Search

• The interconnected petal-like morphology of Co-MOFs on a flexible stainless steel substrate (FSS) was synthesized by using a cost-effective Reaction Diffusion Framework method. • The electrochemical properties of Co-MOFs/FSS were examined in different aqueous electrolytes. • The performance of supercapacitors using Co-MOFs/FSS was evaluated under varying concentrations of LiOH electrolyte. • A high-performance symmetric paper-soaked Co-MOFs/FSS//Co-MOFs/FSS device was designed and fabricated for supercapacitor applications. The electrolyte is a crucial component in supercapacitors (SCs), along with the electrode material, which can affect the electrochemical parameters, such as specific capacitances (C s), energy density (ED), cyclic stability, and potential window. Therefore, the present work explores the effect of different electrolytes on the performance of Co-MOFs/FSS electrodes for SCs. The Co-MOFs/FSS electrode was synthesized on a flexible stainless-steel (FSS) substrate using the reaction-diffusion framework method, and its structural, morphological, and compositional characteristics were analyzed. The SCs performance of Co-MOF/FSS was examined across multiple electrolytes (1M KOH, 1M LiOH, and 1M NaOH). The SCs performance of Co-MOFs/FSS increased in the following sequence: 1M LiOH > 1M NaOH > 1M KOH. Furthermore, the dependence of concentration variation of LiOH electrolyte on Co-MOFs/FSS for SCs was studied. In 2M LiOH electrolyte, the Co-MOFs/FSS demonstrated a maximum C s of 650 F g − 1 and specific capacity (C sp) of 262 C g − 1 at 5 mV s − 1. Furthermore, it exhibited a favourable retention rate of 71 % over 5000 GCD cycles at 10 mA cm−2. It also possessed higher ED and Power Density (PD) of 14.10 Wh kg−1 and 666 W kg−1 at 1 mA cm−2 respectively. Further, a flexible symmetric paper-soaked Co-MOFs/FSS//Co-MOFs/FSS device was fabricated, and its electrochemical performance was assessed. The fabricated device exhibited a higher C s of 122 F g − 1 and C sp of 171 C g − 1 at 10 mV s − 1. Additionally, it showed good retentivity of 46 % after the 3000th cycle at 15 mA; and exhibited higher ED of 6.78 Wh kg−1 and PD of 1500 W kg−1 at 6 mA. This study highlights the importance of selecting the appropriate electrolyte for enhancing the electrochemical performance of Co-MOFs/FSS electrode material. [Display omitted] [ABSTRACT FROM AUTHOR]

• 1T-MoS 2 was applied as a flexible and functional "spacer" to hybridize with Ti 3 C 2 T X MXene, forming flexible capacitive freestanding films. • The insertion of electrically neutral pseudocapacitive could mitigate the restacking of Ti 3 C 2 T X MXene layers and improves the capacity of the composite paper. • The supercapacitor fabricated with acidic gel electrolyte and composite electrode with randomly stacked MXene and 1T-MoS 2 in a mass ratio of 6:1 demonstrated optimal performance. In the case of increasing shortage of non-renewable resources, developing high-efficiency and high-capacity energy storage devices is critical. Supercapacitors have the potential of high-efficiency and high-capacity. MXene and 1T-MoS 2 are two kinds of high performance pseudocapacitive materials. However, the stacking and aggregation of MXene nanosheets greatly reduce its capacity. The poor conductivity of 1T-MoS 2 also limits the full expression of its excellent pseudocapacitive performance. A flexible MXene/1T-MoS 2 composite paper electrode is designed and prepared in this work where the restacking of MXene can be relieved and the whole electrode maintains the conductivity. The interior stacking structure of MXene and 1T-MoS 2 in the composite paper, as well as the gel electrolyte type are explored. The device constructed with the electrode composed of randomly stacked MXene and 1T-MoS 2 (mass ratio 6:1) and acidic electrolyte (PVA/H 2 SO 4 gel electrolyte) demonstrates the optimal performance. The specific areal and volumetric capacitances reach 561.2 mF cm−2 and 1268.17 F cm−3 at the current density of 0.8 mA cm−2 respectively, outperforming most of the previously reported values for MXene based supercapacitors tested in gel electrolyte. The supercapacitor has excellent deformation durability and long cycle stability, demonstrating promising prospect in future flexible electronics. [Display omitted] [ABSTRACT FROM AUTHOR]

Vertically stacked thorn-like nanostructured NiCo 2 S 4 arrays are designed to in-situ grow on the electrochemical oxidized graphite paper by a two-step hydrothermal method where graphite papers act as heterogeneous nuclear sites to rationally construct the unique features of NiCo 2 S 4. Bimetal synergistic effect and the presence of sulfur atoms can improve the ionic and electron conductivity of NiCo 2 S 4. The unique structure of NiCo 2 S 4 fabricated in such way can allow more active sites exposed to reversible redox reactions, as well as provide relatively short ions/electrons transport pathways within the broken crystal structure and rich porous structure. As such, graphite paper supported NiCo 2 S 4 as a self-supported electrode (NiCo 2 S 4 @EGP) shows an extraordinarily high rate capability with the specific capacitance of 1276 F g−1 at 1 A g−1, and even 1218 F g−1 at 20 A g−1, as well as the excellent cycle stability with capacitance retention of 86 % after 5000 cycles. When assembling into a flexible asymmetric all-solid-state supercapacitor device, this device reaches a high-power density of 55.3 Wh kg−1 at a power density of 747.6 W kg−1, together with a superior high cycle stability (retained 95 % in 5000 cycles). These results obviously open interesting perspectives of using NiCo 2 S 4 @EGP as self-supported electrodes to become an advanced flexible power device. Vertically stacked thorn-like nanostructured NiCo 2 S 4 arrays are designed to in-situ grow on the electrochemical oxidized graphite paper, giving an extraordinarily high rate capability for supercapacitor electrodes with the specific capacitance of 1276 F g−1 at 1 A g−1, and even 1218 F g−1 at 20 A g−1. [Display omitted] [ABSTRACT FROM AUTHOR]

