Carbon Cathode Research Articles

Non-conjugated adipamide organic anode materials for high-performance lithium-ion capacitors

Lithium-ion capacitors (LICs) hold promise as next-generation energy storage devices due to the synergy of the advantageous features of lithium-ion batteries (LIBs) and supercapacitors (SCs). Recently, the use of nanostructured conjugated carboxylate organic anode materials in LICs has attracted tremendous attention due to their high capacity, excellent capacitive behavior, design flexibility, and environmental friendliness. Nevertheless, no studies have reported the use of non-conjugated organic compounds in LICs. In this study, we report for the first time that non-conjugated adipamide (ADIPAM) nanocrystals fabricated using a dissolution-recrystallization self-assembly technique serve as an excellent anode material for LICs. The unique ADIPAM nanocrystals–PVDF–Super P conductive integrated network architecture accelerates Li+ ion and electron diffusion and enhances lithium storage capability. Consequently, ADIPAM electrodes exhibit a high capacity of 705.8 mAh/g, exceptional cycling stability (308 mAh/g after 2100 cycles at 5 A/g), and remarkable rate capability. Furthermore, a LIC full cell comprising the ADIPAM anode with a porous activated carbon cathode demonstrates a wide working window (4.5 V), high energy density (238.3 Wh/kg), and superb power density (22,500 W/kg). We believe this work may introduce a new approach to the design of non-conjugated organic materials for LICs.

Исследование флуктуаций автоэмиссионного тока катодов из ПАН углеродных волокон

This paper presents the process of obtaining field emission, as well as the study of fluctuations in the autoemission current of carbon cathodes based on PAN fibers. The relevance of this article is confirmed by the fact that the technology of creating field emission determines the efficiency of electronic devices, and current fluctuations can serve as an indicator of the quality of these devices. At the same time, this study shows that the degree of current fluctuations in the field emission depends on the geometry of the device. As a result, the I–V curve was obtained at different distances between the cathode and the anode.

A novel CaCO3-embedded carbon cathode for highly energy-efficient Li–O2 batteries

A novel CaCO3-embedded carbon cathode for highly energy-efficient Li–O2 batteries

Direct electron transfer mediated electrochemical activation of persulfates by reticulated vitreous carbon (RVC) cathode

The electrochemical activation of peroxymonosulfate (PMS) and peroxydisulfate (PDS) for pollutant degradation has gained increasing attention. In this work, reticulated vitreous carbon (RVC) electrodes were prepared at a low cost and investigated for the cathodic activation of PMS/PDS for Acid Orange 7 degradation. The RVC was characterized by SEM, TGA, XRD, Raman spectroscopy, XPS, EIS, and compression test. The superior activity outperformed previous reports in terms of low current density operation (1–10 mA/cm2), high degradation rates (0.13–0.49 min−1), low energy consumption (0.03–0.23 kWh/m3/order) without involvement of catalysts. The process was optimized for current density, PMS dosage, pollutant concentration, pH, water matrix, and supporting electrolyte. Under the optimal current density (3 mA/cm2), the addition of 0.5 mM of PMS boosted the degradation rate by 9.6 times to 0.4470 min−1 and reduced the electrical energy consumption by 90.1 % to 0.0243 kWh/m3/order in 50 mM of Na2SO4. Moreover, up to 117 mg/L of H2O2 was produced in 1 hour by the reduction of oxygen, with current efficiencies between 78–24 %. The process showed little deterioration in 10 cycles, worked for a variety of pollutants, and was not affected by the water matrix. The H-cell experiments confirmed that 90 % degradation took place on the cathode. Scavenging experiments and electrochemical tests suggested that the transitional state of PMS* and O2•− mediated the direct electron transfer mechanism for AO7 degradation. Eighteen degradation products were identified by HPLC-MS and categorized into 4 degradation pathways. Finally, their toxicity was assessed by the ECOSAR programme.

