ADVANCED FUNCTIONAL MATERIALS
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2021
·Vol. 32
·期 4
·2106176
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IF 18.808
Yurui Deng,Yuelei Pan,Zhongxin Zhang,Yangyang Fu,Lunlun Gong,Chengyuan Liu,Jiuzhong Yang,Heping Zhang,Xudong Cheng
Separators are vital parts of all lithium-ion batteries (LIBs), and they play a critical role in their thermal safety and electrochemical performance. Considering the low thermal stability and inferior electrolyte wettability of commercial polyolefin membranes, in this study, a novel thermotolerant polyimide aerogel (PIA) separator is designed. This is the first report on the use of chemically cross-linked PIA separators for LIBs. The outstanding porosity (78.35%) and electrolyte absorption (321.66%) of PIA separators contribute to the low internal resistance and outstanding electrochemical performance of LIBs, which can retain a high specific capacity of 118 mAh g −1 after 1000 cycles at a current density of 1 C. In addition, The LiFePO 4 |Li metal batteries with PIA separators are extremely stable at 90 °C (>300 cycles), and maintain stability even at 120 °C. More importantly, for pouch batteries, PIA separators result in higher thermal runaway temperatures compared with Celgard separators. In this paper, the pyrolysis mechanism and thermodynamic process of PIA separators are clarified by DFT calculations and in situ synchrotron vacuum UV photoionization mass spectrometry experiments.
研究领域:
材料科学
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能源技术
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产品关联
DOI
高影响因子
JOURNAL OF MEMBRANE SCIENCE
·
2021
·
IF 8.742
Weilin Feng,Jiaqi Li,Chuanjie Fang,Lin Zhang,Liping Zhu
In this work, the design of robust polyimide (PI) membranes applicable for precise molecular sieving in organic solvents using an ingenious thermal annealing process is reported. In this method, a porous PI ultrafiltration membrane was used as precursor and the temperature was controlled at around the glass transition temperature ( T g ) of PI. The crosslinking and relaxation of the polymer chains occurred simultaneously to facilitate in-situ healing of the pores on the surface to form a solvent-resistance, thin, and defect-free separation layer, without affecting the bulk structure. The resultant PI membrane showed superb sieving performance towards molecules with a narrow gap in the molecular weight around 300 Da (i.e., steep S-shape rejection curve), and acceptable permeabilities for many solvents (e.g., 1.5 L m −2 h −1 bar −1 for acetone, and 0.76 L m −2 h −1 bar −1 for ethanol). These permselective performances conferred upon the membrane with great potential for precise organic solvent nanofiltration (OSN). Furthermore, a remarkable stability without obvious change in the perm-selective performances during long-term OSN application was displayed due to the crosslinked structure. This work demonstrated that thermal treatment is a useful and promising method to fabricate organic solvent resistant membranes with molecular-level sieving ability for highly-efficient OSN.
研究领域:
材料科学
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分离技术
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化学工程
✓ 已验证
产品关联
DOI
高影响因子
ELECTROCHIMICA ACTA
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2021
·
IF 6.901
Wenjuan Han,Minhan Li,Yuanyuan Ma,Jianping Yang
Organic materials are promising materials for anode electrodes in aqueous hydronium-ion battery due to their flexible of structural, the abundant resources and the tunable electrochemical properties. However, the dissolution of the organic materials in the electrolytes is still inevitable. Polyimide (PI) possesses stable aromatic core, π–π stacking interaction, and increased conjugated system , which are favorable for fast charge transfer kinetics and stable cycling performance of aqueous hydronium-ion battery. Here, the synthesis PI by 1,4,5,8-naphthalenetetracarboxylic dianhydride (NTCDA) and urea is reported. In this work, the capacity of full cell can retain about 67.9% at the current of 5 A•g −1 after charging-discharging over 5000 cycles. Therefore, our studies are suggesting a potential feasibility of these NTCDA-based carbonyl PI as promising organic anode materials for aqueous hydronium-ion battery.
