Electrode Material For High-performance Supercapacitors Research Articles

Microscopic Origin of Electrochemical Capacitance in Metal-Organic Frameworks.

Electroconductive metal-organic frameworks (MOFs) have emerged as high-performance electrode materials for supercapacitors, but the fundamental understanding of the underlying chemical processes is limited. Here, the electrochemical interface of Cu3(HHTP)2 (HHTP = 2,3,6,7,10,11-hexahydroxytriphenylene) with an organic electrolyte is investigated using a multiscale quantum-mechanics/molecular-mechanics (QM/MM) procedure and experimental electrochemical measurements. Our simulations reproduce the observed capacitance values and reveals the polarization phenomena of the nanoporous framework. We find that excess charges mainly form on the organic ligand, and cation-dominated charging mechanisms give rise to greater capacitance. The spatially confined electric double-layer structure is further manipulated by changing the ligand from HHTP to HITP (HITP = 2,3,6,7,10,11-hexaiminotriphenylene). This minimal change to the electrode framework not only increases the capacitance but also increases the self-diffusion coefficients of in-pore electrolytes. The performance of MOF-based supercapacitors can be systematically controlled by modifying the ligating group.

Valorization of Biomass-Derived Polymers to Functional Biochar Materials for Supercapacitor Applications via Pyrolysis: Advances and Perspectives.

Polymers from biomass waste including plant/forest waste, biological industrial process waste, municipal solid waste, algae, and livestock are potential sources for renewable and sustainable resources. Converting biomass-derived polymers to functional biochar materials via pyrolysis is a mature and promising approach as these products can be widely utilized in many areas such as carbon sequestration, power production, environmental remediation, and energy storage. With abundant sources, low cost, and special features, the biochar derived from biological polymeric substances exhibits great potential to be an alternative electrode material of high-performance supercapacitors. To extend this scope of application, synthesis of high-quality biochar will be a key issue. This work systematically reviews the char formation mechanisms and technologies from polymeric substances in biomass waste and introduces energy storage mechanisms of supercapacitors to provide overall insight into the biological polymer-based char material for electrochemical energy storage. Aiming to enhance the capacitance of biochar-derived supercapacitor, recent progress in biochar modification approaches including surface activation, doping, and recombination is also summarized. This review can provide guidance for valorizing biomass waste to functional biochar materials for supercapacitor to meet future needs.

Rational fabrication and optimized design of hierarchical Ni3S2-MOF electrodes for enhanced electrochemical energy storage

How to design and synthesize of advanced MOF-based electrode materials for high-performance supercapacitors is still a huge challenge, herein, CoNi-MOF@Ni3S2 and ZIF-67/Ni3S2 with unique heterostructures are rationally designed and constructed. The composite electrode materials not only make up for the poor conductivity of MOF, but also improve the structural stability of Ni3S2. As expected, the optimized ZIF-67/Ni3S2 and CoNi-MOF@Ni3S2 electrode demonstrates a remarkably enhanced specific capacitance of 1017.13 F g−1 and 1930.04 F g−1 at 1 A g−1, respectively, which are higher than those of their respective monomeric components. Finally, ZIF-67/Ni3S2//AC and CoNi-MOF@Ni3S2//AC devices were assembled, which delivered an impressive energy density of 94.49 and 125.34 Wh kg−1, along with the corresponding power density of 966.34 W kg−1 971.86 W kg−1, respectively. Moreover, by comparison, the CoNi-MOF@Ni3S2 electrode material exhibits better supercapacitor performance than ZIF-67/Ni3S2. This effective protective strategy provides an alternative way for constructing MOF or sulfide electrodes with remarkably improved energy storage performance.

Fabrication of SrWO4/PPy composite as electrode material for high-performance supercapacitors

The societal major concern of the moment is energy storage, energy production and global warming. Researchers are striving to create novel, highly efficient energy storage materials for developing faster, safer as well as more effective energy storage systems. One effective method to improve the electrochemical performance of supercapacitors (SCs) is the construction of highly efficient electro active materials, employing multivalent binary transition metal oxides (BTMOs) with electrical conducting polymers (CPs). For the first time, we report SrWO4/PPy composite synthesized by In-situ chemical polymerization route. The physio-chemical characteristics of the synthesized material was extensively examined with spectral and analytical techniques. SrWO4/PPy composite on Ni foil was fabricated as an alternate electrode material and was investigated for its capacitive behaviour. SrWO4/PPy electrode achieved a high specific capacitance of 747 Fg-1 at 5 mVs−1 and a remarkable cyclic stability of 93.8% even after 5000 cycles at 1 Ag-1. The notable electrochemical property of the electrode was attributed to its distinctive composite morphology, which is crucial in facilitating high conductivity, quick electron transfer, short ion diffusion distance and excellent active sites for enhanced electrochemical performance. The substantial capacitive behaviour can be attributed to the synergetic effect of SrWO4 and PPy. This work introduces platform to design efficient electrodes for the energy storage devices as well as for wearable electronics.

