Conductive,self-cleaning,and short-circuit proof multi-functional graphene aerogel composite fibers

This work reports the superior properties of flexible multi-functional composite fibers based on graphene aerogel fibers. With the addition of phase change materials, the graphene aerogel fibers were synthesized by wet spinning and supercritical drying. The phase change materials can improve the structural uniformity and thermal stability of the composite fibers. The fibers coated with polydimethylsiloxane and fluorocarbon can respond to various external stimuli (e.g., electrons, photons, and heat), as well as have excellent properties of shape compliance, self-cleaning, and insulated surfaces. After coating fluorocarbon, the maximum water contact angle of graphene aerogel fibers increases from 132.18° to 151.77°. It is worth mentioning that adding an insulation layer of polydimethylsiloxane avoids the high-temperature problem caused by the short circuit of graphene aerogel fibers. The short-circuit temperature of graphene aerogel fibers is as high as 65 °C, while that of the composite fiber is only 41.5 °C after coating with polydimethylsiloxane. The temperature of graphene aerogel fibers with polyethylene glycol can increase to 39.3 °C under simulated sunlight. In addition, graphene aerogel fibers have excellent electrical conductivity (4.85?×?10³ S m^?1) at 300 K. After coating with polyethylene glycol, its electrical conductivity is still as high as 2.95?×?10³ S m^?1. The good electrical conductivity makes the aerogel fibers have promising application in advanced wearable systems.

     

Stretchable All‐Gel‐State Fiber‐Shaped Supercapacitors Enabled by Macromolecularly Interconnected 3D Graphene/Nanostructured Conductive Polymer Hydrogels

Nanostructured conductive polymer hydrogels (CPHs) have been extensively applied in energy storage owing to their advantageous features, such as excellent electrochemical activity and relatively high electrical conductivity, yet the fabrication of self‐standing and flexible electrode‐based CPHs is still hampered by their limited mechanical properties. Herein, macromolecularly interconnected 3D graphene/nanostructured CPH is synthesized via self‐assembly of CPHs and graphene oxide macrostructures. The 3D hybrid hydrogel shows uniform interconnectivity and enhanced mechanical properties due to the strong macromolecular interaction between the CPHs and graphene, thus greatly reducing aggregation in the fiber‐shaping process. A proof‐of‐concept all‐gel‐state fibrous supercapacitor based on the 3D polyaniline/graphene hydrogel is fabricated to demonstrate the outstanding flexibility and mouldability, as well as superior electrochemical properties enabled by this 3D hybrid hydrogel design. The proposed device can achieve a large strain (up to ≈40%), and deliver a remarkable volumetric energy density of 8.80 mWh cm^?3 (at power density of 30.77 mW cm^?3), outperforming many fiber‐shaped supercapacitors reported previously. The all‐hydrogel design opens up opportunities in the fabrication of next‐generation wearable and portable electronics.     

Flexible Zinc‐Ion Hybrid Fiber Capacitors with Ultrahigh Energy Density and Long Cycling Life for Wearable Electronics

Emerging wearable electronics require flexible energy storage devices with high volumetric energy and power densities. Fiber‐shaped capacitors (FCs) offer high power densities and excellent flexibility but low energy densities. Zn‐ion capacitors have high energy density and other advantages, such as low cost, nontoxicity, reversible Faradaic reaction, and broad operating voltage windows. However, Zn‐ion capacitors have not been applied in wearable electronics due to the use of liquid electrolytes. Here, the first quasisolid‐state Zn‐ion hybrid FC (ZnFC) based on three rationally designed components is demonstrated. First, hydrothermally assembled high surface area and conductive reduced graphene oxide/carbon nanotube composite fibers serve as capacitor‐type positive electrodes. Second, graphite fibers coated with a uniform Zn layer work as battery‐type negative electrodes. Third, a new neutral ZnSO₄‐filled polyacrylic acid hydrogel act as the quasisolid‐state electrolyte, which offers high ionic conductivity and excellent stretchability. The assembled ZnFC delivers a high energy density of 48.5 mWh cm^?3 at a power density of 179.9 mW cm^?3. Further, Zn dendrite formation that commonly happens under high current density is efficiently suppressed on the fiber electrode, leading to superior cycling stability. Multiple ZnFCs are integrated as flexible energy storage units to power wearable devices under different deformation conditions.     

