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A conventional electrode composite for rechargeable zinc‐ion batteries (ZIBs) includes a binder for strong adhesion between the electrode material and the current collector. However, the introduction of a binder leads to electrochemical inactivity and low electrical conductivity, resulting in the decay of the capacity and a low rate capability. We present a binder‐ and conducting agent‐free VO2 composite electrode using in situ polymerization of dopamine on a flexible current collector of pyroprotein‐based fibers. The as‐fabricated composite electrode was used as a substrate for the direct growth of VO2 as a self‐supported form on polydopamine‐derived pyroprotein‐based fibers (pp‐fibers@VO2(B)). It has a high conductivity and flexible nature as a current collector and moderate binding without conventional binders and conducting agents for the VO2(B) cathode. In addition, their electrochemical mechanism was elucidated. Their energy storage is induced by Zn2+/H+ coinsertion during discharging, which can be confirmed by the lattice expansion, the formation of by‐products including Znx(OTf)y(OH)2x−y·nH2O, and the reduction of V4+ to V3+. Furthermore, the assembled Zn//pp‐fibers@VO2(B) pouch cells have excellent flexibility and stable electrochemical performance under various bending states, showing application possibilities for portable and wearable power sources. [ABSTRACT FROM AUTHOR]

Solid‐state batteries that employ solid‐state electrolytes (SSEs) to replace routine liquid electrolytes are considered to be one of the most promising solutions for achieving high‐safety lithium metal batteries. SSEs with high mechanical modulus, thermal stability, and non‐flammability can not only inhibit the growth of lithium dendrites but also enhance the safety of lithium metal batteries. However, several internal materials/electrodes‐related thermal hazards demonstrated by recent works show that solid‐state lithium metal batteries (SSLMBs) are not impenetrable. Therefore, understanding the potential thermal hazards of SSLMBs is critical for their more secure and widespread applications. In this contribution, we provide a comprehensive overview of the thermal failure mechanism of SSLMBs from materials to devices. Also, strategies to improve the thermal safety performance of SSLMBs are included from the view of material enhancement, battery design, and external management. Consequently, the future directions are further provided. We hope that this work can shed bright insights into the path of constructing energy storage devices with high energy density and safety. [ABSTRACT FROM AUTHOR]

The polymeric gel electrolytes are attractive owing to their higher ionic conductivities than those of dry polymer electrolytes and lowered water activity for enlarged potential window. However, the ionic conductivity and mechanical strength of the Na‐ion conducting polymeric gel electrolytes are limited by below 20 mS cm−1 and 2.2 MPa. Herein, we demonstrate Na‐ion conducting and flexible polymeric hydrogel electrolytes of the chemically coupled poly(diallyldimethylammonium chloride)‐dextrin‐N,N′‐methylene‐bis‐acrylamide film immersed in NaClO4 solution (ex‐DDA‐Dex + NaClO4) for flexible sodium‐ion hybrid capacitors (f‐NIHC). In particular, the anion exchange reaction and synergistic interaction of ex‐DDA‐Dex with the optimum ClO4− enable to greatly improve the ionic conductivity up to 27.63 mS cm−1 at 25°C and electrochemical stability window up to 2.6 V, whereas the double networking structure leads to achieve both the mechanical strength (7.48 MPa) and softness of hydrogel electrolytes. Therefore, the f‐NIHCs with the ex‐DDA‐Dex + NaClO4 achieved high specific and high‐rate capacities of 192.04 F g−1 at 500 mA g−1 and 116.06 F g−1 at 10 000 mA g−1, respectively, delivering a large energy density of 120.03 W h kg−1 at 906 W kg−1 and long cyclability of 70% over 500 cycles as well as demonstrating functional operation under mechanical stresses. [ABSTRACT FROM AUTHOR]

Due to the demand for next‐generation green wearable and flexible energy storage devices, gel‐based electrolytes are attracting much attention as a key part of this system, but existing materials are problematic because of their low performance. It is necessary to maintain the function of the material by allowing it to be bent in the form of amorphous gels, easily manufactured in large quantities without toxic chemical binders used in everyday life. Here, a new storage device driven by a genetic DNA gel electrolyte is presented. The DNA gel is amorphous and intrinsically high‐electrostatic. The separator‐free device for a supercapacitor exhibits a high ionic conductivity with excellent mechanical integrity and demonstrates a maximum specific capacitance superior to liquid and other gel electrolytes. In LED lighting, the DNA gel supercapacitor (D‐gel‐SC) with higher flexibility delivers maximum energy and power density. It can even survive harsh environmental conditions without further degradation in performance. This material is promising for use as a core material for new energy storage devices. [ABSTRACT FROM AUTHOR]

