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Carbon nanotubes (CNTs), with their extraordinary combination of mechanical, electrical, and thermal properties, have emerged as a revolutionary class of nanomaterials with immense potential in energy storage and harvesting devices. Realizing this potential hinges on a fundamental challenge: the dispersion stability of CNTs within various matrices. This review paper provides a comprehensive exploration of the critical interplay between CNT dispersion stability and its far-reaching implications for the performance of energy storage and harvesting technologies. By delving into the underlying mechanisms of dispersion, the strategies to achieve stability, and the direct effects on device functionality, this review sheds light on the intricate relationship between nanotube dispersion and the advancement of energy-related applications. [ABSTRACT FROM AUTHOR]

Abstract With the huge variety of wearable/stretchable electronic devices that require materials with different properties depending on the applications, securing the large reserves of stretchable material systems is crucial. In this study, trimethylolpropane formal acrylate (TFA)-based polymer films are explored to develop stretchable composite electrodes. The TFA resin containing 1-hydroxycyclohexyl phenyl ketone as a photoinitiator is UV curable and shows a high optical transmittance of ∼93.0 ± 0.3% and a low haze of ∼0.29 ± 0.03%. The TFA films can withstand a tensile strain up to 100% and show excellent mechanical reliability during 30 cycles of tensile tests. Furthermore, the elastomeric TFA films are attachable to polymer or glass substrates, and during multiple adhesion tests, show a lower degradation of the adhesion properties than that showed by typical adhesive materials such as scotch tapes. The electrodes fabricated by embedding Ag nanowires in the surface of the TFA films (TFA/Ag nanowire electrodes) function as stretchable/patchable conductors under severe mechanical deformation such as stretching and crumpling. Furthermore, a patchable/stretchable supercapacitor comprising the TFA/Ag nanowire electrodes as a current collector is demonstrated that shows a reliable electrochemical performance under bending, stretching, and twisting conditions. [ABSTRACT FROM AUTHOR]

In this study, we explored the facile and quick dry transfer method to fabricate a paper-based electrode for flexible printed energy storage system. The conventional Ag nanoparticle suspension with high solid contents above ~50 wt% was confirmed to be deposited on a super hydrophobic polyethylene terephthalate (SHP-PET) substrate without a special ink formulation or surface treatment of substrate. The silver nanoparticle (AgNP) layer on the SHP-PET was able to be transferred only onto the toner-printed region of the paper substrate during a simple lamination process, thereby realizing the patterned AgNP conductive lines on the paper substrates. The AgNP/toner/paper electrodes were highly robust, showing no deterioration in conductivity after taping for 100 times. Moreover, the AgNP/toner/paper electrodes successfully functioned as flexible electrodes; thus, light emitting diodes connected to the AgNP/paper electrodes could be operated under folding deformation without significant loss of brightness. As a potential application in flexible energy storage systems, a flexible supercapacitor based on the AgNP/toner/paper electrodes as the current collector was also demonstrated; it showed an excellent power density of 10.79–16.64 kW/kg and energy density of 1.85–4.65 Wh/kg. [ABSTRACT FROM AUTHOR]

Abstract: In response to the demand for flexible and sustainable energy storage devices that exhibit high electrochemical performance, a supercapacitor system is fabricated using mulberry tree‐derived paper as a substrate and Poly(3,4‐ethylenedioxythiophene)‐poly(styrenesulfonate) (PEDOT:PSS) and carbon black as the active material. The mulberry paper‐based supercapacitor system demonstrates high energy density of 29.8–39.8 Wh kg−1 and power density of 2.8–13.9 kW kg−1 with 90.7% retention of its initial capacity over 15 000 charge–discharge cycles. In addition, the mulberry tree fibers are known to have superior mechanical strength and toughness and the mulberry paper‐based supercapacitor; as a result, exhibit high mechanical and chemical toughness; 99% of its initial capacity is retained after 100 repeated applications of bending strains, and twisting. 94% capacity retention is observed even after exposure to HCl and H2SO4 acid solutions. The fabrication methodology of the mulberry‐based supercapacitor is highly scalable and could be stacked to increase the energy storage capacity, where operation of light‐emitting diode lights with a drive voltage of 12 V integrated in a wearable device is demonstrated. [ABSTRACT FROM AUTHOR]

