Carbon Cathode Research Articles

Electro-dewatering of activated sludge of sewage treatment plants, Ternopol

The sewage sludge formed at wastewater treatment plants constitutes a small percentage of the volume of treated wastewater. However, the costs associated with sludge treatment and disposal account for the lion's share of the operational expenses of wastewater treatment plants. The sludge contains harmful and toxic substances. On the other hand, sludge is a source of carbon, nutrients, and trace elements, meaning it can be effectively utilized. An important stage in sludge disposal is its dewatering, particularly with the use of electric current. The study investigated the electro-dewatering of activated sludge with a moisture content of 98% from secondary clarifiers at the Ternopil wastewater treatment plant using direct electric current. Experiments were conducted on a laboratory setup with a U-shaped glass tube and carbon rod anode and cathode. The effect of the electric field was observed during the fading period, when, after a significant amount of water had been separated from the sludge, the electro-dewatering process slowed down. The obtained results were compared with those from the electro-dewatering of activated sludge with a moisture content of 98% from secondary clarifiers at the Ternopil wastewater treatment plant on a setup with a graphite rod anode and a flat cathode, as reported by other researchers. Electro-dewatering of activated sludge on both setups produced practically the same effect. It was confirmed that sludge dewatering using direct electric current can be applied on sludge drying beds at wastewater treatment plants.

A Facile Approach to Boost the Specific Capacity of Fluorinated Carbon Cathode for Rechargeable Na/CFx Battery

A Facile Approach to Boost the Specific Capacity of Fluorinated Carbon Cathode for Rechargeable Na/CFx Battery

Efficacy Assessment of Sulfated Flavanol Functionalized Silver Nanoparticles against MCF-7 Breast Cancer

Aim: The present research work aims to formulate a cost-effective and less toxic drug for specific and selective delivery at the tumor site. Background: Existing therapeutics, such as chemo, surgery, etc., for fast-paced MCF-7 breast cancer, still face challenges, especially due to their toxic side effects. The unique properties of metal nanoparticles embedded in anti-oxidant plant polymers have sparked great interest in the formulation of less toxic-targeted drugs for cancer cure. Objective: The present work aims to synthesize a targeted formulation of colloidal nanosilver by surface engineering of silver nanoparticles using plant polymers in electrolytic deposition technique, developed indigenously at the institute lab. Methods: A current is passed through an elctrolyte, AgNO3, which splits it into ions. The positive ions of Ag deposit over LDPE wrapped carbon cathode and negative ion, NO3, is liberated. Ag+ ions get capped in-situ. These surface-modified silver nanoparticles formulate a colloidal solution. UV-visible and FTIR spectroscopy, TEM-EDX, and XRD were used to validate asprepared formulation and in vivo human tumor xenograft model in NOD-SCID mouse for efficacy against MCF-7 breast cancer. Results: The as-synthesized formulation consists of pure spherical poly-dispersed silver nanoparticles of average size 5.4 nm, coated with sulphated flavanols. The efficacy evaluation reported that it significantly, T/C = 0.53, reduced tumor volumes with a 100% survival rate and change in animal body weight <4 gms. Conclusion: The as-synthesized formulation can be used as a potential neo-adjuvant or adjuvant drug along with existing therapeutics for MCF-7 breast cancer, significantly reducing the toxicity and cost.

Prepared Fe3O4/rSCCO-700 by ball milling-roasting method from spent carbon cathode from aluminum reduction process as anode for lithium ion batteries

Prepared Fe3O4/rSCCO-700 by ball milling-roasting method from spent carbon cathode from aluminum reduction process as anode for lithium ion batteries

Eliminating the crystal water in hydrated iron fluoride towards fast and high Li-ion storage capacity with ultralong cycling stability

