to the soluble redox mediator to external environment can be prevented.MFCs using the hydrogel-modified carbon anode significantly exhibit shorter acclimation period,and …

Synthesis Of High-Performance Lini1/3Co1/3Mn1/3O2 Cathode Materials Via Azeotropic Distillation Method, Sheng-An Xia, Li-Xia Yuan, Ze Yang, Zhao-Hui Wang, Yun-Hui Huang, Shuang Li, Wu-Xing Zhang, Ya-Bin Meng, Wei-Gong Zheng

Journal of Electrochemistry

Layered LiNi_1/3Co_1/3Mn_1/3O₂ is one of the most promising alternative materials for LiCoO₂ in lithium ion batteries due to its low cost,large capacity and excellent cyclability.In this paper,LiNi_1/3Co_1/3Mn_1/3O₂ was synthesized via azeotropic distillation method with isobutyl alcohol as an azeotropic agent.The structure and surface morphology were characterized by X-ray diffraction(XRD) and scanning electron microscope(SEM),respectively.The as-prepared LiNi_1/3Co_1/3Mn_1/3O₂ shows a layered α-NaFeO₂ structure;the particles are small and uniformly distributed.As compared with the sample prepared by traditional method,the present cathode material …

Electrochemical Behavior Of Co-Ru Composite In Alkaline Solution, Su-Mei Yao, Guo-Chun Li, Xue-Ping Gao

Journal of Electrochemistry

The electrochemical properties of Ru doped cobalt hydroxides synthesized via homogeneous chemical co-precipitation were investigated in 6 mol·L^-1 KOH solution by galvanostatic charge-discharge process and cyclic voltammetry(CV).It is demonstrated that Ru doped cobalt hydroxides exhibited good capacitive characteristic and high specific capacitance.The sample with a Co/Ru molar ratio of 8 /1 shows the optimized electrochemical performance,including capacitive property and discharge capacity.The microstructure and morphology of the obtained Ru doped hydroxides were characterized by X-ray diffraction(XRD) and scanning electron microscope(SEM).The amorphous structure of ruthenium dioxide nanoparticles and single-crystal structure of Co(OH)₂ platelets were confirmed.Based on a structure analysis and …

The Electrochemical Characteristics Of Cpo-Pll/Gc Electrode, Wen Zhao, Xia-Qin Wu, Zhong-Qing Lu, Wen-Jing Hou, He-Xing Li

Journal of Electrochemistry

Poly-L-lysine(PLL) was electropolymerized onto the surface of glassy carbon(GC) electrode.1[(3-dimethylamino)propyl]-3-ethylcarbodiimide hydrochloride(EDC) was used as a Cross-linking agent to immobilized Chloroperoxidase(CPO) onto the PLL/GC electrode.A pair of well-defined redox peaks was observed at CPO-PLL/GC electrode,which clearly suggested that PLL can promote the direct electron transfer between the CPO and the GC electrodes.The cyclic voltammetry results also showed that the electron transfer at CPO-PLL/GC is a surface adsorption-controlled quasi-reversible process,which is accompanied with proton transfer.The CPO-PLL/GC electrode exhibited a good electrochemical stability and excellently electrocatalytic activity for electrochemical reduction of O₂.

Electrochemical Corrosion Behavior Of Tio2/Ha Composite Coating On Medical Titanium In Tyrode's Physiological Solution, Li-Li Kong, Long-Xiang Lin, Rong-Gang Hu, Fan Zhang, Chang-Jian Lin

Journal of Electrochemistry

Titanium and its alloys have been widely used as medical implant materials because of their good mechanical properties and biocompatibility.However,the physiological corrosion of metal will release metal ions,resulting in toxic and side effects.In this paper,in order to improve the corrosion resistance of titanium,and to enhance its bioactivity and osseointegration,the surface modification of titamum were performed.Using eletrochemical methods Tafel polarization and electrochemical impedance spectroscopy(EIS) were applied to study the electrochemical corrosion behavior of TiO₂ /HA composite coating.It is indicated that the corrosion resistance of the prepared TiO₂ /Ti material in Tyrode's physiological solution is improved because of the enhanced …

