High Capacitance Research Articles

Phenolic resin filled wood-derived hierarchically porous carbon monolith for high areal capacitance supercapacitors

Wood-based electrodes are widely used in supercapacitors due to their renewable and three-dimensional self-supported properties. Low space utilization of wood-based electrodes seriously restricts its practical applications. In this paper, a wood/phenolic resin composite was designed, which can effectively enhance the space utilization of wood and ensure a hierarchical porous structure. The prepared balsa wood/phenolic resin composite-derived electrode obtained a high areal capacitance (8169 mF cm–2), which is 954 % of pure balsa wood-based electrode. Moreover, the assembled symmetrical supercapacitor device exhibits outstanding electrochemical performance, displaying a high areal capacitance of 3.3 F cm–2, and a competitive volumetric energy density of 2.88 mWh cm–3. More importantly, this design has been successfully used to prepare various species wood-derived electrodes. Therefore, as a general strategy, which gives a novel idea for the design of wood-derived electrodes and may affect other fields using wood-based materials.

Wearable ion-selective sensors with rapid conditioning and extended stability achieved through modulation of water and ion transport

Solid-contact (SC) ion-selective electrodes (ISEs) are often employed in wearables for electrolytes detection owing to their simplicity and ease of miniaturization. However, to mitigate their inherently unstable open circuit potential signal, ISEs require long hours of conditioning and frequent calibration prior to and during operation, limiting their practicality in wearable applications. Inspired by strategies to address water crossover and flooding in polyelectrolyte fuel cells, we demonstrated a SCISE with minimal conditioning time and long-term stability by modulating the rate-limiting step between mass transfer of water and hydrated ions and redox kinetics in the conducting polymer (CP). Our strategy comprised a wearable ISE with a superhydrophobic CP, PEDOT:TFPB, which reduced water and ion fluxes within the ISE, resulting in a stable and less-swollen CP and diminished water layer formation while maintaining CP's high capacitance. Our PEDOT:TFPB based ISEs functioned after a short conditioning time of 30 min and exhibited extended stability with a reduced signal deviation of only 0.16 % per hour (0.02 mV h−1) during 48 h of continuous measurement. Through systematic studies, we showed that ISE performance could be further tuned by tailoring the thickness of the ion-selective membrane as well as the hydrophobicity and polymerization charges of the CP. Without the need for recurrent calibration, our ISEs sustain high accuracy and prolonged stability upon integration into a wearable format for on-body perspiration analysis. Our strategy allows wearable ion-selective sensors with minimal maintenance at the user-end for long-term continuous monitoring, unveiling their potential in sports, healthcare, and diagnosis fields.

Oxygen-vacancy-rich Ru nanoclusters doped NiCo metal-organic framework for driving overall water electrolysis and supercapacitors

Due to the growing demand for clean renewable hydrogen fuel, the rational design of electrode materials' composition and structure holds significant importance in achieving efficient energy storage and conversion in electrochemical energy devices. In this study, we synthesize NiCo-MOF74/NF substrate using a one-step hydrothermal method, after which we successfully deposit a layer of Ru metal nanoclusters on the substrate by electrodeposition. Ru NCs@NiCo-MOF74/NF exhibits an exceptionally large specific surface area and excellent interface effects, demonstrating outstanding performance in both overall water splitting and supercapacitor applications. In a 1 M KOH alkaline solution, the device requires only 1.47 V output voltage to deliver a current density of 10 mA cm−2 for overall water splitting. As a supercapacitor, the unique nanoflower structure of Ru NCs@NiCo-MOF74/NF enables fast and reversible Faradaic reactions, providing high specific capacitance and rate performance. It shows a high areal capacitance of 1.664 mAh cm−2 at 1 mA cm−2, indicating excellent charge storage capacity. Assembled into an asymmetric supercapacitor (ASC) with Ru NCs@NiCo-MOF74/NF as the positive electrode, the device achieves a high energy density of 511.88 μWh cm−2 at a power density of 545.68 μW cm−2. After 5000 cycles, the capacitance retention rate is approximately 100 %, demonstrating remarkable cycling stability. This paves the way for the synthesis of multifunctional catalysts, opening up new possibilities in the field.

MXene/Nitrogen-Doped Carbon Nanosheet Scaffold Electrode toward High-Performance Solid-State Zinc Ion Supercapacitor.