The ice templating assembly has been investigated to construct macroporous channels of functional nanomaterials with well‐defined homogeneous morphology. Recently, this templating method has been revisited integrating with other materials' synthesis and processing methodologies (such as, spinning, spraying, filtration, hydrothermal, oxygenation, gelation, and 3D printing) for electrochemical energy conversion and storage applications. Herein, the recent progress on "integrative ice frozen assembly" focusing on the hierarchical structures and chemistries of functional nanomaterials such as, organic, inorganic, carbon, and composite materials for a rational design of energy application‐oriented materials is comprehensively reviewed. This integrative process allows functional nanomaterials to be assembled into various dimensions, such as, 0D, 1D, 2D, and 3D macrostructures, as well as, into larger bulk objects such as, fibers, films, monoliths, and powders. The fundamental understanding of the integrative ice frozen assembly is thermodynamically and kinetically discussed with the help of primitive freeze casting domain knowledge and the energy conversion and storage performances of the as‐designed electrodes with their hierarchical structures and chemistries are further correlated. The applications of the as‐assembled electrodes into batteries, supercapacitors, fuel cells, and electrocatalysis are also addressed. Finally, the perspective on the current impediments and future directions in this field is discussed. [ABSTRACT FROM AUTHOR]

Summary: The electrochemical performance of the Faradaic battery‐type binary metal oxide electrodes is dependent on the desirable architecture and the optimal cationic ratio. Herein, we report one‐dimensional nanowire‐like bimetallic spinel NixCo3‐xO4 (NCO) electrode materials for high performance hybrid supercapacitor (HSC) applications. This unique nanowire architecture is beneficial for providing abundant exposed active sites onto the large accessible surface area, which results in facilitating ion transporting pathways. Remarkably, the optimal NCO electrode with the ratio of Ni/Co of 1 to 1 (NCO11) achieves the maximum specific capacitance of 1033 F g−1 at 1 A g−1 and the excellent rate capability of 74.55% at 30 A g−1, far exceeding those of their single counterparts. Furthermore, the as‐assembled HSCs integrating NCO11 and AC electrodes deliver large energy and power densities of 41.54 W h kg−1 and 44.95 kW kg−1 with excellent cyclic retention (96.12%). [ABSTRACT FROM AUTHOR]

Electrochemical capacitors charge and discharge more rapidly than batteries over longer cycles, but their practical applications remain limited due to their significantly lower energy densities. Pseudocapacitors and hybrid capacitors have been developed to extend Ragone plots to higher energy density values, but they are also limited by the insufficient breadth of options for electrode materials, which require materials that store alkali metal cations such as Li+ and Na+. Herein, we report a comprehensive and systematic review of emerging anion storage materials for performance- and functionality-oriented applications in electrochemical and battery-capacitor hybrid devices. The operating principles and types of dual-ion and whole-anion storage in electrochemical and hybrid capacitors are addressed along with the classification, thermodynamic and kinetic aspects, and associated interfaces of anion storage materials in various aqueous and non-aqueous electrolytes. The charge storage mechanism, structure–property correlation, and electrochemical features of anion storage materials are comprehensively discussed. The recent progress in emerging anion storage materials is also discussed, focusing on high-performance applications, such as dual-ion- and whole-anion-storing electrochemical capacitors in a symmetric or hybrid manner, and functional applications including micro- and flexible capacitors, desalination, and salinity cells. Finally, we present our perspective on the current impediments and future directions in this field. [ABSTRACT FROM AUTHOR]

Oxygen electrocatalysis is of great significance in electrochemical energy conversion and storage. Many strategies have been adopted for developing advanced oxygen electrocatalysts to promote these technologies. In this invited contribution, recent progress in understanding the oxygen electrochemistry from theoretical and experimental aspects is summarized. The major categories of oxygen electrocatalysts, namely, noble‐metal‐based compounds, transition‐metal‐based composites, and nanocarbons, are successively discussed for oxygen reduction and evolution. Design strategies of various oxygen electrocatalysts and their relationship on the structure–activity–performance are comprehensively addressed with the perspectives. Finally, the challenge and outlook for advanced oxygen electrocatalysts are discussed toward energy conversion and storage technologies. [ABSTRACT FROM AUTHOR]

