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Textile devices have benefited from the discovery of new conductive materials and innovations in textile device design. These devices include textile‐based supercapacitors (TSCs), encompassing fiber, yarn, and fabric supercapacitors, which have demonstrated practical value in powering wearable devices. Recent review articles have highlighted the limited energy density of TSCs as an important challenge, demanding new electrode materials with higher electronic conductivity and theoretical capacitance than present materials. Ti3C2Tx, a member of the MXene family, is known for its metallic conductivity and high volumetric capacitance in acidic electrolytes due to its pseudocapacitive behavior. Driven by these excellent properties, recent literature has reported promising integration methods of Ti3C2Tx into TSCs with significantly improved areal and volumetric capacitance compared with non‐MXene‐based TSCs. Furthermore, knitted MXene‐based TSCs demonstrated practical application of wearable energy storage devices in textiles. Herein, the techniques used to produce MXene‐based fibers, yarns, and fabrics and the progress in architecture design and performance metrics are highlighted. Challenges regarding the introduction of this new material into fiber/yarn/fabric architectures are discussed, which will inform the development of textile‐based devices beyond energy storage applications. Opportunities surrounding the development of MXene‐based fibers with tunable mechanical, electrical, and electrochemical properties are proposed, which will be the direction of future research efforts. [ABSTRACT FROM AUTHOR]

[Display omitted] • Co 3 Se 4 quantum dot electrode material coated with N doped porous nanocarbon is prepared. • The assembled all-solid-state ASC attenuate only 4.4% of C s after 15,000 GCD cycles. • The assembled all-solid-state ASC has an energy density of 84.59 Wh kg−1 at a power density of 799.99 W kg−1. Transition metal selenides (TMSe) are considered as potential anode materials for supercapacitors because of their abundant reserves and high safety. However, their poor conductivity limits their high rate performance and stability. In this paper, an N -doped porous nanocarbon-coated Co 3 Se 4 quantum dots (NCCS-QDs) composite is prepared as the cathode material of supercapacitor. The formation of Co 3 Se 4 quantum dots complies with a size minimization strategy to speed up ion transport. At the same time, the Co 0.85 Se nanosheets are converted into Co 3 Se 4 quantum dots, avoiding the collapse of the nanosheets during the electrochemical process. In addition, the porous nanocarbon coating increases the number of active sites and the contact area between the electrode and the electrolyte, which can provide more ion transport channels and pore sizes, while avoiding the generation of inactive clusters in the electrochemical reaction of quantum dots. The as-assembled NCCS-QDs-2//AC ASCs devices demonstrate excellent electrochemical performance with an energy density of 84.59 Wh kg−1 at a power density of 799.99 W kg−1. At the same time, the ASCs device showed excellent cycle stability, with 95.6% of the initial capacitance still maintained after 15,000 charge and discharge cycles. The excellent electrochemical performance of NCCS-QDs-2//AC ASC device proves that NCCS-QDs composite material has a broad application prospect in the cathode material of supercapacitor. [ABSTRACT FROM AUTHOR]

[Display omitted] • Hollow carbon spheres (MHCS) with controlled sheath thickness and nanochannels. • The MHCS separated 3D MXene/MHCS electrode by one-step filtration. • Nanochannels on the sphere sheath help the fast diffusion of ions in electrolyte. • Conductive sheath reduces the contact resistance between MXene sheets. The development of electrode materials with a hierarchically porous structure and good electrical connection is key to improving the charging-discharging rate and energy density of supercapacitors. However, the restacking issue of two-dimensional nanomaterials, such as MXene, seriously hinders the diffusion of electrolyte ions. Different from the extensively used sacrificing template method, a hierarchical heterostructure of electrically conducting mesoporous hollow carbon spheres (MHCS) and MXene composite electrode is designed and achieved through simple vacuum filtration without further template removing procedures. This direct preparation strategy not only effectively improves the specific surface area of the electrode but also enhances the abundant surface pores and good conductivity of MHCS, improving the penetration of the electrolyte solution and shortening the ion transport path, leading to a pronounced improvement in specific capacitance and rate performance of the electrodes. Additionally, the influence of sheath thickness of MHCSs on ion transfer rate is deeply discussed. The introduction of carbon nanotubes (CNTs) further improves conductivity and stability while maintaining good flexibility. Consequently, the MXene/MHCS/CNT film delivers a high specific capacitance (395F g−1 at 2 mV s−1), outstanding rate performance (70.9 % at 1000 mV s−1), and excellent cycling stability (98.3 % capacity retention after 10,000 cycles). Furthermore, the assembled symmetric supercapacitor provides a maximum energy density of 14.48 Wh kg−1. This work provides a quick and effective approach for constructing high performance 3D MXene architectures for fast ion transfer electrodes. [ABSTRACT FROM AUTHOR]