Fluorides as conversion electrodes show great promise for Li-ion batteries due to their high theoretical capacity. However, their use is limited by low electronic conductivity and slow reaction kinetics. Additionally, fluorides usually contain crystal water in their structure, and the impact of this water on their performance is not well understood. Herein, we created FeF3@CNF nanofibers using simple electrospinning and fluorination processes as a potential anode for Li-ion batteries. These nanofibers, with FeF3 nanoparticles (∼50 nm) embeded in carbon, provide efficient pathways for lithium ion transport. By comparing the performance of FeF3 with and without crystal water through theoretical calculations and kinetics analysis, we found that removing the crystal water improves reaction kinetics and reduces mechanical strain, resulting in a significantly higher specific capacity, faster kinetics, and excellent cycling stability. In/ex-situ analytical techniques demonstrate that the rapid Li+ storage in the FeF3@CNF anode is due to a reversible conversion mechanism and particle refinement during cycling. The FeF3@CNF anode shows a kinetic advantage that matches well with activated carbon cathode, leading to superior cycling stability. This work highlights the crucial role of removing crystal water in optimizing fluoride-based electrodes and offers new insights for developing high-performance fluoride-based anodes for lithium-ion capacitors.

Recent advances in electrochemical membrane reactor based on cathodic carbon membrane for wastewater treatment: design, materials, application and mechanism

Recent advances in electrochemical membrane reactor based on cathodic carbon membrane for wastewater treatment: design, materials, application and mechanism

Room temperature reversible Ca-metal chemistry in commercial fluorinated calcium salt ester electrolytes enabled by a compact N-rich interphase layer

Multivalent metal batteries serve as crucial complements to lithium-ion batteries. Nevertheless, fluorinated anions designed for energy storage at high voltages readily passivate the metal anodes in common ester electrolytes, particularly for Ca-metal batteries (CMBs). Ca plating/stripping can hardly occur continuously in common fluorinated calcium salt ester electrolytes due to severe corrosion at room temperature. To address the challenging issue, a uniform artificial interface of calcium fluoride nitride nanocrystals (Ca2NF) and amorphous organic species is engineered in the top of Ca-metal electrodes. The compact inorganic/organic hybrid solid electrolyte interphase (SEI) layer avoided the direct reaction of Ca-metal and corrosive fluorinated anions, effectively preventing the continuous passivation of Ca-metal and expediting the diffusion kinetics of calcium ions at the interface. Therefore, for the first time, stable Ca plating/stripping at 0.005 mA cm−2 over 420 h in a commercial fluorinated calcium salt ester electrolyte is achieved for the Ca-metal electrode with the protective SEI, far superior to that of mere hours for the pristine Ca-metal. The enhanced reversibility is also substantiated in Ca-metal full batteries with biomass-derived carbon cathode, delivering stable cycling performance. This work underscores the importance of interface and interphase engineering as an effective avenue for advancing the development of CMBs.

A simple formula to fabricate high performance lithium metal capacitors

Energy storage technologies that are low-cost, with long cyclability, high rate-capability as well as high energy and power densities are under intensive investigation for sustainable clean energy transition. In this paper, we report a high-performance lithium metal capacitor (LMC) achieved by a simple slurry modification during the cathode film preparation. We show that a mere substitution of ~0.4 wt% conductive carbon by single walled carbon nanotubes (SWCNTs) increased the specific energy of LMCs by 22 %. Porous carbon cathode in this study was obtained from a non-edible biomass (coconut rachis); the optimized sample showed desirable surface characteristics (surface area ~1933 m2⸱g−1 and pore diameter ~2.0 nm) as well as high edge-plane fraction (ratio between relative density of edge and basal plane ~0.4). Cathode with no SWCNTs show a specific capacitance (CS) of ~133 F·g−1@0.1 A·g−1 in the potential window 2.0–4.0 V in the Li//LiPF6//AC device configuration. Removal of conductive carbon by SWCNTs up to ~0.6 wt% increased electrical conductivity of the cathode; however, the charge storability enhancements were only up to ~0.4 wt%. The optimum device delivered a CS ~188 F·g−1@100 mA·g−1 in the potential window 2.0–4.0 V with improved rate capability and cycling stability. Electrochemical impedance spectroscopy was used as a tool to understand the charge kinetics at the electrode; these studies collectively validated the observed enhancements in the charge storability. The device hereby developed showed superior specific capacity than most of the reported lithium-ion capacitors and comparable to some of the LMBs. The perceived 22 % increase in the specific energy by a mere 0.4 wt% SWCNT substitution is a step forward in fabricating the high-performance LMCs in addition to support the sustainability agenda through the carbon-negative precursors.