Graphene‐Based Integrated Photovoltaic Energy Harvesting/Storage Device

Energy scavenging has become a fundamental part of ubiquitous sensor networks. Of all the scavenging technologies, solar has the highest power density available. However, the energy source is erratic. Integrating energy conversion and storage devices is a viable route to obtain self‐powered electronic systems which have long‐term maintenance‐free operation. In this work, we demonstrate an integrated‐power‐sheet, consisting of a string of series connected organic photovoltaic cells (OPCs) and graphene supercapacitors on a single substrate, using graphene as a common platform. This results in lighter and more flexible power packs. Graphene is used in different forms and qualities for different functions. Chemical vapor deposition grown high quality graphene is used as a transparent conductor, while solution exfoliated graphene pastes are used as supercapacitor electrodes. Solution‐based coating techniques are used to deposit the separate components onto a single substrate, making the process compatible with roll‐to‐roll manufacture. Eight series connected OPCs based on poly(3‐hexylthiophene)(P3HT):phenyl‐C61‐butyric acid methyl ester (PC₆₀BM) bulk‐heterojunction cells with aluminum electrodes, resulting in a ≈5 V open‐circuit voltage, provide the energy harvesting capability. Supercapacitors based on graphene ink with ≈2.5 mF cm^?2 capacitance provide the energy storage capability. The integrated‐power‐sheet with photovoltaic (PV) energy harvesting and storage functions had a mass of 0.35 g plus the substrate.     

Nano‐RuO2‐Decorated Holey Graphene Composite Fibers for Micro‐Supercapacitors with Ultrahigh Energy Density

Compactness and versatility of fiber‐based micro‐supercapacitors (FMSCs) make them promising for emerging wearable electronic devices as energy storage solutions. But, increasing the energy storage capacity of microscale fiber electrodes, while retaining their high power density, remains a significant challenge. Here, this issue is addressed by incorporating ultrahigh mass loading of ruthenium oxide (RuO₂) nanoparticles (up to 42.5 wt%) uniformly on nanocarbon‐based microfibers composed largely of holey reduced graphene oxide (HrGO) with a lower amount of single‐walled carbon nanotubes as nanospacers. This facile approach involes (1) space‐confined hydrothermal assembly of highly porous but 3D interconnected carbon structure, (2) impregnating wet carbon structures with aqueous Ru³⁺ ions, and (3) anchoring RuO₂ nanoparticles on HrGO surfaces. Solid‐state FMSCs assembled using those fibers demonstrate a specific volumetric capacitance of 199 F cm^?3 at 2 mV s^?1. Fabricated FMSCs also deliver an ultrahigh energy density of 27.3 mWh cm^?3, the highest among those reported for FMSCs to date. Furthermore, integrating 20 pieces of FMSCs with two commercial flexible solar cells as a self‐powering energy system, a light‐emitting diode panel can be lit up stably. The current work highlights the excellent potential of nano‐RuO₂‐decorated HrGO composite fibers for constructing micro‐supercapacitors with high energy density for wearable electronic devices.     

