In this work, a novel flexible electrically resistive-type strain sensor with special three-dimensional conductive network was developed based on reduced graphene oxide (RGO)-decorated flexible ...thermoplastic polyurethane (TPU) electrospun fibrous mats. Scanning electron microscopy results indicated that RGO was localized on surfaces of the TPU fibers uniformly and formed conductive paths. The interaction between electrospun TPU fibers and RGO was investigated by using Fourier transform infrared spectra and X-ray diffraction. These fibers conductive paths connected with each other and constructed an excellent three-dimensional conductive network. The special hierarchical conductive network endowed our RGO/TPU strain sensors with a desirable integration of good stretchability and high sensitivity (gage factor (GF) of 11 in strain of 10% and 79 in strain of 100% in reversible strain regime), good durability and stability (stretch/release test of 6000 cycles) and a fast response speed. The mechanism of the evolution of residual resistance and residual strain of RGO/TPU strain sensors under cyclic loading were investigated in detail. RGO/TPU strain sensors were attached on skin or clothes to monitor various human motions. The results demonstrate that our flexible strain sensors have wide application prospects in smart wearable device.
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Wearable pressure sensors are in great demand with the rapid development of intelligent electronic devices. However, it is still a huge challenge to obtain high-performance pressure sensors with high ...sensitivity, wide response range, and low detection limit simultaneously. Here, a polyimide (PI)/carbon nanotube (CNT) composite aerogel with the merits of superelastic, high porosity, robust, and high-temperature resistance was successfully prepared through the freeze drying plus thermal imidization process. Benefiting from the strong chemical interactions between PI and CNT and stable electrical property, the composite aerogel exhibits versatile and superior brilliant sensing performance, which includes wide sensing range (80% strain, 61 kPa), ultrahigh sensitivity (11.28 kPa–1), ultralow detection limit (0.1% strain, <10 Pa), fast response time (50 ms) and recovery time (70 ms), remarkable long-term stability (1000 cycles), and exceptional detection ability toward different deformations (compression, distortion, and bending). Furthermore, the composite aerogel also shows stable sensing performance after annealing under different high temperatures and good thermal insulation property, making it workable in various harsh environments. As a result, the composite aerogel is suitable for the full-range human motion detection (including airflow, pulse, vocal cord vibration, and human movement) and precise detection of the pressure distribution when it is assembled into E-skin, demonstrating its great potential to serve as a high-performance wearable pressure sensor.
Stretchable strain sensors have promising potentials in wearable electronics for human motion detection, health monitoring and so on. A reliable strain sensor with high flexibility and good stability ...should be designed to detect human joints motions with a large deformation. Here, a simple and facile solution mixing-casting method was adopted to fabricate a highly stretchable strain sensor based on composites mixing polydimethylsiloxane (PDMS) with hybrid carbon nanotubes (CNTs) and carbon black (CB) conductive nanofillers (CNTs-CB). Bridged and overlapped hybrid CNTs-CB nanofillers structure was achieved in the composite on the basis of the morphology observation. In monotonic stretching test, the CNTs-CB/PDMS composites strain sensors exhibited high stretchability, strain-dependent sensitivity in a wide strain sensing range (ca. 300% strain) and an excellent linear current-voltage behavior. During stretching-releasing cycles, the strain sensors presented excellent repeatability, good stability and superior durability (2500 cycles at 200% strain). Combined with the above outstanding strain sensing performances, the fabricated stretchable strain sensors were attached onto different joints of human body to monitor the corresponding human motions, demonstrating their attractive perspective in large human motions detection.