Micro-architectures, such as cellular truss structures, enhance the mechanical properties of structural materials while ensuring that they are lightweight in nature. Among others, stretching-dominated truss structures are known for their high modulus and yield strength, which makes them the best choice for lightweight structural applications. Finite element analysis of octahedral vs. octet structures is used to compare the differences in stress distribution in the stretching-dominated deformation of such trusses. Both octahedral and octet stretching-dominated structures were fabricated by fused deposition modeling (FDM)-based three-dimensional (3D) printing. These micro-architectures are printed with different polymeric materials, such as polylactic acid or polylactide (PLA), nylon 618, and a carbon fiber reinforced composite of PLA (CFRPLA). In addition, the CFRPLA filament with randomly suspended carbon fibers in PLA undergoes shear-induced alignment along the strut direction of the 3D printed micro-trusses, which leads to an improved Young's modulus as compared to the other materials. The properties of the 3D printed stretching-dominated micro-trusses are evaluated by compression testing, finite element analysis (FEA), and thermal analysis. The 3D printed octet structure of CFRPLA with fiber alignment exhibits the highest modulus and yield strength of 0.6 GPa and 17 MPa, respectively. [ABSTRACT FROM AUTHOR]

Silver nanowires (AgNWs) are a potential alternative to conventional transparent conductive materials for various applications, such as flexible and transparent electrodes in optoelectronic devices, including touch screens, solar cells, and flexible displays. However, AgNW electrodes face degradation due to environmental factors, electrical instability, and mechanical stress. To overcome these challenges, strategies to protect AgNW-based electrodes via the incorporation of polymeric materials were widely investigated to improve the durability and stability of AgNW-based electrodes. This review paper gives a comprehensive overview of the incorporation of polymeric materials with AgNW electrodes, emphasizing their performance, and applications. We compare the different polymeric materials and their effect on the electrical, optical, and mechanical properties of AgNW electrodes. Furthermore, we evaluate the key factors affecting the choice of protective layers, such as their compatibility with AgNWs, and also we present current challenges and future opportunities for the development of polymeric materials for AgNW electrodes in emerging technologies. [ABSTRACT FROM AUTHOR]

Abstract: Recently developed textile and paper based supercapacitors are well-suited for wearable energy storage devices due to their mechanical flexibility and stretchability. In this study, the effects of mechanical straining on carbon nanotube coated textiles are studied, and we demonstrate the pre-straining of the textile can result in an enhanced specific capacitance as well as power and energy densities. In-situ resistance measurement during mechanical straining of the textile capacitors show a decrease in resistance with tensile straining, which contributed directly to the enhancement of electrochemical performance. Two different carbon nanotube textiles based on polyester and cotton with different mechanical behaviors are examined, where the polyester textile show an increase in specific capacitance from 53.6 F g−1 to 85.7 F g−1 after the textile is pre-strained to 30% permanent elongation prior to electrochemical testing, constituting a 37% enhancement. Similarly, the cotton textile shows an enhancement in specific capacitance from 122.1 F g−1 to 142.0 F g−1 after 30% permanent elongation, which is a 22% enhancement. Specific capacitance, energy density, and power density are increased further by electroplating of MnO2 nanoparticles on the carbon nanotube coated cotton textile and then imposing a permanent elongation of 30%. Our results indicate that the simple mechanical pre-straining of the textile fibers contribute to significant enhancements in the electrochemical performance of the supercapacitors. [Copyright &y& Elsevier]

