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Pei Yao  - - - 
Top co-authors See all
Yun-Feng Xiao

275 shared publications

State Key Lab for Mesoscopic Physics and Department of Physics; Peking University; Beijing 100871 P. R. China

Xuexin Duan

106 shared publications

State Key Laboratory of Precision Measuring Technology & Instruments, Tianjin University, Tianjin 300072, China

Jun Liu

61 shared publications

Materials Science and Engineering Department, University of Washington, Seattle, Washington 98195, United States

Xiaoying Li

37 shared publications

School of Precision Instrument and Opto-electronics Engineering, Tianjin University, Key Laboratory of Opto-Electronic Information Technology of Ministry of Education, Tianjin 300072, China

Wei Pang

35 shared publications

State Key Laborary of Precision Measuring Technology and Instruments, Tianjin University, Tianjin, China

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Distribution of Articles published per year 
(2008 - 2018)
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23
 
Publications See all
Article 0 Reads 1 Citation Electrochemical performance and stability of a PPy/MMT-PVDF/PMMA composite film at high temperature Shuo Yang, Xuan Li, Huijun Li, Pei Yao Published: 01 August 2018
Synthetic Metals, doi: 10.1016/j.synthmet.2018.05.008
DOI See at publisher website
Article 0 Reads 0 Citations Effect of Nano-ppy/OMMT on the Physical and Electrochemical Properties of an Ionic Liquid Gel Polymer Electrolyte Shuo Yang, Xuan Li, Pei Yao Published: 01 January 2018
Journal of Nanomaterials, doi: 10.1155/2018/8457670
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A new type of nanopolypyrrole/organically modified montmorillonite-ionic liquid gel polymer electrolyte (ppy/OMMT-ILGPE) is prepared based on nanopolypyrrole/organically modified montmorillonite (ppy/OMMT), N-butyl-N- methylpyrrolidinium bis(trifluoromethanesulfonyl)imide (PP14TFSI), lithium-bis(trifluoromethanesulfonyl) (LiTFSI), polyvinylidene difluoride (PVDF), methyl methacrylate (MMA), and benzoyl peroxide (BPO) by an in situ method. The effect of nano-ppy/OMMT on the physical and electrochemical properties of an ionic liquid gel polymer electrolyte is demonstrated. The results show that nano-ppy/OMMT-ILGPE has a porous structure with a large surface area, and the diameter of the pores on the surface is approximately 1-2 μm. The Li+ transference number of 0.72 is achieved, and the ionic conductivity reaches up to 1.2 × 10−3 S/cm at room temperature. Nano-ppy/OMMT-ILGPE has good thermal stability and mechanical properties. Meanwhile, nano-ppy/OMMT-ILGPE has fine cycle performance in the Li|nano-ppy/OMMT-ILGPE|LiNi1/3Co1/3Mn1/3O2 coin cell. The good electrochemistry performance of nano-ppy/OMMT-ILGPE means that it can act as an ideal gel polymer electrolyte material for lithium ion batteries.
Article 0 Reads 1 Citation Synthesis of mesoporous NiCo 2 S 4 deposited on reduced graphite oxide assistant by co-polymer Pluronic F127 for high-pe... Huiya Qin, Shuo Yang, Wenliang Zhao, Zhengchun Yang, Xuan Li... Published: 01 October 2017
Applied Surface Science, doi: 10.1016/j.apsusc.2017.05.048
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Article 0 Reads 0 Citations Metal nanodroplets catalyzed growth of ZnS nanowires with a high aspect ratio via long-pulse-width laser ablation in the... Kui Lin, Pei Yao, Jing Zhao, Shizhen Guo, Fei Tian Published: 01 September 2017
Materials Letters, doi: 10.1016/j.matlet.2017.05.119
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Article 0 Reads 0 Citations Enhancement of Thermal Stability and Cycling Performance of Lithium-Ion Battery at High Temperature by Nano-ppy/OMMT-Coa... Shuo Yang, Huiya Qin, Xuan Li, Huijun Li, Pei Yao Published: 01 January 2017
Journal of Nanomaterials, doi: 10.1155/2017/6948183
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Nanopolypyrrole/organic montmorillonite- (nano-ppy/OMMT-) coated separator is prepared by coating nano-ppy/OMMT on the surface of polyethylene (PE). Nano-ppy/OMMT-coated separator with three-dimensional and multilayered network structure is beneficial to absorb more organic electrolyte, enhancing the ionic conductivity (reach 4.31 ). Meanwhile, the composite separator exhibits excellent thermal stability and mechanical properties. The strong covalent bonds (Si-F) are formed by the nucleophilic substitution reaction between F− from the thermal decomposition and hydrolysis of LiPF6 and the covalent bonds (Si-O) of nano-ppy/OMMT. The Si-F can effectively prevent the formation of HF, POF3, and LiF, resulting in the inhibition of the disproportionation of Mn3+ in LiNi1/3Co1/3Mn1/3O2 material as well as reducing the internal resistance of