While MXene is widely used as an electrode material for supercapacitor, the intrinsic limitation of stacking caused by the interlayer van der Waals forces has yet to be overcome. In this work, a strategy is proposed to fabricate a composite scaffold electrode (MCN) by intercalating MXene with highly nitrogen-doped carbon nanosheets (CN). The 2D structured CN, thermally converted and pickling from Zn-hexamine (Zn-HMT), serves as a spacer that effectively prevents the stacking of MXene and contributes to a hierarchically scaffolded structure, which is conducive to ion movement; meanwhile, the high nitrogen-doping of CN tunes the electronic structure of MCN to facilitate charge transfer and providing additional pseudocapacitance. As a result, the MCN50 composite electrode achieves a high specific capacitance of 418.4 Fg-1 at 1 Ag-1. The assembled symmetric supercapacitor delivers a corresponding power density of 1658.9 Wkg-1 and an energy density of 30.8 Whkg-1. The all-solid-state zinc ion supercapacitor demonstrates a superior energy density of 68.4 Whkg-1 and a power density of 403.5 Wkg-1 and shows a high capacitance retention of 93% after 8000 charge-discharge cycles. This study sheds a new light on the design and development of novel MXene-based composite electrodes for high performance all-solid-state zinc ion supercapacitor.

Nanofiber-Reinforced MXene/rGO Composite Aerogel for a High-Performance Piezoresistive Sensor and an All-Solid-State Supercapacitor Electrode Material.

The assembly of two-dimensional (2D) nanomaterials into a three-dimensional (3D) aerogel can effectively prevent the problem of restacking. Here, nanofiber-reinforced MXene/reduced graphene oxide (rGO) conductive aerogel is prepared via the hydrothermal reduction of GO using pyrrole and in situ composite with MXene. Combined with low-content 2D conductive nanosheets (MXene and rGO) as "brick", conductive polypyrrole as "mortar", and one-dimensional (1D) nanofiber as "rebar", a strong interfacial cross-linking of MXene and rGO nanosheets is realized through covalent and noncovalent bonds to synergistically improve its mechanical performance. Based on the prepared MXene/rGO aerogel, a high-performance piezoresistive sensor with a sensitivity of up to 20.80 kPa-1 in a wide pressure range of 15.6 kPa is obtained, and it can withstand more than 5000 cyclic compressions. Besides, the sensor shows a stable output and can be applied to monitor various human motion signals. In addition, an all-solid-state supercapacitor electrode is also fabricated, which shows a high area-specific capacitance of up to 274 mF/cm2 at a current density of 1 mA/cm2.

Recyclable multiscale composite structural supercapacitor

AbstractThis study presents a proof‐of‐concept for a fully recyclable and sustainable composite structural supercapacitor. The fabricated device shows promising energy storage capabilities and mechanical strength. Generally, structural supercapacitors capacitance is considerably lower than non‐load‐bearing mono‐functional supercapacitors and are made via thermoset polymer electrolyte. Here, the device is fabricated using an optimized solid electrolyte composition of carbon aerogel modified carbon fibers, fumed silica, lithium salt, and a thermoplastic polymer matrix. The supercapacitor exhibits a high capacitance of 5225 mFg−1 (193 mFcm−2) at 1 mVs−1 scan rate and a large voltage window of 4 V. A simple dissolution/reprecipitation method is used to demonstrate the recycling feasibility, with minimal mechanical degradation (<10%) in the polymer matrix and no chemical structure changes in the electrolyte. This work establishes a promising ecologically‐sound structural energy storage technology with favorable performance compared to prior studies.Highlights A proof‐of‐concept fully recyclable composite structural supercapacitor is made. Thermoplastic‐based robust polymer electrolytes are fabricated. Recycling via dissolution and re‐precipitation of components is demonstrated. Comparison to prior structural supercapacitors shows favorable performance.

High Capacitance Porous Ruthenium Nitride Films with High Rate Capability for Micro-Supercapacitors.

The demand for high-performance energy storage devices to power Internet of Things applications has driven intensive research on micro-supercapacitors (MSCs). In this study, RuN films made by magnetron sputtering as an efficient electrode material for MSCs are investigated. The sputtering parameters are carefully studied in order to maximize film porosity while maintaining high electrical conductivity, enabling a fast charging process. Using a combination of advanced techniques, the relationships among the morphology, structure, and electrochemical properties of the RuN films are investigated. The films are shown to have a complex structure containing a mixture of crystallized Ru and RuN phases with an amorphous oxide layer. The combination of high electrical conductivity and pseudocapacitive charge storage properties enabled a 16µm-thick RuN film to achieve a capacitance value of 0.8Fcm-2 in 1m KOH with ultra-high rate capability.

