Core-shell hierarchical porous carbon spheres with N/O doping for efficient energy storage

Radially aligned hierarchical N-doped porous carbon beads derived from oil-sand asphaltene for long-life water filtration and wastewater treatment

The application of waste-derived highly efficient adsorbent for organic pollutants removal from water and wastewater is presented. Highly porous carbon beads with radially aligned macrochannels were prepared from asphaltene. Well-ordered inwardly aligned macrovoids favored solute diffusion and maximized the liquid accommodation capacity. A further N-doping could modulate the sorbent hydrophilicity leading to an outstanding absorption performance for a range of organic solvents and oily chemicals. N-doped carbon beads were effective sorbents of lopinavir (LNV) and ritonavir (RNV) from water and wastewater. The process of sorption was fast, and the highest removal was noted for RNV than LPV. N-doping favored LNV and RNV adsorption due to the increased porous structure of N-doped asphaltene beads. The chemisorption of both LPV and RTV was a rate-limiting step. The presence of co-pollutants in treated wastewater enhanced LPV and RNV removal and an up to 470 % increase was noted. The presence of LPV or RTV in distilled water was not toxic to Aliivibrio fischeri or even can stimulate their growth. However, after the adsorption process, the solution of RTV reduced its toxicity significantly and the final solution was not toxic. The opposite effect was noted for LPV. Given the repeatability, high removal performance, and cost-effectiveness of the asphaltene-based carbon microtubes when compared to other well-known sorbents such as carbon nanotubes, they demonstrated great potential as a low-cost and effective agent for long-life water filtration and wastewater treatment.

High-yield and nitrogen self-doped hierarchical porous carbon from polyurethane foam for high-performance supercapacitors

Confronted with the environmental pollution and energy crisis issues, upcycling of waste plastics for energy-storage applications has attracted broad interest. Polyurethane (PUR) is a potential candidate for the preparation of N-doped carbon materials. However, its low carbon yield limits the utilization of PUR waste. In this study, PUR foam was converted into N-doped hierarchical porous carbon (NHPC) through an autogenic atmosphere pyrolysis (AAP)-KOH activation approach. An ultra-high carbon yield of 55.0% was achieved through AAP, which is more than 17 times the carbon yield of conventional pyrolysis of PUR. AAP converted 83.2% of C and 61.0% of N in PUR into derived carbon material. The high conversion rate and self-doping effect can increase the environmental and economic benefits of this approach. KOH activation significantly increased the specific surface area of carbon materials to 2057 m² g^-1 and incorporated hierarchical porous structure and O-containing functional groups to the carbon materials. The obtained NHPCs were applied to improve the performance of supercapacitors. The electrochemical measurement revealed that NHPCs exhibited a high specific capacitance of 342 F g^-1 (133 F cm^-3) at 0.5 A g^-1, low resistance, and outstanding cycling stability. The energy density and power density of the supercapacitor were improved to 11.3 W h kg^-1 and 250 W kg^-1, respectively. This research developed a possible solution to plastic pollution and energy shortage.

Competition among Refined Hollow Structures in Schiff Base Polymer Derived Carbon Microspheres

Synthetic polymer-derived hollow carbon spheres have great utilitarian value in many fields for which the synthesis of proper polymer precursors is a key process. The exploration of new suitable polymer precursors and the construction of refined hollow structures in emerging polymers are both of great significance for synthetic methodology and novel carbon materials. Here, for the first time Schiff base polymer (SBP) colloid spheres with refined hollow structures were synthesized by tandem gradient growth and confined polymerization processes. The Hill equation was employed as a mathematical model to explain the gradient growth of SBP spheres. The size-dependent inner structure of SBP spheres can be adjusted from hollow to multichamber-surrounded hollow, and then to a multichamber structure. SBP-derived carbon spheres having similar surface area and chemical composition but different inner structures provide an effective way to investigate the relationship between inner structure and performance.

Conversion of Plastic Waste to Carbon-Based Compounds and Application in Energy Storage Devices

At present, plastic waste accumulation has been observed as one of the most alarming environmental challenges, affecting all forms of life, economy, and natural ecosystems, worldwide. The overproduction of plastic materials is mainly due to human population explosion as well as extraordinary proliferation in the global economy accompanied by global productivity. Under this threat, the development of benign and green alternative solutions instead of traditional disposal methods such as conversion of plastic waste materials into cherished carbonaceous nanomaterials such as carbon nanotubes (CNTs), carbon quantum dots (CQDs), graphene, activated carbon, and porous carbon is of utmost importance. This critical review thoroughly summarizes the different types of daily used plastics, their types, properties, ways of accumulation and their effect on the environment and human health, treatment of waste materials, conversion of waste materials into carbon-based compounds through different synthetic schemes, and their utilization in energy storage devices particularly in supercapacitors, as well as future perspectives. The main purpose of this review is to help the targeted audience to design their futuristic study in this desired field by providing information about the work done in the past few years.

