ELECTROCHIMICA ACTA
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2023
·
IF 6.6
Qiang Zhang,Yuxiu Yu,Haojie Li,Fengying Zhang,Yaodong Liu
Binders are expected to play important role in silicon-based anode materials, but have not been well explored. In this work, a serial of silicon containing polyimides and polyamides have been synthesized and used as the binder of high content (80wt%) silicon anode. Systematic characterizations have been done on the chemical structures, physical properties of the binders, and the electrochemical performances of silicon-based anode. It was found that the swelling ratio, adhesion strength, and hardness plays important roles on the initial Coulombic efficiency (ICE) and capacity retention of silicon-based anode, and these parameters highly depend on the types and properties of binders. After optimizing the chemical structures and physical properties of the binders, a high specific capacity of 2941 mAh g −1 , relatively high initial Coulombic efficiency (ICE) of 83%, and good capacity retention of 85% (after 200 cycles) have been obtained. These results would help researchers to design new types of binders for silicon-based anode to improve its ICE and capacity stability.
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高影响因子
COMPOSITES SCIENCE AND TECHNOLOGY
·
2021
·
IF 8.528
Huanyu Chen,Gaohui Sun,Zailin Yang,Ting Wang,Guofeng Bai,Jun Wang,Rongrong Chen,Shihui Han
For the advantages of light weight, rapid recovery, and high sensitivity, the conductive flexible composite sponges with idiographic spatial structure as a stress sensor has received great attention. However, for small pressure and deformation, it is still challenging to achieve high sensitivity and response. Here, the polyimide (PI) sponge with through-hole structure and special functional groups is successfully fabricated through a clever structural design and is used as substrate of the composite sponges. The new PI sponge effectively induces the fabrication of reduced graphene oxide (RGO) sponge that possessing a pleated stacked structure in the cells only by a hydrothermal route. By controlling the GO dispersion concentration, the maximum electrical conductivity of the composite sponges reaches to 10.68 × 10 −4 S/m. The maximum sensitivity of composite sponges arrives at 1.172 kPa −1 and possesses a wide response range from 0 to 1 kPa. Comparing with previous similar works, the maximum sensitivity is improved by 74.9–1231.8%. Meanwhile, composite sponges exhibit excellent cycling stability under different compression rates, and present obvious response to tiny stress or deformation which is as low as 0.09 N and 0.45%. This is of great significance for the application of the conductive composite sponges sensor in tiny stress.
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高影响因子
Journal of Materials Chemistry C
·
2023
·Vol. 11
·期 39
·13446-13458
·
IF 6.4
Long Ni,Zhenling Kang,Yinfu Luo,Liwei Yan,Junyu Lu,Guanchun Wang,Shaoyu Qiu,Mei Liang,Shengtai Zhou,Huawei Zou
Lightweight and anisotropic porous carbon materials have promising applications in thermal insulation and electromagnetic interference (EMI) shielding fields. Herein, lightweight polyimide foams (PIFs) with anisotropic pore structures were prepared by adopting a microwave-assisted foaming method and the obtained PIFs were employed as derivatives to fabricate carbon foams, i.e., PICFs. The PICFs with aligned ellipsoidal strip-like pore structures presented low volumetric shrinkage (44.87–50.24%) and weight loss (36.33–48.17%), along with favorable compressive strength (102.96 kPa), and high temperature thermal resistance. In addition, the anisotropic pore structure imparted efficient thermal insulation and infrared thermal stealth properties to PICFs, with thermal conductivity as low as 0.0356 W (m K)−1 along the horizontal direction (perpendicular to the pore growth direction). When carbonized at 1400 °C, PICF1400 with a low density (22.9 kg m−3) and thin thickness (1.9 mm) exhibited a high electrical conductivity of 23.91 S m−1 in the horizontal direction. The EMI shielding effectiveness (SE) and specific EMI SE reached as high as 53.2 dB and 12216 dB (g cm−2), respectively. Moreover, PICF800 exhibited a high absorption coefficient of 0.91. Therefore, a facile strategy was proposed for fabricating lightweight PICFs which possess multifunctional properties enabling potential applications in high-end engineering sectors.