Fe3O4-doped mesoporous carbon cathode with a plumber’s nightmare structure for high-performance Li-S batteries

Shuttling of lithium polysulfides and slow redox kinetics seriously limit the rate and cycling performance of lithium-sulfur batteries. In this study, Fe3O4-dopped carbon cubosomes with a plumber’s nightmare structure (SP-Fe3O4-C) are prepared as sulfur hosts to construct cathodes with high rate capability and long cycling life for Li-S batteries. Their three-dimensional continuous mesochannels and carbon frameworks, along with the uniformly distributed Fe3O4 particles, enable smooth mass/electron transport, strong polysulfides capture capability, and fast catalytic conversion of the sulfur species. Impressively, the SP-Fe3O4-C cathode exhibits top-level comprehensive performance, with high specific capacity (1303.4 mAh g−1 at 0.2 C), high rate capability (691.8 mAh gFe3O41 at 5 C), and long cycling life (over 1200 cycles). This study demonstrates a unique structure for high-performance Li-S batteries and opens a distinctive avenue for developing multifunctional electrode materials for next-generation energy storage devices.

Elucidating High Initial Coulombic Efficiency, Pseudocapacitive Kinetics and Charge Storage Mechanism of Antiperovskite Carbide Ni3ZnC0.7@rGO Anode for Fast Sodium Storage in Ether Electrolyte.

To explore novel electrode materials with in-depth elucidation of initial coulombic efficiency (ICE), kinetics, and charge storage mechanisms is of great challenge for Na-ion storage. Herein, a novel 3D antiperovskite carbide Ni3ZnC0.7@rGO anode coupled with ether-based electrolyte is reported for fast Na-ion storage, exhibiting superior performance than ester-based electrolyte. Electrochemical tests and density functional theory (DFT) calculations show that Ni3ZnC0.7@rGO anode with ether-based electrolyte can promote charge/ion transport and lower Na+ diffusion energy barrier, thereby improving ICE, reversible capacity, rate, and cycling performance. Cross-sectional-morphology and depth profiling surface chemistry demonstrate that not only a thinner and more homogeneous reaction interface layer with less side effects but also a superior solid electrolyte interface (SEI) film with a high proportion of inorganic components are formed in the ether-based electrolyte, which accelerates Na+ transport and is the significant reason for the improvement of ICE and other electrochemical properties. Meanwhile, electrochemical and ex situ measurements have revealed conversion, alloying, and co-intercalation hybrid mechanisms of the Ni3ZnC0.7@rGO anode based on ether electrolyte. Interestingly, the Na-ion capacitors (SICs) designed by pairing with activated carbon (AC) cathode exhibit favorable electrochemical performance. Overall, this work provides deep insights on developing advanced materials for fast Na-ion storage.

N/S co-doped interconnected hierarchical porous carbon cathode for zinc-ion hybrid capacitors with high energy density

Porous carbon materials (PCMs) are regarded as one of the most promising cathode materials for zinc-ion hybrid capacitors (ZIHCs) because of their low cost and abundant resource. Nevertheless, it is still a major challenge to enhance the energy density of PCMs-based ZIHCs. Herein, N/S co-doped interconnected hierarchical porous carbons (NS–IHPCs) are prepared from coal tar pitch (CTP) via a MgO@ZIF-8 double-template, in situ activation and N/S doping strategy to tune the microstructure and chemical composition. The as-prepared NS-IHPC1.5 features high specific surface area of 1273 m2 g−1, hierarchical pore structure and suitable heteroatom doping. Consequently, as a cathode, the NS-IHPC1.5-based ZIHC exhibits a high energy density of 125.3 Wh kg−1 at 134.5 W kg−1 and still remains 85.3 Wh kg−1 at 14096.1 W kg−1. The calculation results of density functional theory (DFT) demonstrate that the combination of pyrrole nitrogen and ortho-oxidized sulfur in samples achieves more negative Zn2+ adsorption energy. Correspondingly, the high capacity (166.5 mAh g−1 at 0.2 A g−1) and long cycle stability (94.0 % capacitance retention at 5 A g−1 after 20,000 cycles) are achieved for NS-IHPC1.5. This work offers a reliable way for synthesizing remarkable cathode materials from coal chemical by-products for energy storage.