Intrinsically Breathable and Flexible NO2 Gas Sensors Produced by Laser Direct Writing of Self-Assembled Block Copolymers

The surge in air pollution and respiratory diseases across the globe has spurred significant interest in the development of flexible gas sensors prepared by low-cost and scalable fabrication methods. However, the limited breathability in the commonly used substrate materials reduces the exchange of air and moisture to result in irritation and a low level of comfort. This study presents the design and demonstration of a breathable, flexible, and highly sensitive NO₂ gas sensor based on the silver (Ag)-decorated laser-induced graphene (LIG) foam. The scalable laser direct writing transforms the self-assembled block copolymer and resin mixture with different mass ratios into highly porous LIG with varying pore sizes. Decoration of Ag nanoparticles on the porous LIG further increases the specific surface area and conductivity to result in a highly sensitive and selective composite to detect nitrogen oxides. The as-fabricated Ag/LIG gas sensor on a flexible polyethylene substrate exhibits a large response of -12‰, a fast response/recovery of 40/291 s, and a low detection limit of a few parts per billion at room temperature. Integrating the Ag/LIG composite on diverse fabric substrates further results in breathable gas sensors and intelligent clothing, which allows permeation of air and moisture to provide long-term practical use with an improved level of comfort.

Intumescent flame retardants inspired template-assistant synthesis of N/P dual-doped three-dimensional porous carbons for high-performance supercapacitors

Heteroatom-doped three-dimensional (3D) porous carbons possess great potential as promising electrodes for high-performance supercapacitors. Inspired by the inherent features of intumescent flame retardants (IFRs) with universal availability, rich heteroatoms and easy thermal-carbonization to form porous carbons, herein we proposed a self-assembling and template self-activation strategy to produce N/P dual-doped 3D porous carbons by nano-CaCO₃ template-assistant carbonization of IFRs. The IFRs-derived carbon exhibited large specific surface area, well-balanced hierarchical porosity, high N/P contents and interconnected 3D skeleton. Benefitting from these predominant characteristics on structure and composition, the assembled supercapacitive electrodes exhibited outstanding electrochemical performances. In three-electrode 6 M KOH system, it delivered high specific capacitances of 407 F g^-1 at 0.5 A g^-1, and good rate capability of 61.2% capacitance retention at 20 A g^-1. In two-electrode organic EMIMBF₄/PC system, its displayed high energy density of 62.8 Wh kg^-1 at a power density of 748.4 W kg^-1, meanwhile it had excellent cycling stability with 84.7% capacitance retention after 10,000 cycles. To our best knowledge, it is the first example to synthesize porous carbon from IFRs precursor. Thus, the current work paved a novel and low-cost way for the production of high-valued carbon material, and expanded its application for high-performance energy storage devices.

In-situ ZnO template preparation of coal tar pitch-based porous carbon-sheet microsphere for supercapacitor

Three-dimension (3D) porous carbon-sheet microspheres (PCSMs) are prepared through coating coal tar pitch on basic zinc carbonate microspheres followed by in situ ZnO template carbonization and KOH activation. The as-prepared PCSMs show microsphere morphology composed of petal-like carbon nanosheets, which have large specific area (1359.88-2059.43 m² g^-1) and multiscale pores (mainly micropores and mesopores). As the supercapacitor electrodes, the 3D PCSMs present a good electrochemical performance with a large specific capacitance of 313 F g^-1 at 1 A g^-1 and high rate capability of 81.9% capacitance retention when increasing the current density up to 50 A g^-1 in a three-electrode system. In addition, the energy density can reach up to 18.79 Wh kg^-1 at a high power density of 878.4 W kg^-1 for PCSMs-0.2a symmetrical supercapcitor in 1 M Na₂SO₄ electrolyte.