Single-step, in-situ fabrication of flower-like NiCuMn hybrid oxyhydroxide electrodes for enhanced supercapacitor performance

The rational design of highly active and low-cost electrode material is very promising for energy storage applications. The development of supercapacitors with high energy/power density is an imperative and challenging research objective. Herein, we report a highly facile synthesis approach for developing unique nano-porous hybrid NiCuMn oxyhydroxide architecture with remarkable electrochemical energy storage characteristics. The process involves dealloying of Ni15Cu15Mn70 alloy in an oxygen rich environment, resulting in a uniform 3-dimensional flower like morphology. The dealloyed electrode demonstrates ultra-high specific capacitance of 4110 F cm−3 at a high current density of 20 mA cm−2. A symmetric device exhibits a high volumetric capacitance of 365 F cm−3 at a current density of 10 mA cm−2 with a large potential window of 1.7 V. Even at very high-power density of 850 W l−1, the device exhibits a high energy density of 146 Wh l−1 along with remarkable cyclic stability of 95.4% after 10 000 cycles. The superior performance of nano-porous hybrid NiCuMn oxyhydroxide architecture was attributed to its unique microstructure that provides high surface area, and marginal internal resistance ensuring rapid charge transport.

Moisture-enabled self-charging and voltage stabilizing supercapacitor

Supercapacitor is highly demanded in emerging portable electronics, however, which faces frequent charging and inevitable rapid self-discharging of huge inconvenient. Here, we present a flexible moisture-powered supercapacitor (mp-SC) that capable of spontaneously moisture-enabled self-charging and persistently voltage stabilizing. Based on the synergy effect of moisture-induced ions diffusion of inner polyelectrolyte-based moist-electric generator and charges storage ability of inner graphene electrochemical capacitor, this mp-SC demonstrates the self-charged high areal capacitance of 138.3 mF cm−2 and ~96.6% voltage maintenance for 120 h. In addition, a large-scale flexible device of 72 mp-SC units connected in series achieves a self-charged 60 V voltage in air, efficiently powering various commercial electronics in practical applications. This work will provide insight into the design self-powered and ultra-long term stable supercapacitors and other energy storage devices.

Extreme condition-tolerant stretchable flexible supercapacitor and triboelectric nanogenerator based on carrageenan-enhanced gel for energy storage, energy collection and self-powered sensing

As flexible electronics devices for energy storage, mechanical energy collection and self-powered sensing, stretchable flexible supercapacitor and triboelectric nanogenerator (TENG) have attracted extensive attention. However, it is difficult to satisfy the requirements of high safety and resistance to extreme conditions. Dual roles of mechanical and electrical enhancement of inorganic salt are put forward, and a carrageenan (CG) enhanced poly (N-hydroxyethyl acrylamide)/CG/lithium chloride/glycerol (PCLG) conductive gel is prepared by designing hydrogen bonding self-crosslinking and chain entanglement. A high concentration and rapid deposition strategy is proposed to prepare a PCLG gel-based stretchable flexible all-in-one supercapacitor for energy storage, and a single electrode PCLG gel-based TENG is designed for mechanical energy collection, self-powered strain and tactile sensing. The supercapacitor has high capacitance, excellent cycling stability. The TENG possesses efficient energy harvesting with high and stable output voltage and power density, and sensitive and stable self-powered strain and tactile sensing without external power supply. Even under extreme conditions such as low temperatures, self-healing after damage, prolonged placement, deformation, post-deformation, multiple continuous work, pinprick and burning, the supercapacitor and TENG still have excellent properties. Therefore, we provide novel ideas to design flexible supercapacitor and TENG used under extreme conditions for future wearable electronics.