Hematite (α-Fe 2 O 3) is considered a promising electrode material due to its cost-effectiveness and high theoretical specific capacity. In this paper, we prepared Fe 2 O 3 nanoparticles by hydrothermal method. To improve the drawbacks such as poor conductivity and low practical capacity, NiCo 2 O 4 nanorods and graphene oxide (rGO) are added to Fe 2 O 3 nanoparticles. The composite exhibits a specific capacity of 644 F g−1 at a current density of 1 A g−1. The higher ion diffusion rate can improve the specific capacity and energy density in optimized composites. At a current density of 1 A g−1, compared to Fe 2 O 3 , the specific capacity and energy density of Fe 2 O 3 /NiCo 2 O 4 /rGO were increased by 278.8 % and 304.5 %, respectively. In order to stimulate more potential applications, we encapsulated Fe 2 O 3 /NiCo 2 O 4 /rGO-//Co 3 O 4 asymmetric supercapacitors with binder-free Co 3 O 4 as the counter electrode. Determining the optimal positive and negative active substance mass ratio by controlling the amount of charge, the device can deliver a high specific capacity of 280.6 F g−1 at a current density of 1 A g−1 and power density of 354.8 W Kg−1 while providing a high energy density of 56.1 Wh Kg−1. These results indicate that Fe 2 O 3 /NiCo 2 O 4 /rGO has potential for electrochemical energy storage, which could provide new ideas for new commercial supercapacitors. [ABSTRACT FROM AUTHOR]

The emerging field of wearable electronic devices has propelled the demand for advanced energy storage solutions. Among these, wearable supercapacitors have garnered significant attention due to their intrinsic advantages, including high stability, rapid charging discharging capabilities, and cost-effectiveness. This paper unveils the latest strides in flexible and wearable supercapacitors, placing a spotlight on the exceptional performance of a novel V 2 O 5 -pBOA-Graphene nanocomposite. Synthesized through a straightforward chemical approach, the material is meticulously characterized using X-ray diffraction, scanning electron microscopy, cyclic voltammetry, galvanostatic charge-discharge, and electrochemical impedance spectroscopy. The electrochemical behavior of the fabricated wearable supercapacitor devices is scrutinized, revealing an outstanding specific capacitance of 986 Fg−1 in a two-electrode system, coupled with an impressive energy density of 49 Whkg−1. The nanocomposite's robust cycling stability is showcased, with a capacitance retention of 93.47 % over 2000 cycles. Moreover, the device's flexibility is assessed by bending it at various angles, and it retains more than 91 % capacitance even at a 90° angle, underscoring its suitability for wearable applications. The choice of electrode materials, encompassing vanadium pentoxide (V 2 O 5), poly benzoxazole aniline (pBOA), and graphene, synergistically contributes to the nanocomposite's remarkable electrochemical performance. V 2 O 5 , with its pseudocapacitive behavior, is complemented by the conductivity and mechanical stability offered by pBOA and graphene. The ternary V 2 O 5 -pBOA-Graphene nanocomposite emerges as a frontrunner for wearable supercapacitor applications, promising enhanced flexibility, efficiency, and practical utility in real-world scenarios. The findings underscore the potential of the V 2 O 5 -pBOA-Graphene nanocomposite as a key player in the future of wearable energy storage, opening avenues for further exploration, optimization, and integration into practical applications. [ABSTRACT FROM AUTHOR]

The accurate estimation of state-of-charge (SOC) is crucial for the supercapacitor (SC) management system of electric vehicles. In this paper, a salp swarm algorithm (SSA)-optimized high and low degree cubature Kalman filters (CKFs) for SC SOC estimation is proposed. Firstly, the key parameters are identified for the Thevenin model by SSA under SC test data. Secondly, a temperature-varied model with temperature uncertainty is constructed by polynomial fitting. Thirdly, an adaptive rule based on SSA is designed to regulate the noise covariance matrix information in real time. Combining this rule and CKFs, SSA-based generalized high-degree CKF (SSA-GHCKF) and SSA-based low-degree CKF (SSA-CKF) are developed with the minimum prediction error as the objective. Finally, the effectiveness of improved CKFs is evaluated by the urban dynamometer driving schedule in varying temperatures. The simulation results show that the root mean square errors of SOC estimation by CKF, GHCKF, and SSA-CKF are kept within 1.4553 %, 1.2880 % and 1.2152 %, while for SSA-GHCKF, this metric is merely 1.1933 %. The proposed SSA-GHCKF enables superior accuracy and robustness for SOC estimation at extreme temperatures. [ABSTRACT FROM AUTHOR]

• Partially transformation growth of PBA on NiFe-MOF to obtain dual-MOF heterostructure. • NiFe-MOF/PBAs have an ultra-high specific capacity of 4270.19 c g−1 at 1 a g−1. • NiFe-MOF/PBAs//AC device has a high specific capacity up to 1996.01 c g−1 at 1 a g−1. • The device has excellent cycling stability of only 1.14 % decay rate (20,000 cycles). Metal organic framework (MOF) is considered as an excellent electrode material for supercapacitors due to its low cost and homogeneous nanostructure, but the drawbacks of single MOF, such as low specific capacity and stability, limit its development, so the design of bimetallic MOF structural composites is a challenging but favourable strategy for the development of supercapacitors. In this paper, NiFe-MOF/PBAs heterostructure, a bimetallic MOF material with a granular rod-like structure, is successfully prepared by using bimetallic MOF as a precursor and introducing [Co(CN) 6 ]3− ions to further convert it into PBAs (Prussian blue analogs). Due to the special macroporous structure of PBAs, the composite combines the advantages of the two MOF materials, and the specific capacity is as high as 4270.19 C g−1 at 1 A g−1. The composite still has excellent electrochemical properties when assembled into devices. The specific capacity is 1996.01 C g−1 at 1 A g−1, the energy density reached 749.99 W h kg−1 at a power density of 415.85 W kg−1, and the decay rate is only 1.14 % after 20,000 cycles at 10 A g−1. These results indicate that the designed dual MOFs composite electrodes have good application prospects in the field of electrochemical energy storage. [Display omitted] [ABSTRACT FROM AUTHOR]