Synthesis of P‐Doped and NiCo‐Hybridized Graphene‐Based Fibers for Flexible Asymmetrical Solid‐State Micro‐Energy Storage Device

Fiber supercapacitors (FSCs) are promising energy storage devices in portable and wearable smart electronics. Currently, a major challenge for FSCs is simultaneously achieving high volumetric energy and power densities. Herein, the microscale fiber electrode is designed by using carbon fibers as substrates and capillary channels as microreactors to space‐confined hydrothermal assembling. As P‐doped graphene oxide/carbon fiber (PGO/CF) and NiCo₂O₄‐based graphene oxide/carbon fiber (NCGO/CF) electrodes are successfully prepared, their unique hybrid structures exhibit a satisfactory electrochemical performance. An all‐solid‐state PGO/CF//NCGO/CF flexible asymmetric fiber supercapacitor (AFSC) based on the PGO/CF as the negative electrode, NCGO/CF hybrid electrode as the positive electrode, and poly(vinyl alcohol)/potassium hydroxide as the electrolyte is successfully assembled. The AFSC device delivers a higher volumetric energy density of 36.77 mW h cm^?3 at a power density of 142.5 mW cm^?3. In addition, a double reference electrode system is adopted to analyze and reduce the IR drop, as well as effectively matching negative and positive electrodes, which is conducive for the optimization and improvement of energy density. For the AFSC device, its better flexibility and electrochemical properties create a promising potential for high‐performance micro‐supercapacitors. Furthermore, the introduction of the double reference electrode system provides an interesting method for the study on the electrochemical performances of two‐electrode systems.     

A New Facile Route to Flexible and Semi‐Transparent Electrodes Based on Water Exfoliated Graphene and their Single‐Electrode Triboelectric Nanogenerator

Wearable technologies are driving current research efforts to self‐powered electronics, for which novel high‐performance materials such as graphene and low‐cost fabrication processes are highly sought.The integration of high‐quality graphene films obtained from scalable water processing approaches in emerging applications for flexible and wearable electronics is demonstrated. A novel method for the assembly of shear exfoliated graphene in water, comprising a direct transfer process assisted by evaporation of isopropyl alcohol is developed. It is shown that graphene films can be easily transferred to any target substrate such as paper, flexible polymeric sheets and fibers, glass, and Si substrates. By combining graphene as the electrode and poly(dimethylsiloxane) as the active layer, a flexible and semi‐transparent triboelectric nanogenerator (TENG) is demonstrated for harvesting energy. The results constitute a new step toward the realization of energy harvesting devices that could be integrated with a wide range of wearable and flexible technologies, and opens new possibilities for the use of TENGs in many applications such as electronic skin and wearable electronics.     

Freestanding Lamellar Porous Carbon Stacks for Low‐Temperature‐Foldable Supercapacitors

High‐performance supercapacitors (SCs) are important energy storage components for emerging wearable electronics. Rendering low‐temperature foldability to SCs is critically important when wearable devices are used in a cold environment. However, currently reported foldable SCs do not have a stable electrochemical performance at subzero temperatures, while those that are performing are not foldable. Herein, a freestanding pure‐carbon‐based porous electrode, namely, lamellar porous carbon stack (LPCS), is reported, which enables stable low‐temperature‐foldable SCs. The LPCS, which is fabricated with a simple vacuum filtration of a mixture of carbon fibers (CFs), holey reduced graphene oxides (HRGOs), and carbon nanotubes (CNTs), possesses a lamellar stacking of porous carbon thin sheets, in which the CFs act as the skeleton and the HRGOs and CNTs act as binders. The unique structure leads to excellent compression resilience, high foldability, and high electronic and ionic conductivity. SCs made with the LPCS electrodes and ionic liquid electrolyte show a high energy density (2.1 mWh cm^?2 at 2 mA cm^?2), low‐temperature long lifetime (95% capacity after 10 000 cycles at ?30 °C), and excellent low‐temperature foldability (86% capacity after 1000 folding cycles at ?30 °C).     

