Key Takeaways & Executive Findings
- •• • Electrochemical exfoliation introduces oxygen functional groups on carbon paper, increasing pseudocapacitance and enabling a binder-free electrode with a capacitive contribution of 78.8% at 10 mV/s, which is critical for high-rate performance. • • The EECP electrode achieves a maximum specific capacitance of 252.5 F/g at 1 A/g, outperforming many conventional carbon-based electrodes, and retains 81.7% of capacitance after 10,000 cycles, indicating excellent long-term stability. • • A full ZISC device delivers a capacitance of 186.22 F/g at 1 A/g with 97.01% retention after 10,000 cycles, demonstrating robust cycle life for practical energy storage. • • The ZISC achieves an energy density of 46.6 Wh/kg at a power density of 500.4 W/kg, positioning it as a competitive option for renewable energy storage applications.
Abstract
Zinc-ion supercapacitors (ZISCs) are promising energy storage devices due to their low cost, high safety, and minimal environmental impact. However, their low energy density and poor cycling performance hinder practical application. This study presents a simple electrochemical exfoliation method to reconstruct the surface of carbon paper, introducing oxygen functional groups that enhance pseudocapacitance. The resulting binder-free electrode (EECP) exhibits a large surface area and rapid charge transfer, leading to a dominant capacitive-type charge storage mechanism with 78.8% capacitive contribution at 10 mV/s. The EECP electrode delivers a maximum specific capacitance of 252.5 F/g at 1 A/g and retains 81.7% of its capacitance after 10,000 cycles. A full ZISC device, assembled with EECP as the cathode, Zn as the anode, and 1 mol L−1 ZnSO4 aqueous electrolyte, achieves a capacitance of 186.22 F/g at 1 A/g, a capacitance retention of 97.01% after 10,000 cycles, and an energy density of 46.6 Wh/kg at a power density of 500.4 W/kg. These results demonstrate that EECP is a promising cathode material for high-rate, next-generation zinc-ion supercapacitors.
1. Introduction
Zinc-ion supercapacitors (ZISCs) have emerged as a viable alternative to lithium-ion batteries, offering inherent safety, low cost, and environmental benignity. However, their commercial deployment is hampered by limited energy density and poor cycling stability, primarily arising from the lack of high-performance cathode materials. Conventional carbon-based cathodes suffer from low specific capacitance and inadequate rate capability due to limited active sites and sluggish ion transport. The challenge lies in developing electrodes that combine high surface area, fast charge transfer, and robust structural integrity without the use of binders, which often add dead weight and impede ion diffusion.
This study addresses these bottlenecks by employing a simple electrochemical exfoliation technique to reconstruct the surface of carbon paper, introducing oxygen functional groups that enhance pseudocapacitance. The resulting binder-free electrode (EECP) provides a large electroactive surface area and rapid ion diffusion pathways, enabling a dominant capacitive charge storage mechanism. The EECP electrode demonstrates a high specific capacitance of 252.5 F/g at 1 A/g and retains 81.7% of its capacitance after 10,000 cycles. When assembled into a full ZISC with a Zn anode and 1 mol L−1 ZnSO4 electrolyte, the device achieves an energy density of 46.6 Wh/kg at a power density of 500.4 W/kg, with 97.01% capacitance retention after 10,000 cycles. These findings offer a scalable and cost-effective strategy for producing high-performance cathodes for next-generation ZISCs.
Loading authentic research manuscript (Pages 1–5)...
Iqra Ashraf, Awais Ahmad, Ibrahim A. Shaaban, Tensangmu Lama Tamang, Muhammad Sufyan Javed, Haosen Fan, Li Fang (2026). Electrochemical Exfoliation of Carbon Paper for Binder-Free Cathodes in Zinc-Ion Supercapacitors. New Carbon Materials. https://doi.org/10.1016/S1872-5805(25)61029-8
Research & Educational Purpose Only: The translations, structured abstracts, analytical annotations, and data reports provided by SinoGreenTechare intended exclusively for academic research, internal corporate R&D, and educational benchmarking. They do not constitute formal engineering, chemical safety, legal, or professional advice.
Copyright & Intellectual Property Notice: Original copyright of the underlying source articles and experimental data remains with the respective authors, institutions, and original publishing journals. SinoGreenTech claims intellectual property only over its proprietary translations, analytical syntheses, and AEO structured enhancements in accordance with international fair use and academic citation principles.
Frequently Asked Questions
What is the specific capacitance retention of the EECP electrode after 10,000 cycles, and what does this indicate about its long-term stability?
The EECP electrode retains 81.7% of its initial capacitance after 10,000 cycles, demonstrating excellent long-term cycling stability. This is critical for practical applications where electrode degradation over time is a major concern.