• A simple and fast hydrothermal synthesis method was proposed in this paper to synthesize an electrode material with a heterostructure of NiMoO 4 nanoneedles and high-performance flower-shaped NiCoZn-LDH on a foam nickel substrate. • The electrochemical performance of the NiCoZn-LDH@NMO@NF nanoneedle composite electrode material, treated with CTAB, is significantly superior to that of the untreated NiMoO 4 @NF electrode. • It shows excellent electrochemical properties, including a specific capacitance of 3541 mF/cm2 in KOH solution and an outstanding capacity retention of 83.04 % after 10,000 cycles. Transition metal hydroxides have attracted wide attention as promising composite nanomaterials due to their numerous active sites and large specific surface areas. In this study, a two-step hydrothermal synthesis method is proposed to generate a heterostructure (NiCoZn-LDH@NiMoO 4 @NF) consisting of nanoflowers coated with nanoneedles on a foam nickel substrate. The aggregation issue of NiCoZn-LDH is effectively improved by immersing it in CTAB solution after one-step hydrothermal synthesis of NiMoO 4 nanoneedles on Ni Foam (NF). The heterostructure between NiMoO 4 nanoneedles and NiCoZn-LDH significantly enhances the material stability and electrochemical performance. Activated carbon is used as the negative electrode, and the NiCoZn-LDH@NiMoO 4 @NF composite material is used as the positive electrode to assemble an asymmetric supercapacitor (ASC) device for electrochemical testing. The device exhibits a specific capacitance of 3541 mF/cm2 at a current density of 6 mA/cm2. Furthermore, the capacity retention rate remains at 83.04 % after 10,000 cycles of charge and discharge, and a high specific energy density of 0.735 mWh/cm2 is achieved at a power density of 1.6 mW/cm2. The experimental results demonstrate that transition metal hydroxides play a crucial role in enhancing the electrochemical performance of supercapacitors. This study provides new insights into Supercapacitor (SC) active materials and offers a promising experimental approach for synthesizing new nanomaterials. [ABSTRACT FROM AUTHOR]

• The synthesized ILs were used as novel green electrolytes for supercapacitors. • Among the ILs, the smallest anion, formate, exhibited the highest performance. • The highest value of energy density of 70 Wh kg−1 was related to the farmate anion. Supercapacitors are promising technologies for extremely effective energy storage and power management, which is a critical and major area of worldwide technological advancement. Ionic liquids (ILs) are an environmentally benign promising emerging class of versatile solvent systems. In this paper, for the first time, a new approach to the application of monoethanolamine-based ILs with anions formate, acetate, and propionate ([HEA]F, [HEA]A, and [HEA]P) as eco-friendly, affordable, and easy synthesis electrolytes are proposed for activated carbon (AC)-based supercapacitors. The ionic conductivity and the electrochemical stable potential window (ESPW) of ionic liquids were assessed. The electrochemical performance of synthesized ILs as an electrolyte in AC-based supercapacitors was compared. Electrochemical properties were performed by electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV), linear sweep voltammetry (LSV), and galvanostatic charge-discharge (GCD) methods to evaluate the electrolytic performance of ionic liquids in supercapacitors. The charge transfer resistance (R ct) and solution resistance (R s) decreased with decreasing anion size of ILs. At a scan rate of 10 mVs−1, the prepared supercapacitors using [HEA]F, [HEA]A, and [HEA]P ionic liquids deliver specific capacitance of 114, 95, and 73 F g−1, respectively. The maximum power density 2941 W kg−1 and maximum energy density 70 Wh kg−1 were obtained for the prepared supercapacitor using [HEA]F ionic liquid. The supercapacitors prepared with [HEA]F, [HEA]A and [HEA]P electrolytes show capacitance retention of 96%, 91% and 87% after 5000 charge-discharge cycles, respectively. [ABSTRACT FROM AUTHOR]

• Combination of unilateral solution impregnation with laser induction in one-step process to get manganese-assisted graphene electrodes. • The modifier under the laser is cleverly used to achieve the enhancement of the electric double layer capacitance and the incorporation of pseudocapacitance. • Nitrogen, oxygen and manganese in superhydrophilic graphene with high yield, large surface area and low impedance. • The capacitance of as-prepared device is performing ∼25 times of the control. • Balancing cycling performance and capacity improvement of supercapacitors. Laser-induced graphene (LIG) technology has made it possible to prepare graphene-based supercapacitors on a large scale and at low cost. However, the performance of graphene-based supercapacitors fabricated solely by laser still has a great potential for improvement. In this work, we obtained high-performance supercapacitors based on manganese-assisted laser-induced multi-layer graphene-like carbon (MLIGC) by a simple process. Poly-(m-phenylene isophthalamide) (PMIA) papers treated with modifier (KMnO 4) were used as substrates. Modifier not only deepened the cross-sectional carbonization and achieveed uniform dispersing of manganese oxide nanoparticles, but also changeed the surface properties of MLIGC. Benefit from the hybrid structure of manganese oxide nanoparticles uniformly dispersed inside multi-layer graphene-like carbon (LIGC) prepared by one-step laser process, the combination of electric double-layer capacitance and pseudocapacitance allows for a further breakthrough in capacity while maintaining excellent cycling stability. Specifically, the supercapacitors achieve an area capacity of 72.4 mF cm−2 at 0.2 mA cm−2, which is 25 times higher than the control. In addition to the significant capacity increase, the addition of the modifier also achieveed a significant impedance reduction (almost one ninth of the control) and demonstrateed excellent cycling stability (nearly 100 % capacity retention after 7500 cycles at 10 mA cm−2). More importantly, the method is simple, fast, low-cost and high-efficiency, which provides a new path for the large-scale preparation of planar carbon-based supercapacitors. [Display omitted] [ABSTRACT FROM AUTHOR]

• Multilayer MnO 2 /B-containing CNF was prepared by sequential electrospinning. • B-related functional groups and MnO 2 exist independently in different nanosheets. • Each component acts independently to maximize the electrochemical properties. • B-related functional groups and MnO 2 optimize the pseudocapacitance. • The large number of mesopores leads to a high rate response and stable cycle life. One major challenge in capacitor development is achieving high capacitance and large energy density with rapid charge and discharge rates of minutes to seconds. This paper reports boron-containing trilayer structured MnO 2 /carbon nanofiber composites(PPMnB) as promising supercapacitor electrodes with high electrochemical properties under rapid charge and discharge conditions. Multilayer carbon nanofiber(CNF) composites are designed to maximize the advantages of CNF, MnO 2 , and boron functional groups when applying functionalized porous CNF containing transition metal composites to supercapacitor electrodes. The PPMnB electrode exhibits a high specific capacitance (215 Fg−1 at 1 mAcm−2), good rate capability (83 % capacity retention at 20 mAcm−2), high energy density (23.5 Whkg−1 at 400 Wkg−1), and good cycling stability (only 6.0 % loss after 10,000 cycles at 1 mAcm−2). In addition, the asymmetric capacitor of the PPMnB(25) and PPB(0) used as the positive and negative electrode shows excellent electrochemical performance, including an excellent energy density of 46.3 Whkg−1 at a maximum voltage of 1.4 V. High electrochemical performance is achieved through the combined effects of the hierarchical porosity of CNF, high electrochemical activity of MnO 2 , and increased electrical conductivity by boron functional groups in each layer. [Display omitted] [ABSTRACT FROM AUTHOR]

