The rapid development of portable/wearable electronics proposes new demands for energy storage devices, which are flexibility, smart functions and long-time outdoor operation. Supercapacitors (SCs) ...show great potential in portable/wearable applications, and the recently developed flexible, smart and self-sustainable supercapacitors greatly meet the above demands. In these supercapacitors, conductive polymers (CPs) are widely applied due to their high flexibility, conductivity, pseudo-capacitance, smart characteristics and moderate preparation conditions. Herein, we'd like to introduce the CP-based flexible, smart and self-sustainable supercapacitors for portable/wearable electronics. This review first summarizes the flexible SCs based on CPs and their composites with carbon materials and metal compounds. The smart supercapacitors,
i.e.
, electrochromic, electrochemical actuated, stretchable, self-healing and stimuli-sensitive ones, are then presented. The self-sustainable SCs which integrate SC units with energy-harvesting units in one compact configuration are also introduced. The last section highlights some current challenges and future perspectives of this thriving field.
Progress of utilizing conductive polymers and their composites to prepare flexible, smart and self-sustainable supercapacitors for portable/wearable electronics is reviewed.
MWCNTs@silk fabric (CSF) with single-side, good conductive property was prepared via a surface micro-dissolution strategy. In this method, the partial dissolution of silk fibers was regulated by the ...concentration formic acid and the interaction between the protein and its solvent. The dissolved silk protein served as the physical crosslinking agent that connected dispersed carbon nanoparticles to form a continuous conductive network, avoiding complex chemical treatments and the use of physical adhesives. CSF possessed good electrical conductivity (468 Ω cm−1) and durability. Moreover, CSF had a unique single-side loading characteristic and its resistance changed from 98.4% to 102% of the initial value with the bending angle varying from −112.5° to 112.5°, so CSF could be used as sensors to monitor the mechanical activities effectively. Patterned conductive MWCNTs@silk fabric (PCSF) was fabricated by using patterned templates during the deposition process and used for wider applications, such as flexible switches (F-shaped PCSF), soft keyboards (keyboard-like PCSF), electric heating materials (S-shaped PCSF) and microwave-assisted heating materials (butterfly-like PCSF).
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•MWCNTs@silk fabric exhibited good electrical conductivity (468 Ω•cm-1 and good conductive durability.•The resistance of MWCNTs@silk fabric changed with its deformation, making the fabric could be used as mechanical sensors.•MWCNTs@silk fabric was customizable and had potential applications in flexible electronics and heating materials.
In this work, an environmental micro-dissolution method to prepare Fe
3
O
4
NPs@cotton composite fabrics without using binders is reported. The controlled
N
-methylmorpholine
N
-oxide (NMMO) ...treatment can micro-dissolve superficial layers of fibers through the strong hydrogen bonding force. The micro-dissolved superficial layers themselves can work like glue to physically adhere surrounding Fe
3
O
4
NPs and then these Fe
3
O
4
NPs can be embedded onto the layers. In the subsequent heating treatment, the micro-dissolved superficial layers would physically re-coagulate, immobilizing Fe
3
O
4
NPs onto fibers’ surface. The as-obtained Fe
3
O
4
NPs@cotton composite fabrics were systematically characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction and X-ray photoelectron spectroscopy. Additionally, through vibrating sample magnetometry tests, the Fe
3
O
4
NPs@cotton fabrics exhibit para-magnetism, and the saturation magnetization can remain up to 90% after 20 washing cycles. Thermal gravimetric analysis and moisture absorption tests show that there are no obvious influences on thermal stability and moisture absorption capability of cotton fabrics. Even noticeable enhancements in mechanical properties can be observed.
