Physical Chemistry Commons^™

Characterization Of The Separator With Thermal-Shutdown Layer For Use In Lithium Batteries, Li Bai, Yong-Jian Huai, Xin-Ping Ai, Hai Jia

Journal of Electrochemistry

In this paper, the lithium ion battery coated with the thermal-shutdown functional layer has been introduced. The shutdown temperature of the separator could be decreased by using the melting point of thermal-shutdown functional layer. When the internal battery environment reached a critical temperature, the functional layer melted and coated the anode/separator with a non-conductive barrier, halting Li-ion transport and shutting down the cell permanently. The results showed that the functional layer did not affect the resistance, rate performance and cycle life. It was found the functional layer can significantly improve the safety of the battery when misused.

Effects Of Microstructures Of Active Material On Performance Of Vrla Battery, Lei Jiang, Shou-Zhong Yi

Journal of Electrochemistry

The structure, morphology and content of the as-prepared and the processed samples were characterized by the means of SEM and XRD. The discharge capacities and cycle life performances of the as-prepared and the processed samples were tested by electrochemical measurements with different rates. The results indicated that the 4BS technology which can affect the plate design, deep cycle capability and cycle life is a basic technology for the VRLA batteries. It was also confirmed that the contents and structures of α-PbO₂ and β-PbO₂ formed with different processing conditions can affect the performance of the VRLA batteries, suggesting that …

Preparation And Performance Of Lithium-Rich Manganese Layered Materialsâ 0.6li[Li1/3Mn2/3]O2·0.4liniXMnYCo1-X-YO2(X < 0.6, Y > 0), Hai-Lan Feng, Ya-Fei Liu, Yan-Bin Chen

Journal of Electrochemistry

Lithium-rich manganese based cathode materials 0.6Li[Li_1/3Mn_2/3]O₂⋅0.4LiNi_xMn_yCo_1-x-yO₂ (x < 0.6, y > 0) were synthesized by carbonate co-precipitation and high temperature solid-state reaction. The structures and morphologies of the as-prepared materials were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM). The results of high temperature in-situ XRD test show that the lattice parameters change significantly with increasing temperature and Ni content. The cation mixing gets serious and the spinel phase appears in the high Ni content samples when the temperature is up to 800 oC. Under voltages ranging from 2.0 to …

Application Of Pd/Graphene Modified Electrode In The Detection Of 4-Chlorophenol, Peng Shi, Bo-Xuan Wang, Quan-Lin Song, Hui Wang, Xin Liu, Zhao-Yong Bian

Journal of Electrochemistry

The Pd/graphene composites were synthesized by a modified Hummers method and NaBH4 reduction process, and then were characterized using XRD, SEM, XPS, and TEM. The Pd/graphene modified glassy carbon electrode (Pd/graphene/GCE) was prepared based on this method. Cyclic voltammetry was used to study the optimum operation conditions for the 4-chlorophenol detection. It was shown that the surface of the graphene was smooth and Pd nanoparticles were uniformly dispersed on graphene. The average particle size was calculated to be 6.5 ± 0.05 nm. These nanoparticles exhibited high catalytic activity and sensitivity toward chlorophenols. PBS with a concentration of 0.1 mol·L^{-1 …}

Heterogeneous Oxidation Of Catechol, Elizabeth A. Pillar, Ruixin Zhou, Marcelo I. Guzman

Chemistry Faculty Publications

Natural and anthropogenic emissions of aromatic hydrocarbons from biomass burning, agro-industrial settings, and fossil fuel combustion contribute precursors to secondary aerosol formation (SOA). How these compounds are processed under humid tropospheric conditions is the focus of current attention to understand their environmental fate. This work shows how catechol thin films, a model for oxygenated aromatic hydrocarbons present in biomass burning and combustion aerosols, undergo heterogeneous oxidation at the air–solid interface under variable relative humidity (RH = 0–90%). The maximum reactive uptake coefficient of O₃(g) by catechol γ_O3 = (7.49 ± 0.35) × 10^–6 occurs for …