Owing to the earth‐abundant resources, cost effective materials and stable electrochemical properties, sodium‐ions batteries (SIBs) show long‐term potential in responding to the rapid consumption of lithium resources and the ever‐increasing development of new energy storage devices. Nevertheless, the intrinsic properties of the large ion radius (Na+ 1.02 Å vs Li+ 0.76 Å) and positive reduction potential (Na/Na+ −2.71 V vs Li/Li+ −3.04 V) may impede ion diffusion, thus causing serious volume expansion, resulting in poor cycling stability. To address these issues, the incorporation of active sites into carbonaceous anode is considered as an efficient strategy to enhance interfacial compatibility, enlarge interlayer distance, and supply reversible Faradic pseudo‐capacitance. Herein, the multiple active sites carbonaceous anodes for SIBs anode are comprehensively reviewed. Typically, carbonaceous materials are categorized into diffusion and surface controlled based on Na storage mechanism, and the concepts of intrinsic/extrinsic active sites are proposed according to the types of active sites. Furthermore, to reveal the reaction kinetics and guide the rational design of high performance anodes, the (spectro) electrochemical analysis methods and corresponding key parameters are introduced. Additionally, primary superiorities, essential issues, and supposed solutions of multiple active sites carbonaceous Na anodes are discussed and the future development directions are also proposed. This review may provide new design thoughts for high performance carbonaceous Na storage anodes. [ABSTRACT FROM AUTHOR]

Summary: The one‐dimensional (1D) nanoarchitectures are attractive toward energy storage electrode materials because of their large available surface area, a short and efficient pathway for ion/electron transport, structural stability, and highly exposed electrochemically active sites. Herein, we develop the bimetallic single crystalline nickel cobalt carbonate hydroxide (NiCoCO3(OH)2) nanowires for the high capacitance electrode of hybrid supercapacitor (HSC). This unique NiCoCO3(OH)2 nanowire electrode reveals a maximum specific capacitance value of 1948 F g−1 at 1 A g−1 with a high rate capacitance of 859 F g−1 even at 30 A g−1, which is a considerably higher value than the monometallic nickel carbonate hydroxide (1159 F g−1) and cobalt carbonate hydroxide (859 F g−1), respectively. These results are attributed to the presence of abundant redox‐active sites of multivalent Ni and Co and an easy charge transport pathway of NiCoCO3(OH)2 nanowire. The as‐designed HSC full cells, configuring NiCoCO3(OH)2 nanowire and activated carbon as a positive and native electrodes, respectively, deliver energy and power densities of 56.56 W h kg−1 and 44.81 kW kg−1. Moreover, the HSC cells exhibit prominent cycling stability of 91.4% for 12 000 charge‐discharge cycles in 6 M KOH aqueous electrolyte. [ABSTRACT FROM AUTHOR]

Sodium ion batteries are an emerging candidate to replace lithium ion batteries in large-scale electrical energy storage systems due to the abundance and widespread distribution of sodium. Despite the growing interest, the development of high-performance sodium cathode materials remains a challenge. In particular, polyanionic compounds are considered as a strong cathode candidate owing to their better cycling stability, a flatter voltage profile, and stronger thermal stability compared to other cathode materials. Here, we report the rational design of a biomimetic bone-inspired polyanionic Na3V2(PO4)3-reduced graphene oxide composite (BI-NVP) cathode that achieves ultrahigh rate charging and ultralong cycling life in a sodium ion battery. At a charging rate of 1 C, BI-NVP delivers 97% of its theoretical capacity and is able to retain a voltage plateau even at the ultra-high rate of 200 C. It also shows long cycling life with capacity retention of 91% after 10 000 cycles at 50 C. The sodium ion battery cells with a BI-NVP cathode and Na metal anode were able to deliver a maximum specific energy of 350 W h kg−1 and maximum specific power of 154 kW kg−1. In situ and postmortem analyses of cycled BI-NVP (including by Raman and XRD spectra) HRTEM, and STEM-EELS, indicate highly reversible dilation–contraction, negligible electrode pulverization, and a stable NVP-reduced graphene oxide layer interface. The results presented here provide a rational and biomimetic material design for the electrode architecture for ultrahigh power and ultralong cyclability of the sodium ion battery full cells when paired with a sodium metal anode. [ABSTRACT FROM AUTHOR]