Hollow Porous Co0.85Se/ZnSe@MXene Anode with Multilevel Built-in Electric Fields for High-Performance Sodium Ion Capacitors.

Sodium ion capacitors (SICs) are promising candidates in energy storage for their remarkable power and energy density. However, the inherent disparity in dynamic behavior between the sluggish battery-type anodes and the rapid capacitor-type cathodes constrained their performance. To address this, we fabricated a hollow porous Co0.85Se/ZnSe@MXene anode featuring multiheterostructure, utilizing facile etching and electrostatic self-assembly strategies. The hollow porous structure and multiple heterointerfaces stabilize the anode by mitigating the volume changes. Density functional theory (DFT) calculations further revealed that induced multilevel built-in electric fields facilitate the formation of rapid ion diffusion pathways and reduce the Na+ adsorption energy, thereby boosting Na+/electron transport kinetics. The fabricated TA-Co0.85Se/ZnSe@MXene anode demonstrates outstanding long-term cycling stability of 406 mA h g-1 after 1000 cycles at 1 A g-1, with an ultrahigh rate performance of 288 mA h g-1 at 10 A g-1. When paired with the active carbon (AC) cathode, the SICs deliver extraordinary energy/power densities of 144 W h kg-1 and 12000 W kg-1, maintaining over 80% capacity retention at 1 A g-1 after 10000 cycles. This innovative strategy of engineering multiheterostructured anode with the induced multilevel built-in electric fields holds significant promise for advancing high-energy and high-power energy storage systems.

Hybrid Particle Size Template Method for Controllable Synthesis of Nitrogen-Doped Multilevel Porous Carbon as High-Rate Zn-Ion Hybrid Supercapacitor Cathode Materials.

Achieving high rate performance without compromising energy density has always been a critical objective for zinc-ion hybrid supercapacitors (ZHSCs). The pore structure and surface properties of carbon cathode materials play a crucial role. We propose utilizing a hybrid particle size (20 and 40 nm) magnesium oxide templates to regulate the pore structure of nitrogen-doped porous carbon derived from the soybean isolate. The multilevel pore structure enhanced ion transport efficiency while also improving the utilization of micropores. Nitrogen doping and oxygen-containing functional groups enhanced the wettability of carbon materials with aqueous electrolytes and facilitated the chemisorption of Zn2+ on the carbon material surface. The nitrogen-doped multilevel porous carbon material (HT-NMPC-1/1) prepared with a 1 : 1 mass ratio of the two templates exhibited a specific capacity of 146.65 mAh g-1 at 0.2 A g-1. Moreover, the Swagelok cells assembled with HT-NMPC-1/1 and Zn foil achieved a high energy density of 121.5 W h kg-1, high power output of 166 W kg-1, and 93.09 % capacity retention after 8000 cycles at 2 A g-1. Therefore, HT-NMPC-1/1 is a highly promising candidate for ZHSCs cathode materials. Furthermore, the novel pore regulation strategy and straightforward preparation method offer valuable reference points for other porous carbon-based functional materials.

Self-Templating Synthesis of Mesoporous Carbon Cathode Materials for High-Performance Lithium-Ion Capacitors.

Lithium-ion capacitors (LICs) have attracted considerable interest because of their excellent power and energy densities. However, the development of LICs is limited by the low capacity of the cathode and the kinetics mismatch between the cathode and anode. In this work, mesoporous carbon materials (MCs) with uniform pore sizes were prepared using magnesium citrate as the raw material through a self-templating method. During the carbonization process, MgO nanoparticles generated from magnesium citrate act as a template, resulting in a more orderly pore structure. The resultant MCs demonstrate a high specific surface area of 1673 m2 g-1 and an abundance of small mesopores, which significantly accelerated ion migration within the electrolyte and expedited the formation of electric double layers. Benefiting from these advantages, the MCs cathode demonstrates a high reversible specific capacity, excellent cycling stability, and rate performance. The assembled MCs-based LIC provides a high energy density of 152.2 Wh kg-1 and a high power density of 14.3 kW kg-1. After 5000 cycles, a capacity retention rate of 80 % at the current density of 1 A g-1 is obtained. These results highlight the excellent potential of MCs as a cathode material for LICs.