How does the energy density of the ZISC device compare to conventional supercapacitors, and what is the trade-off with power density?
The ZISC device achieves an energy density of 46.6 Wh/kg at a power density of 500.4 W/kg. This is significantly higher than typical supercapacitors (which usually have energy densities below 10 Wh/kg) and is comparable to some battery systems, while still maintaining high power capability.
What is the role of oxygen functional groups introduced by electrochemical exfoliation in enhancing the electrochemical performance?
Oxygen functional groups increase the pseudocapacitive contribution by providing additional redox-active sites, which enhances the overall capacitance. The capacitive contribution is 78.8% at 10 mV/s, indicating that surface-controlled processes dominate, leading to fast charge/discharge kinetics.
What are the potential scalability challenges of the electrochemical exfoliation method for industrial production?
The method is simple and cost-effective, but scaling up requires careful control of exfoliation parameters (e.g., voltage, electrolyte concentration, time) to ensure uniformity and reproducibility. Additionally, the use of carbon paper as a substrate may limit the electrode area, but roll-to-roll processing could be adapted for large-scale manufacturing.
How does the performance of the EECP electrode compare to other carbon-based cathodes reported in the literature?
The EECP electrode achieves a specific capacitance of 252.5 F/g at 1 A/g, which is competitive with or superior to many previously reported carbon-based cathodes for ZISCs. The high capacitance retention (81.7% after 10,000 cycles) and the device-level energy density (46.6 Wh/kg) underscore its potential for practical application.
Related Chinese Research & Cross-Citations
Electrospinning of FeNiCo/carbon nanofibers: a new paradigm for lightweight microwave absorbers
The proliferation of electronic devices has intensified electromagnetic radiation pollution, necessitating advanced microwave absorption materials. This study presents the electrospinning fabrication of FeNiCo/carbon nanofiber (FeNiCo/CNF) composites with exceptional microwave absorption properties. The FeNiCo/CNFs achieved a minimum reflection loss (RLmin) of −55.5 dB at 14.24 GHz with an ultrathin matching thickness of only 1.6 mm. Microstructural analysis and electromagnetic parameter testing revealed that the superior absorption stems from the synergistic interaction between the carbon nanofiber network and FeNiCo alloy nanoparticles, which promotes multiple reflections and efficient energy dissipation. The precise control of coercivity and permeability via systematic modulation of magnetic metal composition enabled enhanced impedance matching and optimized magnetic-dielectric synergy. Furthermore, radar cross-section (RCS) simulations confirmed the material's capability to significantly reduce RCS values across a wide angular range, validating its potential for stealth technology applications. This work introduces a cost-effective and sustainable approach for developing ultralight, high-performance microwave absorbers, addressing the limitations of conventional materials such as high density and poor stability.
Increasing the Strength of Carbon Nanotube Fibers and Their Use as a Polishing Medium
We report a method for increasing the mechanical strength of carbon nanotube (CNT) fibers while enabling the uniform adhesion of cerium oxide (CeO2) abrasive particles to them using polyethyleneimine (PEI). Results show that 5% of PEI increases the tensile strength of CNT fibers by approximately 175%. CeO2 particles were uniformly deposited on the reinforced CNT fibers by electrophoretic deposition. A flexible polishing tool was fabricated by weaving the CeO2-CNT fibers into a non-woven fabric substrate. When used to polish potassium dihydrogen phosphate crystals, the tool reduced the surface roughness from 200 to 7.6 nm within 10 min. This approach has potential use for the development of new precision processing tools.
Engineered mesoporous carbon spheres with tailored pore structures for improved photothermal-chemotherapy
Carbon-based materials have gained significant attention in anticancer treatment due to their exceptional biocompatibility, yet critical challenges persist in establishing definitive correlations between their porous structures and functional performance. We report the use of a silica template to guide pore formation in the design of mesoporous carbon spheres (mC) with tailored pore structures for improved combined photothermal-chemotherapy. The mesopore size of mC was adjusted by kinetic control of resin polymerization and silica hydrolysis. Structural characterization showed that 4.4 nm mesopores enabled an exceptional gemcitabine loading of 228 mg g−1 and a sustained pH/thermal dual-responsive release with >70% drug release under near-infrared (NIR) irradiation. Finite element analysis demonstrated pore size-dependent heat transfer dynamics, with the improved mC achieving a superior photothermal conversion efficiency of 62% by a combination of N-doping and defect engineering. In vitro evaluations confirmed outstanding biocompatibility with >95% cell viability at 200 μg mL−1 and potent tumor suppression in pancreatic and biliary cancer models with an ~5% cell viability at 25 μg mL−1 where combined therapy showed a 3.7-fold increased cytotoxicity over monotherapy. The improved structure of mC facilitated cascade therapeutic effects with enhanced tumor permeability derived from NIR-triggered hyperthermia and prolonged therapeutic exposure due to pH-responsive drug release. This pore engineering strategy establishes a structure-function process for next-generation theranostic platforms, addressing the critical limitations of conventional pancreatic and biliary cancer therapies through spatiotemporal control of multimodal treatment.