The energy storage performance of sodium‐ion batteries has been greatly improved by pairing ether‐based electrolytes with high‐capacity alloy‐type anodes. However, the origin of this performance improvement by a unique electrode/electrolyte interface has yet to be explored. To understand such results, herein, the deterministic and distinct interfacial chemistries and solid electrolyte interphase (SEI) layers in both the ether‐ and ester‐based electrolytes are described, as verified by post mortem, in‐depth X‐ray photoelectron spectroscopy, and electron energy loss spectroscopy analyses, employing a hierarchical Bi/C composite anode as the model system. In the ether‐based electrolyte, fast sodium‐ion storage kinetics and structural integrity are achieved due to the highly ionic‐conducting and robust multi‐layered SEI consisting of an inner dense bismuth‐containing inorganic and outer polyether layer. No drastic capacity decay is observed over 1000 cycles and high capacity retention of 89% is achieved, increasing rates from 0.1 to 10 A g−1. The benefit of this SEI is confirmed to demonstrate a high energy density of 162 Wh kg−1 in a full‐cell and a high areal capacity of 3.3 mAh cm−2 even at a high mass loading of 11 mg cm−2, which is nearly equivalent to the loading of commercial lithium‐ion battery anodes. [ABSTRACT FROM AUTHOR]

Carbon is a simple, stable and popular element with many allotropes. The carbon family members include carbon dots, carbon nanotubes, carbon fibers, graphene, graphite, graphdiyne and hard carbon, etc. They can be divided into different dimensions, and their structures can be open and porous. Moreover, it is very interesting to dope them with other elements (metal or non‐metal) or hybridize them with other materials to form composites. The elemental and structural characteristics offer us to explore their applications in energy, environment, bioscience, medicine, electronics and others. Among them, energy storage and conversion are extremely attractive, as advances in this area may improve our life quality and environment. Some energy devices will be included herein, such as lithium‐ion batteries, lithium sulfur batteries, sodium‐ion batteries, potassium‐ion batteries, dual ion batteries, electrochemical capacitors, and others. Additionally, carbon‐based electrocatalysts are also studied in hydrogen evolution reaction and carbon dioxide reduction reaction. However, there are still many challenges in the design and preparation of electrode and electrocatalytic materials. The research related to carbon materials for energy storage and conversion is extremely active, and this has motivated us to contribute with a roadmap on 'Carbon Materials in Energy Storage and Conversion'. [ABSTRACT FROM AUTHOR]

Abstract: Multidimensional hierarchical architecturing is a promising chemical approach to provide unique characteristics synergistically integrated from individual nanostructured materials for energy storage applications. Herein, hierarchical complex hybrid architectures of CNT‐on‐OCNT‐Fe are reported, where iron oxide nanoparticles are encapsulated inside carbon nanotube (CNT) branches grown onto the ozone‐treated surface of 3D CNT internetworked porous structures. The activated surface of the 3D ozonated CNT (OCNT) interacts with the iron oxide nanoparticles, resulting in different chemical environments of inner and outer tubes and large surface area. The mixed phases of iron oxide nanoparticles are confined by full encapsulation inside the conductive nanotubes and act as catalysts to vertically grow the CNT branches. This unique hierarchical architecture allows CNT‐on‐OCNT‐Fe to achieve a reasonable capacity of >798 mA h g−1 at 50 mA g−1, with outstanding rate capability (≈72% capacity retention at rates from 50 to 1000 mA g−1) and cyclic stability (>98.3% capacity retention up to 200 cycles at 100 mA g−1 with a coulombic efficiency of >97%). The improved rate and cyclic capabilities are attributed to the hierarchical porosity of 3D OCNT internetworks, the shielding of CNT walls for encapsulated iron oxide nanoparticles, and a proximate electronic pathway for the isolated nanoparticles. [ABSTRACT FROM AUTHOR]

It is crucial to control the structure and composition of composite anode materials to enhance the cell performance of such anode materials for lithium ion batteries. Herein, a biomimetic strategy is demonstrated for the design of high performance anode materials, inspired by the structural characteristics and working principles of sticky spider-webs. Hierarchically porous, sticky, spider-web-like multiwall carbon nanotube (MWCNT) networks are prepared through a process involving ozonation, ice-templating assembly, and thermal treatment, thereby integrating the networks with γ-Fe2O3 particles. The spider-web-like MWCNT/γ-Fe2O3 composite network not only traps the active γ-Fe2O3 materials tightly but also provides fast charge transport through the 3D internetworked pathways and the mechanical integrity. Consequently, the composite web shows a high capacity of ≈822 mA h g−1 at 0.05 A g−1, fast rate capability with ≈72.3% retention at rates from 0.05 to 1 A g−1, and excellent cycling stability of >88% capacity retention after 310 cycles with a Coulombic efficiency >99%. These remarkable electrochemical performances are attributed to the complementarity of the 3D spider-web-like structure with the strong attachment of γ-Fe2O3 particles on the sticky surface. This synthetic strategy offers an environmentally safe, simple, and cost-effective avenue for the biomimetic design of high performance energy storage materials. [ABSTRACT FROM AUTHOR]