Photosynthetic Bioelectronic Sensors for Touch Perception,UV‐Detection,and Nanopower Generation: Toward Self‐Powered E‐Skins

Energy self‐sufficiency is an inspirational design feature of biological systems that fulfills sensory functions. Plants such as the “touch‐me‐not” and “Venus flytrap” not only sustain life by photosynthesis, but also execute specialized sensory responses to touch. Photosynthesis enables these organisms to sustainably harvest and expend energy, powering their sensory abilities. Photosynthesis therefore provides a promising model for self‐powered sensory devices like electronic skins (e‐skins). While the natural sensory abilities of human skin have been emulated in man‐made materials for advanced prosthetics and soft‐robotics, no previous e‐skin has incorporated phototransduction and photosensory functions that could extend the sensory abilities of human skin. A proof‐of‐concept bioelectronic device integrated with natural photosynthetic pigment‐proteins is presented that shows the ability to sense not only touch stimuli (down to 3000 Pa), but also low‐intensity ultraviolet radiation (down to 0.01 mW cm^‐2) and generate an electrical power of ≈260 nW cm^‐2. The scalability of this device is demonstrated through the fabrication of flexible, multipixel, bioelectronic sensors capable of touch registration and tracking. The polysensory abilities, energy self‐sufficiency, and additional nanopower generation exhibited by this bioelectronic system make it particularly promising for applications like smart e‐skins and wearable sensors, where the photogenerated power can enable remote data transmission.     

Nitrogen‐Doped Carbon Encapsulated Mesoporous Vanadium Nitride Nanowires as Self‐Supported Electrodes for Flexible All‐Solid‐State Supercapacitors

Flexible 3D nanoarchitectures have received tremendous interest recently because of their potential applications in flexible/wearable energy storage devices. Herein, 3D intertwined nitrogen‐doped carbon encapsulated mesoporous vanadium nitride nanowires (MVN@NC NWs) are investigated as thin, lightweight, and self‐supported electrodes for flexible supercapacitors (SCs). The MVN NWs have abundant active sites accessible to charge storage, and the N‐doped carbon shell suppresses electrochemical dissolution of the inner MVN NWs in an alkaline electrolyte, leading to excellent capacitive properties. The flexible MVN@NC NWs film electrode delivers a high areal capacitance of 282 mF cm⁻² and exhibits excellent long‐term stability with 91.8% capacitance retention after 12 000 cycles in a KOH electrolyte. All‐solid‐state flexible SCs assembled by sandwiching two flexible MVN@NC NWs film electrodes with alkaline poly(vinyl alcohol) (PVA), sodium polyacrylate, and KOH gel electrolyte boast a high volumetric capacitance of 10.9 F cm⁻³, an energy density of 0.97 mWh cm⁻³, and a power density of 2.72 W cm⁻³ at a current density of 0.051 A cm⁻³ based on the entire cell. By virtue of the excellent mechanical flexibility, high capacitance, and large energy/power density, the self‐supported MVN@NC NWs paper‐like electrodes have large potential applications in portable and wearable flexible electronics.     

Atomically Thin Mesoporous Co3O4 Layers Strongly Coupled with N‐rGO Nanosheets as High‐Performance Bifunctional Catalysts for 1D Knittable Zinc–Air Batteries

Under development for next‐generation wearable electronics are flexible, knittable, and wearable energy‐storage devices with high energy density that can be integrated into textiles. Herein, knittable fiber‐shaped zinc–air batteries with high volumetric energy density (36.1 mWh cm^?3) are fabricated via a facile and continuous method with low‐cost materials. Furthermore, a high‐yield method is developed to prepare the key component of the fiber‐shaped zinc–air battery, i.e., a bifunctional catalyst composed of atomically thin layer‐by‐layer mesoporous Co₃O₄/nitrogen‐doped reduced graphene oxide (N‐rGO) nanosheets. Benefiting from the high surface area, mesoporous structure, and strong synergetic effect between the Co₃O₄ and N‐rGO nanosheets, the bifunctional catalyst exhibits high activity and superior durability for oxygen reduction and evolution reactions. Compared to a fiber‐shaped zinc–air battery using state‐of‐the‐art Pt/C + RuO₂ catalysts, the battery based on these Co₃O₄/N‐rGO nanosheets demonstrates enhanced and stable electrochemical performance, even under severe deformation. Such batteries, for the first time, can be successfully knitted into clothes without short circuits under external forces and can power various electronic devices and even charge a cellphone.     