With the continual increase in CO2 levels and toward a sustainable society, developing high-performance lithium-ion batteries (LIBs) is crucial. A suitable electrode design is the key to enhancing the quality of battery cells (e.g., cycle retention characteristics and rate capabilities), and the binder plays an important role in providing sufficient adhesion between the active material, conductive agent, and current collector. Despite significant advances in the development of novel binder materials and solutions that can be employed as anode and cathode materials, careful investigations and summaries of the assessment methods for binder materials remain lacking. In this review, we examine the different analyses used to assess the quality of binder materials and how they help in assessing the quality of the electrode design. In addition, future perspectives on binder assessment are presented, which can be applied to future research directed toward binder development for advanced LIBs or post-LIBs. [ABSTRACT FROM AUTHOR]

PVDF and P(VDF-TrFE) nano- and micro- structures have been widely used due to their potential applications in several fields, including sensors, actuators, vital sign transducers, and energy harvesters. In this study, we developed vertically aligned P(VDF-TrFE) core-shell structures using high modulus polyurethane acrylate (PUA) pillars as the support structure to maintain the structural integrity. In addition, we were able to improve the piezoelectric effect by 1.85 times from 40 ± 2 to 74 ± 2 pm/V when compared to the thin film counterpart, which contributes to the more efficient current generation under a given stress, by making an effective use of the P(VDF-TrFE) thin top layer as well as the side walls. We attribute the enhancement of piezoelectric effects to the contributions from the shell component and the strain confinement effect, which was supported by our modeling results. We envision that these organic-based P(VDF-TrFE) core-shell structures will be used widely as 3D sensors and power generators because they are optimized for current generations by utilizing all surface areas, including the side walls of core-shell structures. [ABSTRACT FROM AUTHOR]

Nanoscale time-dependent mechanical-electrical coupled behavior of single crystal ZnO nanorods was systematically explored, which is essential for accessing the long-term reliability of the ZnO nanorod-based flexible devices. A series of compression creep tests combined with in-situ electrical measurement was performed on vertically-grown single crystal ZnO nanorods. Continuous measurement of the current (I)-voltage (V) curves before, during, after the creep tests revealed that I is non-negligibly increased as a result of the time-dependent deformation. Analysis of the I-V curves based on the thermionic emission-diffusion theory allowed extraction of nanorod resistance, which was shown to decrease as time-dependent deformation. Finally, based on the observations in this study, a simple analytical model for predicting the reduction in nanorod resistance as a function of creep strain that is induced from diffusional mechanisms is proposed, and this model was demonstrated to be in an excellent agreement with the experimental results. [ABSTRACT FROM AUTHOR]

The fibrous supercapacitor is a promising candidate for wearable energy-storage systems due to excellent mechanical reliability under deformation. In this study, a mechanically reliable fibrous supercapacitor with high volumetric power density and energy density was developed using fiber electrodes composed of multilayered active materials coated on silk yarns. The conductive silk yarn electrodes are fabricated via a sequential dip-coating process of silver nanowires, multi-walled carbon nanotubes (MWCNT, three to seven walls), and poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS). The composite-coated silk yarn electrodes were stable under cyclic bending as well as under washing in water. Due to the synergetic effect of the three conducting materials, an excellent electrochemical performance was obtained resulting in high volumetric energy and power densities of 8–13 mWh cm−3 and 8–19 W cm−3, respectively. A yarn-type supercapacitor was demonstrated by integrating composite-coated silk yarn electrodes with a hydrogel electrolyte, showing a promising stability as evidenced by the retention of over 94% and 93% of the specific capacitance after 90-degree bending and stretching. [ABSTRACT FROM AUTHOR]