Graphene (Gr) and its derivatives (such as graphene oxide (GO), reduced graphene oxide (RGO), nanoparticles decorated graphene, etc.) reinforced metal matrix composites (MMC) with good structural ...mechanical properties and functional properties have wide applications in aerospace, automotive, electronics and military fields. However, some problems exist in preparing high performance MMC including poor wettability between Gr-type fillers and metal matrix, and weak interfacial bonding strength. Efficient methods for preparing Gr-related nanomaterials filling metal matrix parts with high performance, especially for complex parts still need be further developed. The engineering application field of Gr MMC needs to be further expanded. In this paper, methods to prepare high performance MMC including surface modification of Gr and its derivatives, properties and applications of these reinforced MMC were reviewed with detailed examples. The main challenges were analyzed and the development trend of Gr-type types reinforced MMC was discussed.
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•Surface modification of graphene improved wettability between graphene and metal matrix.•Methods for preparing metal matrix composites were reviewed.•Properties of graphene reinforced metal matrix composites were reviewed.•Applications of the metal based graphene composites were reviewed.
Hybrid fillers of different geometries are increasingly utilized for the development of functional polymer composites. We herein report the role of HDPE-g-MAH as a compatibilizer for ternary ...composites consisting of HDPE, multi-walled carbon nanotubes and hexagonal boron nitride (BN). Through melt blending, HDPE-g-MAH can reduce the agglomeration of fillers and facilitate the formation of network structure. Due to the synergistic effect, ternary composites have demonstrated significantly higher thermal conductivity than those binary composites, and their maximum increase relative to the matrix is 262%. The mechanical performance and thermal conductivity are explained from perspectives of the morphology and crystallinity of the composites. The rheological properties of both binary and ternary composites have close relationship with their thermal conductivity. Although a high fraction of BN nanosheets can greatly reduce the electrical conductivity of ternary composites, they posed little effect on the electromagnetic interference shielding performance, owing to their electrical insulating nature. This research can provide new clues for the development of functional materials.
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Although lithium–sulfur (Li–S) batteries are one of the most promising energy storage devices owing to their high energy densities, the sluggish reaction kinetics and severe shuttle effect of the ...sulfur cathodes hinder their practical applications. Here, single atom zinc implanted MXene is introduced into a sulfur cathode, which can not only catalyze the conversion reactions of polysulfides by decreasing the energy barriers from Li2S4 to Li2S2/Li2S but also achieve strong interaction with polysulfides due to the high electronegativity of atomic zinc on MXene. Moreover, it is found that the homogenously dispersed zinc atoms can also accelerate the nucleation of Li2S2/Li2S on MXene layers during the redox reactions. As a result, the sulfur cathode with single atom zinc implanted MXene exhibits a high reversible capacity of 1136 mAh g−1. After electrode optimization, a high areal capacity of 5.3 mAh cm−2, high rate capability of 640 mAh g−1 at 6 C, and good cycle stability (80% capacity retention after 200 cycles at 4 C) can be achieved.
Single zinc atom implanted on MXene (Ti3C2Clx) layers not only possesses efficient electrocatalytic activity for polysulfides but also has a strong interaction with polysulfides owing to the high electronegativity of zinc atoms on MXene, greatly facilitating the nucleation and deposition of Li2S2/Li2S on MXene layers. Thus, a stable sulfur cathode with high areal capacity and high rate capabilities is achieved.
In this work, non-covalently functionalized reduced graphene oxide (rGO) reinforced poly(vinyl alcohol) (PVA) nanocomposites were prepared by solution mixing. The agglomeration of graphene sheets was ...prevented by using surface modifying agent poly(sodium 4-styrenesulfonate) (PSS). The improved mechanical properties, including the Young's modulus and tensile strength of the PVA/rGO nanocomposites compared to neat PVA were attributed to the strong interactions between PVA and rGO such as π–π, hydrogen bonding, and CH–π. A 55% maximum increase in the modulus was obtained by adding only 0.1wt% rGO, and an increase of 48% in tensile strength was achieved by adding 0.3wt% rGO. In addition, the thermal properties of the nanocomposites were also improved, which was attributed to the restriction of graphene oxide (GO)/rGO sheets on the chain mobility of polymers on the GO/rGO sheets surface.