Mechanically Strong and Tough Organohydrogels for Wide Temperature Tolerant, Flexible Solid‐State Supercapacitors

AbstractHydrogel‐based flexible solid‐state supercapacitors (SSCs) hold great promise for wearable electronics, yet significant challenges persist in simultaneously achieving excellent mechanical properties, high ionic conductivity, outstanding electrochemical properties, and wide operating temperature ranges. Here, this study presents a straightforward method for synthesizing dual crosslinked polyvinyl alcohol‐polyimide (PVA‐PI) organohydrogels via a simple one‐pot synthesis followed by a freezing‐thawing process. The controlled dual crosslinked networks with significanonetly different crosslinking densities and robust intermolecular hydrogen bonding interactions facilitated by the macromolecular crosslinker of PI, endow the organohydrogels with both high mechanical properties and ionic conductivity. Furthermore, SSCs based on PVA‐PI organohydrogels are fabricated, which can exhibit outstanding electrochemical performance at temperatures ranging from −40 to 80 °C. Specifically, the energy density reaches 16.7 µWh cm−2 even at −40 °C under a power density of 410.0 µW cm−2. These SSCs also show excellent performance stability under various deformations, such as bending and compression, alongside exceptional long‐term cycling stability (over 10 000 cycles) with high capacitance retention from −40 to 50 °C. The synthesis strategy, along with a robust mechanism for enhancing mechanical properties of hydrogels, demonstrated in this study offers insights for the development of strong hydrogels/organohydrogels with broad temperature adaptability for soft electronic applications.

Modulating oxygen vacancies in MXene/MoO3-x smart fiber by defect engineering for ultrahigh volumetric energy density supercapacitors and wearable SERS sensors

MXene fibers are expected to accelerate the sustainable development of intelligent era as multi-functional smart fibers. However, MXene fibers have serious obstacles when used for multi-functional applications. Here, we fabricated a multi-functional MXene fiber by incorporating MoO3-x nanobelts with abundant oxygen vacancies via wet spinning and defect engineering methods. Benefiting from the presence of abundant oxygen vacancies, the produced MXene/MoO3-x fibers not only provide more active sites to interact with electrolyte ions, but also substantially augment the rate capacities of fibers due to the enlarged distances between MXene flakes. Thus, the assembled fiber-based supercapacitor (SCs) realized high capacitance of 869.1F cm−3 at 0.5 A cm−3, good volumetric energy density of 77.3 mWh cm−3 at a power density of 204.8 mW cm−3 and long-term cycling stability along with 86.4 % capacity retention after 5000 cycles. Moreover, due to the narrowed bandgap of MoO3-x produced by defect engineering enhanced the charge transfer between the fiber and molecules, MXene/MoO3-x fiber also demonstrated a low limit of detection and reliable biomarkers detection in artificial sweat. These findings provide the potential application of MXene-based fibers in multi-functional devices.

Iron Sulfide Microspheres Supported on Cellulose-Carbon Nanotube Conductive Flexible Film as an Electrode Material for Aqueous-Based Symmetric Supercapacitors with High Voltage.

Nanostructured iron disulfide (FeS2) was uniformly deposited on regenerated cellulose (RC) and oxidized carbon nanotube (CNT)-based composite films using a simple chemical bath deposition method to form RC/CNT/FeS2 composite films. The RC/CNT composite film served as an ideal substrate for the homogeneous deposition of FeS2 microspheres due to its unique porous architecture, large specific surface area, and high conductivity. Polypyrrole (PPy), a conductive polymer, was coated on the RC/CNT/FeS2 composite to improve its conductivity and cycling stability. Due to the synergistic effect of FeS2 with high redox activity and PPy with high stability and conductivity, the RC/CNT/FeS2/PPy composite electrode exhibited excellent electrochemical performance. The RC/CNT/0.3FeS2/PPy-60 composite electrode tested with Na2SO4 aqueous electrolyte could achieve an excellent areal capacitance of 6543.8 mF cm-2 at a current density of 1 mA cm-2. The electrode retained 91.1% of its original capacitance after 10,000 charge/discharge cycles. Scanning electron microscopy (SEM) images showed that the ion transfer channels with a pore diameter of 5-30 μm were formed in the RC/CNT/0.3FeS2/PPy-60 film after a 10,000 cycle test. A symmetrical supercapacitor device composed of two identical pieces of RC/CNT/0.3FeS2/PPy-60 composite electrodes provided a high areal capacitance of 1280 mF cm-2, a maximum energy density of 329 μWh cm-2, a maximum power density of 24.9 mW cm-2, and 86.2% of capacitance retention after 10,000 cycles at 40 mA cm-2 when tested at a wide voltage window of 1.4 V. These results demonstrate the greatest potential of RC/CNT/FeS2/PPy composite electrodes for the fabrication of high-performance symmetric supercapacitors with high operating voltages.