the cell. Therefore, the nano-ppy/OMMT-coated separator exhibits outstanding capacity retention and cycling performance at 80°C.1. IntroductionWith the extensive application of lithium-ion battery (LIB) to electric vehicles and energy storage, the security of LIB at high temperature should be given more attention. It is worthy to note that the separator plays an essential part in permitting the transportation of Li-ion and preventing the contact of the electrodes in the LIB [1]. PE with excellent mechanical properties and electrochemical stability at room temperature is widely applied in the realm of LIB. However, the hydrophobic group of PE would lead to poor compatibility between PE and organic solution, thus increasing the internal resistance of the cell [1, 2]. A high thermal shrinkage of PE separator is usually found at high temperature, causing internal short circuit of the cell [3, 4]. LiPF6 is a common organic electrolyte. LiF, HF, and POF3 from the thermal decomposition and hydrolysis of LiPF6 at high temperature may be formed on the surface of the electrodes [5]. As insulating materials, LiF and POF3 may hinder the charge transfer reaction [6, 7]; HF can corrode the transition metals of cathode material [5, 8]. Hence, the electrochemical property and stability of LIB at high temperature depend on the thermal stability of organic electrolyte and separator. To handle these problems, inorganic materials, such as TiO2, Al2O3, and SiO2, are coated on the surface of separator [9–12]. Although inorganic coatings can effectively improve the mechanical property and thermal stability of separators, inorganic particles would increase the interface resistance of the cell during the charge and discharge process. To ensure the safety of LIB and achieve its excellent performance at high temperature, it is essential to select proper inorganic coatings to enhance the thermal, mechanical, and electrochemical performances of the separator.Compared with the conventional coated inorganic material, nano-organic montmorillonite (OMMT) layered silicates have a greater promising future for their functional advantages and structure [13–15]. OMMT, with the advantages of high specific surface area (~31.82 m2/g), high aspect ratio large (~1000), high cation-exchange capacity (CEC~80 mequiv./100 g), length scale (clay channel width < m), and appropriate interlayer charge (~0.55), is considered to be suitable for inorganic coating. The structure of montmorillonite (MMT) consists of two fused silica tetrahedral sheets that sandwich an edge-shared octahedral sheet of either Al2O3 or Mg. Ca2+ and Na+ existing in the interlayer can be replaced by alkylammonium ions in the cation-exchange reaction to form the hydrophilic-layered and organophilic silicate. Alkylammonium ions in the interlayer can produce a nanopolymer-MMT, which increases the solubility of lithium salts and improves the mechanical properties of separators, because of its high dielectric property and huge interfacial area [16–18]. OMMT coated with high specific surface area can improve the absorbing ability of organic electrolyte, therefore enhancing the ion conductive ability of electrolyte membrane [17]. When polymer is mixed with MMT, the polymer chain can enter the layer of MMT, decreasing the pore diameter of the polymer electrolyte membranes [19]. OMMT can also react with impurities of the electrolyte, inhibiting the negative reaction between the impurities and Li-ion and then enhancing the stability of the interface between electrolyte and electrode [20–22]. High cation exchanges of OMMT regarded as Lewis acid centers can compete with lithium-ion to form complexes with the polymer. This would enhance conducting pathways for lithium-ion [23]. Therefore, OMMT, favorable inorganic coating for the separator, can improve the thermal stability and electrochemical performance of the cell.In this study, under the interaction with FeCl3 as the oxidant and Sodium p-toluenesulfonate (TSANa) as the swelling agents, pyrrole (py) was polymerized between molecular layers of MMT. Nano-ppy/OMMT was added to the poly(vinylidene fluoride) (PVDF) and N-methyl pyrrolidone (NMP) with different ratios. Then the mixed solution was coated onto the surface of PE separator. This method was used in the preparation of nano-ppy/OMMT-coated separator. The microstructure and the electrochemical performance of nano-ppy/OMMT-coated separator were explored and discussed in detail. The electrochemical performance of the cell assembled with nano-ppy/OMMT-coated separator and LiPF6 was evaluated at high temperature. Then the contents of LiF, HF, and POF3 in the cell after 100 cycles at 0.5 C and 80°C were explored and studied, compared with those of the cell assembled