Synthesis, Structure And Electrochemical Performance Of Na2Mnsio4/C Cathode Material For Na-Ion Batteries, Shou-Ding Li, Jiang-Huai Guo, Yong Xie, Jin-Xiao Mi, Yong Yang

Journal of Electrochemistry

As a promising cathode material for sodium ion batteries, pure phase Na₂MnSiO₄/C nanocomposite was successfully synthesized by a sol-gel method with a citric acid as a complex agent. The as prepared material was characterized by XRD, FTIR, SEM and TEM techniques. XRD and Rietveld refinement results indicated that the sample was indexed as monoclinic structure with space group of Pn. It was observed by SEM and TEM that the obtained product consisted of micro-scaled secondary particles, which were composed of NaMnSiO₄ nanocrystallites and amorphous carbon network. More importantly, the uniform carbon network in the …

Preparation And Characterization Of Carbon Supported Pd-Sb Composite Nanocatalysts For Formic Acid Electrooxidation, Long-Long Wang, Xiao-Lu Cao, Ya-Jun Wang, Jin-Hao Ping, Qiao-Xia Li

Journal of Electrochemistry

Palladium is considered as an efficient anode catalyst with high catalytic activity for electrooxidation of formic acid. To further improve the catalytic activity and stability, alloying or surface modification with Sb is an effective way. In this work, the well dispersed carbon supported Pd-Sb composite nanocatalysts (Pd-Sb/C) were synthesized by traditional impregnation reduction method with trisodium citrate as the complexing agent, sodium borohydride as the reducing agent. The morphologies of Pd-Sb/C and the effects of molar ratio of Pd to Sb on the electrocatalytic properties of Pd-Sb/C for HCOOH electrooxidation were studied. The XRD and XPS analyses on the as-prepared …

Preparation And Enhanced Rate Capability Of Spinel Limn1.9Al0.1O3.95F0.05, Jun-Yan Hu, Meng-Meng Wang, Hong-Tao Liu

Journal of Electrochemistry

Spinel LiMn_1.9Al_0.1O_3.95F_0.05 cathode materials with good crystallinity were synthesized by a sol-gel process followed with a high-temperature solid reaction. The effects of partial substitution of Al for Mn, and F for O on the structure and the electrochemical performance were investigated. The results showed that LiMn_1.9Al_0.1O_3.95F_0.05 exhibited the same crystalline state as LiMn₂O₄, but much better electrochemical stability at higher rate cycling. As a result, LiMn_1.9Al_0.1O_3.95F_0.05 could maintain stable electrochemical lithium storage even suffering from …

An Investigation On Electrochemical Performance Of Supercapacitor Electrode Materials Prepared By Mno2 With Four Different Crystal Forms, Zhen-Kun Wei, Xiao-Zhen Hua, Ke Xiao, Xian-Liang Zhou, Zhi-Guo Ye

Journal of Electrochemistry

Four types of α-MnO₂, β-MnO₂, γ-MnO₂ and δ-MnO₂ powders were synthesized by relatively simple methods. The differences in crystal structures and surface morphologies for these forms of MnO₂ were investigated by using X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), thermogravimetric analysis (TGA) and specific surface area analysis (BET). The electrochemical performances were characterized by cyclic voltammetry (CV) and stability analysis. Based on the experimental results, four kinds of MnO₂ electrodes showed good capacity properties, and the α-MnO₂ electrode had the largest specific capacity due to the highest specific surface …

Effect Of Adsorption Potential On Co Oxidation At Au@Pt Nanoparticles Electrodes, A Surface Enhanced Raman Spectroscopic Study, Pu Zhang, Yi Wei, Yong-Li Zheng, Yan-Xia Chen, Zhong-Qun Tian

Journal of Electrochemistry

The adsorption/oxidation of CO on the 55 nm [email protected] nm Pt nanoparticles electrode in both potentiodynamic and potentiostatic modes were investigated by surface enhanced Raman spectroscopy in a thin layer electrochemical flow cell under controlled mass transport, with the aim of clarifying the origin CO oxidation at lower electrode potentials (in current pre-wave region of corresponding cyclic voltammograms). Our results demonstrated that the CO oxidation kinetics differed significantly from the three kinds of different CO adsorption history, with almost no CO oxidation current in the pre-peak potential region after 0.35 V_RHE CO adsorption with or without subsequent holding the …