Pentafluoropyridine functionalized novel heteroatom-doped with hierarchical porous 3D cross-linked graphene for supercapacitor applications

The fabrication with high energy density and superior electrical/electrochemical properties of hierarchical porous 3D cross-linked graphene-based supercapacitors is one of the most urgent challenges for developing high-power energy supplies. We facilely synthesized a simple, eco-friendly, cost-effective heteroatoms (nitrogen, phosphorus, and fluorine) co-doped graphene oxide (NPFG) reduced by hydrothermal functionalization and freeze-drying approach with high specific surface areas and hierarchical pore structures. The effect of different heteroatoms doping on the energy storage performance of the synthesized reduced graphene oxide is investigated extensively. The electrochemical analysis performed in a three-electrode system via cyclic voltammetry (CV), galvanostatic charging-discharging (GCD), and electrochemical impedance spectroscopy (EIS) demonstrates that the nitrogen, phosphorous, and fluorine co-doped graphene (NPFG-0.3) synthesized with the optimum amount of pentafluoropyridine and phytic acid (PA) exhibits a notably enhanced specific capacitance (319 F g-1 at 0.5 A g-1), good rate capability, short relaxation time constant (τ = 28.4 ms), and higher diffusion coefficient of electrolytic cations (Dk+ = 8.8261 × 10-9 cm2 s-1) in 6 M KOH aqueous electrolyte. The density functional theory (DFT) calculation result indicates that the N, F, and P atomic replacement within the rGO model could increase the energy value (G T) from -673.79 eV to -643.26 eV, demonstrating how the atomic level energy could improve the electrochemical reactivity with the electrolyte. The improved performance of NPFG-0.3 over NFG, PG, and pure rGO is mainly ascribed to the fast-kinetic process owing to the well-balanced electron/ion transport phenomenon. A symmetric coin cell supercapacitor device fabricated using NPFG-0.3 as the anode and cathode material with 6 M KOH aqueous electrolyte exhibits maximum specific energy of 38 W h kg-1, a maximum specific power of 716 W kg-1, and ∼88.2% capacitance retention after 10 000 cycles. The facile synthesis approach and promising electrochemical results suggest this synthesized NPFG-0.3 material has high potential for future supercapacitor application.

Designing Ultrasmall Carbon Nanospheres with Tailored Sizes and Textural Properties for High-Rate High-Energy Supercapacitors

The present work demonstrates the efficient design of ultrasmall porous carbon nanospheres with tailored sizes (5-40 nm in diameter) and optimized intrasphere textural properties for high-rate high-energy supercapacitor application. The carbon nanospheres are synthesized via a miniemulsion polymerization technique followed by KOH activation. It is shown that dual-step activation renders enlarged intrasphere micropores/mesopores, facilitating enhanced ion transports. Meanwhile, a decrease in nanosphere size from 40 to 5 nm significantly improves the rate performance, demonstrating the pronounced size effects due to enhanced intrasphere ion transport. The optimum dual-step-activated carbon nanosphere sample with an average sphere size of 5 nm, ACNS5-2, shows the high specific capacitances along with outstanding high-rate capabilities in both aqueous (272 F g^-1 at 0.5 A g^-1 and 81.6% of retention at 200 A g^-1) and EMIMBF₄ (223 F g^-1 at 0.5 A g^-1 and 67.2% of retention at 100 A g^-1) electrolytes in symmetrical two-electrode cells. In EMIMBF₄, ACNS5-2 displays a high energy density of 48 Wh kg^-1 at a high power density of 14 kW kg^-1, suggesting excellent energy storage efficiency. Moreover, the performance of ACNS5-2 competes well with or is superior to some best-performing porous carbon-based materials reported in the literature for supercapacitor applications even at lowered temperatures (at -20 °C: 150 F g^-1 at 0.5 A g^-1 with a capacitance retention of 64% at 10 A g^-1) and high mass loading (8 mg cm^-2: 205 F g^-1 at 0.5 A g^-1 with a capacitance retention of 64.5% at 20 A g^-1). Our results, combined with structure-performance relationships, offer valuable guidelines for the rational design of carbon nanomaterials of optimum supercapacitive performances.

MWCNT Decorated Rich N-Doped Porous Carbon with Tunable Porosity for CO2 Capture

Designing of porous carbon system for CO2 uptake has attracted a plenty of interest due to the ever-increasing concerns about climate change and global warming. Herein, a novel N rich porous carbon is prepared by in-situ chemical oxidation polyaniline (PANI) on a surface of multi-walled carbon nanotubes (MWCNTs), and then activated with KOH. The porosity of such carbon materials can be tuned by rational introduction of MWCNTs, adjusting the amount of KOH, and controlling the pyrolysis temperature. The obtained M/P-0.1-600-2 adsorbent possesses a high surface area of 1017 m2 g-1 and a high N content of 3.11 at%. Such M/P-0.1-600-2 adsorbent delivers an enhanced CO2 capture capability of 2.63 mmol g-1 at 298.15 K and five bars, which is 14 times higher than that of pristine MWCNTs (0.18 mmol g-1). In addition, such M/P-0.1-600-2 adsorbent performs with a good stability, with almost no decay in a successive five adsorption-desorption cycles.