Vertically Oriented Graphene Nanoribbon Fibers for High‐Volumetric Energy Density All‐Solid‐State Asymmetric Supercapacitors

Graphene fiber based micro‐supercapacitors (GF micro‐SCs) have attracted great attention for their potential applications in portable and wearable electronics. However, due to strong π–π stacking of nanosheets for graphene fibers, the limited ion accessible surface area and slow ion diffusion rate leads to low specific capacitance and poor rate performance. Here, the authors report a strategy for the synthesis of a vertically oriented graphene nanoribbon fiber with highly exposed surface area through confined‐hydrothermal treatment of interconnected graphene oxide nanoribbons and consequent laser irradiation process. As a result, the as‐obtained fiber shows high length specific capacitance of 3.2 mF cm^?1 and volumetric capacitance of 234.8 F cm^?3 at 2 mV s^?1, as well as excellent rate capability and outstanding cycling performance (96% capacitance retention after 10 000 cycles). Moreover, an all‐solid‐state asymmetric supercapacitor based on graphene nanoribbon fiber as negative electrode and MnO₂ coated graphene ribbon fiber as positive electrode, shows high volumetric capacitance and energy density of 12.8 F cm^?3 and 5.7 mWh cm^?3 (normalized to the device volume), respectively, much higher than those of previously reported GF micro‐SCs, as well as a long cycle life with 88% of capacitance retention after 10 000 cycles.     

A Silica‐Aerogel‐Reinforced Composite Polymer Electrolyte with High Ionic Conductivity and High Modulus

High‐energy all‐solid‐state lithium (Li) batteries have great potential as next‐generation energy‐storage devices. Among all choices of electrolytes, polymer‐based systems have attracted widespread attention due to their low density, low cost, and excellent processability. However, they are generally mechanically too weak to effectively suppress Li dendrites and have lower ionic conductivity for reasonable kinetics at ambient temperature. Herein, an ultrastrong reinforced composite polymer electrolyte (CPE) is successfully designed and fabricated by introducing a stiff mesoporous SiO₂ aerogel as the backbone for a polymer‐based electrolyte. The interconnected SiO₂ aerogel not only performs as a strong backbone strengthening the whole composite, but also offers large and continuous surfaces for strong anion adsorption, which produces a highly conductive pathway across the composite. As a consequence, a high modulus of ≈0.43 GPa and high ionic conductivity of ≈0.6 mS cm^?1 at 30 °C are simultaneously achieved. Furthermore, LiFePO₄–Li full cells with good cyclability and rate capability at ambient temperature are obtained. Full cells with cathode capacity up to 2.1 mAh cm^?2 are also demonstrated. The aerogel‐reinforced CPE represents a new design principle for solid‐state electrolytes and offers opportunities for future all‐solid‐state Li batteries.     

Exploration of Advanced Electrode Materials for Approaching High‐Performance Nickel‐Based Superbatteries

The surging interest in high performance, low‐cost, and safe energy storage devices has spurred tremendous research efforts in the development of advanced electrode active materials. Herein, the in situ growth of zinc–iron layered double hydroxide (Zn–Fe LDH) on graphene aerogel (GA) substrates through a facile, one‐pot hydrothermal method is reported. The strong interaction and efficient electronic coupling between LDH and graphene substantially improve interfacial charge transport properties of the resulting nanocomposite and provide more available redox active sites for faradaic reactions. An LDH–GA||Ni(OH)₂ device is also fabricated that results in greatly enhanced specific capacity (187 mAh g^?1 at 0.1 A g^?1), outstanding specific energy (147 Wh kg^?1), excellent specific power (16.7 kW kg^?1), along with 88% capacity retention after >10 000 cycles. This approach is further extended to Ni–MH and Ni–Cd batteries to demonstrate the feasibility of compositing with graphene for boosting the energy storage performance of other well‐known Ni‐based batteries. In contrast to conventional Ni‐based batteries, the nearly flat voltage plateau followed by a sloping potential profile of the integrated supercapacitor–battery enables it to be discharged down to 0 V without being damaged. These findings provide new prospects for the design of high‐performance and affordable superbatteries based on earth‐abundant elements.     

