Abstract:Polyimide (PI) aerogels enable promising application in many fields but are always inhibited by their weak resistance to high temperature and low mechanical properties. Herein, novel PI aerogel composites with efficient heat insulation and high compressive performance are prepared by introducing Silicon carbide whiskers (SiCw) as reinforcement. The SiCw in aerogel function as shrinkage inhibitor and high temperature stabilizer. The addition of SiCw exhibits obvious enhancement and toughening effect, the compre… Show more
“…33 Eventually, compared to previously reported PI aerogel composites, the density of our aerogels was in a lower/ comparable range. 20,31,32 Looking at Figure 2(B), it can be noticed that the density of our aerogels is in a similar range compared to previous PI-CNT aerogels. 20 Nevertheless, it should be highlighted that the previous works only focused on the development of bulk monolithic aerogels, which cannot be used as an electrode for energy storage applications.…”
Section: ■ Results and Discussionsupporting
confidence: 61%
“…(A) Density and shrinkage data of PI-CNT aerogel composites and (B) comparison of the fabricated aerogels’ density with previously reported aerogels, foams, electrospun nanofibers, and commercial polymers at various nanofiller’s contents ,− (comparison data is provided in Table S2). …”
Polyimide (PI) aerogels are promising in various fields of application, ranging from thermal insulators to aerospace. However, they are typically in the form of a bulk monolith, which suffers from a lack of conformability and drapability. Moreover, their electrical conductivity is limited, and they mainly display an insulative behavior. These shortcomings can limit the applications of PI aerogels in energy storage systems, which require ultralightweight flexible conductive films, which at the same time offer high thermal stability, ultralow density, and high surface area. To overcome these obstacles, the present study reports the fabrication of PI-carbon nanotube (PI-CNT) aerogel composite films with varying CNT content prepared through a sol−gel preparation method, followed by a supercritical drying procedure. Compared to pristine PI aerogels, which displayed a large shrinkage and density of 18.3% and 0.12 g cm −3 , respectively, the incorporation of only 5 wt % CNTs resulted in a significant reduction of both shrinkage and density to only 11.5% and 0.10 g cm −3 , respectively. This suggests the importance of CNTs in improving the dimensional stability of aerogels and creating a robust network. Further characterizations showed that incorporation of 5 wt % CNTs also resulted in the highest pore volume (1.25 cm 3 g −1 ), highest surface area (324 m 2 g −1 ), highest real permittivity (80), highest electrical conductivity (3 × 10 −1 S m −1 ), and ultrahigh service temperature (575 °C). It was also shown that the aerogel films can withstand a large degree of bending, can be twisted, and can be fully rolled with no obvious cracks propagated in the structure. The combined outstanding properties of the developed aerogel composite films make them promising potential candidates for supercapacitor electrodes. Therefore, the electrochemical performance of the devices based on aerogel electrodes was further studied. The device demonstrated a high energy density of 2.6 Wh kg −1 at a power density of 303.8 W kg −1 . The total capacitance after 5000 cycles was 91.8% of the initial capacitance, which indicated excellent stability and durability of the device. Overall, this work provides a facile yet effective methodology for the development of high-performance aerogel materials for energy storage applications.