N, F Co-Doped Carbon Material Self-Supporting Cathode for High-Performance Lithium-Oxygen Batteries.

The Li-O2 battery has emerged as a promising energy storage system due to its exceptionally high theoretical energy density of 3500 Wh kg-1. However, the sluggish kinetics associated with the formation and decomposition of discharge product Li2O2 poses several challenges in Li-O2 batteries, including excessive over-potential, limited rate performance, and reduced actual specific energy. Consequently, the development of cost-effective cathode catalysts with enhanced catalytic activity and long-term stability represents a viable approach to address these challenges. In this study, commercial melamine foam is utilized as a precursor material which was subjected to pyrolysis at elevated temperatures with PVDF to synthesize N, F co-doped self-supporting carbon cathode (NF-NSC). Remarkably, thanks to the synergistic effects of N, F heteroatomic in conjunction with the inherent three-dimensional reticular porous structure, NF-NSC exhibited enhanced electrochemical performance when utilized in Li-O2 batteries. Specifically, the NF-NSC cathode demonstrated an impressive discharge specific capacity of up to 35204 mAh g-1 alongside a low over-potential (0.86 V) and excellent cycling stability (146 cycles).

Tailoring ion-accessible pores of robust nitrogen heteroatomic carbon nanoparticles for high-capacity and long-life Zn-ion storage

Designing highly endogenous zincophilic sites and ion-accessible pore architectures is crucial but remains a formidable challenge for carbon cathodes in zinc-ion hybrid capacitors (ZHCs) with superior capacity activity and ultralong cycling life. Herein, nitrogen heteroatomic carbon nanoparticles with hierarchical porous architectures were tailor-made by a well-established and efficient Schiff base reaction. The nucleophilic addition of amine modules and reactive carbonyl groups forms ordered organic nanoparticles with the specific internal ring pore size (1.27 nm) and high-level N heteroatomic doping. The tailored internal ring pore size, the robust macroporous networks formed by aggregated and interwoven nanoparticles and controlled carbonization/activation processes collaborate to obtain hierarchical porous architectures, robust carbon skeletons and high specific surface area (SSA) (2504 m2 g−1). Most notably, the pore architectures of NHPCs-700 (∼1.2 nm) can perfectly match the solvated ion diameter of Zn2+ (0.86 nm) and CF3SO3− (1.16 nm), realizing highly accessibility of zincophilic sites and fast diffusion behaviors. Additionally, ex-situ characterization and DFT calculation reveal the following energy storage mechanism: the ultrahigh zinc-ion capturing ability of pyridine N motifs, and fast diffusion behaviors alternately physical uptake of Zn2+/CF3SO3− charge carriers. The highly endogenous zincophilic sites, ion-accessible pore architectures and dual ion storage mechanism ensure exceptional specific capacity (253 mAh g−1 at 0.2 A g−1), outstanding energy density (157.8 Wh kg−1 at 125.3 W kg−1), and ultralong cycling life (200, 000 cycles at 10 A g−1). This work provides a strategic fabrication method for the advanced carbon cathodes with highly endogenous zincophilic site.

Chemical leaching − Flexible precipitation for sustainable recovery of fluoride from aluminum electrolysis multisource hazardous waste

The spent carbon materials, including anode and cathode, generated from the aluminum electrolysis process contain high fluoride levels and are unavoidable hazardous solid wastes. Chemical leaching, as a promising strategy for large-scale industrial treatment, must address the challenge of secondary recovery of the solution. The co-recovery mechanism preparing various fluorides from acidic and alkaline fluoride-aluminum solutions was investigated. In this process, the F/Al molar ratio and the pH value of the substrate environment are critical factors for achieving synergistic recovery. Different acid and alkali adjustment modalities resulted in a diverse array of products. For instance, adding an alkali to an acid solution generated aluminum hydroxyfluoride hydrate, whereas the reverse sequence yielded cryolite. The precipitation mechanism of acidic solutions is characterized by a complex interplay of multiple substances, whereas the process in alkaline solutions is comparatively straightforward. Specifically, as the pH value increases, the sequence of phase transformations progresses through aluminum hydroxyfluoride hydrate, chiolite, aluminum hydroxide, and cryolite. In addition to pH, localized over-alkalinity was the primary factor contributing to impurity generation. The precipitation phase in an alkaline substrate environment is significantly better controlled. During this process, pure cryolite can be synthesized by adjusting the F/Al molar ratio to 6.0 using the neutralization solution. The synergistic synthesis of fluoride from both acidic and alkaline fluorine-containing solutions is not only feasible but also anticipated to effectively address the significant issues of water swelling and secondary solution recovery that are commonly encountered in industrial applications.