with PE separator under the same conditions.2. Experimental2.1. Modified Principle and Preparation of Nano-ppy/OMMTThe OMMT was prepared by the cation-exchange reaction between Al3+ in the MMT and the Octadecyl Dimethyl Ammonium Chloride (ODAC) as organic intercalation agent. When the grain diameter of OMMT became smaller and its layer spacing was expanded, py enters the molecular layers of OMMT more easily. During the reaction with TSANa as the swelling agents and FeCl3 as the oxidant, py was polymerized between molecular layers to expand layer spacing of OMMT. This method was applied to preparing nano-ppy/OMMT [24].The nano-ppy/OMMT was prepared by mixing the MMT (AR, Aladdin) and ODAC (AR, Tianjin Guangfu) in deionized water and stirring at 60°C for 12 h until the homogenous solution was obtained. The weight ratio between ODAC and MMT was 1 : 5. TSANa (AR, Tianjin Guangfu) and py (AR, Beijing J&K) were dissolved in the mixture solution and vigorously stirred at room temperature for 1 h (TSANa and py in the ratio of 1 : 8 by mass). 30 mL 1 mol/L FeCl3 was added to the mixture solution with the dropping funnel and then stirred at the room temperature for 6 h. py was polymerized in situ under the action of TSANa and FeCl3. At last, the resulting solution was washed, separated by centrifugal, and then putted into the high vacuum drying oven for 10 h at 80°C.2.2. The Preparation of Nano-ppy/OMMT-Coated SeparatorThe PVDF (Aladdin Chemistry Co., Ltd.) and NMP (AR, Tianjin Guangfu) (1 : 8 by mass) were mixed and stirred vigorously for 3 h until PVDF fully dispersed in NMP. And then nano-ppy/OMMT was added to the mixture solution (its mass ratio with PVDF is 0.04 : 1, 0.06 : 1, and 0.08 : 1) and stirred for 10 h until the homogenous solution was formed. The mixed solution was coated onto both sides of the PE separator (10 μm thick, WuHan XuHua) and dried in a vacuum oven at 50°C for 6 h. The nano-ppy/OMMT-coated separator was prepared in the way shown in Figure 1 [25, 26].Figure 1: Schematic representing the preparation process of nano-ppy/OMMT-coated separator.2.3. Electrode Preparation and Cell AssemblyThe positive electrode was prepared by mixing LiNi1/3Co1/3Mn1/3O2 as active material powder, acetylene black, and PVDF binder (in the mass ratio of 8 : 1 : 1) in NMP solvent, which was stirred for 10 h until the viscous slurry was formed. The viscous slurry was coated on the aluminum foil (current collector) and dried at 100°C in the vacuum oven for 10 h. The liquid electrolyte consisted of 1 M LiPF6 in diethyl carbonate (DEC)/ethylene carbonate (EC)/ethyl methyl carbonate (EMC) (1 : 1 : 1 in mass, battery grade, KeJing. Co., Ltd.). The lithium metal served as the negative electrode (battery grade, KeJing. Co., Ltd.). A cell was assembled by sandwiching a nano-ppy/OMMT-coated separator between LiNi1/3Co1/3Mn1/3O2, positive electrode, and the lithium metal, negative electrode. LiPF6 liquid electrolyte was injected into the cell and pressed by the hydraulic press at the pressure of 10 MPa. All cells were implemented in a dry argon atmosphere glove box [27].2.4. CharacterizationThe interlayer spacing and crystallization of both MMT and nano-ppy/OMMT were studied by X-ray diffraction (XRD), an automatic Japanese D/MAX-2500 powder diffract meter with monochromatic Cu Kα radiation: voltage pressure and current of 30 kV and 30 mA, respectively, scanning range of , and scanning speed of 3°/min; the incident X-ray wave length was 0.154 nm. The interlayer spacing was calculated by the following Bragg equation:where is the layer spacing; is the incident angle; is the wavelength of incident X-ray.Transmission electron microscope (TEM, JEM-2100F) was adopted to study the surface morphology of MMT and OMMT. Scanning electron microscopy (SEM, NanoSEM 430) was adopted to study the cross-sectional structure of PE separator and nano-ppy/OMMT-coated separator. Nano-ppy/OMMT-coated separator and PE separator were measured after soaking the separators in LiPF6 liquid electrolyte. The capacity of liquid electrolyte uptake was calculated with the following equation: where is the weight of dry separator and is the weight of liquid electrolyte after removing excess electrolyte on the surface.The tensile properties of nano-ppy/OMMT-coated separator and PE separator were evaluated by Universal Material Testing Machine (WDW5000) with a beam
Article 0 Reads 1 Citation Facile synthesis of CoFe2O4 nanoparticles anchored on graphene sheets for enhanced performance of lithium ion battery Wen Qi, Pei Li, Ying Wu, Hong Zeng, Liting Hou, ChunJiang Ku... Published: 01 October 2016
Progress in Natural Science: Materials International, doi: 10.1016/j.pnsc.2016.09.001
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