Electrochemical properties of Li ion polymer battery with gel polymer electrolyte based on polyurethane

Gel polymer electrolyte (GPE) was prepared using polyurethane acrylate as polymer host and its performance was evaluated. LiCoO₂/GPE/graphite cells were prepared and their electrochemical performance as a function of discharge currents and temperatures was evaluated. The precursor containing a 5 vol % curable mixture had a viscosity of 4.5 mPa s. The ionic conductivity of the GPE at 20 °C was about 4.5 × 10^–3 S cm^–1. The GPE was stable electrochemically up to a potential of 4.8 V vs Li/Li⁺. LiCoO₂/GPE/graphite cells showed a good high rate and low-temperature performance. The discharge capacity of the cell was stable with charge–discharge cycling.     

纳米氧化镁对木材的阻燃特性

将纳米氧化镁作为阻燃剂利用物理机械混合的方法加入到木粉中,经极限氧指数(LOI)、锥形量热仪(CONE)测试结果表明,纳米氧化镁能显著提高木制品的氧指数,燃烧过程中的热释放速率、热释放量、烟产生速率、总生烟量和CO产率明显降低,具有很好的阻燃效果。经计算纳米氧化镁的加入能够提高样品的残炭率,残炭率提高10%左右。其阻燃机理一方面是由于纳米氧化镁可以作为物理屏障层,起到耐高温绝热和隔绝氧气的作用;另一方面,纳米氧化镁会参与木材的燃烧,改变木材的裂解途径,残留有更多的不可燃物质。     

纳米氧化镁对木材的阻燃特性

将纳米氧化镁作为阻燃剂利用物理机械混合的方法加入到木粉中,经极限氧指数(LOI)、锥形量热仪(CONE)测试结果表明,纳米氧化镁能显著提高木制品的氧指数,燃烧过程中的热释放速率、热释放量、烟产生速率、总生烟量和CO产率明显降低,具有很好的阻燃效果。经计算纳米氧化镁的加入能够提高样品的残炭率,残炭率提高10%左右。其阻燃机理一方面是由于纳米氧化镁可以作为物理屏障层,起到耐高温绝热和隔绝氧气的作用;另一方面,纳米氧化镁会参与木材的燃烧,改变木材的裂解途径,残留有更多的不可燃物质。     

Effect on properties of PVDF-HFP based composite polymer electrolyte doped with nano-SiO2

Various kinds of nano-SiO₂ using different catalysts were obtained and characterized by scanning electron microscope (SEM) technique. The results showed that the nano-SiO₂ using NH₃·H₂O as catalyst presented the best morphology. Poly(vinylidenefluoride-co-hexafluoropropylene) (PVDF-HFP) based composite polymer electrolyte (CPE) membranes doped with different contents of nano-SiO₂ were prepared by phase inversion method. The as-prepared CPE membranes were immersed into 1.0 M LiPF₆-EC/DMC/EMC electrolytes for 0.5 h to be activated. The physicochemical and electrochemical properties of the CPEs were characterized by SEM, X-ray diffraction (XRD), electrochemical impedance spectroscopy (EIS), and linear sweep voltammetry (LSV) techniques. The results indicate that the CPEs doped with 10 % nano-SiO₂ exhibit the best performance. SEM micrographs showed that the CPE membranes have uniform surface with abundant interconnected micro-pores, and the uptake ratio was up to 104.4 wt%. EIS and LSV analysis also showed that the ionic conductivity at room temperature and electrochemical stability window of the modified membrane can reach 3.372 mS cm^?1 and 4.7 V, respectively. The interfacial resistance R _i was 670 Ω cm^?2 in the first day, then increased to a stable value of about 850 Ω cm^?2 in 10 days storage at room temperature. The Li/As-fabricated CPEs/LiCoO₂ cell also showed good charge–discharge performance, which suggested that the prepared CPE membranes can be used as potential electrolytes for lithium ion batteries.     

Structural,optical, morphological properties of silver doped cobalt oxide nanoparticles by microwave irradiation method

The synthesis of silver doped cobalt oxide nanoparticles by microwave-assisted method and their structural, optical, antibacterial activities are presented in this study. The doping concentrations were chosen as 5, 10, 15, and 20 wt percentages. The sample was undergone powder X-ray diffraction studies and the result shows the good crystalline nature of the sample. Also, the average crystallite size increases from 13.95 nm, 21.26 nm, 26.13 nm, and 28.35 nm with different doping concentrations. The transmission electron microscopy image shows cubic and spherical morphology. The optical properties were tested by UV–vis–NIR absorption spectrum. It indicates the decrease of band gap value. From the antibacterial activity studies, the 20 wt % Ag doped nanoparticles exhibit better activity.     