The electrodes of a hybrid electrochemical capacitor which utilize the quinone (Q)-hydroquinone (QH2) couple, a prototypical organic redox system known to provide fast and reversible proton-coupled electron-transfer reactions, are deterministically mesostructured via a colloidal templating strategy to provide good ion and electron transport pathways, enabling a high rate performance. Specifically, a conducting polymer, polypyrrole (PPy), is functionalized with a pseudocapacitive material, a Q/QH2-containing catechol derivative, by noncovalent interactions. The mesostructure of this hybrid material is formed into an ordered 3D porous structure by a polystyrene colloidal crystal template-assisted electrosynthesis. The catechol derivative is sufficiently bound to the PPy through noncovalent interactions to provide a volumetric capacitance as high as ≈130 F cm−3 and a capacitance retention of ≈75% over 10 000 charging/discharging cycles. When compared with a randomly structured electrode, the deterministically structured electrode exhibits an improved rate performance due to the mesostructure facilitated electron and ion transport. [ABSTRACT FROM AUTHOR]

With increasing demand for portable, flexible, and even wearable electronic devices, flexible energy storage systems have received increasing attention as a key component in this emerging field. Among the options, supercapacitors, commonly referred to as ultracapacitors or electrochemical capacitors, are widely recognized as a potential energy storage system due to their high power, fast charge/discharge rate, long cycling life-time, and low cost. To date, considerable effort has been dedicated to developing high-performance flexible supercapacitors based on various electrode materials; including carbon nanomaterials (e.g., carbon nanotubes, graphene, porous carbon materials, carbon paper, and textile), conducting polymers (e.g., polyaniline, polypyrrole, polythiophene), and hybrid materials. A brief introduction to the field is provided and the state-of-the-art is reviewed with special emphasis on electrode materials and device configurations. [ABSTRACT FROM AUTHOR]

High porosity combined with mechanical durability in conductive materials is in high demand for special applications in energy storage under limiting conditions, and it is fundamentally important for establishing a relationship between the structure/chemistry of these materials and their properties. Herein, polymer-assisted self-assembly and cross-linking are combined for reduced graphene oxide (rGO)-based aerogels with reversible compressibility, high elasticity, and extreme durability. The strong interplay of cross-linked rGO (x-rGO) aerogels results in high porosity and low density due to the re-stacking inhibition and steric hinderance of the polymer chains, yet it makes mechanical durability and structural bicontinuity possible even under compressive strains because of the coupling of directional x-rGO networks with polymer viscoelasticity. The x-rGO aerogels retain >140% and >1400% increases in the gravimetric and volumetric capacitances, respectively, at 90% compressive strain, showing reversible change and stability of the volumetric capacitance under both static and dynamic compressions; this makes them applicable to energy storage devices whose volume and mass must be limited. [ABSTRACT FROM AUTHOR]

Sodium metal anodes (SMA), featuring high energy content, low electrochemical potential and easy availability, are a compelling option for sustainable energy storage. However, notorious sodium dendrite and unstable solid‐electrolyte interface (SEI) have largely retarded their widespread implantation. Herein, porous amorphous carbon nanofiber embedded with Bi nanoparticles in nanopores (Bi@NC) was rationally designed as a 3D host for SMA. In situ and ex situ characterizations, along with theoretical simulations unlock that the in‐situ formed Na−Bi alloy significantly accelerates sodium metal nucleation and sodium ion diffusion kinetics, enabling uniform sodium plating within the void spaces and a stable SEI outside the carbon nanofiber. Particularly, the Bi@NC electrode achieved a high coulombic efficiency of 99.99 % at 3 mA cm−2 and 3 mAh cm−2 in half‐cell tests, a cycle life of 1000 hours at 5 mA cm−2 and 10 mAh cm−2, and sustained performance over 600 cycles under harsh conditions under 30 mA cm−2 and 3 mAh cm−2 within symmetrical cells. The full battery assembled with a Na3V2(PO4)3@C cathode and Bi@NC anode delivered long‐term cyclability over 800 cycles, demonstrating its potential for flexible application of sodium‐based energy storage systems. This work highlights the Bi@NC electrode as a promising candidate for high‐performance and flexible sodium metal batteries. [ABSTRACT FROM AUTHOR]