Fabrication of CoMnFeO4/PANI nanocomposite as an efficient electrode in supercapacitors

In this study, a CoMnFeO4/Polyaniline (S2) nanocomposite was prepared using the in-situ polymerization method of Polyaniline (PANI) in the presence of CoMnFeO4 (S1) nanoparticles as high-performance supercapacitor electrode materials. The high specific capacitance of 1610 F/g at a current density of 1 A/g and the capacitance retention of about 100 % at a current density of 20 A/g after 600 cycles indicate the relatively high efficiency of the S2 nanocomposite. In addition, the excellent electrochemical performance of the S2 nanocomposite results from the synergy between the good properties of PANI and the pseudo-capacitance properties of CoMnFeO4 nanoparticles. Hence, a new electrode material with superior performance and long-term stability has been developed for energy storage systems.

Multicore-shell MnO2@Ppy@N-doped porous carbon nanofiber ternary composites as electrode materials for high-performance supercapacitors

In this study, a multicore-shell ternary composite electrode material (MnO2@Ppy@NPCNFs) with excellent electrochemical performances was prepared by using surface modification, in which core–shell Ppy@N-doped porous carbon nanofibers (Ppy@NPCNFs) with large specific surface area and high conductivity were used as the substrate (a multicore layer), and MnO2 was loaded on the substrate by hydrothermal synthesis to form a shell layer, further improving the SC of electrode material. The parameters of hydrothermal growth of MnO2 on Ppy@NPCNFs were explored by means of the control variable method and response surface methodology, and the optimal parameters were predicted and verified. Electrochemical test results showed that the SC of MnO2@Ppy@NPCNFs prepared under the optimal reaction parameters was as high as 595.77 F g−1, and its capacitance retention was 96.2 % after 1000 cycles. Moreover, a symmetric supercapacitor prepared with the optimal multicore-shell electrode showed an energy density of 9.36 Wh kg−1 at a power density of 1000 W kg−1 and a retention rate of 92.46 % after 1000 cycles, indicating the promising application of multicore-shell ternary composite electrode material in high-performance supercapacitors.

Novel strategy for efficient conversion of biomass into N-doped graphitized carbon nanosheets as high-performance electrode material for supercapacitor

The transformation of low-cost, renewable and eco-friendly biomass into energy conversion or storage materials with high energy density is one of the effective means to alleviate the energy crisis. In this study, a scalable route was proposed to synthesize porous, hetero-atom doped graphitized carbon nanosheets from the biomass-fish scales, and the as-prepared material was further used to construct a high-performance electrode for supercapacitor application. The synthesized N-doped graphitized carbon nanosheets (GNC-900) exhibit an average scale of 1–2 μm in size and hierarchical porous structure with a specific surface area of 1261.5 m2 g−1. The results of cyclic voltammetry (CV) and galvanostatic charge-discharge show that GNC-900 owns the quasi-electric double layer capacitance behavior in 6.0 M KOH electrolyte due to the presence of heteroatoms, and it exhibits a distinguished specific capacitance value of 448 F g−1 at a current density of 1 A g−1 in three-electrode cell. The CV curves at different scan rates reveal that this electrode has superior reversible stability and rapid response. Meanwhile, it delivers a high energy density of 57.7 Wh kg−1 at a power density of 999 W kg−1 in a two-electrode system. This novel and low-cost strategy provides an effective route to transform fish scales into highly valuable electrode materials in energy storage fields.

