High Gravimetric Specific Capacitance Research Articles

3D porous PEDOT/MXene scaffold toward high-performance supercapacitors

3D architectures of conductive polymer, especially PEDOT hold great promise in energy storage and conversion fields. However, the facile construction of 3D PEDOT and its functionalization have still been challenges due to its poor processability. Herein, the fabrication of 3D porous PEDOT:PSS and its functionalization with MXene are realized synchronously through a simple and low-cost self-assembly process. The prominent capacitive performance of MXene, excellent chemical stability of PEDOT:PSS and 3D porous architecture with inhibited aggregation of MXene nanosheets, large amount of active sites, and electrolyte storage chamber endow the PEDOT/MXene-based porous structure with superior capacitive performance than individual PEDOT:PSS or MXene porous and flat structures. Furthermore, the PEDOT/MXene-based porous structure can be applied as a flexible scaffold for the deposition of conductive polymer to construct excellent electrodes for supercapacitors (SCs). When polypyrrole (PPy) is deposited, the prepared porous PEDOT:PSS/MXene/PPy electrode exhibits a high gravimetric specific capacitance of 345 F g−1 at a current density of 0.5 A g−1 and a remarkable capacitance retention of 89 % over 5000 cycles. Based on it, an asymmetric supercapacitor (ASC) with a high energy density of 56.34 Wh kg−1 at the power density of 120 W kg−1, and a capacitance retention of 75 % after 5000 cycles is developed. Besides, the porous PEDOT:PSS/MXene/PPy can be constructed on various substrates in any pattern with high design freedom, thus enabling customizable electrochemical performance. When constructing on a flexible substrate, excellent deformation-tolerant performance is shown. This work provides a high-performance electrode for SCs, as well as a universal route for the construction and functionalization of 3D PEDOT-based structures.

Reduced Graphene Oxide Wrapped Polypyrrole on Carbon Cloth for High‐Performance Flexible Solid‐State Supercapacitors

AbstractThe nature of rigidity and low energy density of polypyrrole (PPy)‐based electrodes limits their wide application in flexible energy storage devices. In this study, reduced graphene oxide (rGO) wrapped polypyrrole (PPy)/oxidized carbon cloth (OCC) (rGO@PPy/OCC) is prepared by the polymerization of pyrrole using MnO2 as the oxidant on the surface of OCC followed by the adsorption and reduction of graphene oxide (GO). The prepared rGO@PPy/OCC electrode exhibits a high gravimetric specific capacitance of 547 F g−1 at a current density of 0.5 A g−1 and a high area specific capacitance of 1641 mF cm−2 at a current density of 1.5 mA cm−2. It nearly maintains the initial capacitance after 8000 cycles at a high scan rate of 200 mV s−1 and at a large current density of 10 A g−1. Moreover, the flexible rGO@PPy/OCC electrodes are used to construct flexible solid‐state supercapacitors (FSSC). The FSSC based on rGO@PPy/OCC exhibits a high energy density (33.89 Wh kg−1 and 101.81 µWh cm−2) and a capacitance retention of 95.10% after 1000 bending cycles, demonstrating the excellent cycling stability and flexibility. Therefore, it is potential for rGO@PPy/OCC as a flexible electrode to fabricate high‐performance FSSC.

Dense graphene composite hydrogels as advanced electrode materials for high-performance supercapacitors

In this work, alanine functionalized nanocellulose/graphene composite hydrogels (NCGHalas) were prepared via an easy hydrothermal reaction using alanine, GO, and nanocellulose as reactant. Thanks to this synthesis strategy, NCGHalas exhibited large bulk density, abundant heteroatom functional groups, reasonable porous structure and moderate specific surface area. Based on the above characteristics, the aqueous symmetric supercapacitors (ASSC) assembled by NCGHala25 presented high gravimetric and volumetric specific capacitance of 276.5 F g−1 and 320.8 F cm−3 at 0.3 A g−1, excellent rate performance (77.9 % at 10 A g−1), and long working life of 95.4 % retention after 10,000 cycles at 10 A g−1. Furthermore, the NCGHala25 based ASSC also exhibited large gravimetric and volumetric specific energy densities of 9.6 Wh kg−1 and 11.1 Wh L−1. More importantly, the flexible solid-state supercapacitors (FSSC) fabricated by NCGHala25 and PVA-KOH electrolyte delivered high specific capacitance (178.2 F g−1, 0.3 A g−1), and this value can be maintained for 74.2 % even at 10 A g−1.