Effect of aluminum oxide nanoparticles additives and gamma irradiation on the structural and optical properties of syndiotactic polystyrene

Aluminum oxide nanoparticles (Al₂O₃) were prepared and the obtained structure and size of the prepared Al₂O₃ nanoparticles were studied via X‐ray diffraction (XRD) and transmission electron microscopy. The effect of adding various concentrations of the Al₂O₃ and gamma radiation on the structural and optical properties of syndiotactic polystyrene (sPS) were investigated using XRD and UV‐spectroscopy. XRD data showed that the addition of the various concentrations of the Al₂O₃ influenced the crystallinity of the nanocomposites. A significant change in the lattice structure and the optical parameters were observed. The results showed that a sample with the Al₂O₃ concentration of 10% achieved a higher refractive index and optical conductivity. Effect of gamma irradiation on sPS sample loaded with 10% Al₂O₃ was studied. The results showed several changes in the structure and optical properties of the resulting films due to crosslinking between the polymer chains. This result reflects that the polymer suffered from structural rearrangement due to the irradiation treatments. POLYM. ENG. SCI., 59:555–565, 2019. © 2018 Society of Plastics Engineers     

Preparation and photochemical properties of nanoparticles of ceria doped with zinc oxide

Abstract

Nanoparticles of CeO₂ doped with ZnO were syn thesised via soft solution chemical processes at 40°C and a final pH of 6. The particle size of CeO ₂decreased markedly after doping with ZnO. The solubility limit of ZnO in Ce_1-xZn_xO_2-x was determined to be x = 0·561. The oxidation catalytic activity of CeO₂ was effectively decreased by doping with ZnO. For the oxidation of phenol, the photocatalytic activity of ZnO doped CeO₂ was much lower than that of fine titania particles. ZnO doped CeO₂ showed excellent UV absorption and transparency in the visible region, in a similar manner to undoped CeO₂.     

Preparation of polymer/inorganic nanoparticles composites through ultrasonic irradiation

In this paper, ultrasonic induced encapsulating emulsion polymerization was first used to prepare the novel polymer/inorganic nanoparticles composites. The behaviors of several inorganic nanoparticles (SiO₂, Al₂O₃, TiO₂) under ultrasonic irradiation, such as dispersion, crushing, and activation, were studied. The dispersion stability, morphology, and structure of the ultrasonic irradiated nanoparticles were characterized by means of transmission electron microscopy (TEM), Fourier transform infrared (FTIR), and spectrophotometry, respectively. The results show that the inorganic nanoparticles in the aqueous solution can redisperse more effectively by ultrasonic irradiation than by conventional stirring. This is the basis for preparation of polymer/inorganic nanoparticles composites. By this technique, the long‐term stable latex, which mainly consists of polymer/inorganic nanoparticles composite latex particles, were successfully prepared. TEM, FTIR, thermogravimetric analysis, X‐ray photoelectron spectroscopy, spectrophotometry, and element analysis confirmed that well‐dispersed nanoparticles were encapsulated by the formed polymer, and the thickness of encapsulating polymer layer was in the range of 5–65 nm. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 1478–1488, 2001     

Enhanced transport properties in polymer electrolyte composite membranes with graphene oxide sheets

Polymer electrolyte membranes have been widely investigated for high performance fuel cells. Here, we report the synthesis of ionic conductive Nafion/graphene oxide (GO) composite membranes for application in direct methanol fuel cells. GOs interact with both the non-polar backbone and the polar ionic clusters of Nafion because of their amphiphilic characteristics attributable to hydrophobic conjugation and hydrophilic functional groups. Accordingly, GO sheets serve to modify the microstructures of two domains of Nafion. In particular, the transport properties of Nafion are favorably manipulated by the incorporation of GO. This modulated the ionic channels of Nafion and decrease methanol crossover while preserving ionic conductivity. Furthermore, strong interfacial interactions due to the insertion of GO nanofillers into the Nafion matrix improve the thermal and mechanical properties of the material. In particular, we exploit Nafion/GO composite membrane as electrolyte material for direct methanol fuel cell (DMFC) in order to resolve current issue of methanol crossover. This composite membrane-based DMFC compared to the Nafion 112-based DMFC remarkably enhanced cell performance, especially in severe operating conditions.     