Metal–organic frameworks (MOFs) with intrinsically porous structures are promising candidates for energy storage, however, their low electrical conductivity limits their electrochemical energy storage applications. Herein, the hybrid architecture of intrinsically conductive Cu‐MOF nanowire arrays on self‐supported polypyrrole (PPy) membrane is reported for integrated flexible supercapacitor (SC) electrodes without any inactive additives, binders, or substrates involved. The conductive Cu‐MOFs nanowire arrays afford high conductivity and a sufficiently active surface area for the accessibility of electrolyte, whereas the PPy membrane provides decent mechanical flexibility, efficient charge transfer skeleton, and extra capacitance. The all‐solid‐state flexible SC using integrated hybrid electrode demonstrates an exceptional areal capacitance of 252.1 mF cm−2, an energy density of 22.4 µWh cm−2, and a power density of 1.1 mW cm−2, accompanied by an excellent cycle capability and mechanical flexibility over a wide range of working temperatures. This work not only presents a robust and flexible electrode for wide temperature range operating SC but also offers valuable concepts with regards to designing MOF‐based hybrid materials for energy storage and conversion systems. [ABSTRACT FROM AUTHOR]

Wire‐supercapacitors have drawn extensive attentions as a promising candidate for future wearable electronic devices. However, the relative lower energy densities and imperfect physical properties (e.g., length, tenacity, flexibility, and stability) seriously hinder their real applications as energy storage devices in wearable electronics. Herein, the fabrication of wire‐supercapacitors is reported with the length of longer than 1 m, based on CoNiO2‐nanowires@carbon‐fibers electrodes with a high capacity of 1.68 mF cm−1 and a high energy density of 0.95 mWh cm−3, respectively. The device shows no obvious performance degradation when suffering cycling, bending, pulling, tying, and weaving. After weaving as Chinese knot, watchband, belt, and clothes textile, the wire‐supercapacitors work well as the wearable energy‐storage units to power the personal electronics. [ABSTRACT FROM AUTHOR]

In article number 1501115, Ho Seok Park and co‐workers demonstrate the transition of layered dichalcogenides from a diffusion‐controlled intercalation into extrinsically pseudocapacitive charge storage by downscaling into nanometric sheets. The resulting nanosheets are hybridized with electronically conductive reduced graphene oxide. The unique surface‐dominant phenomena originating from the strong interplay and heterostructure of the heteronanosheets is associated with the outstanding capacitive performances. [ABSTRACT FROM AUTHOR]

Reversibly compressible and durable graphene aerogels are demonstrated by J. Kong, H. S. Park, and colleagues on page 1053 for energy storage where volume and mass must be limited. Taking advantage of the polymer assisted self assembly and cross linking, high porosity and low density yet mechanical durability and elasticity are achieved in cross linked reduced graphene oxide aerogels. They are highly and reversibly compressible while maintaining 3D interconnecting networked pathways for applications in ultra compact electrochemical capacitors. [ABSTRACT FROM AUTHOR]

• Mesoporous graphite felts (mp-GF), prepared through a simple thermal decomposition process, offered a mesopore-rich surface and an increase in oxygen content proportional to the specific surface area. • The mp-GF improved the charge transfer kinetics and shorter the ion diffusion lengths. • VRFBs assembled with mp-GF exhibited high energy efficiency of 79.6 % and voltage efficiency of 83.1 % at current density of 200 mA cm−2 and stable cycling for over 500 cycles at current density of 350 mA cm−2. • A surrogate model employing Polynomial Chaos Expansion confirmed that VRFBs assembled with mp-GF operate in wider SOC ranges with lower overpotentials under higher applied current density and specific surface area. Vanadium redox flow batteries (VRFBs) have attracted considerable attention due to their outstanding safety, design flexibility, and high performance. However, the severe polarization and the limited activity of carbon-based electrodes confine VRFB applications to large-scale energy storage systems. This study introduces a facile method for preparing mesoporous graphite felt (mp-GF) via thermal decomposition, employing a manganese oxide coating derived from alkylammonium permanganate. The resulting mp-GF offers mesopores, abundant oxygen-containing functional groups, and Mn 3 O 4 catalysts, enhancing electrochemical activity and electrolyte utilization. VRFBs assembled with mp-GF electrodes achieved a voltage efficiency of 83.1 % and an energy efficiency of 80 % at a high current density of 200 mA cm−2, outperforming the 78.3 % and 75.3 % efficiency of thermally treated graphite felt (TGF), the conventional electrode in VRFBs. We further investigate the dynamics of VRFBs using an electrochemical model that incorporates parameter identification based on the measured charge–discharge curves. The identified specific surface area of mp-GF is approximately 30 times greater than that of thermal-treated graphite felt. Consequently, the cell with mp-GF operates within a broader state of charge (SOC) range and at lower overpotentials. [ABSTRACT FROM AUTHOR]