This paper investigates the feasibility of a proposed underground gas storage facility. Based on S gas storage, a large-scale 2D hydromechanical coupling FEA model is established to explore the ...geo-mechanical properties of S gas storage under a multi-cycle alternating injection and production and validated by the interference logging test. To account for the damage development of fault damage area under the influence of seepage-stress coupling, the soil adopts the Mohr–Coulomb constitutive assumption. Additionally, a zero-thickness cohesive element is proposed as a mechanical model to simulate the fault gouge. The mechanical parameters of zero-thickness cohesive elements are verified by a ring shear test and a preliminary FE model. Thereafter, another refined conceptual finite element (FE) model considering the fault damage area, fault core, water-containing damaged area, overburden damaged area, and the contact model between different damaged areas of the fault and the fault core is developed and validated. The simulation results demonstrate that the initial seal ability of the caprock and faults remains intact. Specifically, (i) the maximum caprock and ground displacements are 8.5 cm and 5.4 cm, respectively. (ii) The most significant slip distance is 0.125 mm, indicating that, leakage under the action of multi-period alternating injection–production, the S aquifer structure had no fault activation and caprock. (iii) The risk of fault activation is higher for high-angle faults compared to low-angle faults. Low-angle faults are more susceptible to shear slip. Providing a scientific reference for the feasibility study of gas storage.
Iron fluoride (FeF3) is considered as a promising cathode material for Li-ion batteries (LIBs) due to its high theoretical capacity (712 mAh/g) with a 3e− transfer. Herein, we have designed a ...strategy of hierarchical and mesoporous FeF3/rGO hybrids for LIBs, where the hollow FeF3 nanospheres are the main contributor to the specific capacity and the 2D rGO nanosheets are the matrix elevating the electronic conductivity and buffering the volume expansion. The unique FeF3/rGO hybrid can be rationally synthesized by a non-aqueous in-situ precipitation method, offering the merits of large specific surface area with rich active sites, fast transport channels for lithium ions, effective alleviation of volume expansion during cycles, and accelerating the electrochemical reaction kinetics. The FeF3/rGO hybrid electrode possesses a high initial discharge capacity of 553.9 mAh/g at a rate of 0.5 C with 378 mAh/g after 100 cycles, acceptable rate capability with 168 mAh/g at 2 C, and feasible high-temperature operation (320 mAh/g at 70 °C). The superior electrochemical behaviors presented here demonstrates that the FeF3/rGO hybrid is a potential electrode for LIBs, which may open up a new vision to design high-efficiency energy-storage devices such as LIBs based on transition metal fluorides.
A strategy of hierarchical and mesoporous FeF3/rGO hybrids have been designed and synthesized by a rational non-aqueous in-situ precipitation method for LIBs, possessing a high initial discharge capacity of 553.9 mAh/g at a rate of 0.5 C with 378 mAh/g after 100 cycles and feasible high-temperature operation (320 mAh/g at 70 °C) Display omitted
The rapidly increasing demand for the consumption of natural gas has attracted the interests to store natural gas in aquifer reservoir. However, natural gas injected into the aquifer reservoir, which ...could cause ground surface deformation and mechanical integrity destruction of caprock. Taking the aquifer gas storage of S trap as the research object, according to the geological structure and hydrogeological information, a coupling large-scale hydromechanical model is established to evaluate the damage risk of the gas reservoir in S aquifer. The proposed methodology is based on the development of fluid-solid coupling and application of FEM. The different failure mechanisms of S aquifer gas storage caprock can be evaluated on the basis of the tensile failure criterion and Mohr-Coulomb shear failure criterion. To analyze the change of caprock in gas injection and production process more clearly, a reference model is defined as an ideal calculation condition to discuss the mechanical response, pore pressure variation, and surface deformation characteristics of the caprock during injection and production. On this basis, the second scheme of sensitivity analysis is defined. The pressure injection rate, reservoir parameters, in situ stress, and other factors are considered, respectively, and the influence of different input parameters on mechanical stability and surface deformation of caprock is analyzed. Finally, the mechanical stability is analyzed and combined the above two criteria to predict the upper limit injection pressure of S. Simulation results show that the permeability and in situ stress have a significant influence on ground surface deformation and mechanical integrity of caprock, but Young’s modulus and Poisson’s ratio can be ignored; the upper limit pressure coefficient of S is 1.908.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
In this study, cotton fabric samples were treated by the surface micro-dissolve process to improve their crease-resistance properties. The surface micro-dissolve treatment was conducted in the ...presence of sodium hydroxide/urea as an effective cellulose solvent at low temperature. The treated cotton fabrics were characterized by scanning electron microscopy, X-ray diffraction and Fourier transform infrared spectroscopy. Crease-resistance, tearing strength, breaking strength, whiteness degrees and moisture sorption values of the fabrics were also studied. The results indicated that the surface micro-dissolve treatment could effectively improve the crease-resistance properties of cotton fabrics. Moreover, the mechanical properties and whiteness degrees of fabric samples were retained well.