Highly porous nanocomposites of Mn doped cobalt-based hydroxide/sulfide as high-performance electrode materials for hybrid supercapacitors

Cobalt-based nanomaterials are a highly promising class of energy storage materials with high theoretical capacity and excellent long-term service life, such as metal doping and structural porousness of these cobalt-based nanocomposites, have been regarded as effective methods to further increase their active sites and improve their conductivity and performance. However, synthesizing cathode materials with high specific capacity and energy density through simplistic methods remains an immense obstacle. In this study, Mn doped cobalt-based hydroxide/sulfide nanocomposites with large pore volume as well as specific surface area were successfully synthesized. The Co(OH)2/CoS electrode doped with Mn has better charge storage capacity (capacity increase from 586.5C g−1 to 1030.8C g−1 at 0.5 A g−1), excellent rate performance (with a capacity retention of 75.8 % at 10 A g−1). Additionally, a hybrid supercapacitor (HSC) was constructed utilizing Mn-Co(OH)2/CoS and activated carbon (AC). HSC exhibited excellent charge storage capacity (166.3 F g−1 at 0.5 A g−1) and remained at 164.1 % of its original value after 30,000 cycles of testing with high current density. In addition, at a power density of 410.0 W kg−1, the assembled HSC device demonstrates a significant energy density of 62.1 Wh kg−1, revealing that porous Mn-Co(OH)2/CoS electrode materials showed excellent energy storage properties.

A 3D stacked corrugated pore structure composed of CoNiO2 and polyaniline within the tracheids of wood-derived carbon for high-performance asymmetric supercapacitors

A novel 3D stacked corrugated pore structure of polyaniline (PANI)/CoNiO2@activated wood-derived carbon (AWC) has been successfully constructed to prepare high-performance electrode materials for supercapacitors. AWC functions as a supporting framework that provides ample attachment sites for the loaded active materials. The CoNiO2 nanowire substrate, consisting of 3D stacked pores, not only serves as a template for subsequent PANI loading, but also acts as an effective buffer to mitigate the volume expansion of the PANI during ionic intercalation. The distinctive corrugated pore structure of PANI/CoNiO2@AWC facilitates electrolyte contact and significantly enhances the electrode material properties. The PANI/CoNiO2@AWC composite materials exhibit excellent performance (14.31F cm−2 at 5 mA cm−2) and superior capacitance retention (80% from 5 to 30 mA cm−2), owing to the synergistic effect among their components. Finally, PANI/CoNiO2@ AWC//reduced graphene oxide (rGO)@AWC asymmetric supercapacitor is assembled, which has a wide operating voltage (0 ∼ 1.8 V), high energy density (4.95 mWh cm−3 at 26.44 mW cm−3) and cycling stability (90.96% after 7000 cycles).

MnO decorated biomass derived carbon based on hyperaccumulative characteristics as advanced electrode materials for high-performance supercapacitors

MnO decorated biomass derived carbon based on hyperaccumulative characteristics as advanced electrode materials for high-performance supercapacitors

Controllable fabricate hierarchical CoMoO3@Co9S8/Ni3S2 core-shell arrays for high-performance hybrid supercapacitor

Rational design and construction of multiphase composite with specifical structure is an effective strategy to fabricate high-performance supercapacitor electrode materials. Herein, the hierarchical CoMoO3@Co9S8/Ni3S2 core-shell arrays are constructed by preparing Co9S8/Ni3S2 core with ion-exchange reaction and fabricating CoMoO3 shell through in situ transformation behavior. Thanks to the special heterostructures core-shell structure, the synergistic effect between multiple components, and the driving action of S-vacancies, hierarchical CoMoO3@Co9S8/Ni3S2 core-shell arrays exhibit battery-type features and deliver a great area specific capacity of 8.14 C cm−2 at current density of 5 mA cm−2. In addition, when assembled into a hybrid supercapacitor with capacitive-type electrode, the device achieves high energy density of 0.33 mWh cm−2 at the power density of 5.66 mW cm−2 and displays long-term durability with capacity retention of 93.7% and high Coulombic efficiency of 95.01% after 6000 cycles.

Tuning the Mn2+/Mn3+ ratio of ZnMn2O4 from spent zinc-carbon battery powder to enhance the electrochemical performance

Recycling metal resources from spent battery powder to prepare electrode materials is an eco-friendly and sustainable strategy. However, direct utilization of spent battery powder is mostly ignored, and the prepared electrode materials by this approach exhibit limited electrochemical performance. Herein, we employ unpurified spent zinc-carbon battery powder (SP) and carbon nanotubes (CNTs) as raw materials to fabricate SP/CNTs via the ball milling method, and then use a novel electrochemical activation strategy to obtain oxygen vacancy-rich SP@CNTs (Ov-SP@CNTs) materials. Under the combined action of CNTs doping and oxygen vacancies caused by the tuning of Mn2+/Mn3+ ratio via the electrochemical activation strategy, the optimum electrode (Ov-SP@CNTs-10) for supercapacitor shows the specific capacitance of 443.9 F g−1 at 1 A g−1, which is nearly six and three times higher than that of SP and SP/CNTs electrodes, respectively. Additionally, the packaged asymmetric supercapacitor (ASC) device with Ov-SP@CNTs-10 as the cathode and commercial active carbon (AC) as the anode manifests a large energy density of 25.51 Wh·kg−1 at the power density of 399.98 W kg−1, and the capacity retention of 88.58% after 10,000 cycles at 4 A g−1. This work opens up a new way for the direct utilization of SP to prepare high-performance supercapacitor electrode materials.