In a pursuit to satisfy the rising energy demand, researchers to create novel, environmentally safe electrode materials for several energy storage devices. The electrochemical performance could be compromised as a result of the polymer binders employed in the electrode coating procedure. Binder-free electrode materials accelerate electron transport pathways by providing enough room to accommodate the active material's large volume changes during charging and discharging. Lower electronegativity of sulphur compared to oxygen provides increased flexibility in the structure of transition metal sulphides which makes them stand out as the promising candidates in the search for innovative electrode materials. Likewise, although PANI possess high conductivity and specific capacitance, it's ineffective to be used in the purest form for practical applications owing to its inability to retain the capacitance when it undergoes multiple charging/discharging cycles. In this work, we describe the development of binder-free Cu-Mn mixed sulphide and its nanocomposite with PANI on carbon fibre paper (CP) substrates. Characterization techniques such as XPS, FE-SEM along with elemental mapping helped in understanding the successful formation of the nanocomposite. In contrast to pure PANI and Cu-Mn mixed sulphide at the same current density in a neutral 1 M Na 2 SO 4 electrolyte, the composite of Cu-Mn mixed sulphide and PANI demonstrated an enhanced areal capacitance of 550.95 mF cm−2 at 1 mA cm−2. Incorporating PANI with Cu-Mn mixed sulphides has not only improved their capacitance but also reduced the rate at which pristine PANI's capacitance degrades when subjected to a greater number of charge/discharge cycles which is reflected in the enhanced capacity retention property of the nanocomposite, wherein the composite maintained 99.02% of its original capacitance at a current density of 10 mA cm−2 than of pure PANI on CP substrates. [Display omitted] [ABSTRACT FROM AUTHOR]

Porous structures grown in situ increase the electrode contact area with the electrolyte, reduce ion diffusion distance, and enhance electrode material electrochemical properties. In this paper, we have adopted a dual-channel electrodeposition strategy with simultaneous electrodeposition and phosphorylation to construct metal-semiconductor contact heterostructures by depositing Ni@NiCo phosphate microspherical nanostructures directly on a copper foam (CF) (Ni@NiCoP/CF) framework at room temperature. The results show that Ni@NiCoP/CF has excellent electrochemical performance with a high specific capacity of 200 mAh g –1 at 1 A g –1, 147.2 mAh g –1 at 20 A g –1 and 93.6 % after 5000 cycles, showing excellent ration performances and cycling stability. In addition, the hybrid supercapacitor composed of Ni@NiCoP/CF as the positive electrode and activated carbon as the negative electrode achieves a high energy density of 48.7 Wh kg−1 at 874 W kg−1 and has excellent cycling stability with 113.23 % capacity retention after 30,000 charge/discharge cycles at a high current density of 10 A g –1. This study serves as a guide for the development of high-performance capacitor cathode materials with high electrochemical activity and capacity. [ABSTRACT FROM AUTHOR]

• A novel MoS 2 is prepared through facile hydrothermal method. • An interesting nano-worm based aggregates morphology and crystallinity of MoS 2 is obtained. • Excellent electrode material along good specific capacitance and high energy density is attained. • MoS 2 is believed to be a potential electrode material for asymmetric supercapacitor as shown in manuscript. Nowadays, supercapacitors and batteries are trending electrochemical energy storage devices. However, their low energy density and uncertain power density limited their applications, respectively. Recently, the latest innovation in energy storage devices, called hybrid supercapacitors, has appeared as an eventual energy storage device that demonstrates a hybrid storage mechanism of both supercapacitors and batteries. In this work, MoS 2 has been prepared by the facile hydrothermal method, characterized by different techniques, and applied as an electrode in supercapacitors and supercapatteries. The XRD patterns and EDX confirm the successful synthesis of MoS 2 with an average crystallite size of 62.25 nm, while the SEM images show the randomly oriented nanoworms of MoS 2. The XPS spectrum depicts the presence of variable oxidation states of molybdenum (Mo4+and Mo6+) in the MoS 2. The electrochemical performance shows that the highest specific capacitance and specific capacity reached 1866.66 F/g and 1119.99 C/g, respectively, at a scan rate of 5 mV/s for MoS 2. The asymmetric supercapacitor device is made from (Graphite/MoS 2) using as a working electrode and activated carbon as a cathode, which are separated by filter paper. Furthermore, the Dunn's model is utilized to evaluate of capacitive and battery mechanisms and shows the dominant role of diffusive and surface-controlled developments at low and high scan rates, respectively, owing to the change in diffusion time of electrolyte species. The fabricated device shows an energy density and power density of 103.51 Wh/kg and 3807.59 W/kg at a current density of 1 and 7 A/g, respectively, with 93.52% capacity stability and 99.8% coulombic efficiency. This excellent performance of MoS 2 is believed to be a potential electrode candidate for asymmetric supercapacitor applications. [ABSTRACT FROM AUTHOR]

Hierarchical microstructures are unique characteristic in various natural organisms with optimized functions. The anisotropic structure offers low-tortuosity with hierarchical porosity, providing sufficient multifunctional channels for mass/ion transport, which is desirable for the design of low temperature tolerant energy storage device. Conductive hydrogels are elastic crosslinked polymeric networks that adaptable in various environmental conditions, exhibiting promising potentials for energy storage and conversion devices. However, conventional hydrogel based energy storage devices would inevitably freeze at low temperatures (< 0 °C) due to the high content of solvent water, which fundamentally lead to the fatal deterioration of the ionic conductivity and limit their applications in extreme conditions. In this paper, a flexible solid-state supercapacitor was prepared using wood inspired anisotropic polyvinyl alcohol (PVA) hydrogel electrolyte via directional freezing strategy. The hierarchical channels are tuneable by varying the concentrations of PVA solutions. The ionic conductivity of hydrogel electrolyte was significantly enhanced in the full temperature range attributing to the hierarchical microstructures, specifically, the microscale vessel-like directional ion transport channels coupled with nanopores on the inner walls. With co-mixing of dimethyl sulfoxide/ethylene glycol as the organic solvent medium, the assembled solid-state supercapacitors exhibited excellent electrochemical performance of 65% capacity retention at -30 °C, remarkably flexibility and decent cycling stability of 75% capacity retention after 5000 cycles at -20 °C. This work demonstrates that the hierarchical anisotropic channels and organic anti-frozen additive could significantly enhance the low temperature performance of solid-state supercapacitors, opening up new strategy for advancing energy storage devices at extreme conditions via the bio-mimicked optimization of microstructure and electrolyte composition. [ABSTRACT FROM AUTHOR]