Application of N/P-rGO composite electrode materials and novel electrolytes in high-performance supercapacitors

Traditional graphene-based electrode materials often can not have excellent gravimetric and volumetric electrochemical properties at the same time. Furthermore, the gel electrolyte widely used at present has the disadvantages of poor water retention, easy solidification, low ionic conductivity, and narrow working temperature range during the working process. In this paper, nanocellulose/N, P co-doped reduced graphene oxide composites (NC-NPrGOs) were synthesized via a simple approach using graphene oxide (GO), ammonium dihydrogen phosphate, and nanocellulose (NC) as raw materials. Meanwhile, a new type of gel electrolyte (SNG) with renewable, wide working temperature range and ultra-high water retention properties was prepared using sodium alginate (SA), NC, GO, and potassium hydroxide as precursors. Benefiting from the unique physical and chemical properties of NC-NPrGOs, the assembled aqueous symmetric supercapacitors assembled by NC-NPrGOs present high gravimetric (303.9 F/g) and volumetric specific capacitance (416.5 F cm−3), large gravimetric (10.5 Wh kg−1) and volumetric energy density (14.6 Wh/L). Due to the multiple interactions of several components in SNG, the flexible solid-state supercapacitors (ASSC) assembled by NC-NPrGO55 and SNG deliver high specific capacitance (240.0 F/g), ultra-long cycling life, excellent bending resistance, a wide range of operating temperatures, and good regenerative performance. In summary, NC-NPrGOs and SNGs are ideal for the investigation of new energy storage devices.

Mass scale synthesis of graphene nanosheets using waste cardboard for application in perovskite solar cells and supercapacitors

Advanced graphene-based materials have been proficiently incorporated into next-generation solar cells and supercapacitors because of their high electrical conductivity, large surface area, excellent charge-transport ability, and exceptional optical properties. Herein, we report the synthesis of graphene nanosheets (GNs) from waste cardboard via pyrolysis, with ethyl alcohol as the growth initiator. Additionally, we demonstrated the use of GNs in energy conversion and storage applications. Using the GN electrode in perovskite solar cells resulted in an excellent power conversion efficiency of ∼10.41 % for an active area of 1 cm2, indicating an enhancement of approximately 27 % compared to conventional electrodes. Furthermore, the GNs were used as active electrode materials in supercapacitors with excellent electrochemical performance and a high gravimetric specific capacitance of 167.5 F/g at a scan rate of 2 mV/s. The developed GNs can be efficiently used for energy storage, conversion, and electrochemical sensing applications.

High-performance supercapacitors based on compact graphene composite hydrogels

Because of its ultra-high specific surface area and outstanding electrochemical performance, graphene has become a study focus of electrode materials for supercapacitors. However, severe agglomeration and poor volumetric electrochemical properties greatly reduce its potential for practical applications. Here, we proposed a simple hydrothermal strategy to synthesize L-glutamic acid functionalized nanocellulose/reduced graphene oxide composite hydrogels (GNGHs) with compact porous structures and plentiful heteroatom functional groups. In the hydrothermal process, a high concentration of graphene oxide solution (GO) was employed to boost the packing density of the samples. Nanocellulose (NC) and the molecular chains of L-glutamic acid were used as spacers to modulate the porous structure of GNGHs. At the same time, NC and heteroatomic groups can also boost the surface wettability of GNGHs, thereby increasing their ion-available specific surface area. The GNGH-15 based symmetric aqueous supercapacitors (SASC) deliver high gravimetric (282.0 F g−1) and volumetric (329.9 F cm−3) specific capacitance, remarkable rate capacity, and good cycling durability. Moreover, the all-solid-state flexible supercapacitors (ASSC) assembled by GNGH-15 also exhibit prominent specific capacitance (154.7 F g−1) and good rate performance. These brilliant electrochemical properties make GNGHs a strong contender for electrode materials of energy storage devices.