Broadband Sum-Frequency Generation Spectroscopic Invstigations Of Thiocyanate On Polycrystalline Au Electrode In Alkaline Solutions, Mei Xu, Jing-Jing Wang, Zhi-Chao Huangfu, Ng Ying Wa, Yu-Han He, Zhao-Hui Wang

Journal of Electrochemistry

Broadband sum frequency generation (BB-SFG) spectroscopy has been used to investigating the potential-dependent adsorption behaviors of thiocyanate ions on polycrystalline Au electrode in alkaline solutions. During the positive scan, a change in the Stark slope (dω_C-N/dE) for C—N stretching mode can be observed in the range of -1.1 V ~ 0.2 V (vs. SCE), which implies that the orientation of adsorbed thiocyanate ions at Au electrode surface changes from N-bound (dω_C-N/dE=45 cm^-1·V^-1) form to S-bound (dω_C-N/dE = 16.2 cm^-1·V^{-1 …}

Synthesis And Electrochemical Performance Of Mn3O4/Graphene Composites, Shan-Shan Yang, Qian Zhang, Xiong-Gui Lin, Ming-Sen Zheng, Quan-Feng Dong

Journal of Electrochemistry

The Mn₃O₄/Graphene composites were synthesized by hydrothermal method with the in-situ redox reaction of graphene oxide (GO) and manganese acetate (Mn(Ac)₂). The phase structures and morphologies of the materials were characterized by XRD, SEM and TEM. The XPS and IR techniques were used for studying the residual function groups of reduced graphene oxide (RGO). The electrochemical performances of the hybrids were tested in a coin cell. Results showed that the composites prepared with the addition of ammonia water (RM-A) have better performance. The graphenes in RM-A were better-reduced and the Mn₃O_{4 …}

Tungsten Carbide/Carbon Electrode Material Synthesized By Block Copolymer Template Method, Xiao-Ling Lang, Ye-Kun Jiang, Mei-Qin Shi, Ling-Zhi Kang, Chun-An Ma

Journal of Electrochemistry

At present, one of the major hurdles for commercialization of system with direct methanol fuel cell (DMFC) is still the requirement of a significant amount of platinum (Pt) catalyst to achieve an acceptable power density. Pt and Pt-based metals are expensive due to limited supplies. In order to find the catalyst alternative to the Pt metal, we selected tungsten carbide (WC) and its composites as the study object. We synthesized WC with carbon materials as the suitable support to modify the electronic structure and to increase the specific surface area of WC. In this study, tungsten carbide/carbon (WC/C) was prepared …

Electrochemical Removal Of Low Concentration Pb(Ii) From Aqueous Solution Based On Ppy/α-Zrp/Ptcf Electrode, Ru-Yi Chen, Peng-Le Zhang, Sen-Liang Liao, Zhong-De Wang, Xiao-Gang Hao

Journal of Electrochemistry

A novel organic-inorganic hybrid film consisting of polypyrrole/α-zirconium phosphate (PPy/α-ZrP) was prepared in an aqueous phase by cyclic voltammetry method. It was proved by FT-IR, XRD and XPS characterizations that the electroactive PPy/α-ZrP hybrid film was synthesized successfully. The PPy/α-ZrP film electrode prepared on a porous three-dimensional carbon felt (PTCF) was used for removal of a low concentration of Pb(II) ions from an aqueous solution by electrochemically switched ion exchange (ESIX). A quick uptake and release rate of Pb(II) onto the film electrode was obtained by adjusting redox state of the hybrid film. The removal efficiency and adsorption capacity of …

Mechanism Study On The Electrocatalytic Oxidation Of Acetylene To Oxalic Acid, Xiu-Li Song, Rui-Long Jia, Wen-Yan Dong, Zhen-Hai Liang