Construction of advanced Nb9VO25 electrode material by introducing graphene quantum dot for high energy supercapacitors with exceptionally high diffusive capacitance

Unreasonable tunnel structure and low intrinsic conductivity limit practical applications of niobium oxide in high-performance supercapacitors. The study reports the construction of Nb9VO25 electrode material via coordination of Nb(V) and V(V) with histidine and serine-functionalized and boron-doped graphene quantum dot (HSBGQD) and subsequent annealing. The introduction of HSBGQD and rambutan peel leads to formation of small Nb9VO25 nanocrystal and low valent Nb and V species. The combination of small size and more reasonable tunnel structure accelerates the ion diffusion. The Nb(IV) and V(IV) double doping optimizes the tunnel structure, narrows the bandgap and creates new pathways for high-speed electron transfer. The integration of defect engineering with graphene surface modification enhance the intrinsic conductivity. The Nb9VO25 electrode shows exceptionally high specific capacitance of 2925.3 F/g, which is more than 142 times that of Nb2O5. The symmetrical supercapacitor with Nb9VO25 electrodes and PVA/Li2SO4 gel electrolyte offers high specific capacitance (263 F/g at 1 A/g), high-rage capacity (138 F/g at 50 A/g), cycling stability (capacitance retention of 99.4 % after 10000-cycle), energy density (146 W h Kg−1 at 996 W Kg−1 and 77 W h Kg−1 at 50181 W kg−1) and broad application prospect in wearable electronic devices.

Interfacial Charge Transport Enhancement of Liquid-Crystalline Polymer Transistors Enabled by Ionic Polyurethane Dielectric.

In organic field-effect transistors (OFETs) using disordered organic semiconductors, interface traps that hinder efficient charge transport, stability, anddevice performance are inevitable. Benchmark poly(9,9-dioctylfuorene-co-bithiophene) (F8T2) liquid-crystalline polymer semiconductor has been extensively investigated for organic electronic devices due to its promising combination of charge transport and light emission properties. This study demonstrates that high-capacitance single-layered ionic polyurethane (PU) dielectrics enable enhanced charge transport in F8T2 OFETs. The ionic PU dielectrics are composed of a mild blending of PU ionogel and PU solution, thereby forming a solid-state film with robust interfacial characteristics with semiconductor layer and gate electrode in OFETs and measuring high capacitance values above 10 µF cm-2 owing to the combined dipole polarization and electric double layer formation. The optimized fabricated ionic PU-gated OFETs exhibit a low-voltage operation at -3V with a remarkable hole mobility of over 5 cm2 V-1 s-1 (average = 2.50 ± 1.18 cm2 V-1 s-1), which is the highest mobility achieved so far for liquid-crystalline F8T2 OFETs. This device also provides excellent bias-stable characteristics in ambient air, exhibiting a negligible threshold voltage shift of -0.03V in the transfer curves after extended bias stress, with a reduced trap density.

Cultivating High-Performance Flexible All-in-One Supercapacitors With 3D Network Through Continuous Biosynthesis.

Flexible supercapacitors can potentially power next-generation flexible electronics. However, the mechanical and electrochemical stability of flexible supercapacitors under different flexible conditions is limited by the weak bonding between adjacent layers, posing a significant hindrance to their practical applicability. Herein, based on the uninterrupted 3D network during the growth of bacterial cellulose (BC), a flexible all-in-one supercapacitor is cultivated through a continuous biosynthesis process. This strategy ensures the continuity of the 3D network of BC throughout the material, thereby forming a continuous electrode-separator-electrode structure. Benefitting from this bioinspired structure, the all-in-one supercapacitor not only achieves a high areal capacitance (3.79 F cm-2) of electrodes but also demonstrates the integration of high tensile strength (2.15MPa), high shear strength (more than 54.6kPa), and high bending resistance, indicating a novel pathway toward high-performance flexible power sources.

Achieving Exceptional Volumetric Desalination Capacity Using Compact MoS2 Nanolaminates.