Walnut shell derived N, S co-doped activated carbon for solid-state symmetry supercapacitor device

The kernel of the walnut constitutes a nutrient-dense food source. However, the walnut shell is useless and was thrown away. Therefore, as a small initiative towards waste-to-wealth, herein we developed walnut shell-derived highly porous heteroatom (nitrogen and sulfur) doped activated carbon (NS-WAC) via KOH activation and post-processing treatment by thioacetamide (TAA). The NS-WAC exhibits a high specific surface area (SSA) and various particle size distribution (PSD) involving micropores, mesopores, and macropores, conferring substantial supercapacitor advantages. The NS-WAC possesses a significant proportion of mesopores, which can decrease the ion diffusion path length and improve ion transport efficiency. Hence, NS-WAC demonstrates promising electrochemical performance achieving a high gravimetric specific capacitance of 271.4 Fg−1 at 0.5 Ag−1 in 3 M KOH aqueous electrolyte. Furthermore, the solid-state symmetric supercapacitor (SSC) device exhibited a gravimetric specific capacitance of 52 Fg−1 and volumetric specific capacitance of 74.36F cm−3 at a current density of 0.5 Ag−1. This SSC device also exhibited a gravimetric energy density of 23.4 Wh Kg−1 at a power density of 250 W Kg−1 at a current density of 0.5 Ag−1. It showed superior cycle stability of 91.8% after 10,000 cycles at 5 Ag−1.

In Situ S‐Doped Graphene Film using NaHSO3 as Sulfur Source for High‐Performance Flexible Supercapacitors

Herein, sulfur‐doped graphite film (SGF) is developed by a facile method. Graphene oxide (GO) film and low‐cost NaHSO3 are used for carbon and sulfur sources, respectively. A single‐step sulfur doping reaction is used to obtain SGF at 180 °C. The scanning electron microscopy (SEM) analysis of SGF reveals highly loose, highly crumpled characteristics. The SEM–energy‐dispersive spectroscopy shows that S is evenly distributed on the surface of SGF and doping amount of S is 4.6 wt%. SGF can attain high gravimetric and areal specific capacitance of 232.8 F g−1 and 672.5 mF cm−2 at 0.5 A g−1 and 1 mA cm−2 current density, respectively. The SGF shows excellent cycle stability (94.1% capacity retention after 10 000 cycles at 2.0 mA cm−2). Then, the assembled flexible SGF//SGF all‐solid‐state symmetric supercapacitor device can deliver a high energy density of 12.17 Wh kg−1 at a power density of 499.85 kW kg−1. The in situ doping method provides a simplistic and low‐cost synthesis process, which is suitable for large‐scale production of SGF. Furthermore, the well‐developed approach is applied to prepare arbitrary S‐doped matrix of carbon. Simultaneously, the fabricated SGF as the electrode material of flexible supercapacitor devices has great advantages in wearable electronics.