Merging N-Hydroxyphthalimide into Metal-Organic Frameworks for Highly Efficient and Environmentally Benign Aerobic Oxidation

Two highly efficient metal-organic framework catalysts TJU-68-NHPI and TJU-68-NDHPI have been successfully synthesized through solvothermal reactions of which the frameworks are merged with N-hydroxyphthalimide (NHPI) units, resulting in the decoration of pore surfaces with highly active nitroxyl catalytic sites. When t-butyl nitrite (TBN) is used as co-catalyst, the as-synthesized MOFs are demonstrated to be highly efficient and recyclable catalysts for a novel three-phase heterogeneous oxidation of activated C-H bond of primary and secondary alcohols, and benzyl compounds under mild conditions. Based on the high efficiency and selectivity, an environmentally benign system with good sustainability, mild conditions, simple work-up procedure has been established for practical oxidation of a wide range of substrates.

Kinetics control over the Schiff base formation reaction for fabrication of hierarchical porous carbon materials with tunable morphology for high-performance supercapacitors

Schiff base formation reaction is highly dynamic, and the microstructure of Schiff base polymers is greatly affected by reaction kinetics. Herein, a series of Schiff base cross-linked polymers (SPs) with different morphologies are synthesized through adjusting the species and amount of catalysts. Nitrogen/oxygen co-doped hierarchical porous carbon nanoparticles (HPCNs), with tunable morphology, specific surface area (SSA) and porosity, are obtained after one-step carbonization. The optimal sample (HPCN-3) possesses a coral reef-like microstructure, high SSA up to 1003 m²g^-1, and a hierarchical porous structure, exhibiting a remarkable specific capacitance of 359.5 F g^-1(at 0.5 A g^-1), outstanding rate capability and cycle stability in a 1 M H₂SO₄electrolyte. Additionally, the normalized electric double layer capacitance (EDLC) and faradaic capacitance of HPCN-3 are 0.239 F m^-2and 10.24 F g^-1respectively, certifying its superior electrochemical performance deriving from coral reef-like structure, high external surface area and efficient utilization of heteroatoms. The semi-solid-state symmetrical supercapacitor based on HPCN-3 delivers a capacitance of 55 F g^-1at 0.5 A g^-1, good cycle stability of 86.7% after 5000 GCD cycles at 10 A g^-1, and the energy density ranges from 7.64 to 4.86 Wh kg^-1.

Emulsion-template synthesis of mesoporous nickel oxide nanoflowers composed of crossed nanosheets for effective nitrogen reduction

A novel emulsion-template synthesis approach was developed for the preparation of nickel oxide nanoflowers (NiO-NFs) composed of crossed mesoporous nanosheets. The interface assembly process was regulated by tuning the dosage of NH3·H2O, resulting in the tunability of thickness and size of mesoporous NiO nanosheets. The as-prepared NiO-NFs were characterized by field emission scanning electron microscopy, transmission electron microscopy, Brunauer-Emmett-Teller analysis, X-ray diffraction, and X-ray photoelectron spectroscopy (XPS). The results indicate that NiO-NFs have a mesopore size of about 9.5-15 nm and a crossed nanosheet thickness of about 12.4-50 nm. XPS results demonstrated that all NiO-NF samples consisted of Ni2+ and Ni3+. Electrochemical nitrogen reduction reaction (NRR) measurements revealed that NiO-NF-3.0 showed an optimal NRR performance of NH3 yield and faradaic efficiency (16.16 μg h-1 mg-1cat. and 9.17% at -0.4 V vs. RHE) in 0.1 M Na2SO4. Interestingly, NiO-NF-3.0 also displayed the highest Ni3+ content, which correlates with the order of electrochemical NRR performance. This can be attributed to the fact that Ni3+ promotes the electropositivity of NiO-NFs, resulting in more facile adsorption of N2 gas than Ni2+, and leading to enhanced electrocatalytic properties. These enhanced NRR performances are comparable or superior to those of reported noble-metal catalysts. This study provides a novel method for the fabrication of low-cost metal oxide nanomaterials that allows the construction of electrochemical NRR catalysts to meet the needs of industrial production. Also, it provides a new approach to improve the electrochemical properties by increasing the content of high-valent metal ions in a metal oxide.