Toward Wearable Self‐Charging Power Systems: The Integration of Energy‐Harvesting and Storage Devices

One major challenge for wearable electronics is that the state‐of‐the‐art batteries are inadequate to provide sufficient energy for long‐term operations, leading to inconvenient battery replacement or frequent recharging. Other than the pursuit of high energy density of secondary batteries, an alternative approach recently drawing intensive attention from the research community, is to integrate energy‐generation and energy‐storage devices into self‐charging power systems (SCPSs), so that the scavenged energy can be simultaneously stored for sustainable power supply. This paper reviews recent developments in SCPSs with the integration of various energy‐harvesting devices (including piezoelectric nanogenerators, triboelectric nanogenerators, solar cells, and thermoelectric nanogenerators) and energy‐storage devices, such as batteries and supercapacitors. SCPSs with multiple energy‐harvesting devices are also included. Emphasis is placed on integrated flexible or wearable SCPSs. Remaining challenges and perspectives are also examined to suggest how to bring the appealing SCPSs into practical applications in the near future.     

Wet‐Spun Superelastic Graphene Aerogel Millispheres with Group Effect

Graphene aerogel has attracted great attention due to its unique properties, such as ultralow density, superelasticity, and high specific surface area. It shows huge potential in energy devices, high‐performance pressure sensors, contaminates adsorbents, and electromagnetic wave absorbing materials. However, there still remain some challenges to further promote the development and real application of graphene aerogel including cost‐effective scalable fabrication and miniaturization with group effect. This study shows millimeter‐scale superelastic graphene aerogel spheres (GSs) with group effect and multifunctionality. The GSs are continuously fabricated on a large scale by wet spinning of graphene oxide liquid crystals followed by facile drying and thermal annealing. Such GS has an unusual core–shell structure with excellent elasticity and specific strength. Significantly, both horizontally and vertically grouped spheres exhibit superelasticity comparable to individual spheres, enabling it to fully recover at 95% strain, and even after 1000 compressive cycles at 70% strain, paving the way to wide applications such as pressure‐elastic and adsorbing materials. The GS shows a press‐fly behavior with an extremely high jump velocity up to 1.2 m s^?1. For the first time, both free and oil‐adsorbed GSs are remotely manipulated on water by electrostatic charge due to their ultralow density and hydrophobic properties.     

Ultrahigh‐Conductivity Polymer Hydrogels with Arbitrary Structures

A poly(3,4‐ethylenedioxythiophene):poly(4‐styrenesulfonate) (PEDOT:PSS) hydrogel is prepared by thermal treatment of a commercial PEDOT:PSS (PH1000) suspension in 0.1 mol L^?1 sulfuric acid followed by partially removing its PSS component with concentrated sulfuric acid. This hydrogel has a low solid content of 4% (by weight) and an extremely high conductivity of 880 S m^?1. It can be fabricated into different shapes such as films, fibers, and columns with arbitrary sizes for practical applications. A highly conductive and mechanically strong porous fiber is prepared by drying PEDOT:PSS hydrogel fiber to fabricate a current‐collector‐free solid‐state flexible supercapacitor. This fiber supercapacitor delivers a volumetric capacitance as high as 202 F cm^?3 at 0.54 A cm^?3 with an extraordinary high‐rate performance. It also shows excellent electrochemical stability and high flexibility, promising for the application as wearable energy‐storage devices.     