Journal of Electrochemistry

A new method of electrocatalytic synthesis oxalic acid from acetylene was explored and the synthesized oxalic acid was characterized by Ultraviolet-visible spectrophotometry (Uv-vis) and Infrared spectroscopy (IR). First-principles calculations were carried out to examine the adsorption of acetylene over the Pt(111) surface. The electrocatalytic oxidation behavior of acetylene has been investigated on a Pt electrode by cyclic voltammetry (CV) and steady-state polarization in Na₂SO₄ solution. The formation mechanism of oxalic acid in the Na₂SO₄ solution was proposed and the transfer coefficients of the reaction were calculated. The results show that acetylene molecule tends to …

Effect Of Carbon Nanotubes On Anodic Properties Of Ti/Ru-Ir-Sn Oxides, Feng Lian, Yong-Lei Xin, Bo-Jiang Ma, Li-Kun Xu

Journal of Electrochemistry

The Ru-Ir-Sn metal oxide anodes coated on titanium (Ti/Ru-Ir-Sn) were prepared by thermal decomposition. The effects of amounts of carbon naotubes (CNTs) on anodic properties were studied by TGA, SEM, EDS, cyclic voltammetry, EIS, polarization measurements and accelerated life test. The thermogravimetric analysis and EDS spectrum data showed that the high temperature oxidation decomposition of CNTs did not take place under the condition of the sintering temperature of 470 ℃, and the CNTS still existed in the anode coating in an element form. Compared with the contrast samples, the surface crack of the coating increased, but remained typical morphology. Adding …

Reaction Mechanisms Study Of Pb Electrodes In Sulfuric Acid And Sodium Sulfate Solutions By Eqcm, Xian-Ping Zou, Zong-Xuan Kang, Yu-Lan Huang, Dong Shu, Ya-Yun Zhong, Jun-Nan Hao, Yu-Qing Liao

Journal of Electrochemistry

Surface reaction processes of Pb electrodes were investigated in H₂SO₄ and Na₂SO₄ solutions by LSV, CV and EQCM. The results in the voltammogram and the mass change curve of the Pb electrode indicated that the oxide products of lead included PbSO4 and PbO·PbSO₄ in sulfuric acid solution with a positive-going potential scan from -1.0 V to -0.4 V and then PbO·PbSO₄ transformed into PbSO₄. However, the oxide product of lead was only PbSO₄ in sodium sulfate solution. The experimental results revealed that the acid solution is necessary for the …

Effect Of Surface Omniphobicity On Drying By Forced Convection, Madani A. Khan, Jeffrey Alston, Andrew Guenthner

STAR Program Research Presentations

Low energy surfaces can strongly repel both oil and water. Recently these surfaces have been fabricated on various substrates including fabric, aluminum, stainless steel and many other materials. In this experiment we explore the use of low energy surface deposition on aluminum alloy, stainless steel and silicon substrates, to enhance the drying rate of liquids removed from the surface by forced convection. We control surface roughness by substrate abrasion and by the growth of Al₂O₃ nanograss to enhance liquid repellence by use of a hierarchical texture. Liquid repellence of the substrates is measured by contact angles of …

Morphology-Property Relationship For Binary Organic Thin Films, Alyssa Lynn Griffin

Master's Theses

Organic thin films can be readily mass-produced through solution-based fabrication methods including ink-printing and solution-casting because their light weight, flexibility, and inexpensive sources. Their applications range from organic field-effect transistors (OFET), organic solar cells (OSC), to organic light emitting diodes (OLEDs). Compared with pure component films, binary organic thin films (BOTF) allows for novel characteristics and specialized features to handle more demanding tasks. Due to the complex intermolecular interactions in BOTF, various microscopic phases with different morphological and electronic properties may be formed and this information is difficult to extract through conventional bulk measurements.