2,6-diaminopyridine (DAP), an active organic molecule containing amino groups and pyridine N is expected to be an attractive material for energy storage due to its fast and reversible proton-involved redox activity. Herein, the novel N-doped (or CNTs) and DAP organic molecules double-modified reduced graphene oxide nanocomposites with hierarchical porous nanoarchitectures were successfully designed and synthesized by a simple solvothermal method. Benefiting from the advantages of the three components and the positive synergistic enhancement between them, the newly synthesized N-RGO/DAP and CNTs/RGO/DAP nanocomposites exhibit excellent electrochemical properties, such as high specific capacitance, excellent rate capability and cycling stability. Furthermore, the Zn-ion hybrid supercapacitor further assembled with the optimal N-RGO/DAP as cathode delivers excellent Zn-ion energy storage performance in aqueous electrolyte, with a high specific capacitance (capacity) of 320.2 F g−1 (158.3 mAh g−1), excellent energy density of 140.9 Wh kg−1 at a power density of 534 W kg−1, and an ultra-long durability of 95.3% capacitance retention after 16,000 cycles at a large current of 100 mV s−1. This paper provides a novel strategy and advanced electrode nanocomposite with excellent electrochemical properties, which shows great promise in high-performance energy storage devices with high-flexibility, light-weight and sustainability. [ABSTRACT FROM AUTHOR]

NiCo 2 S 4 is a promising electrode material for supercapacitors due to its high conductivity and rich elemental valence distribution. However, the low specific capacitance and poor cycling stability of NiCo 2 S 4 electrode material restricted its practical application. In this paper, we proposed a dual regulation strategy of nitrogen-doped carbon cloth current collector (NCC) and the introduction of S vacancies in the NiCo 2 S 4 (NCS) to prepare a high electrochemical performance of integrated electrode material. The introduction of N doping into the CC current collector helped to improve the loading capacity of NCS and contributed to capacitance, while the rich S vacancies in NCS could provide more electroactive sites and increase its electrical conductivity. Benefiting from the synergistic effect of NCC and S vacancies, the fabricated NCS 4–0.5 /NCC integrated electrode material illustrated an ultra-high specific capacitance of 4075.89 mF cm−2 (2079.53 F g−1) at 1 mA cm−2 and superior electrochemical cycling stability with 80.03% of initial capacitance at a high current density of 20 mA cm−2 after 5000 cycles. Therefore, the present dual regulation strategy provides a new route to fabricate supercapacitor electrode materials with excellent electrochemical properties. [ABSTRACT FROM AUTHOR]

Most metal-organic frameworks (MOFs) cannot be used as electrode materials due to their high cost, poor stability in aqueous solutions, inferior intrinsic electrocatalytic activity, and poor conductivity. The novel application of a nickel (II) cluster-based two-dimensional MOF, Ni-mba ([Ni(II) 6 Ni(III) 2 (mba) 6 (Cl) 2 (OH−) 2 (O2−)] n , H 2 mba is 2-mercaptobenzoic acid), is reported for use as electrode materials. Ni-mba is an insulator and H 2 mba is an inexpensive chemical raw material. The conductivity of Ni-mba is 2.180 × 10−9 Scm−1 at 30 °C. The electrocatalytic activity of Ni-mba is enhanced by the hexanuclear nickel (II) cluster subunit containing the sulfhydryl group and the mixed valence Ni2+/Ni3+ ions. Ni-mba shows excellent performance, stability in 6 M KOH, and a high inherent density (1.828 gcm−3) and specific capacity (704.4 Fg−1 at 1 Ag−1 and 1088.5 mAhg−1 at the first cycle) for lithium-ion batteries and supercapacitors. This paper provides a novel application of nonconductive two-dimensional MOFs in the energy storage field and the design recommendations of high-performance electrode materials for energy conversion and storage based on its structure and performance differences. An insulating layered MOF was used as electrode materials for lithium-ion batteries and supercapacitors, and exhibited high performance and excellent stability in 6 M KOH. Design recommendations for nonconductive two-dimensional MOFs were provided based on its structure and performance differences. [Display omitted] [ABSTRACT FROM AUTHOR]

The aim of this paper is the development of an innovative method for the recycling of carbon-based ashes waste derived from the production plant CMD ECO 20, designed by the company Costruzioni Motori Diesel (C.M.D.) for the combined production of electricity and heat. In this work we propose, for the first time, an original way for a technological/industrial valorisation of the carbon ashes waste, produced from biomass pyro-gasification plant, by using them as fillers of electrically conductive inks suitable for the fabrication of supercapacitors. A water-based dispersion containing nanometric waste carbon ashes (nCA), of around 300 nm, was obtained from carbon waste ashes of wooden biomass through an eco-friendly process. The developed inks based on PEDOT:PSS and nCA showed good capacity performance, explored by cyclic voltammetry (CV) measurements, with CV characterised by approximately rectangular shape and long-term stability in the time. Indeed the best specific capacitance of 26.80 ± 0.21 F/g, achieved for the nCA0.5PEDOT:PSS film was retained at 96.8% of the initial capacitance after 1000 cycles. The PEDOT:PSS/ nCA based suspensions were then characterised by rheological and surface tension analysis, as a function of the nCA concentration ahead of printing deposition with the aim to investigate the printability of the developed inks Finally, the printability of the inks was investigated and demonstrated by means of Aerosol Jet Printing (AJ®P) setup with the aim to identify a production technology suitable for their use in printed electrical applications. [ABSTRACT FROM AUTHOR]

Although layered double hydroxide (LDH) materials have delivered numerous merits, such as low cost, ease of synthesis, environmental friendliness and high theoretical specific capacity, the shortcomings of unsatisfactory rate capability and poor cycle stability seriously limit their practical applications. Controllable preparation of electrode materials possessing exquisite microstructure is considered as one of the most effective strategies to improve the electrochemical performance. In this paper, a new quaternary nickel cobalt manganese iron layered double hydroxide (NiCoMnFe-LDH) material with a delicate microstructure design of combining dense nanosheets grown on NiCoMnFe-LDH thin film and outspread nanospheres assembled by tiny nanosheets is electrodeposited on carbon cloth by introducing moderate amount of ion elements and regulating the growth time. Ternary NiCoMn-LDH material is also prepared under the same condition for comparison, which shows a distinct morphology feature of thick nanosheets stacking. NiCoMnFe-LDH electrode delivers more outstanding electrochemical properties than NiCoMn-LDH electrode from the aspects of specific capacity, rate capability, electrical conductivity and cyclic stability. Moreover, the as-assembled NiCoMnFe-LDH//AC aqueous hybrid supercapacitor device possesses a high specific energy and a satisfactory lifespan. The ease of fabrication and brilliant energy storage characteristics enable this newly-constructed aqueous hybrid supercapacitor a powerful candidate for practical applications. [ABSTRACT FROM AUTHOR]