Controllable synthesis of hollow spherical nickel chalcogenide (NiS2 and NiSe2) decorated with graphene for efficient supercapacitor electrodes

New carbon-loaded nickel chalcogenide electrode materials (NiS2/GO and NiSe2/rGO) have been synthesized through an easy-to-operate process: NiSe2 was obtained based on NiS2 hollow spheres, and was successfully synthesized with l-cysteine assistance under the hydrothermal method at 120 °C. GO of different mass fraction was added together with l-cysteine. The electrochemical performance of NiS2/GO and NiSe2/rGO has been greatly improved because the formation of a carbon-loaded layer effectively increased the specific surface area and reduced the charge transport resistance. Compared with pure NiS2 and NiSe2, NiS2/GO and NiSe2/rGO presented much better specific capacitance (1020 F g-1 and 722 F g-1 respectively at a current density of 1 A g-1) and more superior rate capability (when the current density was raised to 5 A g-1 the specific capacitance remained at 569 F g-1 and 302 F g-1). This work highlights the advantages of nickel compounds through a very simple experimental method, and contributes to providing a good reference for preparation of superior supercapacitor materials with high performance.

In Situ Formation of "Dimethyl Sulfoxide/Water-in-Salt"-Based Chitosan Hydrogel Electrolyte for Advanced All-Solid-State Supercapacitors

Biodegradable hydrogel electrolytes are particularly attractive in the fabrication of all-solid-state supercapacitors due to environmental benignity and avoiding of leakage. The introduction of "water-in-salt" (WIS) electrolytes into hydrogels will further broaden the electrochemical stability window of aqueous supercapacitors significantly. Meanwhile, the addition of an organic co-solvent can effectively overcome the inevitable salt precipitation and extend the temperature adaptability. Herein, an in situ cross-linking approach was demonstrated without any extra binder to obtain a "dimethyl sulfoxide/water-in-salt"-based (DWIS) chitosan hydrogel electrolyte. Interestingly, the addition of 4-7 mol L^-1 of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) salts not only conforms to the criterion of WIS, but also promoted the successful gelation through the supramolecular complexation between Li⁺ -solvated complexes and chitosan chains. A hydrogel-based all-solid-state supercapacitor was fabricated using the DWIS chitosan hydrogel as the electrolyte and separator while nitrogen-doped graphene hydrogel (NG) was used as the electrode. The optimized supercapacitor with a wide operating voltage of 2.1 V showed a high specific capacitance of 107.6 F g^-1 at 1 A g^-1 , remarkable capacitance retention of 80.1 % after 5000 cycles, a superior energy density of 62.9 Wh kg^-1 at a power density of 1025.5 W kg^-1 , and excellent temperature stability in the range of -20 to 70 °C. These findings suggest that the as-prepared hydrogel electrolyte holds great potential in the practical application of high-performance solid-state energy storage devices.

Link between Alkali Metals in Salt Templates and in Electrolytes for Improved Carbon-Based Electrochemical Capacitors

Various alkali metal (Li⁺, Na⁺, K⁺, Rb⁺, and Cs⁺) chlorides with Pluronic F127 were used as a soft-salt template for tuning the textural and structural properties of carbon. Highly conductive metal hydroxide solutions, where the cations are the same as those in the salt template, have been used as electrolytes. By increasing the size of the cation in the template, the textural properties of carbon, such as the specific surface area, micropore volume, and pore size, were remarkably enhanced. It directly translates to an increase in the specific capacitance of the electrode material. For a constant current charge/discharge at 0.1 A g^-1, the electrode composed of LiCl-T and operating with 1 mol L^-1 LiOH demonstrates the capacitance of 124 F g^-1, whereas CsCl-T with the same electrolyte has a capacitance of 216 F g^-1. Moreover, the materials show the highest capacitance retention (up to 75%) vs. the current regime applied when the cation used during synthesis matches the cation present in the electrolyte (i.e., LiCl-T with LiOH). Interestingly, capacitance normalized by specific surface area has been found to be the highest when LiOH solution is applied as an electrolyte. Thus, for this metric, the size of ions seems to be a crucial parameter. The importance of mesoporosity is highlighted as well by using materials with a similar fraction of micropores and with or without mesopores. Briefly, the presence of mesopore fraction proved to be essential for improved capacity retention (69% vs. 30%). Besides textural properties, the graphitization degree impacts the electrochemical performance as well. It increases among the samples, in accordance with cation-π binding energy, e.g., LiCl-T is the most "graphitic-like" material and CsCl-T is the most disordered. Thus, the more graphitic-like materials demonstrate higher rate capability and cycle stability.