“…33 Eventually, compared to previously reported PI aerogel composites, the density of our aerogels was in a lower/ comparable range. 20,31,32 Looking at Figure 2(B), it can be noticed that the density of our aerogels is in a similar range compared to previous PI-CNT aerogels. 20 Nevertheless, it should be highlighted that the previous works only focused on the development of bulk monolithic aerogels, which cannot be used as an electrode for energy storage applications.…”
Section: ■ Results and Discussionsupporting
confidence: 61%
“…(A) Density and shrinkage data of PI-CNT aerogel composites and (B) comparison of the fabricated aerogels’ density with previously reported aerogels, foams, electrospun nanofibers, and commercial polymers at various nanofiller’s contents ,− (comparison data is provided in Table S2). …”
Polyimide (PI) aerogels are promising in various fields of application, ranging from thermal insulators to aerospace. However, they are typically in the form of a bulk monolith, which suffers from a lack of conformability and drapability. Moreover, their electrical conductivity is limited, and they mainly display an insulative behavior. These shortcomings can limit the applications of PI aerogels in energy storage systems, which require ultralightweight flexible conductive films, which at the same time offer high thermal stability, ultralow density, and high surface area. To overcome these obstacles, the present study reports the fabrication of PI-carbon nanotube (PI-CNT) aerogel composite films with varying CNT content prepared through a sol−gel preparation method, followed by a supercritical drying procedure. Compared to pristine PI aerogels, which displayed a large shrinkage and density of 18.3% and 0.12 g cm −3 , respectively, the incorporation of only 5 wt % CNTs resulted in a significant reduction of both shrinkage and density to only 11.5% and 0.10 g cm −3 , respectively. This suggests the importance of CNTs in improving the dimensional stability of aerogels and creating a robust network. Further characterizations showed that incorporation of 5 wt % CNTs also resulted in the highest pore volume (1.25 cm 3 g −1 ), highest surface area (324 m 2 g −1 ), highest real permittivity (80), highest electrical conductivity (3 × 10 −1 S m −1 ), and ultrahigh service temperature (575 °C). It was also shown that the aerogel films can withstand a large degree of bending, can be twisted, and can be fully rolled with no obvious cracks propagated in the structure. The combined outstanding properties of the developed aerogel composite films make them promising potential candidates for supercapacitor electrodes. Therefore, the electrochemical performance of the devices based on aerogel electrodes was further studied. The device demonstrated a high energy density of 2.6 Wh kg −1 at a power density of 303.8 W kg −1 . The total capacitance after 5000 cycles was 91.8% of the initial capacitance, which indicated excellent stability and durability of the device. Overall, this work provides a facile yet effective methodology for the development of high-performance aerogel materials for energy storage applications.
“…89,96 The developed PI aerogels exhibited super thermal insulation performance, with thermal conductivity as low as 27.5 mW m À1 K À1 . A comparison of thermal conductivity of fabricated aerogels in this work with previously reported PI aerogels 17,24,44,48,62,89,[97][98][99] and other commercial insulation materials 100 is provided in Fig. 8(C).…”
Due to their high service temperature, excellent thermal insulation, nanoporous morphology, and low dielectric constant, polyimide (PI) aerogels have potential capability to be used in the next generation of microelectronic...
“…This phenomenon can be explained by the densification mechanism that larger liquid volume allow faster carbon rearrangement. 26,27 Therefore, compared with PI-GF (Table 4), the mass ablation rate of PI-BE40-GF is reduced by 83%, the linear ablation rate is reduced by 168%, and the back temperature is reduced by 70°C after 10 min of ablation (Figure 8), which indicates that the introduction of BE component can meet the requirements of heating and oxygen enrichment thermal protection, and can significantly improve the ablation and thermal insulation properties of polyimide composites. 28 Figure 6.Macroscopic of polyimide samples after ablation.…”
Section: Resultsmentioning
confidence: 99%
“…This is due to the high-temperature porcelain forming reaction between albite and glass powder provides the physical barrier, which can not only prevent the escape of decomposition gas, but also prevent the diffusion of oxygen into the material. 26,27 Ablation and heat insulation performances of samples…”
Section: Thermogravimetric Analysis Of Samplesmentioning
Polyimide is a class of resins with high heat resistance, and their composites have a wide range of applications in military and civilian. However, the application of polyimides as an ablation and thermal insulation material has always been a challenge due to their low char yield during ablation in the air. Herein, we described the first application of polyimide composites—albite/glass powder doped polyimide hybrid materials - as an ablation and thermal insulation material. The key to the success of this case is that the process of the ceramization of albite/glass powder can greatly reduce the carbon loss of polyimide during the ablation process in the air. Moreover, the mechanical properties, thermal stability, ablation and thermal insulation properties of these polyimide hybrid materials have been studied systematically. This work not only opens up a new application for polyimide, but also provides a new idea for the design of novel ablation and thermal insulation material.
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