研究领域:
材料科学
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电化学
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产品关联
DOI
高影响因子
Crystals
·
2021
·Vol. 11
·期 11
·1383
·
IF 2.589
Panpan Zhang,Lize Zhang,Ke Zhang,Jiupeng Zhao,Yao Li
Due to the high value of its dielectric constant, polyimide does not meet the requirements of the development of integrated circuits and high-frequency printed circuits. The development of novel low dielectric constant polyimide materials for the preparation of flexible copper clad laminates is of theoretical and practical significance in the application of polyimide for 5G communications. In this work, different fluorinated graphene/polyamic acids (FG/PAA) were used as the precursor, and the porous polyimide film was successfully prepared by phase inversion. The dielectric constant of the porous polyimide film is relatively low, being less than 1.7. When the content of fluorinated graphene is 0.5 wt%, the overall dielectric performance of the porous film is the best, with a dielectric constant of 1.56 (10 kHz) and a characteristic breakdown field strength of 56.39 kV/mm. In addition, the mechanical properties of the film are relatively poor, with tensile strengths of 13.87 MPa (0.2 wt%), 13.61 MPa (0.5 wt%), and 6.25 MPa (1.0 wt%), respectively. Therefore, further improving the breakdown resistance and mechanical properties of the porous film is essential for the application of porous ultra-low dielectric polyimide materials.Keywords:polyimide;phase inversion;dielectric constant;porous films
研究领域:
材料科学
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电子工程
✓ 已验证
产品关联
DOI
高影响因子
Gels
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2022
·Vol. 8
·期 1
·57
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IF 4.432
Zhongxin Zhang,Yurui Deng,Zhiyi Lun,Xiao Zhang,Mingyuan Yan,Pan He,Caihong Li,Yuelei Pan
Polyimide (PI) aerogels were prepared using self-designed silicone polymer cross-linkers with multi-amino from low-cost silane coupling agents to replace conventional small-molecule cross-linkers. The long-chain structure of silicone polymers provides more crosslinking points than small-molecule cross-linkers, thus improving the mechanical properties of polyimide. To investigate the effects of amino content and degree of polymerization on the properties of silicone polymers, the different silicone polymers and their cross-linked PI aerogels were prepared. The obtained PI aerogels exhibit densities as low as 0.106 g/cm3and specific surface areas as high as 314 m2/g, and the maximum Young’s modulus of aerogel is up to 20.9 MPa when using (T-20) as cross-linkers. The cross-linkers were an alternative to expensive small molecule cross-linkers, which can improve the mechanical properties and reduce the cost of PI aerogels.Keywords:aerogel;polyimide;low-cost cross-linkers;silicone polymers
研究领域:
材料科学
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化学工程
✓ 已验证
产品关联
DOI
PubMed
高影响因子
CHEMICAL ENGINEERING JOURNAL
·
2022
·
IF 16.744
Changcheng Jiang,Jiayun Chen,Xuejun Lai,Hongqiang Li,Xingrong Zeng,Yinan Zhao,Qingtao Zeng,Jiefeng Gao,Zhengzhong Wu,Yunkun Qiu
Multifunctional smart fire-protection aerogels are urgently needed to meet the requirement of the Internet of Everything era. Herein, we fabricated a mechanically robust and high fire-safe polyimide/MXene composite aerogel (denoted as PI@MXene) with sensitive temperature-sensing and fire-warning capability. Thanks to the unique thermoelectric effect and high electrical conductivity of the 2D transition metal carbide (MXene) nanosheet, PI@MXene exhibited a linear relationship between the thermoelectric voltage and the temperature difference, showing sensitive temperature-sensing capability. When being burned, it could repeatedly trigger the fire-warning system in less than 5 s. More importantly, owing to the lamellar barrier and skeleton supporting effect of the MXene nanosheets, PI@MXene exhibited excellent flame retardancy, which self-extinguished within 1 s after exposing to a flame for 60 s and whose peak heat release rate was significantly decreased by 78% compared with PI aerogel. Besides, PI@MXene showed impressive thermal insulation, outstanding thermostability and durable piezoresistive sensing. This work provides a novel strategy to fabricate next-generation multifunctional fireproof aerogel, showing promising applications in intelligent robots, aerospace, and railway transportation.