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高影响因子
COMPOSITES PART B-ENGINEERING
·
2023
·
IF 13.1
Zhiqiang Wu,Jie Dong,Xiuting Li,Xin Zhao,Chengchang Ji,Qinghua Zhang
Polyimide (PI) materials have found widespread utilization in advanced electronic systems. PIs with enhanced out-of-plane thermal conductivity ( K ⊥ ) are urgently required to address the rising need for heat dissipation. However, their production remains a formidable challenge due to the difficulty of constructing heat transmission channels along the thickness direction. This study introduces an innovative approach to enhance the K ⊥ values of PI-based composites by utilizing binary fillers to construct an inter-external dual heat conduction network. To achieve this, we first prepared PI/reduced graphene oxide (rGO) hybrid microspheres via solution mixing and precipitation. The microspheres were then coated with boron nitride nanosheets (BNNS) by self-assembly to form a core-shell architecture. This assembly undergoes further refinement via cold-pressing and subsequent densification through hot-pressing, ultimately producing the (PI/rGO)@BNNS composites. This strategy improved K ⊥ values significantly, with a 13-fold and 3-fold increase in the K ⊥ value (3.98 W m −1 K −1 ) in comparison to pure PI (0.31 W m −1 K −1 ) and the random distribution composite (1.45 W m −1 K −1 ), respectively. The finite element analysis confirmed that the synergistic effect of rGO inside the PI phase and BNNS outside the PI phase greatly increased the heat transfer in PI-based composites. When utilized as a thermal interface material (TIM) for LED bulbs, the (PI/rGO)@BNNS composites exhibit an excellent heat dissipation capacity. Additionally, the prepared composites also maintain electrical insulation and present a reduced coefficient of thermal expansion . Overall, our work provides a simple and efficient technique for enhancing the out-of-plane thermal conductivity and maintain the electrical insulation of high-performance PI-based materials, which could have broad application potential in next-generation electronic devices.
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Polymers
·
2021
·Vol. 13
·期 4
·523
·
IF 4.329
Geng Cheng,Zhen Li,Shan Ren,Dongmei Han,Min Xiao,Shuanjin Wang,Yuezhong Meng
As a key component of direct methanol fuel cells, proton exchange membranes with suitable thickness and robust mechanical properties have attracted increasing attention. On the one hand, a thinner membrane gives a lower internal resistance, which contributes highly to the overall electrochemical performance of the cell, on the other hand, strong mechanical strength is required for the application of proton exchange membranes. In this work, a sulfonated poly (fluorenyl ether ketone) (SPFEK)-impregnated polyimide nanofiber mat composite membrane (PI@SPFEK) was fabricated. The new composite membrane with a thickness of about 55 μm exhibited a tensile strength of 35.1 MPa in a hydrated state, which is about 65.8% higher than that of the pristine SPFEK membrane. The antioxidant stability test in Fenton’s reagent shows that the reinforced membrane affords better oxidation stability than does the pristine SPFEK membrane. Furthermore, the morphology, proton conductivity, methanol permeability, and fuel cell performance were carefully evaluated and discussed.Keywords:electrospun mat;proton exchange membrane;direct methanol fuel cell;composite membrane
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PubMed
高影响因子
NEW JOURNAL OF CHEMISTRY
·
2017
·Vol. 41
·期 23
·14272-14278
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IF 3.269
Ting Wang,Rui Xue,Huiqin Chen,Peiling Shi,Xi Lei,Yuli Wei,Hao Guo,Wu Yang
Two new polyimide based porous covalent organic frameworks (PI-COF 201 and PI-COF 202) were synthesized in high yields by directly heating mixtures of melamine and pyromellitic dianhydride and naphthalenetetracarboxylic dianhydride in a N2 atmosphere, respectively. Their structures and properties were characterized using elemental analysis, Fourier transform infrared spectra, X-ray photoelectron spectroscopy, X-ray powder diffraction, N2 adsorption–desorption and scanning electron microscopy and their fluorescence properties were studied in detail. These two COFs emitted strong fluorescence in appropriate solvents that originated from the π* → n transition caused by the high electro-delocalization and inherently rigid structure of the COF materials. The strong quenching effects of Fe3+ on the fluorescence of the COFs allowed selective chemosensing for Fe3+.