Nonisothermal crystallization behaviors and conductive properties of PEO‐based solid polymer electrolytes containing yttrium oxide nanoparticles

Lithium solid polymer electrolytes (SPE) composed of polyethylene oxide (PEO) and yttrium oxide (Y₂O₃) nanoparticles were prepared. The influence of the Y₂O₃ nanoparticles on the non‐isothermal crystallization behaviors, crystal structure, and conductive properties of the SPE were investigated. The peak temperature, crystallinity, and crystallization half‐time (t_1/2) of the SPE were strongly dependent on the concentration of Y₂O₃ and the cooling rate. The non‐isothermal crystallization data were analyzed by the modified Avrami model, which successfully described the nonisothermal crystallization process of the SPE. The Avrami exponents suggested that the Y₂O₃ nanoparticles significantly affected both the nucleation mechanism and crystal growth of the PEO matrix. The nucleating and crystallization activation energies (ψ and E_c) estimated with different theories indicated that the Y₂O₃ nanoparticles were inclined to serve as heterogeneous nucleating agents to benefit the crystallization at lower concentration whereas as physical hindrance to inhibit the crystal growth at relatively higher concentration. The maximum conductivity (σ) of 5.95 × 10^?5 S cm^?1 at room temperature for the SPE was obtained at the Y₂O₃ weight ratio of 0.10. POLYM. ENG. SCI., 2011. © 2011 Society of Plastics Engineers     

Morphological properties of composite solid polymer electrolytes based on polyethylene oxide

Morphological properties of polymer electrolytes based on blends of polyethylene oxide and a perfluorinated polyphosphazene solvated with LiCF₃SO₃ with and without the addition of dispersed γ-LiAlO₂ are reported. The effect exerted on the morphology of the complex electrolytes by the addition of a plasticizer-like propylene carbonate has also been studied. Results indicate the incorporation of γ-LiAlO₂ leads to changes on the morphology of the complex electrolyte, as verified by X-ray diffraction analysis. The major effect observed by plasticizer addition was a decrease on the crystallinity of the system together with a displacement of the T_g towards lower temperatures. © 1998 John Wiley & Sons, Inc. J. Appl. Polym. Sci. 69: 2435–2440, 1998     

Preparation and properties of a novel green solid polymer electrolyte for all-solid-state lithium battery

Solid polymer electrolyte (SPE)-based lithium batteries have easy processing and safety for energy vehicles and storage. However, the preparation process of SPEs mostly used a lot of organic solvents, which will threaten human living space and body health. Herein, a novel green solid polymer electrolyte (ionic liquid type waterborne polyurethane, IWPUS) without no organic solvents was prepared from hybrids of ionic liquid-based waterborne polyurethane (IWPU) and LiClO₄. The structure and properties of IWPUS were investigated by IR, SEM, XRD, TGA, ion conductivity test. The results showed that Li⁺ of LiClO₄ could coordinate with  CO and  C O C in the polyurethane matrix. LiClO₄ had been well dispersed in IWPU. The conductivity of IWPUS increased with the increase of LiClO₄ content. The higher conductivity of IWPUS with 20% LiClO₄ at 80°C was 1.8 × 10⁻⁴ s•cm⁻¹. IWPUS based on ionic liquid-based waterborne polyurethane would be promised to become an environmentally friendly candidate for all solid-state lithium ion batteries.     

Electrochromism of nickel oxide thin film with polymer gel electrolyte

Polymer gel electrolytes were investigated for an electrochromic device (ECD) using nickel oxide thin film. Poly(ethylene oxide) (PEO) derivatives were cross‐linked and swelled in KOH–aqueous solution giving a hydrogel electrolyte. The ECD containing the uniformly cross‐linked hydrogel showed good result in electrochromic switching performance. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 1305–1308, 2002     

Synthesis and properties of heptadecane-functionalized poly(propylene oxide) based single-ion polymer electrolytes

Lithium methacrylate and heptadecane-functionalized poly(propylene oxide) (PPO) methacrylate based single-ion polymer electrolytes have been synthesized by radical copolymerization and neutralization. The thermal and electrical properties of the polymer electrolyte have been characterized by differential scanning calorimetry (DSC) and AC impedance spectroscopy, respectively. The results showed that the crystalline melting behavior of PPO segment was changed significantly by the presence of lithium ion due to the coordinative interaction and enhanced crystallinity. The ionic conductivity was 1.8 × 10^?7 S cm^?1 at 25 °C in the case of the lithium ion concentration of [PO]:[Li] = 30:1 due to the single-ion nature but its transference number reached roughly 1, indicating no migration of counter anions. Inspection with control sample suggested that the polymer electrolyte with ion conduction channel formed by a self-assembly is favored to realize relatively high ionic conductivity and decoupled lithium ion motion. The contact angle measurement onto the polymer electrolyte surface showed a strong hydrophobic wetting behavior due to the integrated hydrophobic nature of PPO and heptadecane alkyl chains.     