The preparation of porous carbon materials derived from bio-protic ionic liquid with application in flexible solid-state supercapacitors

Ionic liquids have attracted much more attentions for its wide application in catalyst, green solvents and carbon precursors. Herein, N/P co-doped porous carbon materials with developed pore structure were facilely prepared from the phosphoric acid protic ionic liquid of arginine (Arg[H₂PO₄]₂) and (NH₄)₂HPO₄. The former acted as the carbon precursor, heteroatom source and mesopore generator, while the latter worked as the activator which had great impact on the pore distribution and microstructure. The porous carbon materials were characterized by SEM, XRD, Raman and N₂ adsorption analysis in system, indicating that Arg-2-900 was promising electrode materials for supercapacitors. It exhibited high specific capacitance retention of 94% after 10000 cycles with stable electric double layer capacitors. The assembled symmetrical supercapacitors exhibited a wide voltage window in alkaline electrolyte and neutral aqueous electrolyte, displaying high energy density and power density, respectively. In addition, the solid-state supercapacitors were prepared and showed good flexibility after bending the flexible supercapacitor cell at different angles. The results demonstrated the successful synthesis of N/P co-doped porous carbon materials form Arg[H₂PO₄]₂ and broad application in wearable storage device.

Impact of carbon pores size on ionic liquid based-supercapacitor performance

A comprehensive comparison of symmetrical supercapacitors assembling carbon electrodes with exclusively microporous, mesoporous or combined micro-mesoporous networks provides a critical outlook on the influence of pores size on the performance with ionic liquid-based electrolyte 1-Ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (EMIm-TFSI) dissolved in acetonitrile. Contrary to widespread claims, the results for an electrodes set involving carbons of different origin indicate that the presence of large pores does not ensure a better supercapacitor performance. At low current density, the capacitance is basically determined by the surface in pores above 0.8 nm, regardless of the pore size distribution. In addition, the beneficial effect of large pores on the response rate of the supercapacitor cannot be concluded in a straightforward manner. On the contrary, wide porosity in electrodes has detrimental effects that should not be underestimated as far as the competitiveness of the final device is concerned. The greater amount of electrolyte required by larger pores will increase both the weight and the cost of the cell. More importantly, the widening of carbon pores (even in the range of micropores) notably reduces the density of the corresponding electrodes and, consequently, the supercapacitor performance in volumetric terms may not be suitable for practical applications.

Engineering Kinetics-Favorable Carbon Sheets with an Intrinsic Network for a Superior Supercapacitor Containing a Dual Cross-linked Hydrogel Electrolyte

Despite the physicochemical advantages of two-dimensional (2D) carbons for supercapacitors, the inappropriate texture within 2D carbon materials suppresses the charge storage capability. Reported here are heteroatom-rich carbon sheets with the overall network engineered by molecular structure modulation and subsequent chemical activation of a three-dimensional (3D) cross-linked polymer. The 3D-to-2D reconstruction mechanism is unveiled. The architecture with a large active surface, fully interpenetrating and conductive network, and rich surface heteroatoms relieves well the ionic diffusion restriction within thick sheets and reduces the overall resistance, exhibiting fast transport kinetics and excellent stability. Indeed, high gravimetric capacitance (281.1 F g^-1 at 0.5 A g^-1), ultrahigh retention rate (92.5% at 100 A g^-1), and impressive cyclability (89.7% retention after 20 000 cycles) are achieved by this material. It also possesses a high areal capacitance of 3.56 F cm^-2 at 0.5 A g^-1 under a high loading of 25 mg cm^-2. When coupled with the developed dual cross-linked hydrogel electrolyte (Al-alginate/poly(acrylamide)/sodium sulfate), a quasi-solid-state supercapacitor delivers an energy density of 28.3 Wh kg^-1 at 250.1 W kg^-1, which is significantly higher than those of some reported aqueous carbon-based symmetric devices. Moreover, the device displays excellent durability over 10 000 charge/discharge cycles. The proposed cross-linked polymer strategy provides an efficient platform for constructing dynamics-favorable carbon architectures and attractive hydrogel electrolytes toward improved energy supply devices.