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CHEMICAL ENGINEERING JOURNAL
·
2024
·
IF 13.3
Shiping Shao,Shuzhi Xing,Ke Bi,Tingting Zhao,Hao Wang,Yunxiang Tang,Jiurong Liu,Fenglong Wang
The fabrication of dielectric/magnetic multicomponent hybrids represents a promising strategy for achieving advanced electromagnetic wave (EMW) absorption performances. However, it also poses a significant challenge due to the difficulty in fully utilizing the properties of each component. Here, in this work, metal–organic frameworks (MOFs) derived Co-N-C species were combined with graphene oxide/polyamide acid and then freeze-dried and annealed to produce PI/rGO/CNC aerogels. These aerogels exhibit outstanding EMW absorption properties owing to their multiple heterogeneous interfaces and synergetic electromagnetic losses while retaining satisfying mechanical properties and lightweight features of PI/rGO aerogels. In particular, PI/rGO/CNC-1 aerogel shows the optimal EMW attenuation performance with a minimal reflection loss (RL min ) value of –75 dB, and its maximal effective absorption bandwidth (EAB max ) is as broad as 7.28 GHz. Moreover, the lightweight nature, elastic feature, structural stability, thermal insulation and hydrophobicity of the PI/rGO/CNC aerogels ensure that they have vast application prospects as advanced EMW absorption materials in complicated environment.
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高影响因子
Materials Today Communications
·
2024
·
IF 3.7
Dandan Li,Qibin Ye,Dong Zhao,Mingzhu Xie,Dongpeng Li,Youhai Yu,Guangtao Qian,Chunhai Chen
The fabrication of polyimide (PI) composite aerogels can promote and optimize the characteristics and performance efficiency. But in fact, interface effect and assembly technique are the key problems in preparing PI composite aerogels . To settle this critical issue, a series of PI composite aerogels were designed via forming multi-coordination structure between PI molecular chain and Cu(II) metal ions. Multi-coordination structure connects the two-phase systems closely to obtain the improved comprehensive performances. The resulting PI composite aerogels still have high specific surface and mesoporous structure. The addition of Cu(II) improves the thermal and mechanical properties of the PI composite aerogels with an over 581 °C initial decomposition temperature, tensile strength of up to 9.48 MPa and modulus of up to 232.4 Mpa，along with compression Young’s modulus increased by 173% (up to 28.7 MPa) and stress at 10% strain improved by 150% (up to 1.70 Mpa). In the meantime, the brilliantly controllable dielectric property (with the dielectric constant down to 1.60 and the dielectric loss reaching 0.0171 at 10 MHz) and thermal insulation property (with the thermal conductivity down to 31.9 mWm −1 K −1 ) of PI composite aerogels make them can be used as low dielectric and thermal protection materials. The small heat-induced shrinkage between 100 and 250 °C allows the PI composite aerogels to operate in persistent extreme conditions. Besides, this work can provide a new strategy for preparing PI composite aerogels.
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ACS Applied Polymer Materials
·
2024
·
IF 4.4
Kun Peng,Xinyan Yang,MD Zahidul Islam,Xiangyu Mei,Yuhao Jiang,Xiaoming Qi,Yaqin Fu
As 5G technology rapidly progresses, the demand for insulating dielectric materials with low dielectric constants, minimal dielectric loss, and enhanced thermal and mechanical properties has become increasingly critical. In order to combine the advantages of both fluoropolyimide (FPI) and polytetrafluoroethylene (PTFE), this study successfully developed an FPI/PTFE/FPI composite film with a sandwich structure that seamlessly integrated a commercial hydrophilic PTFE porous fibrous film and FPI. This structure capitalizes on the permeation effect of the FPI wet film to significantly improve interfacial interactions compared to traditional sandwich-structured composites. Consequently, the composite films have an excellent combination of properties. When the proportion of PTFE reaches 50%, the composite film remains stable across high-frequency bands (8.2 to 12.4 GHz), with an impressively low value of 1.5 at 9 GHz. The composite film also exhibits exceptional electrical breakdown strength (385.2 kV mm–1), tensile mechanical robustness (σb = 64 MPa, E = 2.1 GPa), thermal stability (Td5% = 496.1 °C, Tg = 306.2 °C), and a low coefficient of thermal expansion (51.7 ppm/K). Notably, the composite film still maintains good hydrophobic properties, with a water contact angle of 81.2° and a water absorption rate of 3.1%. This research also details an efficient coating method to fabricate flexible dielectric films, proposing a strategy for the development of advanced insulating materials suitable for high-frequency and high-speed communication applications.