P-modified carbon nanosheet with abundant through-hole channels for boosting Zn-ion storage under low-temperature

Zinc-ion hybrid capacitors (ZIHCs) as a promising energy storage system suffer from unsatisfactory capability due to mismatched pore structure and lack of active sites in the carbon cathodes. Herein, a coupling strategy of oxidation template and in-situ doping is proposed to design a P-modified carbon nanosheet with abundant through-hole channels. Phosphorus doping not only reduces the electrode/electrolyte interface impedance, but also increases the available active sites. Through-hole channels enhance the Zn2+ accessibility. Therefore, the assembled ZIHCs provide an ultra-high energy density of 194.23 Wh kg−1. Even at 0 °C, the ZIHCs retain a superior capacity of 166.0 mAh/g and stabilize for 10,000 cycles with capacity retention of 95.33 %. This work provides new insights into the design of carbon cathodes for boosting the Zn2+ storage.

Highly conductive composite cathode prepared by dry process using Nafion-Li ionomer for sulfide-based all-solid-state lithium batteries

All-solid-state lithium batteries (ASSLBs) offer safe operation and high energy density, making them potential alternatives to liquid-electrolyte-based lithium-ion batteries. Sheet-type composite cathodes for sulfide-based ASSLBs are typically fabricated using a nonconducting polytetrafluoroethylene (PTFE) binder by a solvent-free dry process, resulting in poor cycling stability and low rate capability. We demonstrate a strategy for using a Li+-incorporated Nafion (Nafion-Li) binder to fabricate a composite cathode via a dry process for improving cycling performance of ASSLBs. The solid-state cell assembled with Li6PS5Cl and LiNi0.7Co0.15Mn0.15O2 cathode using an optimal amount of Nafion-Li delivers a discharge capacity of 177.8 mAh g−1 (4.1 mAh cm−2) at 25 °C and exhibits a high capacity retention of 97% after 200 cycles at 0.5C. The improved cycling performance results from enhanced electrical conductivity (ionic and electron conductivity) and better interfacial contacts between cathode active material, solid electrolyte, and conducting carbon in the composite cathode, provided by Nafion-Li binder.

Coupling effect of defects and enriched adsorption sites in bimetal-MOF derived porous carbonaceous anode for high-performance lithium-ion capacitor

Lithium-ion capacitors (LICs) have attracted considerable attention for their ability to combine the high energy characteristics of lithium-ion batteries and the high power densities of supercapacitors. However, the development of LICs still faces critical challenges. Herein, a robust bimetal-MOF derived fluorine and nitrogen co-doped hierarchical porous carbon embedding with Co nanoparticles anode materials (Co@NFC-800) for LICs are developed, which combined with the advantages of amplified interlayer, enriched active sites and improved electrical conductivity. Both theoretically and experimentally results demonstrate that such advantaged structure via fluorine doping to introduce defects and regulate doped nitrogen atom configuration to enrich Li+ adsorption sites and enhance diffusion kinetics synergistically is attempted. Co@NFC-800 deliveres a high reversible capacity and excellent long cycling stability as anode in LIBs, By coupling the Co@NFC-800 anode with commercial activated carbon (AC) cathode, the assembled LICs deliver a high specific energy of 164 Wh kg−1 at 162.9 W kg−1 and maintained to 68.3 Wh kg−1 even at high specific power of 9.1 kW kg−1 as well as long cycling stability (80.2 % over 2000 cycles).The fluorine doping induced both enriched defects and regulable nitrogen atom configuration strategy opens up a new way of carboneous materials for lithium storage.