Enhanced performance of hybrid supercapacitors by the synergistic effect of Co(OH)2 nanosheets and NiMn layered hydroxides

A self-supporting composite electrode material with a unique three-dimensional structure was synthesized by in-situ growth of nanoscale NiMnLDH-Co(OH)2 on a nickel foam substrate via hydrothermal electrodeposition. The 3D layer of NiMnLDH-Co(OH)2 provided abundant reactive sites for electrochemical reactions, ensuring a solid and conductive skeleton for charge transfer and resulting in significant enhancement of electrochemical performance. The composite material showed a strong synergistic effect between the small nano-sheet Co(OH)2 and NiMnLDH, which promoted reaction kinetics, while the nickel foam substrate acted as a structural conductivity agent, stabilizer, and good conductive medium. The composite electrode showed impressive electrochemical performance, achieving a specific capacitance of 1870F g−1 at 1 A g−1 and retaining 87% capacitance after 3000 charge–discharge cycles, even at a high current density of 10 A g−1. Moreover, the resulting NiMnLDH-Co(OH)2//AC asymmetric supercapacitor (ASC) demonstrated remarkable specific energy of 58.2 Wh kg−1 at a specific power of 1200 W kg−1, along with outstanding cycle stability (89% capacitance retention after 5000 cycles at 10 A g−1). More importantly, DFT calculations reveal that NiMnLDH-Co(OH)2 facilitates charge transfer, accelerating surface redox reactions and increasing specific capacitance. This study presents a promising approach towards designing and developing advanced electrode materials for high-performance supercapacitors.

High-performance diatom co-doped Ti3C2Tx electrode material based on guanidine salt

The co-doping of a variety of heteroatoms can enhance the chemical reactivity and electron transport capacity of the composites. However, the doping process of Ti3C2Tx is usually carried out under harsh reaction conditions such as high temperature and protective atmosphere, which is easy to destroy the two-dimensional structure of Ti3C2Tx. Therefore, it is necessary to create doping conditions with reducing environment. In this work, Sulfur-nitrogen and phosphorus-nitrogen diatomic co-doped Ti3C2Tx ((S, N)-Ti3C2Tx and (P, N)-Ti3C2Tx) are first prepared using two weakly reducing guanidine salts, and the corresponding electrodes are prepared. The electrochemical test results show that at 1 A g−1, the Cm of (S, N)-Ti3C2Tx and (P, N)-Ti3C2Tx is 269.3 F/g and 168.3 F/g, which are 2.03 times and 1.27 times that of Ti3C2Tx (132.6 F/g), respectively. In addition, guanidine salt doping also gives Ti3C2Tx improves cycle stability. These results show that (S, N)-Ti3C2Tx and (P, N)-Ti3C2Tx can be used as excellent electrode materials for high-performance supercapacitors. Guanidine salt is a new heteroatomic source, and its processing operation provides a broader and more convenient experimental idea for heteroatomic doping.

In-situ NaCl nanocrystals template-induced self-assembly method to prepare anthracite-based hierarchical porous carbon with network-like structure for high-rate-performance supercapacitors

Using anthracite with high aromatic carbon content as the precursor, we propose an in situ sodium chloride (NaCl) nanocrystals template-induced self-assembly method to prepare high rate performance supercapacitor electrode materials. The capacitive carbon prepared in this method is characterized by hierarchical porous structure, network-like structure, and good electrical conductivity. With the synergistic effect of these structural features, it exhibits excellent supercapacitor performance. The optimum product (CPC-Na-5) displays high capacitance of 373 F g−1 at 0.5 A g−1 and still has 43 % capacity retention at 100 A g−1. The assembled symmetrical supercapacitor shows excellent rate performance with 86 % capacitance retention from 0.5 A g−1 (202 F g−1) to 50 A g−1 in 6 M KOH electrolyte. In the EMIMBF4 electrolyte, the energy density is 56.4 Wh kg−1 at 441.3 W kg−1 and remains 10 Wh kg−1 when the power density is increased to 27,375 W kg−1.