研究领域:
材料科学
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智能材料
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火灾安全工程
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产品关联
DOI
高影响因子
ACS Applied Nano Materials
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2022
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IF 6.14
Zhimin Hao,Juntao Wu
A complex air pollution environment requires filters to be multifunctional. Nanofibrous materials with surface-loaded metal–organic frameworks (MOF-fibers) are reasonable structures for multifunctional air filtration. These materials can not only utilize the network structure of fibers to intercept particulate matter (PM) but also retain the porous structure of the MOFs to adsorb toxic gas. Epitaxial growth methods are commonly utilized to prepare MOF-fibers but are uneconomical and time-consuming. Herein, a facile self-assembly strategy is developed to prepare zeolitic imidazolate framework-polyimide (ZIF-PI) nanofibers with an interconnected network structure and high porosity for air filtration applications. Due to their unique structure, the ZIF-PI nanofibrous membrane exhibited high PM2.5 filtration efficiency and enhanced SO2 adsorption capacity. Moreover, by exploring the morphology evolution of the ZIF-PI nanofibrous membrane, a possible “synergistic effect of hydrophobic and electrostatic force” self-assembly mechanism was demonstrated.
研究领域:
材料科学
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环境科学
✓ 已验证
产品关联
DOI
高影响因子
POLYMERS FOR ADVANCED TECHNOLOGIES
·
2019
·Vol. 31
·期 3
·433-439
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IF 2.162
Fengmei Cheng,Hao Li,Haidong Li
High dielectric constant is highly desirable in capacitors and memory devices. In this work, oleic acid (OA)-capped BaTiO 3 nanocrystals were synthesized by a two-phase approach. Polyimide (PI)/BaTiO 3 -nanocrystal composite thin films with high dielectric constant have been successfully fabricated. The morphologies and dielectric properties of the hybrid films were exploited. The results showed that BaTiO 3 nanocrystals can be uniformly dispersed in the PI thin films owing to the surface modification of OA-capped BaTiO 3 nanocrystals. It was found that the dielectric constant of composite film varies with the volume fraction of BaTiO 3 nanocrystals and sintering temperatures and reaches a maximum value of 44.1, which is around 13 times higher than that of pristine PI thin film (3.2). These results demonstrated that PI/BaTiO 3 -nanocrystal composite films have considerable application potential in microelectronic fields.
研究领域:
材料科学
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电子工程
✓ 已验证
产品关联
DOI
高影响因子
RSC Advances
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2022
·Vol. 12
·期 12
·7276-7283
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IF 4.036
Yajun Zhang,Jie Wang,Yinjie Chen
A novel high-strength polyimide (PI) nanocomposite film was designed and constructed by the copolymerization of epoxidized polyhedral oligomeric silsesquioxane-modified hexagonal boron nitride and polyamic acid (PAA). The composite filler (EPPOSS@Gh-BN) was composed of silane coupling agent KH550 modified hexagonal boron nitride (Gh-BN) and epoxidized polyhedral oligomeric silsesquioxanes (EPPOSS), which improved not only the dispersion of the h-BN but also the effective interfacial stress transfer, leading to an enhanced mechanical strength of the resultant PI nanocomposite film of 114 MPa even with a slight EPPOSS@Gh-BN loading of 0.30 wt%, and the storage modulus was increased by more than 30% to 4 GPa compared to pure PI. Meanwhile, the PI/EPPOSS@Gh-BN nanocomposite has better heat transfer performance, higher hydrophobicity, lower dielectric properties, and higher heat stability than pure PI, and is therefore expected to provide an ideal platform for the development of highly flexible electronics in the future.