The voltage limit of water-based asymmetric supercapacitors is usually 2 V, which prevents further improvement of energy density. Na 0.6 CoO 2 nanoarrays with high Na content are formed on carbon cloth (CC) by cyclic electrochemical oxidation (EO) and can work stably in 0–1.2 V wide potential, and the specific capacitance is up to 575.98C g−1 at 1 A g−1. Using carbon coated Fe 2 O 3 nanoarrays on CC as the negative electrode and Na 0.6 CoO 2 /CC as the positive electrode, a water-based asymmetric supercapacitor (ASC) which can operate stably in 0–2.5 V wide voltage window is assembled. The Na 0.6 CoO 2 /CC//Fe 2 O 3 @C/CC ASC exhibits an energy density of 133.92 Wh kg−1 at a power density of 1250 W kg−1, which is better than previously reported Co-based supercapacitors. This study provides a scheme for the working voltage of water-based ASCs to be further expanded to more than 2 V. Utilizing cationic pre-inserted Co 3 O 4 nanoarray to construct high operating voltage composite electrode should have broad application prospect. [Display omitted] • Na 0.6 CoO 2 nanosheets with high Na content are prepared by electrochemical oxidation. • The prepared Na 0.6 CoO 2 /CC electrode can work stably at a wide potential range of 0–1.2 V. • The Na 0.6 CoO 2 /CC//Fe 2 O 3 @C/CC ASC device can operate stably at 0–2.5 V wide potential range. [ABSTRACT FROM AUTHOR]

[Display omitted] • MgCo 2 O 4 @NiMn-LDH core-shell nanoarrays is fabricated on Ni foams. • The materials are obtained by a facile hydrothermal strategy. • MgCo 2 O 4 @NiMn-LDH electrode exhibits superb supercapacitive performance. In this work, MgCo 2 O 4 @NiMn layered double hydroxide (LDH) core-shell structured nanocomposites on Ni foam (NF) are synthesized by facile hydrothermal and calcination methods. MgCo 2 O 4 /NF is synthesized first via a hydrothermal reaction and annealing treatment, and then utilized to prepare MgCo 2 O 4 @NiMn-LDH/NF core-shell structured nanocomposites via the second hydrothermal process. It is found that the MgCo 2 O 4 @NiMn-LDH/NF nanocomposite prepared from 6 h hydrothermal reaction (MC@NM-LDH-2) exhibits an excellent specific capacitance of 3757.2 F g−1 (at 1 A g−1). Moreover, a high capacitance retention (86.9% after 6000 cycles) and a low internal resistance (Rs) (0.565 Ω) can be achieved. Furthermore, an all-solid-state asymmetric supercapacitor (ASC) is assembled using MgCo 2 O 4 @NiMn-LDH/NF-2 as positive electrode and activated carbon (AC) as negative electrode. The as-fabricated MgCo 2 O 4 @NiMn-LDH/NF-2//AC ASC shows a high energy density of 62.33 Wh kg−1 at 750 W kg−1. Meanwhile, the MgCo 2 O 4 @NiMn-LDH/NF-2//AC ASC device possesses an outstanding cycling stability of 93.7% retention of the initial capacitance after 6000 cycles and three ASC devices connected in series can light up a LED bulb for 15 min. Our results manifest that these core-shell structure MgCo 2 O 4 @NiMn-LDH nanocomposites could envision huge potential application in energy storage devices. [ABSTRACT FROM AUTHOR]