Mixed Ni-Co selenides as advanced electrode materials for high-performance supercapacitor

Mixed Ni-Co selenides as advanced electrode materials for high-performance supercapacitor

Self-supporting NiO-coated activated carbon nanofibers based on atomic layer deposition for supercapacitor

The rapid development of consumer electronics, electric vehicles, and smart meters demands high-performance energy storage devices. By now, supercapacitors are expected to become one of the most promising energy devices for future energy technology. In this work, NiO nanoparticles supported on activated carbon nanofibers (NiO/ACNFs) have been synthesized by atomic layer deposition technique, which is directly used as self-supporting binder-free electrodes for supercapacitors. Scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, and Raman results show that NiO nanoparticles (3.1 nm) are uniformly coated on ACNFs. The NiO/ACNFs-600 electrodes demonstrate a specific capacitance of 870 F·g−1 (1 A·g−1) and good rate capability (remain 67% at 10 A·g−1). The asymmetric supercapacitor devices with NiO/ACNFs-600//ACNFs electrodes yield a fairly high energy density of 39.85 Wh·kg−1 at 2000 W·kg−1 and excellent capacitance retention of 87% after 10,000 cycles. The excellent electrochemical capacitance performance for NiO/ACNFs is attributed to the high conductivity and large specific surface area of ACNFs, high capacity, small size, and even dispersion of NiO as well as the synergistic effect between them. These results demonstrate that NiO/ACNFs can serve as excellent electrode materials for high-performance asymmetric supercapacitors.

Spindle-shaped MoS2/ MnNi bimetallic hydroxide derived from metal-organic frameworks as electrode materials for high performance supercapacitors

Hydroxides produced from metal-organic frameworks (MOFs) offer a promising platform for high performance as supercapacitor electrode materials. By alkalinizing the precursor MoS2/MnNi-MOF-74, a novel MoS2/manganese-nickel double hydroxide (MoS2/MnNiDH) with a spindle shape has been successfully prepared. The composite material MoS2/MnNiDH exhibits a high specific capacitance of 2194.4 F/g at 1 A/g, and good capacity retention of 87.1% after 5000 charge/discharge cycles in a three-electrode system. Impressively, an asymmetric supercapacitor (MoS2/MnNiDH//AC, ASC) delivers a high energy density of 56.1 Wh/kg at the power density of 931.0 W/kg and more remarkable cycling stability retention of 95.0% after 10000 cycles in a two-electrode system. Finally, two assembled ASC connected in series can keep a blue LED blazing for more than 10 min, demonstrating that the MoS2/MnNiDH is a promising electrode material for high-performance supercapacitors.

Synthesis of Co3O4/NiO nanospherical composites as electrode material for high-performance supercapacitors

Synthesis of Co3O4/NiO nanospherical composites as electrode material for high-performance supercapacitors

Construction of tunable ZnCoOx/C-PANI electrode materials for high-performance supercapacitors

Polyaniline (PANI) has been widely studied because of its unique physicochemical properties, but its practical significance in supercapacitors is seriously affected by its structural collapse during charging and discharging. We have successfully synthesized transition metal oxide/carbon-polyaniline composite electrode materials by in situ growth of polyaniline using the electrodeposition method with a metal-organic skeleton as a sacrificial template. This method not only can obtain high capacitance materials but also carbon materials provide buffer space during long-term charge/discharge to improve the overall stability. ZnCoOx/C-PANI-3 has a smaller charge transfer resistance and solution resistance compared to other materials, indicating that the interfacial coupling between PANI and ZnCoOx/C shortens the ion transport path between electrolyte and electrode surface, which is beneficial for rapid ion transfer and thus enhances its electrochemical performance. ZnCoOx/C-PANI-3 as an electrode material in the three-electrode system, has remarkable specific capacitance (1055 F.g−1 at a current density of 1 A.g−1) and good cycling stability (85.7% capacitance retention after 10,000 cycles of charge and discharge at high current density). Similarly, the asymmetric supercapacitor (ZnCoOx/C-PANI-3//AC) assembled with ZnCoOx/C-PANI-3 as the positive electrode material and activated carbon as the negative electrode material has a maximum energy density of 42.77 Wh.kg−1 at a power density of 705 W.kg−1 and a remarkable cycle life with a capacitance retention rate of 80% after 5000 cycles. This research opens up new avenues for studying polyaniline/MOF derivatives (transition metal oxide-carbon) composites.