研究领域:
材料科学
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高分子科学
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纳米技术
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复合材料
✓ 已验证
DOI
PubMed
高影响因子
HIGH PERFORMANCE POLYMERS
·
2022
·
IF 1.73
Yihao Nie,Xibin Yi,Xinfu Zhao,Shimo Yu,Jing Zhang,Xiaochan Liu,Sijia Liu,Zhipeng Yuan,Minna Zhang
The cost of CO2 separation and energy consumption can be decreased through the use of CO2 adsorption. Due to the electron-rich heteroatoms in its network, polyimide (PI) has a remarkable affinity for CO2. Polyethylene glycol (PEG) can increase the layer spacing of polymers, so as to change the mass transfer of CO2 in it. Furthermore, the ether bond (-O-) in PEG has good affinity for CO2. In this study, PEG-1000 was introduced into PI aerogel by mild sol-gel method at low temperature, and freeze-drying was used to produce PI/PEG composite aerogels with directional pore structure. The effect of PEG-1000 content and directional pore structure of the PI/PEG composite aerogels on CO2 adsorption performance were further studied. The L-PI/PEG-4 composite aerogel, which contains 4 g PEG and is directionally frozen in liquid nitrogen, has a CO2 adsorption capacity of 16.76 cm3/g at 25°C and 1 bar. L-PI/PEG-4 aerogel also exhibits high CO2/N2 selectivity and adsorption cycle stability.
研究领域:
材料科学
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环境科学
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化学工程
✓ 已验证
产品关联
DOI
高影响因子
Polymers
·
2022
·Vol. 14
·期 22
·4910
·
IF 4.967
Jianyun Wu,Wenhe Zhou,Xiaowei Wang,Shicheng Li
Polyimide (PI) film is widely used as the key component of the capacitive humidity sensor, whose diffusion coefficient has a significant impact on the sensor’s dynamic characteristics, but is rarely discussed. This paper provides a test method and processes for effective diffusion coefficients of water molecules in self-synthesis PI films. The films were formed by four ingredients (PMDA-ODA, BPDA-ODA and BPDA-BAPP, PMDA-BAPP) with PI acid concentrations of 23%, 20%, 17% and 15%, and tested in temperatures of 20 °C, 35 °C and 50 °C, respectively. The results indicated that BPDA-BAPP film was good as a moisture sensitive film, whose average effective diffusion coefficient was 2.709 × 10−14m2/s. The temperature of the environment had a significant effect on the humidity-sensitive properties, but the PI acid concentration effect could be indirect.Keywords:humidity sensor;polyimide film;humidify-sensitive properties;effective diffusion coefficient
研究领域:
材料科学
·
传感器技术
✓ 已验证
产品关联
DOI
PubMed
高影响因子
JOURNAL OF MEMBRANE SCIENCE
·
2022
·
IF 10.53
Shan Xu,Ning Zhao,Lei Wu,Shuanyan Kang,Zhiguang Zhang,Guolong Huo,Zhongde Dai,Nanwen Li
Tuning the relationship between the microporous structure of carbon molecular sieve (CMS) membranes and the corresponding gas permeability performance enables optimization for gas separation applications. The pre-crosslinked structure of the precursor plays a key role in improving the performance of the CMS membrane. Herein, the thermally crosslinkable brominated 6FDA-based polyimide (BMPI) by debromination is prepared and selected as the precursor to fabricate high performance CMS gas separation membranes . By heat-treating the BMPI membrane at 350 °C for 10 h, the debromination-induced crosslinking exhibited higher permeability over the uncrosslinked precursors, as it forms a pre-crosslinked structure that is more stable at 550 °C. A representative BMPI-350/10h-550 °C CMS membranes pyrolyzed at 550 °C had CO 2 and O 2 permeabilities of 11169 and 2182 Barrer with a CO 2 /CH 4 and O 2 /N 2 ideal selectivity of 26.5 and 5.4. These values are much higher than that of the un-crosslinkable precursor (6FDA-DAM) derived CMS membrane (P CO2 = 3465, α CO2/CH4 = 21.1). Even at the high carbonization temperature of 800 °C, the as-obtained CMS membrane still show a promising CO 2 permeability of 1119 Barrer and a CO 2 /CH 4 ideal gas selectivity of 41.2. Importantly, the excellent gas separation performance of CMS membranes obtained in this work exceeds the Robeson's upper-bound. This work outlines a new protocol to tailor CMS membrane microstructures to meet high permeability performance needs. These CMS membrane materials hold great potential in corrosive natural gas purification applications.
研究领域:
材料科学
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化学工程
✓ 已验证
产品关联
DOI
高影响因子
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