[Display omitted] • Multifunctional 0D@2D (Mo x -Mn)S y -NPs@MXene is developed for Li-ion battery & ASC device. • 0D@2D (Mo x -Mn)S y -NPs@MXene displays high Li-ion storage capacity up to 698 mA h gm−1. • (Mo x -Mn)S y -NPs@MXene hybrid material displays excellent supercapacitive performance. • Newly designed 0D@2D (Mo-Fe 7)S x -NPs@MXene anode material is reported for ASC device. • All Mo-MXene-driven ASC device displays excellent cycling stability after 30 000 cycles. 0D@2D heterostructures constituted by binary transition metal sulfides@transition metal carbides can illustrate the combined advantages of each material with their improved electrochemical performance for energy storage devices. 2D transition metal carbides (MXene ∼ Ti 3 C 2) have presented themselves as the most appropriate candidates for the construction of lower-dimensional 0D ∼ like electroactive nanoparticles (NPs). Due to the high theoretical capacity values and versatile valence states, the molybdenum incorporated mixed metal sulfides ((Mo x -Mn)S y) nanoparticles decorated over 2D Ti 3 C 2 sheets are reported for Li-ion battery and asymmetric supercapacitor. A uniquely designed (Mo x -Mn)S y -NPs@MXene hybrid material displays a high Li-ion storage capacity of up to 698 mA h g−1 at 50 mA g−1, and a commendable areal capacity performance (∼1.27 mA h cm−2 at 2 mA cm−2) for supercapacitor, along with outstanding capacity retention at higher current density and stable cycling performance. Furthermore, a 0D@2D (Mo-Fe 7)S x -NPs@MXene hybrid material is utilized as anode material to construct a coin cell-like (Mo x -Mn)S y -NPs@MXene//(Mo-Fe 7)S x -NPs@MXene asymmetric supercapacitor (ASC) device. A high-voltage (∼1.90 V) ASC device based on unique 0D@2D heterostructures displays an ultra-high energy density of 78.8 W h Kg−1 at a power density of 634.63 W Kg−1 along with maximum specific capacity retention and cycling stability performance. This study emphasizes the importance of 0D@2D based heterostructure materials for the development of efficient energy storage devices. [ABSTRACT FROM AUTHOR]

We demonstrate the microwave synthesis of tin oxide (SnO 2 ) nanoparticles and direct deposition on the surface of restacking inhibited reduced graphene oxide (rGO) nanosheets for an application into lithium ion battery anodes. The mesoporous rGO-SnO 2 nano-composite (G-SnO 2 ), where the SnO 2 nanoparticles are intercalated in the layer-by-layer structure of the restacking rGO nanosheets, can be synthesized within 10 min by microwave irradiation, simultaneously promoting the reduction of graphene oxides (GO). The size of SnO 2 nanoparticles ranges from 5 to 10 nm and they are highly crystalline structure along with the change in the oxidation states from Sn 2+ to Sn 4+ in the process of the microwave synthesis. The G-SnO 2 anodes show 1200 mAh g −1 at 50 mA g −1 and their specific capacity is preserved up to 1000 mAh g −1 during the 100 cycles. The coulombic efficiency keeps 97% after the 1st cycle and the high specific capacity of 747 mAh g −1 is maintained with 66.3% of capacity retention even when the current density increases from 50 mA g −1 to 300 mA g −1 . These results indicate that the improvement of specific capacity, rate capability and cycle stability is attributed to the mesoporous layer-by-layer structure of G-SnO 2 , where the well-defined SnO 2 nanoparticles are deposited on the restacking inhibited rGO nanosheets. [ABSTRACT FROM AUTHOR]

The composition and pore alignment of three-dimensional (3D) internetworked materials may be a critical parameter for determining the electrochemical properties, but it has yet to be explored. Herein, hierarchically structured reduced graphene oxide (rGO)/MoS 2 frameworks (GMfs), as lithium ion batteries (LIB) electrode, are assembled via an ice-templating process on a basis of the interaction between 2D MoS 2 and 2D rGO. The morphology and chemical structure of GMfs are investigated by various microscopic and spectroscopic methods and their alignment is dependent on the compositional variations. The as-obtained GMfs exhibit randomly networked and crumpled morphology, achieving the enhanced electrochemical performances for LIB anodes due to the redox-active MoS 2 deposited on the 3D macroporous internetworks. The GMfs with 16% MoS 2 (GMfs-16) shows high discharge capacity of 1362 mAh g −1 at the specific current of 100 mA g −1 along with a reasonable rate capability of 53.4% from 50 to 1000 mA g −1 and good cycle capability of 86.4% after 100 charge/discharge cycles. It is concluded that for the case of the randomly networked GMfs-16 composites, MoS 2 is the key active component to lithium ions storage, while rGO is the skeleton to improve conductivity and maintain the structural stability for MoS 2 nanosheets. [ABSTRACT FROM AUTHOR]