Supermolecule-mediated defect engineering of porous carbons for zinc-ion hybrid capacitors

Zinc ion hybrid capacitors hold great potential for future energy storage that requires both high energy density and high power capability. However, the charge storage mechanism of porous carbon cathode is ambiguous in Zn2+ ion-containing aqueous solutions, albeit porous carbon usually stores charge by electric double-layer capacitance. Herein, we developed a supermolecule-mediated direct pyrolysis carbonization strategy to convert sustainable sodium lignosulfonate resources into three-dimensional highly heteroatom-doped porous carbons with large mesopores. Through this strategy, we obtained lignin-derived porous carbons with high heteroatom dopings (14.9 at% nitrogen and 4.7 at% oxygen) and relatively high specific surface areas. Furthermore, the nitrogen doping configurations were mainly edge-nitrogen dopants even under high pyrolysis temperatures (> 900 °C). Lignin-derived nitrogen-doped porous carbon showed a high gravimetric specific capacitance of 266 F g−1 with high rate capability, which is endowed by the increased surface pseudocapacitance. First-principles calculations and molecular dynamics simulations indicate that the edge nitrogen and oxygen dopants contribute to the reversible adsorption/desorption of zinc ions and protons. Pores size less than 6.8 Å can cause a significant diffusion energy barrier for the hydrated zinc ions, thus degrading the capacitance and rate capability.

Characterization of Co-Mn layered double hydroxide nanostructures covered on Co3O4 as electrode material for supercapacitor applications

In the present work, hybrids of porous Co3O4 nanostructures coated Co-Mn layered double hydroxide nanostructures array on Ni foam (Co3O4/Co-Mn LDH/NF) were designed and prepared via the hydrothermal reactions and calcination processes. The Co3O4 nanostructures can be utilized as the backbone to grow the Co-Mn layered double hydroxide (Co-Mn LDH) nanostructures. The effects of precursors on the morphology of the as-prepared electrodes were investigated by x-ray diffraction, energy dispersive x-ray analysis, field-emission scanning electron microscopy, and transmission electron microscopy. The electrochemical performance of the prepared Co3O4/Co-Mn LDH/NF electrode, compared with Co3O4/NF electrode, illustrated a high gravimetric specific capacitance 1462 F g−1 at current density 2 A g−1, excellent rate capability 71% at 22 A g−1, and excellent cycling stability of 83% capacitance retention after 3000 GCD cycles. Additionally, an asymmetric supercapacitor (Co3O4/Co-Mn LDH/NF//AC) based on the Co3O4/Co-Mn LDH/NF as a positive electrode and activated carbon (AC) as a negative electrode was successfully fabricated with excellent electrochemical performance. The asymmetric supercapacitor with a maximum voltage of 1.6 V has demonstrated a high energy density of 60.37 Wh kg−1 and a high power density of 800 W kg−1. Additionally, a LED can be lit up approximately for 6 min when two ASCs were connected in series. Therefore, this Co3O4/Co-Mn LDH/NF with outstanding electrochemical performance should envision potential practical applications in high-energy storage appliances.

Improved energy density of reduced graphene oxide based aqueous symmetric supercapacitors in redox-active and “water-in-salt” electrolytes

This work demonstrates an eco-friendly and sustainable approach for developing high-energy-density aqueous supercapacitors. Herein, the energy density of reduced graphene oxide-based aqueous symmetric supercapacitors (rGO-SCs) was augmented using two facile strategies, viz. redox-active electrolyte and water-in-salt electrolyte. The rGO-SCs with commercial-level electrode mass loading (9–10 mg cm−2), exhibited high gravimetric specific capacitance, excellent cyclic stability, and rate capability in three aqueous electrolytes, viz. 1 M H2SO4 (0–1 V), 6 M KOH (0–1 V), and 1 M Li2SO4 (0–1.8 V). The rGO-SCs demonstrated a superior energy density of 15.39 W h kg−1 (at 180 W kg−1) in neutral Li2SO4 electrolyte, which is ~2.6–3× higher compared to the acidic and alkaline electrolyte. Incorporating 0.1 M Na2MoO4 as the redox-additive in Li2SO4 enhanced the energy density of the device to 21.42 W h kg−1 (at 180 W kg−1) via reversible redox reactions at the electrode surface. In addition, the redox-enhanced supercapacitor displayed high cycle stability of 99.3% even after 5000 cycles. Furthermore, a high cell voltage of 2.1 V was achieved for the rGO-SC using a water-in-salt electrolyte (11 M NaNO3). This high voltage supercapacitor exhibited an energy density of 22.87 W h kg−1 (at 210 W kg−1) and 98.1% capacitance retention over 5000 cycles.