• Antimonene show a mixture of surface-controlled and battery-like responses in acid. • Power-law and kinetics simulation further confirm the energy storage mechanism. • EQCM and DFT reveal that hydrated H +can access the inner surface sites of antimonene. • The as-prepared ASC exhibits wide operating voltage and great cycling performance. Advanced secondary energy storage technologies and key components are crucial to the efficient use of energy resources. Layered antimonene can facilitate ions transport and intercalation. However, the electrochemical mechanism of antimonene is very much a gray area. Herein, we show that the electrolyte ions can make appreciable differences in the energy storage behavior of antimonene. Accordingly, a high value of 599 F g −1 can be obtained by scanning antimonene electrode in 1 M H 2 SO 4 at a rate of 5 mV s −1, which is more than twice the capacitance of those KOH, LiOH and LiCl based electrolyte systems. Systematic investigation including kinetics simulation and extrapolation of surface charge suggests a mixture of surface-controlled and battery-like Faradaic responses of antimonene in acid electrolyte. Electrochemical quartz crystal microbalance (EQCM) combined with first-principles calculation further reveals that hydrated H + is expected to access the "inner" surface sites of antimonene and thus insert or intercalate into the antimonene nanosheets. Notably, an asymmetric supercapacitor composed of antimonene positrode and carbon nanotube negatrode exhibits a wide operating voltage of 1.8 V, a relatively high energy density of 46 Wh Kg−1 at a power density of 450 W Kg−1 and great cycling performance (capacitance retention of up to 112.7% after 5000 cycles, 1.5 A g −1). The paper offers fundamental insights into the influence of electrolyte ions on the electrochemical behavior of 2D Xenes and pushes back the frontiers of designing energy storage systems. [Display omitted] [ABSTRACT FROM AUTHOR]

In this paper, several approaches to the synthesis of molybdenum-based electrode materials for supercapacitors are presented, including anodization, hydrothermal process and annealing. For the material prepared via anodization of a molybdenum plate, followed by a hydrothermal process in thiourea aqueous solution, a thorough study of the Pt-surface modification through repetitive cycling in 1 M sulfuric acid with Pt acting as a counter electrode is performed, including X-ray photoelectron spectroscopy analysis and energy storage mechanism contribution. Along with the increasing number of cycles, an increase of the capacitance value is observed up to 1.064 F cm−2 after 60 000 cycles, resulting in more than tenfold growth (by over 1 150%). The analysis reveals progressive changes in the electrode material's chemical composition and the increasing pseudocapacitance contribution in energy storage processes, which is strictly caused by the formation of mixed molybdenum oxides with oxygen vacancies. Thus, Pt-surface modification effectively improves the electrochemical performance of the electrode material with excellent coulombic efficiency and capacitance retention. In a symmetric two-electrode configuration with Pt-modified electrode materials, the areal capacitance of 140.5 mF cm−2 is obtained after 50 000 cycles (with capacitance retention of 123%) indicating that Pt-surface modification of MoS 2 may provide a novel approach for electrode materials for high-performance supercapacitors. [ABSTRACT FROM AUTHOR]

The development of high-performance and flexible supercapacitors is of urgent demand but still challenging. MXene, a novel two-dimensional material, has metallic conductivity, good hydrophilicity, and high redox activity. Significantly, its good electrochemical and mechanical properties suggest its great potential in flexible supercapacitors. However, the poor interlayer conductivity and self-stacking of MXene flakes hinder the charge transfer and ion transport. Herein, a three-dimensional porous structure composed of MXene, carbon nanocoils (CNCs) and Poly(3,4-ethylenedioxythiophene): poly(styrenesulfonate) (PEDOT:PSS) (denoted as MXene/CNC/PP) has been successfully prepared by a facile drop-coating method for flexible film electrode. The CNCs, having unique 3D helical structures and excellent dispersity, insert into the MXene flakes to prevent their over stack and provide spaces and channels for electrolyte storage and ion transport inside the composite structure. Meanwhile, the CNCs also act as highly conductive bridges to connect the MXene flakes, enhancing the charge transfer. To increase the stability of the composite structure, the conducting polymer PEDOT:PSS was selected as an conductive binder to prepare self-supported MXene/CNC/PP film electrodes without additional additives. The MXene/CNC/PP electrode exhibits an areal capacitance of 232 mF cm−2 at 10 mV s−1 with superior rate capability, excellent cycling stability and flexibility. This paper provides a new strategy for construction of wearable high-performance flexible electrodes and supercapacitors. [ABSTRACT FROM AUTHOR]

A rapid technological advancement observed in recent decades has indicated the urgent need for the development of robust and efficient energy storage devices. An interesting concept that has just emerged in the literature describes the use of biologically-derived materials, particularly living electroactive bacterial biofilms, for the development of supercapacitors. The aim of this paper is to present a recent state-of-the art in the field of bacteria-based supercapacitors, indicating current limitations and future opportunities of this microbial electrotechnology. Starting from a brief characterization of electrochemically active bacteria, we describe the mechanism of electron transfer in biofilms, identify structural units responsible for electron transfer, characterize supercapacitive properties of bacteria as confirmed by different measuring techniques, and provide a summary of recent literature studies employing bacteria, either in a living or in a mineralized form, in the design of novel supercapacitors. In the last section, we indicate the most important issues that need to be resolved to allow for the practical implementation of bacteria-based supercapacitors in energy storage applications. [ABSTRACT FROM AUTHOR]

ZnO is an appealing electrode material for supercapacitors due to its high capacitance, low cost, environmental friendliness, and good electrochemical reversibility. In this paper, we present the synthesis of a newly designed ZnO covered with ZnS and paired with CdS to produce a ternary heterostructure. According to the morphological research, ZnO has an urchin-like shape coated with ZnS and CdS nanoparticles on the surface with no undesired by-product residues, which improves the surface functionalities. First, we combined ZnO and ZnS to make a binary nanocomposite that outperformed its bulk equivalent ZnO by 322 mAh g−1 at 175 mAh g−1 during the charge-discharge process when a low current flow of 1 A g−1 was used. Meanwhile, the synergistic effect of multiple components, a new class of ternary ZnO-ZnS-CdS heterostructure was developed which effectively improved the electrochemical properties of the individual constituents, e.g., a capacity of 434 mAh g−1, and charged transfer kinetics (over pristine ZnO, and ZnO-ZnS electrodes). Inspired from the good capacitive behavior in a three-electrode mode, we further assembled an ASC that exhibits exceptional energy-storage performance of 36 Wh kg−1, 5422 W kg−1 after adding an optimal voltage (1.8 V), and retain only ∼91% at a higher current response. Last but not least, compositing is a vital strategy to boost the overall capacitive performance of the nanomaterials. [ABSTRACT FROM AUTHOR]