Capacitive deionization (CDI) has emerged as a promising technology for freshwater recovery from low-salinity brackish water. It is still inapplicable in specific scenarios (e.g., households, islands, or offshore platforms) due to too low volumetric adsorption capacities. In this study, a high-density semi-metallic molybdenum disulfide (1T'-MoS2) electrode with compact architecture obtained by restacking of exfoliated nanosheets, which achieve high capacitance up to ≈277.5Fcm-3 under an ultrahigh scan rate of 1000mVs-1 with a lower charge-transfer resistance and nearly tenfold higher electrochemical active surface area than the 2H-MoS2 electrode, is reported. Furthermore, 1T'-MoS2 electrode demonstrates exceptional volumetric desalination capacity of 65.1mgNaClcm-3 in CDI experiments. Ex situ X-ray diffraction (XRD) reveal that the cation storage mechanism with the dynamic expansion of 1T'-MoS2 interlayer to accommodate cations such as Na+, K+, Ca2+, and Mg2+, which in turn enhances the capacity. Theoretical analysis unveils that 1T' phase is thermodynamically preferable over 2H phase, the ion hydration and channel confinement also play critical role in enhancing ion adsorption. Overall, this work provides a new method to design compact 2D-layered nanolaminates with high-volumetric performance for CDI desalination.

FeNP@MIL-101(Fe)-Based Carbon Nanotube Composite for Energy Storage Applications.

Metal-organic frameworks (MOFs) are of great interest for energy applications due to their high porosity, high charge storage capacity, and large number of active redox sites. It is important to enhance the performance of metal-organic frameworks through modification in order to increase their potential applications. Unique Fe nanoparticle (NP) in the Materials of Institute Lavoisier (MIL) series embedded in the carbon nanotube (CNT), FeNP@MIL-101(Fe)/CNT-based, nanocomposites have been synthesized using suitable hierarchical micromesoporous structures. These were fabricated by simple and straightforward solvothermal methods, and their electrochemical charge storage performance was investigated. The energy storage application using the FeNP@MIL -101(Fe)/CNT composite as a supercapacitor electrode was implemented for the first time. Various techniques were used to characterize this composite. It has excellent electrochemical properties when used as electrode material in 1 M KOH solution, including a high capacitance of up to 1305 F g-1 at 1 A g-1 and a long cycling stability of 95.7% capacitance retention after 10,000 cycles. Moreover, symmetric two-electrode electrochemical experiments showed that the composite achieved an energy density of 98.65 Wh kg-1 and a power density of 9000 W kg-1, The combination of microporous and mesoporous structures, increased surface area, and higher electrical conductivity are the main reasons for the high performance. The integration of FeNP@MIL-101(Fe) with the CNT creates new ion diffusion pathways, improves the hierarchical pore properties, and exposes the FeNP@MIL-101(Fe) cluster to more redox active sites, which improves the charge storage performance.

Elevating Platinum to Volumetric Capacitance: High Surface Area Electrodes through Reactive Pt Sputtering.

Platinum is the most widespread electrode material used for implantable biomedical and neuroelectronic devices, motivating exploring ways to improve its performance and understand its fundamental properties. Using reactive magnetron sputtering, PtOx is prepared, which upon partial reduction yields a porous thin-film form of platinum with favorable properties, notably record-low impedance values outcompeting other reports for platinum-based electrodes. It is established that its high electrochemical capacitance scales with thickness, in the way of volumetric capacitor materials like IrOx and poly(3,4-ethylenedioxythiophene), PEDOT. Unlike these two well-known analogs, however, it is found that PtOx capacitance is not caused by reversible pseudofaradaic reactions but rather due to high surface area. In contrast to IrOx, PtOx is not a reversible valence-change oxide, but rather a porous form of platinum. The findings show that this oxygen-containing form of Pt can place Pt electrodes on a level competitive with IrOx and PEDOT. Due to its relatively low cost and ease of preparation, PtOx can be a good choice for microfabricated bioelectronic devices.

Deep learning prediction and experimental investigation of specific capacitance of nitrogen-doped porous biochar

N-doped porous biochar is a promising carbon material for supercapacitor electrodes due to its developed pore structure and high chemical activity which greatly affect the capacitive performance. Predicting the capacitance and exploring the most influential factors are of great significance because it can not only avoid the trial-and-error experiments but also provide guidance for the synthesis of biochar with the aim of capacitance enhancement. In this study, a CNN model with ReLU activation function was established using DenseNet architecture for specific capacitance prediction. The importance and impacts of the physiochemical properties of N-doped porous biochar to the capacitance were revealed. With the guidance of the model, N-doped porous biochar samples with high capacitance were synthesized, the data of which were further used for model validation. This study provides not only a deep learning model which can be used in practice for capacitance prediction but also directions for the synthesis of N-doped porous biochar with high capacitive performance.