Textile-based energy storage devices offer an exciting replacement for bulky and uncomfortable batteries in commercial smart garments. Fiber and yarn-based supercapacitors, currently dominating research in this field, have demonstrated excellent performance below ∼4 cm in length, but suffer at longer lengths due to increased resistance. Herein, a new architecture of wearable energy storage devices, 3D knitted supercapacitors, is designed and prototyped with the intention of exploiting the architecture of a knit textile to improve the performance of long yarn electrodes. While Computer-Aided Design (CAD) knitting is a ubiquitous technology for producing textiles, knitted energy storage devices have been largely unexplored due to the need for meters of highly conductive yarn electrodes that meet the strenuous strength and flexibility requirements for CAD knitting. MXenes, a family of solution processable and conductive two-dimensional (2D) materials, have been realized as inks, slurries, pastes, and now dyes for the development of on-paper, on-plastic, and on-textile microsupercapacitor electrodes. In this work, Ti 3 C 2 T x MXene was adopted as an active material for coating meters of commercial natural and synthetic yarns, enabling the production of knitted planar microsupercapacitors. The impact on electrochemical performance of knit structure and geometry was systematically studied in an attempt to produce energy storing textiles with power and energy densities that can be used for practical applications. The resulting energy storing textiles demonstrate high capacitance, up to 707 mF cm−2 and 519 mF cm−2 at 2 mV s−1 in 1 M H 3 PO 4 and PVA-H 3 PO 4 gel electrolyte, respectively, and excellent cycling stability over 10,000 cycles. This work represents an important step towards the mass production of MXene-based conductive yarns and 3D knitted energy storage devices and demonstrates how knit structure plays a significant role on device performance. [ABSTRACT FROM AUTHOR]

[Display omitted] • Carbon fibre based flexible structural supercapacitor. • Carbon fibre functionalized with poly(o -phenylenediamine) to enhance the capacitance. • Epoxy-solvate ionic liquid bi-continuous electrolyte system. • Capacitance of 909 mF g−1 and energy density of 181.79 mW h kg−1 at 0.5 mA g−1. • Shows good electrochemical and thermal stability required for desired applications. The "mass-less" energy storage technology based on the concept of multifunctional structural energy storage composites has the potential to revolutionize the design and performance of electric vehicles in the future. This work presents the fabrication process and properties of a structural supercapacitor laminate made of surface functionalized carbon fiber (CF), glass fiber separator and an epoxy-solvate ionic liquid bi-continuous electrolyte. CF surface has been electrochemically functionalized with a covalently grafted layer of redox-active poly(o -phenylenediamine) significantly improving the pseudocapcitance. The bi-continuous electrolyte contains 70% (w/w) lithium-triethylene glycol dimethyl ether bis(trifluoromethanesulfonyl)imide [Li-G3]TFSI in RIM935/RIMH936 epoxy resin. This fabricated supercapacitor device demonstrated a specific capacitance of 909 mF/g at 0.5 mA g−1, a 45-fold improvement compared to a device made with unfunctionalized CF. The device showed a maximum energy density of 181.79 mW h kg−1 at 0.5 mA g−1 and power density of 6.18 W kg−1 at 2.5 mA g−1, while maintaining excellent thermal stability, and possesses a multifunctional index of 1.01. They also possess a capacitance retention of 77.4% and coulombic efficiency of 90.9% after 10 000 charge–discharge cycles. Most notably, we show that the capacitance of the composite can be improved simply by bending the device at different angles, effecting a 3-fold increase when bent at 90° and 135°. This is the first time that the geometry of a composite has been shown to influence the electrochemical performance of a capacitor device and opens new avenues of investigation into structural energy optimization. [ABSTRACT FROM AUTHOR]