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高影响因子
JOURNAL OF MATERIALS SCIENCE
·
2024
·Vol. 59
·期 32
·15283-15297
·
IF 3.5
Li Dandan,Ye Qibin,Zhao Dong,Li Hui,Chen Chunhai,Qian Guangtao,Yang Jinjun
As the continuous development of aerospace and outer space exploration, high-performance thermal insulation materials with high-temperature resistance and attractive mechanical properties have always been a fascinating topic of research to protect human body or components from extreme environments. In this research, hydrophobic silicon dioxide (SiO 2 ) nanoparticles as molecular skeleton enhancers and heat transfer inhibitors are introduced in crosslinked polyimide (PI) aerogels with rigid molecular structure to maintain the stable nanoporous network structure. The density, shrinkage, porosity, specific surface area and pore size distribution of PI/SiO 2 composite aerogels can be adjusted by the addition of SiO 2 nanoparticles, so as to improve the comprehensive performances. The excellent thermal stability and mechanical properties of PI/SiO 2 composite aerogels with super-high working temperature of over 550 °C and high modulus of compression and tension (compression Young’s modulus of 37.75 MPa and tensile modulus of 237.1 MPa) ensure their use as a structural component. The charming thermal conductivity (29.7 mWm −1 K −1 ) and excellent flame resistance make them a candidate for high-performance thermal insulation materials. Graphical abstract
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高影响因子
JOURNAL OF MEMBRANE SCIENCE
·
2022
·
IF 10.53
Jun Long,Wenheng Huang,Jingfeng Li,Yafei Yu,Bo Zhang,Jinchao Li,Yaping Zhang,Hao Duan
As a key component of vanadium redox flow battery (VRFB), the ideal membrane with high proton conductance together with high vanadium ions resistance is urgently required. In this work, a permselective monomer di(aminobenzo)-18-crown-6 with proper aperture of 0.26–0.32 nm is synthesized to prepare branched sulfonated polyimide containing crown ether (ce-bSPI-x) membranes. In virtue of the excellent balance between vanadium ions resistance and proton conductance, the ce-bSPI-60 membrane possesses the optimum physico-chemical properties among all ce-bSPI-x membranes. Subsequently, in comparison with commercial Nafion 212 membrane, the ce-bSPI-60 membrane demonstrates higher coulomb efficiencies ( CE s) (96.50%–99.39%) and energy efficiencies ( EE s) (69.36%–85.45%). Furthermore, the ce-bSPI-60 membrane can achieve 80% of EE at 140 mA cm −2 , which is in a superior position compared with other SPI-based membranes reported in recent years. 1000-time cycles at 140 mA cm −2 without obvious structural and morphological changes proves the excellent durability of ce-bSPI-60 membrane. To sum up, the as-prepared ce-bSPI-60 membrane exhibits a great potential to match the demand of application in VRFB.
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RSC Advances
·
2017
·Vol. 7
·期 26
·16210-16216
·
IF 3.108
Guangjie Yang,Tianli Ning,Wei Zhao,Wenxiu Deng,Xikui Liu
Here, using water as the only solvent, we report the first green approach to the morphological controlled synthesis of robust ambient dried polyimide aerogels composed of interconnected hollow spheres. The addition of graphene oxide can direct the growth of polyimide into nanofibers and form 1D–2D nanohybrid aerogels. The mechanism behind is a soft/hard template directed dissolution-polymerization-reprecipitation process. After carbonization, a monolith carbon aerogel with monodisperse micropores could be formed. Such a green approach for the morphology controlled synthesis of robust polyimide aerogels and their carbon aerogels should be of great value for their environmental and energy related applications.
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危险品化学品经营许可证（带存储）