Layered double hydroxide (LDH) is a promising pseudocapacitive electrode material with adjustable interlayer spacing, good electrochemical properties, and ion exchange ability. However, low conductivity and low exposure of electrochemically active sites limit its application in electrode materials. In the paper, NiMn-LDH nanoarrays with large interlayer spacing were synthesized on nickel foam (NF) by hydrothermal and modified by different degrees of incomplete sulfidation by controlling the times. The results show that NiMn-LDH/Ni 3 S 2 is obtained when the sulfidation time is 3, 5, and 7 h. The best electrochemical performance is obtained at 3 h, with a specific capacity of 682 mA h g–1 at a current density of 5 mA cm–2 and maximum multiplicative performance of 59% (at 100 mA cm–2). The assembled hybrid supercapacitor obtains an energy density of 49 Wh kg–1 at a power density of 815 W kg–1 and capacity retention of 102% after 10,000 cycles (74 F g–1 at 10 A g–1). This is because the expanded interlayer spacing decreases the diffusion resistance between the interlayers, making it easier for OH– to enter the interlayers to improve the interaction with LDH. The sulfidation enhances the interfacial interaction by enhancing the electrical conductivity, while the conductive substrate provides additional electrical conductivity to the electrodes, leading to improved electrochemical performance. [ABSTRACT FROM AUTHOR]

In this paper, a free-standing and robust asymmetric flexible supercapacitor was developed using electrodeposited MnO 2 and MoS 2 /Fe 2 O 3 on carbon cloth (CC) and molybdenum mesh (MM) as positive and negative materials, respectively, and neutral LiCl/polyvinyl alcohol hydrogel as the gel electrolyte. The supercapacitor achieved an operating voltage window of up to 2.0 V and an excellent areal capacitance of 727.1 mF cm−2 at 1 mA cm−2, which delivered outstanding energy and power densities of 101 μWh cm−2 and 0.502 mW cm−2, respectively. Moreover, benefitting from the complementary mechanical properties of the two substances, the as-prepared flexible supercapacitor has the characteristics of high-strength and excellent resistant to bending, which maintained almost unchanged capacitance when bent to an arbitrary angle. The flexible supercapacitor has the potential of being a high-performance energy storage device with a simple preparation, high cost efficiency, and environmentally friendly properties. [ABSTRACT FROM AUTHOR]

• Ammonia solution and ozone treatment was used to modify the activated carbon. • Modified carbon is characterized by a higher content of oxygen and nitrogen moieties. • Double doped carbon was used as the electrode material of supercapacitor. • Electrochemical measurements confirmed an enhanced supercapacitor performance. This paper discusses the electroactivity of carbon materials doped by heteroatoms. Activated carbons were modified by the reaction with an ammonia solution followed by ozone treatment. Ozone treatment allows the introduction of not only oxygen functionalities but also nitrogen functional groups through the ammoxidation process. The modified and unmodified carbon materials were used as electrode materials of an electrochemical capacitor. To determine the processes occurring at the electrode/electrolyte interface, a broad physicochemical and electrochemical analysis was performed. The electrical characteristic of supercapacitors was measured in two- and three-electrode cells assembled in a Swagelok® system in aqueous electrolytes. The electrochemical properties were examined by cyclic voltammetry and electrochemical impedance spectroscopy. [Display omitted] [ABSTRACT FROM AUTHOR]

• Flexible asymmetric supercapacitor device based on CC/PANI-MnO 2 as the positive electrode and CC/MXene as the negative electrode is successfully fabricated. • The device exhibits specific capacitance of 21.1 f g−1 at 0.5 a g−1, voltage window of 1.5 v and energy density of 47.25 μWh cm−2 at power density of 2.40 mW cm−2. • Two devices after bending 500 times greater than 90° connected in series can easily power a 1.8 v LED. Polyaniline (PANI) and manganese dioxide (MnO 2) are forward-looking electrode materials due to their high specific capacitance. But poor cyclic stability of PANI and low power density of MnO 2 limit their development. In this paper, PANI and MnO 2 were synthesized on carbon cloth (CC) by electrochemical polymerization with the addition of LiClO 4. The capacitance of CC/PANI-MnO 2 increases to 634.0 F g−1 (380.4 C g−1) at 1 A g−1. And its decent electrochemical performances can be ascribed to the synergistic effect of PANI and MnO 2. Moreover, an asymmetric supercapacitor based on CC/PANI-MnO 2 as positive electrode and CC/MXene as negative electrode were assembled to broaden the potential range. The device has capacitance of 21.1 F g−1 at 0.5 A g−1 and the capacitance retention of 83% after 4000 cycles. The device shows an energy density of 47.25 μWh cm−2 at a power density of 2.40 mW cm−2. Furthermore, the ductility of the device was explored to resist the bending and stretching from external forces. The research of flexible asymmetric supercapacitors herein further improves the practical application of energy storage devices. [Display omitted] Flexible asymmetric supercapacitor device based on CC/PANI-MnO 2 //CC/MXene in acidic electrolyte are successfully fabricated, exhibiting specific capacitance of 21.1 F g−1 at 0.5 A g−1, voltage window of 1.5 V and energy density of 47.25 μWh cm−2 at power density of 2.40 mW cm−2. Moreover, two devices after bending 500 times greater than 90° connected in series can easily power a 1.8 V LED. [ABSTRACT FROM AUTHOR]