Organic thin films can be readily …

Surface Modification Of Noble Metal Nanostructures Toward Biomedical Applications, Samir V. Jenkins

Graduate Theses and Dissertations

Noble metal nanostructures have seen a steady increase in biomedical application over the last several decades; new diagnostic and therapeutic modalities are under intense investigation. Many of these applications are possible because of post-synthetic modifications to the particle surface. These modifications take a variety of forms and can significantly affect the pharmacokinetics of these particles. In this work, various surface modifications were investigated. Particle agglomeration, which occurs when particle surfaces remain in contact, can significantly affect the toxicity and efficacy of a nanomedicine. Darkfield microscopy and single-particle ICP-MS were developed as complementary methods to detect agglomeration in blood, with the …

Current Status And Prospect Of Cathode Materials For Lithium Sulfur Batteries, Lan Zhou, Ai-Shui Yu

Journal of Electrochemistry

Elemental sulfur has been extensively investigated as a promising candidate of cathode material for next generation lithium secondary batteries. However, some troublesome issues, such as the low electric conductivity of sulfur (5×10^-30 S·cm^-1) and the high solubility of lithium polysulfide intermediates in organic electrolytes, resulting in a low utilization of active material and a redox shuttling of dissolved polysulfide ions between the sulfur cathode and the lithium anode, which eventually leads to a deposition of insoluble and insulating Li₂S₂/Li₂S on the electrode surface and a fast reduction in the specific capacity. …

Research Status And Application Prospects Of Limnpo4 As A New Generation Cathode Material For Lithium-Ion Batteries, Lai-Fen Qin, Yong-Gao Xia, Li-Peng Chen, Hua-Sheng Hu, Feng Xiao, Zhao-Ping Liu

Journal of Electrochemistry

Olivine-structured lithium manganese phosphate (LiMnPO₄) has the following advantages: excellent thermal stability, low cost, high safety and environmental benignity. Importantly, the theoretical energy density of LiMnPO₄ is about 20% higher than that of commercialized LiFePO₄ due to its higher Li⁺ intercalation potential of 4.1 V (vs. Li⁺/Li). Moreover, the high operating voltage of LiMnPO₄ is compatible with present non-aqueous organic electrolytes of lithium-ion batteries. Therefore, LiMnPO₄ is considered as a next generation cathode material for lithium-ion batteries. However, LiMnPO₄ suffers from poor electronic conductivity and low lithium diffusivity, resulting in …

Preparations And Applications Of Layered Carbon And Layered Carbon-Pbso4 Composite, Shu-Kai Zhang, Hao Zhang, Wei-Hua Xue, Jie Cheng, Wen-Feng Zhang, Gao-Ping Cao, Hai-Lei Zhao, Yu-Sheng Yang

Journal of Electrochemistry

The layered carbon materials (similar to graphene) have been synthesized by chemical vapor deposition (CVD) on the cheap catalyst (potassium or sodium carbonate substrate). The layered-carbon- lead sulfate (PbSO₄) composite could be prepared by in situ chemical deposition based on the layered carbon. The XRD, SEM and TEM results showed that the layered carbon materials was amorphous carbon layer, and the composite was a compound made of fine lead sulfate grains and layered carbon. Thermogravimetric analysis determined the carbon content in the composite. Adding a certain amount of layered carbon or layered-carbon-PbSO₄ composite into negative active materials …

Preparation Of Zro2-Doped Nb/Pbo2 Electrode And Electrocatalytic Performance Of Methyl Orange Degradation, Li Zhang, Wen-Yan Dong, Tai-Lai Yang, Zhen-Hai Liang

Journal of Electrochemistry

The zirconium oxide (ZrO₂)-doped niobium based lead oxide (Nb/PbO₂) electrode was prepared by electrodeposition. The microstructures and electrochemical properties of Nb/ZrO₂+PbO₂ electrode were investigated using scanning electron microscopy (SEM), X-ray diffraction (XRD), linear sweep voltammetry, electrochemical impedance spectroscopy and cyclic voltammotry. In addition, the Nb/PbO₂ electrode was used as an anode for the electrochemical degradation of methyl orange (MO). Results revealed that the ZrO₂ doping made the Nb/PbO2 electrode surface denser and rougher with smaller sized crystal particles, which increased the specific surface area and enhanced the electrocatalytic activity of the …

Electrochemical Mass Spectrometric Study Of Lithium-Oxygen Batteries, Xin-Xiu Yan, Li-Po Ma, Zhang-Quan Peng

Journal of Electrochemistry

Mass Spectrometry, coupled with electrochemistry, is a powerful research tool to study mechanisms for a broad range of electrode reactions by identifying and quantifying reaction products and intermediates. In this review, we summarize the recent advances in the Li-O₂ battery researches offered by electrochemical mass spectrometry based on our group investigations. These include the research progresses in electrolytes, cathode materials (electrocatalysts), and parasitic reactions, i.e., the key issues associated with Li-O₂ research. In addition, we also discuss the effects of irreversible side reactions involved in battery systems on charge and discharge processes.