Comparative Studies on Nanocarbon-Modified Carbon Paper Electrodes for Enhanced Electrocatalytic Performance in Vanadium Redox Flow Batteries
Vanadium redox flow batteries (VRFBs) are a promising technology for large-scale energy storage due to their scalability, safety, long cycling life, and decoupled power and energy capacities. However, the slow redox kinetics of vanadium species on conventional carbon electrodes limits their performance. This study investigates the deposition of carbon black (CB), carbon nanotubes (CNTs), and electrochemically exfoliated graphene (Exf-Gr) onto thermally-activated carbon paper (ACP) via spray coating to enhance electrode electrocatalytic activity. Modified electrodes were characterized using scanning electron microscopy, X-ray diffraction, Raman spectroscopy, X-ray photoelectron spectroscopy, and surface area analysis. Electrochemical properties were evaluated by cyclic voltammetry, electrochemical impedance spectroscopy, and single-cell VRFB testing. Among the modified electrodes, Exf-Gr/ACP exhibited the best performance, achieving a 2.9-fold reduction in charge transfer resistance compared to pristine ACP and delivering 2.5 times the discharge capacity in single-cell tests. This improvement is attributed to Exf-Gr's high surface area, favorable catalytic activity, and excellent dispersion on the ACP substrate. Surface modification with electrochemically exfoliated graphene is a highly effective strategy for improving electrode performance in VRFB systems, with significant implications for large-scale energy storage.
Carbon nanotube-based materials as capacitive deionization electrodes
Capacitive deionization (CDI) is an emerging desalination technology that removes dissolved salts from brackish water via ion electrosorption at electrically charged electrode interfaces. It has gained recognition as a sustainable and cost-effective alternative to conventional methods such as reverse osmosis, electrodialysis, and thermal distillation, which often suffer from high energy consumption and environmental impact. Among electrode materials, carbon nanotubes (CNTs) are particularly attractive due to their high specific surface area, superior electrical conductivity, and excellent electrochemical stability. This review comprehensively analyzes recent advances in performance optimization strategies for CNT-based CDI electrodes, including material engineering and structural design. Key strategies include hybridization with activated carbon, graphene, metal oxides, and metal-organic frameworks (MOFs), as well as surface functionalization and three-dimensional architecture construction. These approaches enhance salt adsorption capacity, charge efficiency, and cycling stability. For instance, dispersing CNTs in activated carbon electrodes improves conductivity and ion transport, while MOF-derived nitrogen-doped carbon/CNT heterostructures exhibit high desalination performance. The review also evaluates the pivotal role of CNT-based electrodes in driving technological progress in CDI and discusses persistent challenges such as electrode fouling, scalability, and cost-effectiveness. Promising research directions, including flow-electrode systems and selective ion removal, are highlighted to overcome current limitations. Overall, CNT-based materials hold significant promise for advancing CDI as a viable water purification technology.
Boron and Nitrogen Co-Doped Coal-Based Activated Carbon as Cathode Material for High-Performance Aqueous Zinc-Ion Hybrid Capacitors
Aqueous zinc-ion capacitors (ZICs) are promising energy storage systems due to their high specific capacity and superior reliability. Heteroatom-doped carbon materials have been shown to substantially increase the capacitance of ZICs, yet the underlying mechanisms remain poorly understood. In this work, coal-based activated carbon was functionalized with both boron (B) and nitrogen (N) to serve as the cathode material in ZICs. The optimized material, designated CAC-120, exhibits a high specific capacity of 371.4 mAh g−1 at 1 A g−1 and retains 74% of its initial capacity after 10,000 cycles. Electrochemical analysis and density functional theory (DFT) calculations reveal that pyridinic N plays a crucial role in enhancing Zn2+ storage, demonstrating superior electrochemical reversibility. Furthermore, an assembled aqueous ZIC using the CAC-120 cathode achieves a high reversible capacity of 90.8 mAh g−1 at 0.2 A g−1 and exceptional long-term stability over 17,000 cycles. This work provides valuable insight into the design of high-capacity and ultrafast pseudocapacitive carbon cathodes for ZICs, highlighting the synergistic effects of pore structure engineering and heteroatom doping.