Study of a new polymer electrolyte poly(ethylene oxide): NaClO3 with several plasticizers for battery application

Sodium ion conducting thin film polymer electrolytes based on poly(ethylene oxide) (PEO) complexed with NaClO₃ were prepared by a solution‐casting method. Characterization by XRD, IR spectroscopy and AC conductivity has been carried out on these thin film electrolytes to analyse their properties. The conductivity studies show that the conductivity value of PEO:NaClO₃ complex increases with the increase in salt concentrations. Increase in conductivity was found in the electrolyte system by the addition of low molecular weight polymer poly(ethylene glycol) (PEG) and the organic solvents dimethylformamide (DMF) and propylene carbonate (PC). Using these electrolyte systems, cell parameters were measured from the discharge study with the application of load 100 kΩ at room temperature with common cell configuration Na|electrolyte|C:I₂:electrolyte. The open circuit voltage (OCV) ranges from 2.81 to 3.23 V and the short circuit current (SCC) ranges from 340 to 1180 µA. © 2001 Society of Chemical Industry     

Chemical compatibility of chromium-based interconnect related materials with doped cerium oxide electrolyte

X-ray diffraction and scanning electron microscopy were used to study the chemical compatibility of (La, Sr)CrO₃, SrCrO₄, CaCrO₄ and Cr₂O₃ (materials associated with the interconnect of a solid oxide fuel cell) with gadolinia-doped cerium oxide electrolyte (CGO). Powder mixtures and multilayer pellets of the interconnect related materials were annealed with CGO in air at temperatures ranging from 650 to 1600°C for durations of up to 400 h. No reaction was observed between (La,Sr)CrO₃ and Ce_0.8Gd_0.2O_1.9 after annealing at 1600°C for 10 h. However, SrCrO₄, CaCrO₄ and Cr₂O₃ reacted with CGO, forming an unidentified phase.     

添加TiO2的聚合物电解质膜PVDF-HFP的性能研究

通过添加不同质量分数的TiO2纳米粒子制备多孔聚合物电解质膜PVDF-HFP,制备的聚合物电解质膜通过红外,交流阻抗,线性伏安扫描、首次充放电测试等方法进行了性能测试。添加TiO2纳米填料后,降低了聚合物链的结晶度和极性,当填料的质量分数为8%时,表现出较好的电化学性能,吸液率为184%,孔隙率为93%,室温电导率达到2.05×10-3 S/cm,电化学稳定窗口为4.7V,能满足要求。     

Nanometer-thick films of titanium oxide acting as electrolyte in the polymer electrolyte fuel cell

0-18 nm-thick titanium, zirconium and tantalum oxide films are thermally evaporated on Nafion 117 membranes, and used as thin spacer electrolyte layers between the Nafion and a 3 nm Pt catalyst film. Electrochemical characterisation of the films in terms of oxygen reduction activity, high frequency impedance and cyclic voltammetry in nitrogen is performed in a fuel cell at 80 °C and full humidification. Titanium oxide films with thicknesses up to 18 nm are shown to conduct protons, whereas zirconium oxide and tantalum oxide block proton transport already at a thickness of 1.5 nm. The performance for oxygen reduction is higher for a bi-layered film of 3 nm platinum on 1.5 or 18 nm titanium oxide, than for a pure 3 nm platinum film with no spacer layer. The improvement in oxygen reduction performance is ascribed to a higher active surface area of platinum, i.e. no beneficial effect of combining platinum with zirconium, tantalum or titanium oxides on the intrinsic oxygen reduction activity is seen. The results suggest that TiO₂ may be used as electrolyte in fuel cell electrodes, and that low-temperature proton exchange fuel cells could be possible using TiO₂ as electrolyte.     

PVDF-HFP接枝PEG聚合物电解质的制备和性能研究

以聚偏二氟乙烯-六氟丙烯(PVDF-14VP)接枝聚乙二醇(PEG)为基质,用萃取法制备了均相结构的微孔型聚合物电解质.对此共聚物电解质和纯PVDF-HFP电解质进行比较表征,并以接枝共聚物电解质组装扣式电池进行了性能检测.结果表明,PVDF-HFP接枝PEG后可提高吸液率、保液能力和电导率.20℃时PVDF-HFP和PVDF-HFP-g-PEG的电导率分别为2.60×10-3S/cm和3.28×10-3S/cm.0.2 C充放电时,电池首次放电比容量为119.3 mAh/g.50次充放电循环过程中,充放电效率为99%.初始放电比容鼍为120.7 mAh/g,终止放电容量为115.9 mAh/g.0.5、1、2 C的放电比容量分别为0.2 C放电容量的96.2%、94.5%和81.3%.