Graphitization transformation of aluminum electrolytic spent carbon cathode

Aluminum electrolysis spent cathode carbon (SCC), as typical solid hazardous waste, poses significant environmental risks. Harmless treatment of SCC and recycling of its carbon component are important research areas. In this study, SCC was subjected to microwave hydrothermal acid leaching to remove harmful components, followed by the production of high-quality graphite via iron-catalyzed graphitization. The effects of reaction temperature, heating time, and catalyst loading on the graphitization conversion of SCC were investigated. The catalytic graphitization process of SCC was optimized using the response surface method. The results show that when the reaction temperature is 1520 °C, the heating time is 85.24 min, and the catalyst loading is 46.15 wt%, the graphitization degree of the sample is 97.61 %. The samples prepared under the optimal conditions were characterized using XRD, Raman, SEM, and TEM. The results reveal that the catalytic graphitization process significantly influences the conversion of microcrystalline structures in SCC into graphite structures. The iron-catalyzed transformation of microcrystalline carbon was analyzed to elucidate the graphitization transformation mechanism. This study offers an effective pathway for the high-value utilization of SCC. It also serves as a technical reference for the catalytic graphitization conversion of carbon materials.

The promotion mechanism of different nitrogen doping types on the catalytic activity of activated carbon electro-Fenton cathode: Simultaneous promotion of H2O2 generation and phenol degradation ability

Doping with nitrogen atoms can improve the catalytic activity of activated carbon cathodes in electro-Fenton systems, but currently there is a lack of understanding of the catalytic mechanism, which limits the further development of high-performance activated carbon cathodes. Here, a multi-scale exploration was conducted using density functional theory and experimental methods to investigate the mechanism of different nitrogen doping types promoting the redox performance of activated carbon cathodes and the degradation of phenol. The density functional theory results indicate that the introduction of nitrogen atoms enhances the binding ability between carbon substrates and oxygen-containing substances, promotes the localization of surrounding electrons, and makes it easier for O2 to bind with protons and catalyze the hydrogenation reaction of *OOH. Due to its weak binding ability with oxygen-containing substances, AC is difficult to form H2O2, resulting in a tendency towards the 4e−ORR pathway. The binding energy between graphite-N carbon substrate and pyridine-N carbon substrate with *OOH is closer to the volcano top, so graphite n and pyridine n can better promote the selectivity of activated carbon for 2e-ORR. In addition, the calculation results also indicate that pyrrole-N and graphite-N are more capable of catalyzing the reaction energy barrier between ·OH and phenol. Finally, the simulation results were used to guide the modification of nitrogen doped activated carbon and experimental verification was carried out. The degradation results of phenol confirmed the efficient synergistic effect between different types of nitrogen doping, and the NAC-800 electrode exhibited efficient and stable characteristics. This work provides a guiding strategy for further developing stable and highly selective activated carbon cathode materials.

Efficient zinc protection enabled by polyhedral metal-organic framework and ionic-crosslinking binder

Towards the efficient reversibility and cyclability of Zinc (Zn) plating/stripping, surface modification has been recognized as one of the straightforward strategies for Zn electrodes. In this study, 20 μm of a composite layer prepared by blending ZIF-8 and sodium alginate (SA) was uniformly coated on the Zn foil (Z8-SA@Zn) as an alternative protective layer to explore their synergistic contributions in suppressing the side reaction under the aqueous electrolyte. Benefiting from the following characteristics: (a) ionic crosslinking between SA and Zn2+, (b) improved Zn2+ flux, (c) more hydrophilic / zincophilic, and (d) chemical stability, the resulting Z8-SA@Zn revealed the remarkably anti-corrosive property, insignificant zincate growth, high Coulombic efficiency, and prolong cyclability. Encouragingly, the zinc-ion hybrid supercapacitor assembled by Z8-SA@Zn anode and commercial activated carbon cathode not only delivers an impressive rate capability (45 mAh/g at 1 mA/cm2, 37 mAh/g at 10 mA/cm2) but also achieves the excellent cycling stability (capacity retention: 91 % after 20,000 cycles at 5 mA). According to the results disclosed here, combining ZIF-8 and SA as the interfacial layer provides multifunctional features, enabling the effective protection of Zn foil. Consequently, it is rationally believed that the Z8-SA@Zn can be a promising anode material for Zn2+ storage applications.