[Display omitted] • MgCo 2 O 4 @α-Co(OH) 2 core–shell nanoarrays is fabricated on Ni foams. • The materials are obtained by a facile hydrothermal strategy. • MgCo 2 O 4 @α-Co(OH) 2 electrode exhibits superb supercapacitive performance. In this work, the MgCo 2 O 4 @α-Co(OH) 2 core–shell structure (MgCo 2 O 4 @α-Co(OH) 2 /NF) on foam nickel was prepared using hydrothermal annealing and chemical bath deposition processes to form a supercapacitor positive electrode. MgCo 2 O 4 @α-Co(OH) 2 /NF-2 composite material, with a deposition time of 20 min in a chemical bath, showed a specific capacitance of 1634.8 F g−1 at 1 A g−1, a long cycle stability of 89.4% (in 10,000 cycles) and a rate performance of 78.29%, with excellent electrochemical impedance performance (Rs ≈ 0.507 Ω). The MgCo 2 O 4 @α-Co(OH) 2 /NF-2//AC asymmetric supercapacitors (ASCs) showed a specific capacitance of 185.46 F g−1 at 1 A g−1, with a good long-cycle stability of 91.7% preservation rate after 10,000 cycles. At a power density of 773.19 W kg−1, the energy density is high (65.94 Wh kg−1). We demonstrated that three prepared ASCs devices can produce a diode with a rated voltage of 3 V that continues to emit light for 10 min. This study shows that the MgCo 2 O 4 @α-Co(OH) 2 /NF-2 electrode can be used as a positive electrode for high-efficiency energy storage devices. [ABSTRACT FROM AUTHOR]

A hierarchical structure electrode material composed of MgCo 2 O 4 nanowire loaded NiCo-LDH nanosheets shows excellent capacitance and stability and superb energy density. Impressively, two MgCo 2 O 4 @NiCo-LDH/NF-2//AC asymmetric supercapacitor devices connected in series can light up the LED indicators for up to 15 min, showing a broad practical application prospect. • MgCo 2 O 4 @NiCo layered double hydroxide (LDH) hierarchical structure nanocomposites is fabricated on 3D Ni foams. • The materials are obtained by a facile hydrothermal strategy. • MgCo 2 O 4 @NiCo-LDH electrode exhibits superb supercapacitive performance. In this work, MgCo 2 O 4 @NiCo layered double hydroxide (LDH) hierarchical structure nanocomposites on Ni foam (NF) are synthesized by facile hydrothermal and calcination methods. MgCo 2 O 4 /NF is synthesized first via a hydrothermal reaction and annealing treatment and then utilized to prepare MgCo 2 O 4 @NiCo-LDH/NF hierarchical structure nanocomposites via the second hydrothermal process. It is found that the MgCo 2 O 4 @NiCo-LDH/NF nanocomposite prepared from 9 h hydrothermal reaction (MC@NC-LDH-2) exhibits an excellent specific capacitance of 5701.2 F g−1 at the current density of 1 A g−1. Moreover, a high capacitance retention (83.7% maintained after 5000 cycles) and a low internal resistance (Rs) (0.783 Ω) can be achieved. Furthermore, a quasi-solid state asymmetric supercapacitor (ASC) is assembled using MgCo 2 O 4 @NiCo-LDH/NF-2 as positive electrode and activated carbon (AC) as negative electrode. The as-fabricated MgCo 2 O 4 @NiCo-LDH/NF-2//AC ASC shows a high energy density of 89.79 Wh kg−1 at 800 W kg−1. Meanwhile, the MgCo 2 O 4 @NiCo-LDH/NF-2//AC ASC device possesses an excellent cycling stability of 89.03% retention of the initial capacitance after 5000 cycles and two ASC devices connected in series can light up a LED bulb for 15 min. Our results manifest that these hierarchical MgCo 2 O 4 @NiCo-LDH composites could envision huge potential application in energy storage devices. [ABSTRACT FROM AUTHOR]