Synthesis Of Graphene Wrapped Li-Rich Layered Metal Oxide And Its Electrochemical Performance, Meng-Yan Hou, Ke Wang, Xiao-Li Dong, Yong-Yao Xia

Journal of Electrochemistry

In present work, lithium-rich layered transition metal oxide (LLO) was synthesized by a co-precipitation method in combination with a solid-state reaction. The graphene wrapped Li-rich layered oxide composite (LLO/Gra) was obtained by sintering the LLO/GO composite at 300 ^oC for 30 min in an air. The morphologies and the electrochemical performances were characterized by means of SEM, TEM, XRD, XPS, EIS and charge/discharge tests. The results indicated that the LLOe particles were uniformly wrapped with graphene. The resulting material exhibited better rate capability than that of pristine LLO since the wrapped graphene demonstrated the enhanced electronic conductivity. Accordingly, the …

Research Progress In Carbon Coating On Lifepo4 Cathode Materials For Lithium Ion Batteries, Ning Zhang, Yong-Chang Liu, Cheng-Cheng Chen, Zhi-Qiang Zhu, Zhan-Liang Tao, Jun Chen

Journal of Electrochemistry

Olivine-structured LiFePO₄ has been received much attention because of its flat voltage profile, low cost, abundant material supply and better environmental compatibility. However, the poor electronic and ionic conductivities have limited its application in industry. One of the best methods to improve the electrochemical performance is carbon coating. In this review, we summarize the recent developments of LiFePO₄/C cathode. Moreover, the different effects caused by coating methods and carbon sources, as well as the mechanism of carbon coating on the properties of LiFePO₄/C are reviewed.

Enhancing Stability Of Pem Fuel Cell Catalysts Via Support Changing, Xiao-Hong Xie, Zi-Dong Wei

Journal of Electrochemistry

The Pt/C catalyst with highly dispersed Pt nanoparticles supported on carbon has been widely used as the state-of the-art catalyst in proton exchange membrane fuel cells (PEMFCs), while the durability of Pt/C is one of the major barriers for large-scale applications of PEMFCs. Thus, enhancing the stability of Pt/C has been a hot issue in this field. In this review, we summarize the recent progress in enhancing the catalyst stability in the view of support material. The future prospects of the PEMFCs catalyst should focus on adopting more stable supports or strengthening the interactions between Pt and supports.

Pt/C Modified Proton Exchange Membrane For Improved Fuel Cell Performance, Zhi Cui, Chao Wang, Shui-Yun Shen, Feng-Jing Jiang, Jun-Liang Zhang

Journal of Electrochemistry

The property of proton exchange membrane greatly affects the performance of proton exchange membrane fuel cells (PEMFC). During the operation of a PEMFC, the water produced at the cathode, the water vapor from the humidified feed gas and the water migrated by electro-dragging will reach a balance in the membrane and determine the resistance of PEMFC, and thus affect the performance of PEMFC. Normally, the PEMFC performance strongly depends on the relative humidity of the feed gas, and the performance decreases at lower humidity as a result of lower proton conductivity of the membrane. In this paper, we proposed to …

Electrolytes For Lithium And Lithium-Ion Batteries, Zong-Rang Zhang

Journal of Electrochemistry

This is an up-to-date book published by Springer last year and focuses on the field of the electrolytes for lithium and lithium-ion batteries. A brief introduction and review of this book are given in this paper. The main contents of this book are introduced briefly in the order of ten different chapters along with a short review of recent progress in those fields.