With the great success in developing high-performance cathode materials for hybrid aqueous supercapacitors, there is an urgent need to explore anode materials with excellent electrochemical performance to replace the currently used carbon anodes of low specific capacitance in order to increase the energy density of the supercapacitors. In this paper, we report a hierarchical CoNb 2 O 6 @CoOOH core-shell composite on carbon fabric prepared by the in-situ conversion from CoNb 2 O 6 to CoOOH via an electrochemical activation strategy, which possesses CoNb 2 O 6 nanoparticles "core" and CoOOH nanosheets "shell" supported by carbon fabric. When used as the anode of supercapacitors, the CoNb 2 O 6 @CoOOH core-shell composite exhibits a high specific capacitance of 1015.67 F g−1 at a current density of 2 A g−1 in 6 mol•L−1 KOH aqueous solution as well as excellent rate capability. Additionally, the anode delivers a super-long life at a current density of 15 A g−1 with the capacitance retention of approximately 100% after 40,000 cycles. The outstanding comprehensive electrochemical performance may be attributed to the synergistic effect of efficiently using all the desired functions of CoNb 2 O 6 and CoOOH components in the unique hierarchical structure of the composite, which contributes to a larger electrochemical active surface area and a more stable electrochemical process. [ABSTRACT FROM AUTHOR]

• Both cation and anion defects are introduced into gallium oxynitride (GON) nanoparticles. • The GON-based electrode performance is dramatically improved via defect engineering. • V Ga and V O are conducive while V N is adverse to the improved electrode performance. • There is no linear relationship between defect concentration and improved performance. Gallium oxynitride (GON) with phase resembling that of wurtzite gallium nitride (GaN) is a promising electrode material for supercapacitors. However, pristine GON nanoparticles exhibit relatively low specific capacitance, limiting their wide application in energy storage systems. In this paper, we report on dramatic increase in electrochemical performance of GON nanoparticle-based electrodes through purposefully introducing both cation and anion defects in the electrodes via controllable electrochemical etching. The textural property, band structure, and defect concentration of the electrodes can be engineered by altering the etching time. The functions of both cation and anion defects on the electrode performance have been clarified on the basis of experimental and theoretical computation results. The enhanced electrochemical performance for the etched electrodes is attributed to (i) elimination of the surface oxide layer; (2) improved specific surface area (S BET) and pore volume (V pore); and (iii) engineered cation and anion defects. It is the synergistic effect of cation and anion defects, rather than S BET and V pore , that determines the electrochemical performance of the electrodes. The GON nanoparticle-based electrodes with engineered defects have potential application in supercapacitors. Electrochemical etching on gallium oxynitride nanoparticle-based electrodes generates both cation and anion defects, in which V Ga and V O are conducive while V N is adverse to the improved electrode performance. [Display omitted] [ABSTRACT FROM AUTHOR]

• A high-performance self-supporting flexible cathode of NiCo 2 O 4 @NiCoMnS 4 on CC is developed. • 4836.2 mF cm–2 at 1 mA cm–2, and excellent rate and cycle performance are delivered. • The 1.7 V aqueous asymmetric supercapacitors deliver 0.399 mWh cm–2 at 0.85 mW cm–2 and good cycle performance. In this paper, we report a self-supported flexible electrode consisting of NiCoMnS 4 nanosheets on NiCo 2 O 4 nanowires, denoted as NiCo 2 O 4 @NiCoMnS 4 (NCO@NCMS) prepared by the hydrothermal growth (NiCo 2 O 4) and the following electrodeposition (NiCoMnS 4) on a carbon cloth (CC) substrate. The electrode delivers a high specific capacity of 4836 mF cm–2 at 1 mA cm–2 and excellent rate performance, i.e., 3820 mF cm–2 at 10 mA cm–2 and 2820 mF cm–2 even at 60 mA cm–2. An aqueous asymmetric supercapacitor (AASC) assembled using NCO@NCMS on CC as the cathode, activated carbon on CC as the anode and 2 M KOH as the electrolyte delivers a high energy density of 0.399 mWh cm–2 at 0.85 mW cm–2 and excellent cycle stability with ∼81.2% capacity retention after 20000 cycles at a high current density of 20 mA cm–2. In view of the excellent performance and facile preparation, this study is believed to provide a valuable exploration of developing high-performance electrodes and AASCs. [ABSTRACT FROM AUTHOR]

• Pseudo-composite behaviour of 2D porous NiCo 2 O 4 nanostructures. • Alteration of electrochemical performance of metal oxides under magnetic field. • Performance improvement with increase in magnetic redox ions in electrode material. • Theoretical correlation between diffusion coefficient and the specific capacitance. • Carbon footprint for the materials using the life cycle assessment studies. Till date, magnetic field dependent variations in specific capacitance have only been reported in simple binary oxides or alloys. Ternary spinels are often considered to be a composite of two or more mono-cationic entities, which allows them to deliver high specific capacitance. This paper deals with one such spinel i.e. NiCo 2 O 4 (NCO), with 2-dimentional porous morphology, for obtaining highly responsive magnetic supercapacitors. Compared to the constituent oxides viz., NiO and Co 3 O 4 , NiCo 2 O 4 shows nearly 100% higher response under magnetic field. Such results make this spinel furthermore useful for industrial applications. The results can be explained by the variation in dielectric constant, ESR, and ion diffusion as a function of applied magnetic fields. In such 2-dimentional porous oxides, a modified theoretical model has to be utilized to explain the magnetic field induced specific capacitance changes. There is a need to consider the impact of diffusion coefficient and additional convection term that is induced by the Fick's law. Another aspect, related with the carbon footprint for the materials, is determined using the life cycle assessment studies. This shows another advantage of using NiCo 2 O 4 in energy storage devices. [Display omitted] [ABSTRACT FROM AUTHOR]

A facile one-step solvothermal method is developed to prepare heterostructured nanocomposite Ni 0.85 Se/MnSe. High-resolution transmission microscopy confirms the formation of the heterostructure. When coated onto carbon cloth and used as the electrode material for supercapacitors, the electrode with the optimized Ni 0.85 Se/MnSe exhibits specific capacity of 1118 C g−1 at the current density of 1 A g−1, and a capacity retention at 83.2% after 5000 charge-discharge cycles at 10 A g−1 in 4 M KOH using three-electrode system. The assembled asymmetric supercapacitor exhibits the specific energy of 49.3 Wh kg−1 at the power density of 799.81 W kg−1, and 97.8% of the initial capacity is retained after 5000 charge-discharge cycles at 5 A g−1. Kinetic study indicates that the major contribution of the capacity is the diffusion-controlled process, and the electrode exhibits battery-type behavior. The excellent charge storage performance is originated from the higher number of electrochemically active sites, improved reaction kinetics and facilitated diffusion that are induced by the charge redistribution at the heterostructure interface. Conversion of the surface metal selenides to oxides and (oxy)hydroxides is observed during the long-term charge-discharge cycling. The heterostructured nanocomposite Ni 0.85 Se/MnSe is a promising candidate as the electrode material for supercapacitors. [ABSTRACT FROM AUTHOR]