Ultrasimple air-annealed pure graphene oxide film for high-performance supercapacitors

Realizing both high gravimetric and volumetric specific capacitances (noted as CW and CV, respectively) is an essential prerequisite for the next-generation, high performance supercapacitors. However, the need of electronic/ionic transport for electrochemical reactions causes a “trade-off” between compacted density and capacitance of electrode, thereby impairing gravimetric or volumetric specific capacitances. Herein, we report a high-performance, film-based supercapacitor via a thermal reduction of graphene oxide (GO) in air. The reduced, layer-structured graphene film ensures high electrode density and high electron conductivity, while the hierarchical channels generated from reduction-induced gas releasing process offer sufficient ion transport pathways. Note that the resultant graphene film is employed directly as electrodes without using any additives (binders and conductive agents). As expected, the as-prepared electrodes perform particularly well in both CW (420F g−1) and CV (360F cm−3) at a current density of 0.5 A g−1. Even at an ultrahigh current density of 50 A g−1, CW and CV maintain in 220F g−1 and 189F cm−3, respectively. Furthermore, the corresponding symmetric two-electrode supercapacitor achieves both high gravimetric energy density of 54 W h kg−1 and high gravimetric power density of 1080 W kg−1, corresponding to volumetric energy density of 46 W h L-1 and volumetric power density of 917 W L-1.

Rapeseed meal-derived N,S self-codoped porous carbon materials for supercapacitors

N,S self-doped porous carbon with high specific surface area and gravimetric specific capacitance from rapeseed meal was successfully synthesized.

N-O-P co-doped porous carbon aerogel derived from low-cost biomass as electrode material for high-performance supercapacitors

Heteroatom-doped porous carbon materials have attracted great interest and are considered promising candidate electrode materials for supercapacitors. Here, a facile and effective strategy is developed for the synthesis of porous carbon aerogels from abundant renewable radishes. Based on the high oxygen content of biomass, N-O-P co-doped of the carbon aerogel was achieved by introducing NH4H2PO4 during ZnCl2 activation process. A continuous three-dimensional porous network interconnected was obtained with uniform distribution of O, N and P on the whole aerogel framework. The N-O-P co-doped functional groups improve the conductivity and wettability of the material and stimulate the additional Faraday reaction, and thus can impart a variety of beneficial effects to the electrochemical performance of the material. The N-O-P co-doped carbon aerogel exhibits a high gravimetric specific capacitance of 352 F/g at a current density of 1 A/g in the three-electrode system using 6 M KOH as the electrolyte. Besides, the material also exhibits a high specific capacitance retention rate of 78.4% by increasing the current density from 1 to 10 A/g. In 10,000 cycles of charging and discharging performance, the N-O-P co-doped aerogel exhibits excellent cycle stability with only a slight capacitance loss of less than 10%.

LaMnO3 nanocomposite double network hydrogel electrodes with enhanced electrochemical and mechanical performance for flexible supercapacitors

Flexible supercapacitors are of tremendous interest to power future wearable electronics. The performance of a flexible supercapacitor strongly depends on the properties of electrode materials. In addition to the electrochemical performance, flexible electrodes must be mechanically robust or even stretchable during operation. Electrically conductive hydrogels (ECHs) are an ideal framework for flexible electrode design and construction, owing to their three-dimensional conductive network, toughness, and scalable synthesis. In this work, we synthesized modified LaMnO3 (MLMO) perovskites with porous tubular skeleton structure by a typical sol-gel method, and integrated the MLMO nanoparticles into a double network (DN) hydrogel, where the MLMO perovskites are uniformly dispersed in polyacrylamide (PAM)/polyvinyl alcohol (PVA) matrixes. The mechanical properties of this new composite hydrogel dramatically increase, with a remarkable enhanced tensile strength of 1.81 MPa and a high breaking elongation of over 440%. In addition, the composite hydrogel electrode shows exceptional capacitive characteristics, including a high gravimetric specific capacitance of 392 F g− 1 (at 1 A/g) and robust cycling stability (90% capacitance retention over 10,000 cycles). Our manufacturing strategy opens the opportunity to design flexible and stretchable supercapacitors with ideal nanostructures and outstanding hydrogel electrodes.