The development of highly stable and efficient oxide-based red phosphors is urgently required for next-generation lighting devices. Herein, we report the micro/crystal structures and luminescent properties of single-phase Eu 2 (WO 4) 3 and Eu3+-doped WO 3 -Eu 2 (WO 4) 3 composite phosphors prepared by a one-step conventional solid-state reaction method in air atmosphere. As increasing Eu contents in the mixtures of WO 3 and Eu 2 O 3 , the intensities of the X-ray diffraction peaks of Eu 2 (WO 4) 3 increased while that of WO 3 decreased. The photoluminescence intensity of the synthesized phosphors increased with increase in the Eu content when calcined at 900 °C, while it degraded at a higher temperature. Red-emitting single-phase Eu 2 (WO 4) 3 powders were successfully obtained when the WO 3 and Eu 2 O 3 powders were calcined in the ratio of 3:1. The intensity of the red emission spectra of the Eu 2 (WO 4) 3 phosphor was higher than those of the 6, 12, and 24 at.% Eu-added WO 3 composites at excitation wavelengths of 394 and 465 nm. On the other hand, the intensity of emission from the single-phase phosphor was lower than that of the Eu-doped WO 3 -Eu 2 (WO 4) 3 composites under excitation of UV light at 254 nm. Thus, we propose two prospective phosphors for application as red phosphors at various wavelengths. [ABSTRACT FROM AUTHOR]

• Synthesis of MFC from low-grade gum wastes. • The synthesized MFC possesses high tap density (1.4–1.7 g cm−3). • High tap density leads to outstanding volumetric capacity at 3.0 A g−1. • MFC also exhibits ultra-stable high-rate cyclability (0.001881% decrease per cycle). • Structural integrity was well maintained even after cycling. Among various natural wastes, gum wastes pose major issues, as they are unusable and hard to be disposed due to their acidic and sticky nature. Herein, a rational synthetic strategy is employed to transform various kinds of gum wastes into micron-sized carbon, which also exhibit high tap density (1.4–1.7 g cm−3) desirable for practical application in lithium-ion batteries (LIBs). Gum karaya (GK) micron-size functional carbon (GKMFC) exhibits the most outstanding electrochemical performance, with a volumetric capacity of 175.4 mAh cm−3 at a current density of 3000 mA g−1 for 5000 cycles, and possesses ultra-stable high-rate cyclability (a capacity decay of only 0.001881% per cycle). Additional electrochemical analyses reveal that GKMFC exhibits stable structural integrity as well as minimal cell resistance even after cycling, showing its practical application as viable electrode for LIBs. This work sheds light on utilizing high tap density carbon from gum wastes for LIBs, which can also be applicable to other natural wastes and carbon. Image, graphical abstract [ABSTRACT FROM AUTHOR]

The disposal of natural wastes has become a global problem and the use of lower-grade gums is very limited owing to their impurities as well as sticky nature. Rather than disposing these wastes, nanoporous carbon (nC) has instead been synthesized by carbonization and exfoliation. The synthesized nC exhibits a substantially high surface area along with abundant micro/mesopores. This desirable and useful nature of nC is well-suited for water-driven effective electrical energy conversion, which enables the fast evaporation of water via a capillary action through nanopores. Under asymmetric wetting in a water container and ambient conditions, the nC-based energy harvesters showed high capability of electricity production and reliable output generation, easily turning on a blue light-emitting diode (2.5 V and 20 mA) using a stored power source. In summary, many energy harvesters can be manufactured for the scale-up of electricity, and the suitability of regenerated carbon nanomaterials for green energy harvesting can contribute toward alleviating chronic environmental issues. [ABSTRACT FROM AUTHOR]