Cobalt-Doped Todorokite Prepared By Refluxing At Atmospheric Pressure As Lithium-Ion Battery Cathode, Rui-Qi Li, Chun-Hua Song, Chao Xu, Li-Xing Tu, Guo-Hong Qiu, Fan Liu

Journal of Electrochemistry

Cobalt-doped todorokites were prepared by refluxing at atmospheric pressure,and then charactered by X-ray diffraction(XRD),thermogravimetry(TG) and the analysis of chemical compositions.These measurements showed that all of the refluxing products were single phase of todorokites and the structure formulas were Mg_xCo_yMnO_z·nH₂O,where 0.18 ≤ x ≤ 0.22,0 ≤ y ≤ 0.24,2.10 ≤ z ≤ 2.53,and 0.35 ≤ n ≤0.73.The electrochemical characteristics of cobalt-doped todorokites were examined as lithium insertion hosts for cathodes in rechargeable lithium batteries.The first discharge capacity of undoped todorokite electrode was 211 mAh/g and the discharge capacity became 37 mAh/g after 30 …

Fabrication And Characterization Of The Ni-Scsz Composite Anodes With A Lscm-Ceo2 Catalyst Layer In Thin Film Sofc, Yun-Yun Wang, Bo Huang, Xin-Jian Zhu, Wan-Qi Hu, Qing-Chun Yu

Journal of Electrochemistry

Solid oxide full cell(SOFC) running directly on hydrocarbon fuels has attracted much attention in recent years. In this paper, a dual-layer structure anode was fabricated by tape casting and screen printing method. The addition of a LSCM-CeO₂ catalyst layer to the supported anode surface yielded better performance in ethanol fuel. The maximum power density reached 710 and 669 mW/cm² at 850 ℃ running on hydrogen gas steam and ethanol steam,respectively. No significant degradation in performance has been observed after 216 h of cell testing when the Ni-ScSZ13 anode was exposed to the ethanol steam at 700 ℃. Very …

Performance Of Sulfur-Super Conductive Carbon Black Composite In Electrolyte Mixed With Room Temperature Ionic Liquid, Bo Zhang, Si-Ting Chen, Xue-Ping Gao

Journal of Electrochemistry

The sulfur-super conductive carbon black composite was prepared as cathode material of lithium/sulfur battery.The composite was characterized by scanning electron microscopy(SEM),X-ray diffraction(XRD),and electrochemical impedance spectroscopy(EIS).The sulfur composite shows a high discharge capacity and a good cycle performance in electrolyte mixed with 50% of room temperature ionic liquid.In particular,the discharge capacity of the composite was stabilized at 483.6 mAh/g after 50 cycles.

Electrochemical Properties Of Ni(Oh)2 Doped By Nio, Fei-Biao Chen, Bo-Rong Wu, Wei-Feng An, Zhao-Jun Yang, Feng Wu, Shi Chen

Journal of Electrochemistry

The Ni(OH)₂ cathode material of MH/Ni was doped by NiO,which behaves as a capacitor and can improve the charge-discharge rate capacity of Ni(OH)₂.The electrochemical properties of Ni(OH)₂ was characterized by charge-discharge curves and cyclic voltammetry.The results showed that the material had the best discharge property when doped by 5% NiO,and the discharge specific capacity could reach 310.1 mAh/g at 0.2 C rate and remianed 79.5% at 3 C rate.The difference oxidation and reduction potentials between the of the battery was 164 mV when the Ni(OH)₂ was doped by 5% NiO,which showed a good cyclic property.

Study Of Electrodes Modified With Hybrid Copper Cobalt Hexacyanoferrate-Mwcnts Composites, Shan Jiang, Yun Zhang, Xiao-Yan Wang, Xiao-Fei Yao

Journal of Electrochemistry

The hybrid modified electrodes were obtained by electrochemical deposition of copper-cobalt hexacyanoferrate(CuCoHCF) /multi-walled carbon nanotubes(MWCNTs) on the surface of glassy carbon electrode.The effects of the amount of MWCNTs and composition of electrolyte on the properties of modified electrode had been researched.The copper cobalt hexacyanoferrate-MWCNTs modified electrodes show excellent electrochemical properties compared with that modified only copper-cobalt hexacyanoferrate.The CuCoHCF-MWCNTs/GCE exhibits obvious electrocatalytic activity towards oxidation of hydrogen peroxide.The oxidation peak current increased linearly with the concentration of hydrogen peroxide in the range of 3.16 × 10^-5 ～ 2.92 × 10^-3 mol· L^-1.The linear equation is given up …