Facile synthesis of biomass-derived porous carbons incorporated with CuO nanoparticles as promising electrode materials for high-performance supercapacitor applications

Supercapacitors with large capacity, good stability and low cost are attractive to the development of energy storage technology. Herein, a new method for preparing biomass-derived carbon materials incorporated with CuO nanoparticles is proposed using cheap peanut shells as the carbon resource and copper acetate as the CuO precursor. The as-prepared CuO-AC sample retains a large BET surface area of 2640.55 m2/g with hierarchical micro-mesoporous structures. CuO nanoparticles with a particle size of 10–20 nm are formed and uniformly dispersed on the surface of the carbon skeleton. The synergetic effect of the double-layer capacitance of the porous carbon matrix and the Faraday capacitance introduced by CuO nanoparticles was successfully achieved, benefiting from which the CuO-AC electrode exhibits a high gravimetric specific capacitance up to 530 F/g at 1 A/g with prominent cycling stability of 92.5% after 10,000 cycles in the three-electrode system. CuO-AC was also used as the anode to assemble an asymmetric supercapacitor to investigate its practical application, showing that a high energy density of 11.7 W h/kg was reached at a power density of 628.73 W/kg. The large specific capacitance, high energy density and long cycle life of CuO-AC endow it a potential electrode material for supercapacitors.

Synthesis of biomass-derived carbon aerogel/MnOx composite as electrode material for high-performance supercapacitors

Synthesis of economical and high-performance carbon materials from biomass has been seen as an emerging strategy for energy storage devices. In this work, using radish as the raw material, a facile method for the synthesis of 3D carbon aerogels incorporated with MnOx nanoparticles has been developed. At a suitable impregnation amount of Mn(NO3)2, MnOx nanoparticles with a diameter of around 110 nm grow uniformly on the surface of the carbon aerogel, during which ordered carbon structures can be formed and results in an increase in the graphitization degree. The cross-linked 3D dimensional carbon structure and uniform growth of MnOx nanoparticles are beneficial to the electrochemical performance of the carbon aerogel/MnOx composite as electrode materials in supercapacitor applications. The carbon aerogel/MnOx composite impregnated with 1.6 mmol Mn(NO3)2 and activated under CO2 atmosphere (CAC@MnOx-1.6) reached the highest gravimetric specific capacitance of 557 F g−1 at a current density of 1 A g−1 in the three-electrode system using 2 M KOH as the electrolyte. In a two-electrode system, a high gravimetric specific capacitance of 447 F g−1 was obtained using the CAC@MnOx-1.6-based electrode, and the power density reached 4786.44 W kg−1 at an energy density of 248.23 Wh kg−1 with a current density of 1 A g−1 in the voltage range of -1~1 V.

Covalent modified reduced graphene oxide: Facile fabrication and high rate supercapacitor performances