This paper presents a new constitutive model for describing the strain-hardening and strain-softening behaviors of clayey rock. As the conventional Mohr-Coulomb (CMC) criterion has its limitation in ...the tensile shear region, a modified Mohr-Coulomb (MMC) criterion is proposed for clayey rock by considering the maximal tensile stress criterion. Based on the results of triaxial tests, a coupled elastoplastic damage (EPD) model, in which the elastic and plastic damage laws are introduced to describe the nonlinear hardening and softening behaviors, respectively, is developed so as to fully describe the mechanical behavior of clayey rock. Starting from the implicit Euler integration algorithm, the stress-strain constitutive relationships and their numerical formulations are deduced for finite element implementation in the commercial package ABAQUS where a user-defined material subroutine (UMAT) is provided for clayey rock. Finally, the proposed model is used to simulate the triaxial tests and the results validate the proposed model and numerical implementation.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
Due to the strong hydration sensitivity of mudstone, drilling of deep mudstone is difficult and pricy, which results in the study on its physical and mechanical properties inseparable from similar ...material tests. On these bases, triaxial compression and Brazilian tensile tests of the original mudstone drilled from the caprock of the D5 aquifer structure are carried out. Then, orthogonal experiments of mudstone similar materials with river sand and barite powder as aggregate and cement and gypsum as the binder are conducted, which include 3 factors that, respectively, are mass ratio of aggregate to binder, mass ratio of cement to gypsum, and barite powder content, and each factor contains 5 levels, totalling 25 groups of 150 samples. By comparing the results of mudstone and artificial samples made of similar materials, it is obvious that artificial samples and mudstone are significantly similar in terms of density, compressive strength, elastic modulus, and compressive strength when the aggregate-binder ratio is about 4, 8, 5, and 4, respectively. Further sensitivity analysis showed that the aggregate-binder ratio played a major role in controlling the properties of artificial samples, while the sensitivity of different parameters to the cement-gypsum ratio and barite content was different. The results indicate that the selected raw materials and their proportion are feasible, which can meet similar requirements and can be a reference for similar material experimental research of target mudstone.
•The difference and necessity of each metal selenide are emphasized.•The correlations bewteen performance and structures of metal selenides are revealed.•The challenges and outlook of metal selenides ...in energy storage and conversion are also discussed.
Developing advanced energy devices with long-term operation characteristics has attracted much attention in energy storage and conversion. It proposes new demands for electrode and catalyst materials with structural controllability, electrochemical stability, and intrinsic conductivity. Fortunately, metal selenides can meet these requirements, which are the rising star of emerging candidates for energy devices nowadays. This article provides a comprehensive and critical review on the recent state-of-the-art progress of metal selenides for energy storage and conversion. The difference and necessity of each metal selenide are emphasized. The crystal and electronic structures and synthesis and modification methods of metal selenides are summarized to reveal their correlation with the performance of energy storage and conversion devices. The challenges and outlook of metal selenides in energy storage and conversion are also discussed. This review is expected to give us a deep understanding of the structure, methodology, and application of metal selenides in energy storage and conversion, which will certainly facilitate the research on this issue in the near future.
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