Metal organic framework derived heteroatom doped porous carbon nanocubes enable efficient charge storage in a lithium-ion capacitor

Lithium-ion capacitors (LICs) are regarded as one of the promising technologies towards realizing energy & power dense energy storage systems. However, their energy densities at higher power densities are still limited due to the discrepancy between electrode kinetics of capacitor-like cathode and battery-like anode. Developing carbon materials with well-defined structures, porosity to match the chemical kinetics between electrodes are the major challenges to overcome. In the present work, we have devised a strategy to fabricate S, N dual-doped porous carbon nanocubes (S, N-PCNs) using zeolitic imidazole framework (ZIF)-8 precursors, and employed the PCNs as anode material in LICs. With its well-defined structure, hierarchical porous nature, and abundant heteroatom presence (1.9 % S, 16.2 % N), the pre-lithiated S, N-PCNs based anode has offered a greatly improved reversible storage capacity of ∼930 mAh g−1 at 0.1 A g−1 along with an impressive rate capability and cycling life. When S, N-PCNs anode is paired with activated carbon cathode, the 4 V dual-carbon LIC yields an energy density as high as 120.24 Wh kg−1 and 10.2 kW kg−1 of power density with a good cycle stability of 90.6 % after 5000 charge-discharge cycles. This work would open new scopes of exploring metal-organic framework derived heteroatom-doped porous carbons to make metal-ion capacitors more efficient.

Hollow carbon nanofibers with self-induced internal electric field for high-performance full-carbon sodium ion capacitors

Self-induced internal electric field (SIEF) is crucial to achieve high capacity, high rate and long cycle life of carbon anodes in Na+ storage, but it is also a huge challenge currently. Herein, a template-assisted electrospinning process and subsequent low-temperature pyrolysis method is employed to synthesize S, N co-doped hollow carbon nanofibers (SNHCF) with rich micropores and chemisorption sites. The rich micropores and interconnected macroporous in SNHCF provide large internal availability that effectively exposing the active sites, inhibiting the volume expansion and shortening the Na+ diffusion distance. Besides, S, N co-doping in the carbon skeleton can act as an electron acceptor and electron donor respectively to form a SIEF to boost adsorption of Na+. Theoretical calculation and ex-situ characterizations confirmed that S, N co-doping can regulate the electronic configuration and reduce the diffusion barrier of Na+. As a result, SNHCF anode has ultra-high specific capacity (588.2mAh g−1 at 0.05 A/g) and impressive rate performance (264.3mAh g−1 at 20 A/g). The full-carbon sodium ion capacitors assembled with SNHCF anode and activated carbon cathode exhibits high energy density (119 Wh kg−1) and ultra-long cycle stability (80.06 % capacity retention after 12,000 cycles).

Local Oxygen Reconstruction Enables Dual‐Ion Active Sites in Carbon Cathode for High Energy Density Sodium‐Ion Capacitors

AbstractCarbon materials are the promising cathode material for sodium‐ion capacitors (SICs) with high energy/power density, however, clarifying the evolution processes of functional groups in carbon materials and revealing their energy storage mechanisms are full of challenges. Inspired by the ancient practice of alchemy, which sought to purify Dan medicine and remove impurities through precise control of the refining temperature, the local oxygen reconstruction strategy, to alter the functional groups species in SP3‐C, is pioneeringly utilized, achieving targeted regulation of carbonyl groups with increase from 27.9 to 43.3 at%, which efficiently change the electronic structure of the carbon framework and realize the dual‐ion adsorption of Na+ and ClO4−, according well with the theoretical calculations. As expected, the obtained carbon cathode delivers a specific capacity of 145 mAh g−1, higher than that of the parent carbon material (95 mAh g−1). Impressively, the ex situ X‐ray Photoelectron Spectroscopy and in situ Raman reveals that carbonyl can act as dual‐ion active sites for Na+ and ClO4− through pseudocapacitive behavior under different voltage states. Notably, the assembled SIC using the carbonyl‐rich carbon cathode exhibits an ultrahigh energy density of 162 Wh kg−1. This work opens a novel avenue for regulating the carbonyl content of carbon materials.