Covalent modified graphene (denoted as DMFrGO180) was facilely fabricated by one-step solvothermal process with graphene oxide (GO) and N, N-dimethylformamide (DMF) as the raw materials. DMF serves as not only the solvent but also reactants to generate a reductive amination environment. Solvothermal treatment at 180 °C promotes the reductive amination and produces DMFrGO180 with covalent bonded dimethylamine groups, spit-ball like morphologies, and hierarchical micro- and mesoporous structure. The abundant covalent acidamide bonds render DMFrGO180 plenty of seamless ohmic contact to provide more electron transfer paths. The excellent electrical conductivity enhances and accelerates the redox reversibility of oxygen-containing functional groups to provide more pseudocapacitance. The hierarchical porous structure also accelerates the electrolyte transportation. These features bestow DMFrGO180 excellent rate capability. In three-electrode tests, DMFrGO180 exhibits high gravimetric specific capacitance of 287 F g−1 at 1 A g−1 and 192 F g−1 at 100 A g−1. Quasi-solid-state symmetrical two-electrode supercapacitors by using PVA/KOH gel as electrolyte also shows excellent supercapacitive properties with 193.5 F g−1 and 86.9 F g−1 at 1 A g−1 and 50 A g−1. Especially, it achieves high energy density 11.35 W h kg−1 at a power density of 649.7 W kg−1 and 5.09 W h kg−1 at power density of 32.4 KW kg−1. The present results may open a door of graphene oxide for applications in energy storage and conversion fields via a green and energy-efficient process.

Three-dimensional porous reduced graphene oxide/PEDOT:PSS aerogel: Facile preparation and high performance for supercapacitor electrodes

Graphene derivatives have great potential in the field of energy storage, because of their high specific surface area, great electrical conductivity, and stable electrochemical properties. For the graphene-based electrodes with a three-dimensional (3D) porous structure, the interlayer stacking of the graphene sheets largely limits their capacitive performance, and thus hinders their wide applications. In this work, we successfully developed a lightweight, freestanding and 3D porous reduced graphene oxide (rGO)/poly(3,4-ethylenedioxythiophene): poly(styrenesulfonate) (PEDOT:PSS) composite aerogel by incorporating the conducting polymer PEDOT:PSS into interconnected rGO networks through a facile, low-cost and all-water-processable two-step synthesis route. PEDOT:PSS covering on the rGO sheets was found to not only prevent the stacking of rGO sheets, but also greatly improve the ion accessibility and mechanical stability of this highly porous spongy meshwork. Due to the synergistic effect of rGO and PEDOT:PSS, the aerogel electrodes delivered a high gravimetric specific capacitance (471 F g−1 at 0.2 A g−1), an excellent rate capability, and a remarkable capacitance retention (98.71% over 20,000 cycles at 20 A g−1). Furthermore, the aerogel-based symmetric supercapacitor exhibited a wide potential window (0–1.4 V) and an excellent energy storage performance. A high energy density of 48.18 Wh kg−1 with the power density of 1.4 kW kg−1 at 0.5 A g−1, or an energy density of 32.67 Wh kg−1 corresponding to the great power density of 14,000 W kg−1 at 5 A g−1 was achieved. These results demonstrate the great potential of the rGO/PEDOT:PSS aerogel as an excellent electrode material for energy storage applications.

Nitrogen/Oxygen Enriched Hierarchical Porous Carbons Derived from Waste Peanut Shells Boosting Performance of Supercapacitors

AbstractThe high specific surface area and the fine electrical conductivity are the vital impacts, but they are always a pair of mutually counterbalancing factors in carbon‐based supercapacitors. Herein, a facile strategy of the combined CoCl2 catalytic graphitization and ZnCl2 activation is applied to synthesize porous carbonaceous materials with enriched nitrogen and oxygen doping from a cheap and abundant biowaste of peanut shells. The as‐produced carbon materials possess high surface area (1745–2257 m2 g−1), naturally nitrogen/oxygen co‐doping, and hierarchical porous structure. These physicochemical properties jointly endow these materials excellent supercapacitive performances: a high gravimetric specific capacitance of 343 F g−1 at 0.5 A g−1 and enduring long‐cycle performance of 90.9% capacitance retention after 10 000 cycles at 10 A g−1 in a 3‐electrode system with 6 m KOH electrolyte as well as a superior energy density of 42 Wh kg−1 at the high power density of 375 W kg−1 in an organic electrolyte. This low‐cost and facile approach shall open a new avenue to produce carbon materials with both high surface area and superior graphitization from the plentiful biomass for the potential energy storage applications.