Self-Activating Safety Mechanisms For Li-Ion Batteries, Xin-Ping Ai, Yu-Liang Cao, Han-Xi Yang

Journal of Electrochemistry

The safety concerns of LIBs are considered to be a main obstacle to their high rate or large capacity applications in electric vehicles.This paper describes briefly our research works on the development of self-activating safety mechanisms for LIBs,including redox shuttle,potential-sensitive separator,temperature-sensitive electrode,and fire-retardent electrolyte.The problems and future in this research area are also discussed.

Preparation And Characterizations Of Li3V2(Po4)3 Cathode Material For Lithium Ion Batteries, Hong Chen, Tao Jiang, Chun-Zhong Wang, Gang Chen, Ying-Jin Wei

Journal of Electrochemistry

The carbon-coated Li₃V₂(PO₄)₃ was prepared by carbothermal reduction method.The structural and morphological properties of the material were studied by X-ray diffraction,FTIR and transmission electron microscopy.The synthesized material was a pure phase of Li₃V₂(PO₄)₃,with the particle size of about 100 nm.The values of Li ion diffusion coefficient of the material in the potential window of 3.0 ～ 4.3 V were nearly 3 orders larger than those in 3.0 ～ 4.8 V.In addition,the charge-transfer resistances in 3.0 ～ 4.3 V were much smaller than those in 3.0 …

Investigation Of Ceo2 As Cathode Electrocatalyst For Direct Borohydride Fuel Cell, Xue-Min Ni, Ya-Dong Wang, Mu Pan

Journal of Electrochemistry

The performance of CeO₂ as oxygen reduction electrocatalyst in direct borohydride fuel cell was investigated.The experimental results indicate that CeO₂ shows significant electrocatalytic performance for oxygen reduction and exhibits no observed promotion effect on hydrolysis or electro-oxidation of BH₄^-.The power density of experimental one-compartment fuel cell with CeO₂ as cathode electrocatalyst can reach a 67.8 mW·cm^-2 at room temperature.

Preparation And Electrochemical Behavior Of Li4Ti5O12 Nanosheets As Anode Material For Lithium Ion Battery, Yi-Fei Wang, Yu-Feng Tang, Zheng Qiu, Li Yang

Journal of Electrochemistry

Spinel lithium titanate(Li₄Ti₅O₁₂) nanosheets with a size range of 200 ～400 nm were synthesized by hydrothermal process from the amorphous hydrous titanium oxide precursors.The as-prepared products were characterized by X-ray powder diffraction(XRD),scanning electron microscopy(SEM) and transmission electron microscopy(TEM).The electrochemical behaviors of Li₄Ti₅O₁₂ electrode in conventional organic electrolyte and ionic liquid electrolyte were investigated by using cyclic voltammetry,galvanostatic charge-discharge and AC impedance techniques.The experimental results indicate that the as-prepared nanostructured Li₄Ti₅O₁₂,evaluated as anode material,exhibited good reversibility and cycle performance.It is expected to be a …

Studied Corrosion Behaviors Of Reinforcing Steel In Concrete By A Single-Dimensional Array Electrode, Lan-Qiang Li, Shi-Gang Dong, Rong-Gui Du, Chang-Jian Lin

Journal of Electrochemistry

A single-dimensional array electrode was developed as a new electrochemical technique to image corrosion potential,galvanic current and polarization curves of reinforcing steel in concrete during corrosion process.Combining with the polarization behavior for each micro-electrode,the interactions between corrosion macrocell and corrosion microcell of the steel in concrete were evaluated.It was noticed that the corrosion macrocell and microcell occurred independently in difference regions at the initial stage of corrosion.The corrosion macrocell current can be in situ followed by corrosion potential imaging.The corrosion propagation of steel in concrete is closely related to the interactions between corrosion macrocell and corrosion microcell.