In this work, hierarchical MgCo 2 O 4 @CoFe layered double hydroxide (LDH) core-shell nanowire arrays on Ni foam (NF) are synthesized by facile hydrothermal and calcination methods. MgCo 2 O 4 /NF has been first synthesized via a hydrothermal reaction and annealing treatment and then utilized to prepare MgCo 2 O 4 @CoFe-LDH/NF core-shell nanocomposites via the second hydrothermal reaction. It is found that the MgCo 2 O 4 @CoFe-LDH/NF core-shell nanocomposite prepared from 3 h hydrothermal reaction (MC@CF-LDH-3) exhibits an excellent specific capacitance of 903.15 C g−1 (2007 F g−1) at the current density of 1 A g−1. Moreover, a high capacitance retention (80.2% maintained after 5000 cycles) and a low internal resistance (Rs) (0.75 Ω) can be acquired. Furthermore, an all-solid-state asymmetric supercapacitor (ASC) is assembled using MgCo 2 O 4 @CoFe-LDH/NF-3 as the positive electrode and activated carbon (AC) as the negative electrode. The as-fabricated MgCo 2 O 4 @CoFe-LDH/NF-3//AC ASC shows a high energy density of 60.82 Wh kg−1 at 725 W kg−1. Meanwhile, the MgCo 2 O 4 @CoFe-LDH/NF-3//AC ASC device possesses an excellent cycling stability of 93.6% retention of the initial capacitance after 5000 cycles and two ASC devices connected in series can light up a LED bulb for 8 min. Our results manifest that this hierarchical MgCo 2 O 4 @CoFe-LDH composite has huge potential application in energy storage devices. Image 1 • MgCo 2 O 4 @CoFe-LDH core-shell nanoarrays is fabricated on Ni foams. • The materials are obtained by a facile hydrothermal strategy. • MgCo 2 O 4 @CoFe-LDH electrode exhibits superb supercapacitive performance. [ABSTRACT FROM AUTHOR]

Here we report the development of a high-performance electrode material composed of Zn and Ni co-substituted Co carbonate hydroxide (ZnNi-Co 2 (CO 3)(OH) 2) nanothorns branched on Cu(OH) 2 nanorods array (Cu(OH) 2 @ZnNi-Co 2 (CO 3)(OH) 2), which are grown directly on copper foam current collector. The electrode materials are obtained by a simple in situ oxidation reaction and a hydrothermal strategy. The as-obtained Cu(OH) 2 @ZnNi-Co 2 (CO 3)(OH) 2 electrode exhibits significantly enhanced electrochemical performance with a high specific capacitance (2746 F g−1 at 1 A g−1), and extraordinary cycling stability (maintained 95.61% of the initial capacitance after 6000 cycles at 20 A g−1), which are much superior to those of Cu(OH) 2 , Cu(OH) 2 @ Co 2 (CO 3)(OH) 2 , Cu(OH) 2 @Ni-Co 2 (CO 3)(OH) 2 , and bare ZnNi-Co 2 (CO 3)(OH) 2 nanospheres electrodes. Additionally, the Cu(OH) 2 @ZnNi-Co 2 (CO 3)(OH) 2 nanorods array can also be utilized as the positive electrode to fabricate an asymmetric supercapacitor device with an active carbon negative electrode, realizing a high cell voltage of 1.5 V and the energy density of up to 34.75Wh kg−1 at a power density of 375 W kg−1. The excellent electrochemical properties can be credited to the three-dimensional hierarchical core-shell architecture. Image 1 • Hierarchical Cu(OH) 2 @ZnNi-CoCH nanorods array is fabricated on 3D Cu foams. • The materials are obtained by an oxidation reaction and a hydrothermal strategy. • Cu(OH) 2 @ZnNi-CoCH electrode exhibits superb supercapacitive performance. [ABSTRACT FROM AUTHOR]