Sustainable electro-Fenton simultaneous reduction of Cr (VI) and degradation of organic pollutants via dual-site porous carbon cathode driving uncoordinated molybdenum sites conversion

Simultaneous removal of heavy metals and organic contaminants remains a substantial challenge in the electro-Fenton (EF) system. Herein, we propose a facile and sustainable “iron-free” EF system capable of simultaneously removing hexavalent chromium (Cr (VI)) and para-chlorophenol (4-CP). The system comprises a nitrogen-doped and carbon-deficient porous carbon (dual-site NPC-D) cathode coupled with a MoS2 nanoarray promoter (MoS2 NA). The NPC-D/MoS2 NA system exhibits exceptional synergistic electrocatalytic activity, with removal rates for Cr (VI) and 4-CP that are 20.3 and 4.4 times faster, respectively, compared to the NPC-D system. Mechanistic studies show that the dual-site structure of NPC-D cathode favors the two-electron oxygen reduction pathway with a selectivity of 81 %. Furthermore, an electric field-driven uncoordinated Mo valence state conversion of MoS2 NA enchances the generation of dynamic singlet oxygen and hydroxyl radicals. Notably, this system shows outstanding recyclability, resilience in real wastewater, and sustainability during a 3 L scale-up operation, while effectively mitigating toxicity. Overall, this study presents an effective approach for treating multiple-component wastewater and highlights the importance of structure-activity correlation in synergistic electrocatalysis.

Stable and improved voltage plate of Li/SOCl2 battery using carbon electrodes with active carbon

Active carbon (AC) is synthesized using pitch coke as a precursor with a KOH activation approach followed. AC with different specific surface areas can be obtained by controlling the activation time of KOH. The activation time of AC1, AC2 and AC3 is 1 h, 1.5 h and 2 h, with the surface areas of 1233, 1484 and 1639 m2 g−1, respectively. The phase, surface chemical structure, morphology as well as the microstructure of the AC are investigated by XRD, Raman, IR, XPS, BET, SEM and TEM. The obtained ACs displayed a size around 300 μm with lots of nanoholes and functional group involving –OH, –COOH. When employed as the catalytic active materials in the carbon cathodes for Li/SOCl2 batteries, the discharged voltage was improved to around 0.15 V with an enhanced stable platform. Whereas the energy of the batteries containing the ACs is similar as that the conventional batteries, as well as the morphology of the carbon cathode with ACs exhibited a dense LiCl on the surface, suggesting that the ACs can enhance the reduction reaction of SOCl2, but could not act as the nucleation sites for the synthesis of nanoscale LiCl to form a loose film for a long discharge life.

Using a non-precious metal catalyst for long-term enhancement of methane production in a zero-gap microbial electrosynthesis cell

Microbial electrosynthesis (MES) cells exploit the ability of microbes to convert CO2 into valuable chemical products such as methane and acetate, but high rates of chemical production may need to be mediated by hydrogen and thus require a catalyst for the hydrogen evolution reaction (HER). To avoid the usage of precious metal catalysts and examine the impact of the catalyst on the rate of methane generation by microbes on the electrode, we used a carbon felt cathode coated with NiMo/C and compared performance to a bare carbon felt or a Pt/C-deposited cathode. A zero-gap configuration containing a cation exchange membrane was developed to produce a low internal resistance, limit pH changes, and enhance direct transport of H2 to microorganisms on the biocathode. At a fixed cathode potential of –1 V vs Ag/AgCl, the NiMo/C biocathode enabled a current density of 23 ± 4 A/m2 and a high methane production rate of 4.7 ± 1.0 L/L-d. This performance was comparable to that using a precious metal catalyst (Pt/C, 23 ± 6 A/m2, 5.4 ± 2.8 L/L-d), and 3–5 times higher than plain carbon cathodes (8 ± 3 A/m2, 1.0 ± 0.4 L/L-d). The NiMo/C biocathode was operated for over 120 days without observable decay or severe cathode catalyst leaching, reaching an average columbic efficiency of 53 ± 9 % based on methane production under steady state conditions. Analysis of microbial community on the biocathode revealed the dominance of the hydrogenotrophic genus Methanobacterium (∼40 %), with no significant difference found for biocathodes with different materials. These results demonstrated that HER catalysts improved rates of methane generation through facilitating hydrogen gas evolution to an attached biofilm, and that the long-term enhancement of methane production in MES was feasible using a non-precious metal catalyst and a zero-gap cell design.