Expanded Graphite as a Superior Anion Host Carrying High Output Voltage (4.62 V) and High Energy Density for Lithium Dual-Ion Batteries.

The demand for safer, sustainable, and economical energy storage devices has motivated the development of lithium dual-ion batteries (Li_DIBs) for large-scale storage applications. For the Li_DIBs, expanded graphite (EG) cathodes are valuable as anion intercalation host frameworks to fabricate safer and more cost-effective devices. In this study, three different carbon cathode materials, including microwave-treated expanded graphite (MW-EG), ball-milled expanded graphite (BM-EG), and high-temperature-carbonized carbon nanoflakes (CNFs), were developed by different synthesis methods. Li_DIBs were configured by employing 4 M of LiPF6 in a dimethyl carbonate electrolyte and MW-EG/BM-EG/CNF as an anion host cathode. After 600 cycles, a Li-MW-EG Li_DIB exhibited a reversible capacity of 66.1 mAh/g with a high Coulombic efficiency of 96.2% at a current rate of 0.05 A/g and an outstanding average energy density of 298.97 Wh/kg (with an output voltage of 4.62 V). The remarkable electrochemical results are associated with (i) moderate structural defects with a very low ID/IG ratio (0.848), (ii) degree of graphitization, which improves the mechanical stability and conductivity, and (iii) large pore volume and pore diameter, easy facilitating the accumulation of PF6- ions. The energy density characteristics demonstrate the feasibility of utilizing MW-EG as a promising cathode for energy-related Li_DIB applications.

Valorization of Residue from Aluminum Industries: A Review.

Recycling and reusing industrial waste and by-products are topics of great importance across all industries, but they hold particular significance in the metal industry. Aluminum, the most widely used non-ferrous metal globally, generates considerable waste during production, including dross, salt slag, spent carbon cathode and bauxite residue. Extensive research has been conducted to recycle and re-extract the remaining aluminum from these wastes. Given their varied environmental impacts, recycling these materials to maximize residue utilization is crucial. The components of dross, salt slag, and bauxite residue include aluminum and various oxides. Through recycling, alumina can be extracted using processes such as pyrometallurgy and hydrometallurgy, which involve leaching, iron oxide separation, and the production of alumina salt. Initially, the paper will provide a brief introduction to the generation of aluminum residues-namely, dross, salt slag, and bauxite residue-including their environmental impacts, followed by an exploration of their potential applications in sectors such as environmental management, energy, and construction materials.

Supermolecule-opitimized defect engineering of rich nitrogen-doped porous carbons for advanced zinc-ion hybrid capacitors.

Pitch-based porous carbons with adjustable surface chemical property and controllable pore structure are regarded as promising cathode materials for aqueous zinc-ion hybrid capacitors (ZIHCs), while its disordered carbon matrix and microstructure as well as insufficient surface defects often result in low Zn2+-storage capacity and poor rate capability of ZIHCs. Herein, a synergetic strategy of self-assembled supermolecule and enriched defective carbon engineering was developed to achieve ultrahigh edge-nitrogen doping for ZIHCs. The crystallite defects and surface structure of porous carbon could be effectively achieved through grafting electronegative oxygen-containing small molecules and high-level nitrogen-containing functional groups between modified polycyclic aromatic hydrocarbon and supermolecule framework. The optimized three-dimensional carbon structure delivered high capacity of 218 mAh g-1 at 0.2 A g-1, fast charge/discharge capability, enhanced energy density (165.4 Wh kg-1) and superior cycling stability (95% retention after 10000 cycles as cathode of ZIHCs). This provided new insight into the controllable synthesis of carbon cathodes for ZIHCs and expects to prepare functional porous carbon by supermolecules and special precursors.