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•Non-covalently functionalized rGO PVA nanocomposites were prepared by solution mixing.•Uniform dispersion of rGO was achieved with the assistance of poly(sodium 4-styrenesulfonate).•Strong rGO-PVA interactions and effective load transfer from rGO to PVA significantly improved the mechanical properties.
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•Enhanced piezoresistive performance of piezoresistive sensor was achieved with the assistance of brittle CNC.•The existence of amphiphilic CNC is beneficial for the dispersion of CNT ...and the improved compression properties.•The flexible piezoresistive sensor could be applied for human motion detection and artificial electronic skin.
Recently, piezoresistive sensors with wide response range and high sensitivity are in great demands with the rapid development of flexible electronic industry. To meet the demands, highly compressible waterborne polyurethane (WPU)/carbon nanotube (CNT) composite foam with enhanced piezoresistive performance was designed through incorporating the brittle cellulose nanocrystal (CNC) during the fabrication process. Here, the homogeneous dispersion of CNT with the assistance of amphiphilic CNC and the good interfacial interaction between CNC and TPU endowed the composite foam with improved compression properties. In addition, the brittle CNC/CNT conductive network is easier to be destructed, generating more significant resistance variation and about as high as 2.5 times the sensitivity of composite foam without CNC. As a piezoresistive sensor, it exhibits good compressibility and stable piezoresistive sensing signal in 80% compression strain range due to the porous structure and good elasticity of WPU. Cyclic piezoresistive sensing tests under different compression strains and rates demonstrate the excellent recoverability and reproducibility of the piezoresistive sensor after the initial stabilization process. More importantly, it also displays a fast response time of about 30 ms and good durability and reproductivity over 1000 compression cycles. Finally, the piezoresistive sensor can be successfully applied to detect various human motions (such as vocal cords/cheeks/fingers/wrists/feet movements) and to fabricate artificial electronic skin. The investigation provides an effective strategy for the fabrication of high-performance piezoresistive sensor.
Based on the contributions of carbon nanostructures and their composited species, great advances in electromagnetic wave interference shielding have been achieved. In this article, recent progress in ...electromagnetic wave shielding enabled by the synergism of carbon nanostructures and their corresponding composites is discussed encompassing the factors of microstructural defects, filler concentration, filler alignment, filler inherent conductivity and the surrounding temperature. Carbon nanostructures and their composites would energize the advanced electromagnetic wave shielding because of their light weight, high corrosion resistance, excellent thermal, mechanical, and electrical properties, broad absorption frequency bandwidth and cost-effectiveness. In this context of identifying suitable carbon composites that can enhance electromagnetic wave absorption. This review provides updated electromagnetic wave shielding knowledge of carbon nanostructures and their composites as well as their prospects and challenges.
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Compared with conventional liquid batteries, all‐solid‐state batteries (ASSBs) show great promise for enabling higher safety in electric vehicles without compromising operational durability and ...range. As a key component of ASSBs, solid‐state electrolytes (SSEs) need high ionic conductivity and favorable interfacial compatibility between electrodes and SSEs. In the recent decade, numerous efforts have been devoted to SSE advancement and fruitful achievements have been made, particularly regarding metal anode‐oriented SSEs with high energy density. This review focuses on the historical process of SSEs employed in ASSBs. The new understanding and origins for the enhanced ionic conductivity and mechanical properties of SSEs are first summarized. As to the cathode/SSE interface, its decomposition mechanism and modification strategies are analyzed. As to the interfacial issues of SSEs with anodes, the mechanisms of dendrite formation and penetration into the SSEs are discussed in detail. Additionally, assisted by a library of big data sources, contributions are systematically highlighted from different countries, institutions, and corresponding authors to significantly advance SSE progress, and certain insights are provided into the underlying relationships between various items in a collective manner. Finally, current challenges and potential strategies are identified for the future development of SSEs in ASSBs.
By illustrating the correlation between performance improvement/failure of solid state electrolytes (SSEs) and microscale material design, this review aims to provide a comprehensive evolution view and an iterative historical perspective of the SSEs over the past 10 years.