Printable Fabrication of Nanocoral‐Structured Electrodes for High‐Performance Flexible and Planar Supercapacitor with Artistic Design

Planar supercapacitors with high flexibility, desirable operation safety, and high performance are considered as attractive candidates to serve as energy‐storage devices for portable and wearable electronics. Here, a scalable and printable technique is adopted to construct novel and unique hierarchical nanocoral structures as the interdigitated electrodes on flexible substrates. The as‐fabricated flexible all‐solid‐state planar supercapacitors with nanocoral structures achieve areal capacitance up to 52.9 mF cm^?2, which is 2.5 times that of devices without nanocoral structures, and this figure‐of‐merit is among the highest in the literature for the same category of devices. More interestingly, due to utilization of the inkjet‐printing technique, excellent versatility on electrode‐pattern artistic design is achieved. Particularly, working supercapacitors with artistically designed patterns are demonstrated. Meanwhile, the high scalability of such a printable method is also demonstrated by fabrication of large‐sized artistic supercapacitors serving as energy‐storage devices in a wearable self‐powered system as a proof of concept.     

Mesoporous Nitrogen‐Doped Carbon Nanospheres as Sulfur Matrix and a Novel Chelate‐Modified Separator for High‐Performance Room‐Temperature Na‐S Batteries

Room‐temperature sodium‐sulfur (RT/Na‐S) batteries are considered among the most promising next‐generation energy storage and conversion systems because of the earth‐abundant reserves of sodium and sulfur. These batteries also possess the advantages of high theoretical gravimetric capacity, high energy density, and low cost. Herein, highly uniform Fe³⁺/polyacrylamide nanospheres (FPNs) are fabricated on a large‐scale by a facile, low‐cost approach. Subsequently, mesoporous nitrogen‐doped carbon nanospheres (PNC‐Ns), obtained by carbonizing FPNs, are applied as a sulfur matrix to improve the utilization of sulfur, enhance the overall conductivity of the cathode, and inhibit the shuttling of sodium polysulfides (SPSs). In addition, graphene and FPNs are simultaneously coated onto the side of the separator to form a FPNs‐graphene‐functionalized separator (FPNs‐G/separator); here, the mesoporous FPNs effectively anchor and block the SPSs, while the large specific area graphene sheets eliminate the intrinsic mechanical brittleness of the FPNs and improve the overall conductivity of RT/Na‐S batteries. When S/PNC‐Ns as a cathode and FPNs‐G/separator are assembled into an RT/Na‐S battery, it delivers a high discharge capacity (639 mAh g^‐1 at 0.1 C after 400 cycles), stable cycle life (396 mAh g^‐1 at 0.5 C after 800 cycles), and good rate performance (228 mAh g^‐1 at 2 C).     

Agglomeration Dynamics of 1D Materials: Gas‐Phase Collision Rates of Nanotubes and Nanorods

The agglomeration and self‐assembly of gas‐phase 1D materials in anthropogenic and natural systems dictate their resulting nanoscale morphology, multiscale hierarchy, and ultimate macroscale properties. Brownian motion induces collisions, upon which 1D materials often restructure to form bundles and can lead to aerogels. Herein, the first results of collision rates for 1D nanomaterials undergoing thermal transport are presented. The Langevin dynamic simulations of nanotube rotation and translation demonstrate that the collision kernels for rigid nanotubes or nanorods are ≈10 times greater than spherical systems. Resulting reduced order equations allow straightforward calculation of the physical parameters to determine the collision kernel for straight and curved 1D materials from 10² to 10⁶ nm length. The collision kernels of curved 1D structures increase ≈1.3 times for long (>10² nm), and ≈5 times for short (≈10² nm) relative to rigid materials. Applications of collision frequencies allow the first kinetic analysis of aerogel self‐assembly from gas‐phase carbon nanotubes (CNTs). The timescales for CNT collision and bundle formation (0.3–42 s) agree with empirical residence times in CNT reactors (3–15 s). These results provide insights into the CNT length, number, and timescales required for aerogel formation, which bolsters our understanding of mass‐produced 1D aerogel materials.