• The interlayer spacing of V 2 O 5 was adjusted through the intercalation of PEDOT. • V 2 O 5 interacts with PEDOT with the phase transition from Quinoid to Benzoid. • A reversible and fast Mg2+ ion storage of V 2 O 5 /PEDOT was achieved. • The enlarged interlayer and water activation improved the kinetic performances. • Bilayer structured V 2 O 5 /PEDOT achieved the high rate and cycling performances. Magnesium ion batteries (MIBs) are attracting attention as promising alternatives to next-generation energy storage systems owing to their high safety, high volumetric capacity, low reduction potential, abundant raw materials, and economic efficiency. However, developing highly reversible and kinetically fast MIB cathode materials is very challenging owing to the sluggish Mg2+ ion diffusion and low reversible capacity typical of bivalent magnesium ions, as well as the strong electrostatic interactions with the host cathode material. Herein, we designed a charge transfer interaction of a bilayered V 2 O 5 /PEDOT (VOP) complex with involving the phase transition of PEDOT from a quinoid to a benzoid structure which could be realized because of reversible and fast Mg2+ ion storage through an enlarged interlayer spacing of 19.02Å. Furthermore, the effect of water activation on the enhancement of the kinetics was confirmed by conducting electrochemical and in-situ/ex-situ characterizations. Consequently, the as-designed VOP electrodes delivered a high specific capacity of 339.7 mAh/g at 100 mA g−1, high-rate capacity of 256.3 mAh/g at 500 mA g−1, and long-term cyclic stability with a 0.065 % decay rate and high capacity of 172.5 mAh/g after 500 cycles. [ABSTRACT FROM AUTHOR]

Micro/meso-porous reduced graphite oxide (MMRGO) nanosheets were produced using precursor carbide-derived carbon (CDC), which was produced at a high temperature of 1200 °C, through a massive wet chemistry synthetic route involving graphite oxidation and microwave reduction. X-ray diffraction (XRD) and transmission electron microscopy (TEM) show that the MMRGO nanosheets were fabricated with 2–3 layers and ripple-like corrugations. N 2 sorption isotherms confirmed that micro/meso-pores coexisted in the RGO sample from CDC. In the anode application of Li-ion batteries, this RGO sample had an enhanced capacity performance at the 0.1 C rate and 1 C rate, with ∼1200 mAh g −1 at the 100th cycle and ∼1000 mAh g −1 at the 200th cycle, respectively. [ABSTRACT FROM AUTHOR]

We report the incorporation of sulfur (S)-containing groups into the reduced graphene oxide (RGO) architectures for high performance supercapacitor (SC) electrodes. The S-incorporated RGO aerogel (SRGA) have three-dimensional (3D) internetworked morphology, thereby improving the accessibility to storage sites and ion diffusion. The morphology and chemical structure of the SRGA are comprehensively investigated by spectroscopic methods. The SC electrodes show excellent electrochemical properties such as high specific capacitance of 445.6 F g −1 at scan rate of 5 mV s −1 , good rate capability of 78.2% and cyclic stability of 73.4% over 1500 cycles due to the existence of S-containing groups and 3D macroscopic structure. As a consequence of the pseudocapacitive feature of S-containing groups, these capacitance enhancements become more pronounced in an aqueous electrolyte despite the enlargement of operating window in organic and ionic liquid electrolytes for high energy applications. [ABSTRACT FROM AUTHOR]

Two-dimensional (2D) transition metal carbides (MXenes) have been considered a promising electrode material in energy storage devices due to their outstanding electrical conductivity, excellent electrochemical performance and unique surface terminations. Herein, with inspiration from the interesting functional structure of layered MXene, we report an efficient and facile sonochemical method to synthesize an anode material; functionally activated titanium carbide nanorods grown on Ti 3 C 2 MXene nanosheets (FTCN-MXene) in deionized water and dimethylformamide mixture. In a striking contrast to pristine Ti 3 C 2 T x MXene, FTCN-MXene exhibits outstanding specific anode capacity of 1,034 mAh/g, high coulombic efficiency (98.78%) after 250 cycles, and excellent reversible cyclic stability (retention of 96.05%). Functionalized nanorods grown on metallic conducting Ti 3 C 2 sheets create more active sites and surface area, improving Li ion insertion/extraction capability. This study opens new avenues for developing functionalized MXene-based electrode materials with enhanced performance for electrochemical energy storage devices and systems. [ABSTRACT FROM AUTHOR]