Designing P-doped graphite-like hierarchical porous carbon nanosheets from coal tar pitch for enhanced Zn-ion hybrid capacitors

The innovative design of pitch-based carbon cathodes holds profound implications for optimizing the efficient utilization of coal tar pitch (CTP) and hastening the progress of Zn-ion hybrid capacitors (ZIHCs). Herein, P-doped graphite-like porous carbon nanosheets (PGCNs) were designed by cleverly combining pre-oxidation, catalytic graphitization, and H3PO4 modification. Throughout oxidation, adjustments were made to the surface functional groups and molecular sizes of CTP to ensure subsequent catalytic and activation effects. Then a uniform lamellar structure and highly graphitized porous carbon matrix were successfully generated through catalytic graphitization. The pore structure and surface chemical properties were further enhanced through H3PO4 modification. When PGCNs were integrated into ZIHCs, the assembled Zn//PGCNs device demonstrated a specific capacity of 133.2 mAh/g at 1 A/g, an energy density of 113.8 Wh/kg at 404.7 W/kg, and maintained a cycle stability of 90.6% after 10,000 cycles.

Alveoli‐Inspired Carbon Cathodes with Interconnected Porous Structure and Asymmetric Coordinated Vanadium Sites for Superior Li−S Batteries

AbstractAccelerating sulfur conversion catalysis to alleviate the shuttle effect has become a novel paradigm for effective Li−S batteries. Although nitrogen‐coordinated metal single‐atom (M−N4) catalysts have been investigated, further optimizing its utilization rate and catalytic activities is urgently needed for practical applications. Inspired by the natural alveoli tissue with interconnected structure and well‐distributed enzyme catalytic sites on the wall for the simultaneously fast diffusion and in situ catalytic conversion of substrates, here, we proposed the controllable synthesis of bioinspired carbon cathode with interconnected porous structure and asymmetric coordinated V−S1N3 sites for efficient and stable Li−S batteries. The enzyme‐mimetic V−S1N3 shows asymmetric electronic distribution and high tunability, therefore enhancing in situ polysulfide conversion activities. Experimental and theoretical results reveal that the high charge asymmetry degree and large atom radius of S in V−S1N3 result in sloping adsorption for polysulfide, thereby exhibiting low thermodynamic energy barriers and long‐range stability (0.076 % decay over 600 cycles).

Alveoli-Inspired Carbon Cathodes with Interconnected Porous Structure and Asymmetric Coordinated Vanadium Sites for Superior Li-S Batteries.

Accelerating sulfur conversion catalysis to alleviate the shuttle effect has become a novel paradigm for effective Li-S batteries. Although nitrogen-coordinated metal single-atom (M-N4) catalysts have been investigated, further optimizing its utilization rate and catalytic activities is urgently needed for practical applications. Inspired by the natural alveoli tissue with interconnected structure and well-distributed enzyme catalytic sites on the wall for the simultaneously fast diffusion and in situ catalytic conversion of substrates, here, we proposed the controllable synthesis of bioinspired carbon cathode with interconnected porous structure and asymmetric coordinated V-S1N3 sites for efficient and stable Li-S batteries. The enzyme-mimetic V-S1N3 shows asymmetric electronic distribution and high tunability, therefore enhancing in situ polysulfide conversion activities. Experimental and theoretical results reveal that the high charge asymmetry degree and large atom radius of S in V-S1N3 result in sloping adsorption for polysulfide, thereby exhibiting low thermodynamic energy barriers and long-range stability (0.076 % decay over 600 cycles).

NiCo MOF@Carbon Quantum Dots Anode with Soot Derived Activated Carbon Cathode: An Efficient Asymmetric Configuration for Sustainable High‐Performance Supercapacitors

NiCo MOF@Carbon Quantum Dots Anode with Soot Derived Activated Carbon Cathode: An Efficient Asymmetric Configuration for Sustainable High‐Performance Supercapacitors