Abstract Lithium-ion batteries (LIBs) with higher energy density are necessary to meet the increasing demands of energy storage system (ESS) in near future. Tin (IV) oxide, SnO 2 , is one of highly promising anode candidates due to its high theoretical capacity (782 mAh g−1), abundance, environmental friendliness, and safety with organic electrolytes. However, a rapid capacity fading and poor rate capabilities arising from the large volume expansion and subsequent agglomeration of Sn nanoparticles have been major issues of SnO 2. Here, we have synthesized one-dimensional (1D) SnO 2 -amorphous titanium (IV) oxide NTs (SnO 2 -a-TiO 2 NTs), which allow both facile ionic and electron transport as well as easy penetration of electrolytes. The resultant SnO 2 -a-TiO 2 NTs not only alleviate volume expansion by maintaining their structural integrity but also possess minimal charge transfer resistance even after a number of cycles. SnO 2 -a-TiO 2 NTs exhibit both excellent cycle retention characteristics (1050.2 mAh g−1 after 250 cycles) and outstanding rate capability (522.3 mAh g−1 at a current density of 5000 mA g−1), which is attributed to the introduction of amorphous TiO 2 that not only acts as buffer agent for volume changes of SnO 2 but also allows fast surface-controlled diffusion process due to its pseudocapacitive charge storage mechanisms. Graphical abstract Image 1 Highlights • Introduction of amorphous TiO 2 into SnO 2 nanotubes (SnO 2 -a-TiO 2 NTs). • SnO 2 -a-TiO 2 NTs fabricated by one-step electrospinning and calcination. • Incorporation of amorphous TiO 2 leads to higher Li diffusivity. • SnO 2 -a-TiO 2 NTs exhibit excellent cycle retention and rate capabilities. • Amorphous TiO 2 effectively alleviates the volume changes of SnO 2. [ABSTRACT FROM AUTHOR]

Hydrous ruthenium oxide (RuO 2) has been considered a potential electrode for supercapacitors. However, RuO 2 is not easy to be hydrous, which impedes advancement in RuO 2 -based supercapacitors. Here, strontium cation (Sr2+) – with a lower oxidation state than Ru4+ – doping effects on improving the capability of RuO 2 to be hydrous are reported. The Sr2+ doping in the RuO 2 was simply possible using electrospinning and subsequent calcination, affecting hydrous properties and promoting miniaturization of nanograins in one-dimensional (1D) nanofibers. The compositions of hydrous Sr2+-doped RuO 2 (H-Sr x Ru 1−x O 2−x) nanofibers were optimized considering correlations between synthesis temperature and degree of hydration. It was found that the H-Sr 0.2 Ru 0.8 O 1.8 nanofibers synthesized at 400 °C were hydrous compared with the pristine RuO 2 and H-Sr 0.1 Ru 0.9 O 1.9 nanofibers. The H-Sr 0.2 Ru 0.8 O 1.8 nanofibers (400) could possess the smallest nanocrystallites, increasing electrochemically active surface area and satisfying specific capacitance of 612.6 A/g at a scan rate of 50 mV s–1. • A Sr2+-doped RuO 2 nanofibers were successfully fabricated by electrospinning and calcination. • Sr2+ doping enabled RuO 2 nanofibers to be hydrous and to possess miniaturized nanograins. • Sr2+ doping in RuO 2 was optimized for annealing temperature and composition. • The highly hydrous Sr 0.2 Ru 1.8 O 1.8 nanofibers boost the capacitance performance. [ABSTRACT FROM AUTHOR]

• Metal coordinated phthalocyanine improves Zn2+ intercalation reversibility. • The types of metal ligand have affected on Zn2+ adsorption efficiency. • Iron-phthalocyanine maximizes energy capacity, and electrochemical reliability. • Phthalocyanine-ITO-PET electrode is highly efficient Zn ion flexible battery. Aqueous Zn-ion battery has developed as an alternative to overcome the limitations of conventional Li-ion batteries, but its application is insufficient due to low reversibility and electrochemical reliability. In this study, we developed a cathode for aqueous Zn-ion battery with improvement of reversibility and electrochemical reliability utilizing phthalocyanine (PTC) that efficiently transports metal ions and electrons. The intercalation/de-intercalation reaction of Zn2+ ions changes according to the central metal ligand ion of PTC, and iron (II) coordinated PTC exhibited the outstanding energy storage capacity (161.34 mAh/g) and electrochemical reliability (99%, 100 cycles). Based on maximized electrochemical performance and reliability, Zn-ion flexible battery was successfully demonstrated by utilizing air-spray coating. [ABSTRACT FROM AUTHOR]