Large Interlayer Spacing Research Articles

Tailored Regulation of Graphite Microcrystals via Tandem Catalytic Carbonization for Enhanced Electrochemical Performance of Hard Carbon in the Low‐Voltage Plateau

AbstractThe sodium storage behavior in the plateau region is crucial for determining the capacity and rate capability of hard carbon (HC) anodes in sodium‐ion batteries (SIBs). Key structural features for achieving excellent plateau performance include extended graphite domains and increased interlayer spacing. However, synchronously optimizing these two structures is challenging due to their inherent trade‐off. Herein, a tandem catalytic carbonization strategy is developed to construct HC with long graphite domains (La = 5.31 nm) and large interlayer spacing (d002 = 0.389 nm) simultaneously. Comprehensive in situ and ex situ tests unravel the catalytic selective bond breaking and aromatization effects of ZnCl2, the catalytic graphitic layers enlargement and occupied effects of formed ZnO and Zn in different temperature stages, leading to the formation of the unique structure. The optimal HCZ‐0.1 exhibits a high reversible capacity of 346.9 mAh g−1 with a plateau capacity of 249.4 mAh g−1, and high‐rate performance (114.0 mAh g−1 at 5 A g−1). In addition, the sodium storage mechanism and origin of enhanced Na+ kinetics of HCZ‐0.1 are also revealed. This work offers a precise method to engineer the graphite microcrystal structure in HC for superior sodium storage in the plateau region.

Biomass-Derived Carbon With Large Interlayer Spacing for Anode of Potassium Ion Batteries.

Potassium-ion batteries (PIBs) are emerging as powerful candidate for grid-oriented energy storage owing to their potentially low cost. Carbon is considered the promising anode for PIBs on the basis of its high conductivity and abundant sources. The biggest challenge confronted by carbon anodes lies in insufficient cycle life as well as rate capability, resulting from the limited interlayer spacing of the sp2-hybrid carbon incompatible with the large-radius potassium. Herein, a biomass-derived carbon with a large interlayer spacing of 0.44nm is fabricated via a zinc-assisted pyrolysis synthesis. The unique structure endows the carbon with superior capacity, rate capability, and cycle durability. The large interlayer spacing of carbons can promote fast potassium diffusion and alleviate the volume expansion during potassiation, conferring those rate capabilities and cycleability. The interconnected network structure is also able to shorten both the transport distances of electrons and ions. The demonstration exemplifies an advanced carbon for anodes of PIBs for energy storage applications.

Nitrogen-Doped Graphene Uniformly Loaded with Large Interlayer Spacing MoS2 Nanoflowers for Enhanced Lithium-Sulfur Battery Performance.

Lithium-sulfur (Li-S) batteries offer a high theoretical energy density but suffer from poor cycling stability and polysulfide shuttling, which limits their practical application. To address these challenges, we developed a PANI-modified MoS2-NG composite, where MoS2 nanoflowers were uniformly grown on graphene oxide (GO) through PANI modification, resulting in an increased interlayer spacing of MoS2. This expanded spacing exposed more active sites, enhancing polysulfide adsorption and catalytic conversion. The composite was used to prepare MoS2-NG/PP separators for Li-S batteries, which achieved a high specific capacity of 714 mAh g-1 at a 3 C rate and maintained a low capacity decay rate of 0.085% per cycle after 500 cycles at 0.5 C. The larger MoS2 interlayer spacing was key to improving redox reaction kinetics and suppressing the shuttle effect, making the MoS2-NG composite a promising material for enhancing the performance and stability of Li-S batteries.

MXene-montmorillonite nanocomposites-based scaffold sensors for early pancreatic cancer diagnosis

Pancreatic cancer is increasingly prevalent and characterized by a high mortality rate. Due to the limitations of current diagnostic methods, early-stage detection remains elusive, contributing to persistently low survival rates among affected individuals. Nanomaterials have garnered significant attention in cancer research for their potential diagnostic applications. Among these, MXenes – a novel family of two-dimensional nanomaterials composed of transition metal carbides, nitrides, and carbonitrides – are of particular interest due to their unique properties. These include high electrical conductivity, hydrophilicity, thermal stability, large interlayer spacing, tunable structure, and high surface area. These characteristics make MXenes highly effective for detecting trace amounts of various analytes. In addition, their tunable structure enables precise manipulation of their properties, allowing for optimized sensing responses. Montmorillonite nanoclay (MMT), a member of the smectite group of natural clay minerals, is known for its ability to promote bone development and influence cell behavior. When combined with MXenes, MMT forms promising nanocomposites for early pancreatic cancer detection through sensing applications. The Ti3C2 MXene-MMT nanocomposites exhibit potential as scaffold sensors capable of distinguishing cancerous from non-cancerous samples by observing the distinctive patterns in resistance changes. In addition, MXenes possess excellent selectivity, allowing for the reliable identification of targeted analytes from a complex mixture of chemical and biological analytes. Due to the advanced sensing capabilities of MXene-MMT composite scaffold sensors, they hold great promise for early cancer diagnosis and tissue regeneration, providing a novel therapeutic approach to improving patient outcomes.

Construction of Low‐Softening‐Point Coal Pitch Derived Carbon Nanofiber Films as Self‐Standing Anodes Toward Sodium Dual‐Ion Batteries

AbstractTo achieve high‐quality hard carbon nanofibers (HCNFs), and particularly flexible HCNFs films is the eternal pursuit from low‐cost coal pitch (CP). However, it is still trapped seriously by the inborn bottleneck of low‐softening‐point (LSP) characteristics of CP itself. Herein, an efficient Bi(NO3)3·5H2O‐assisted electrospinning‐carbonization methodology is creatively devised to obtain flexible HCNFs films directly from LSP CP. The essential roles of Bi(NO3)3·5H2O and pre‐oxidation in constructing flexible films are rationally proposed. With further regulation in Bi(NO3)3·5H2O dosage and calcination temperatures, specific micro‐structures/morphologies of flexible HCNFs films are finely optimized. The optimum HCNFs‐1.2 film is endowed with robust structural flexibility/stability, high‐content active oxygen/nitrogen groups, abundant graphic microcrystalline zones of large interlayer spacing, and convenient ion‐diffusion channels. Thanks to such remarkable merits, HCNFs‐1.2 retains a large reversible capacity of 125.3 mAh g‒1 over 1000 cycles at 1.0 A g‒1, when evaluated as a self‐supporting film anode for sodium dual‐ion batteries (SDIBs). Furthermore, the HCNFs‐1.2‐based SDIBs deliver a specific capacity of 90.9 mAh g‒1 at 0.1 A g‒1, along with a capacity retention of 78.4% after 1500 cycles at 1.0 A g‒1. The insightful understanding here will provide meaningful guidance for rational design of advanced flexible film electrodes toward next‐generation SDIBs and beyond.

Dual-Driven Ion/Electron Migration and Sodium Storage by In Situ Introduction of Copper Ions and a Carbon-Conductive Framework in a Tin-Based Sulfide Anode.

Tin sulfide (SnS) has emerged as a promising anode material for sodium ion batteries (SIBs) due to its high theoretical capacity and large interlayer spacing. However, several challenges, such as severe insufficient electrochemical reactivity, rapid capacity degradation, and poor rate performance, still hinder its application in SIBs. In this study, in situ introduction of copper ions and a carbon conductive framework to form SnS nanocrystals embedded in a Cu2SnS3 lamellar structure heterojunction composite (SnS/Cu2SnS3/RGO) with graphene as the supporting material is proposed to achieve dual-driven sodium ion/electron migration during the continuous electrochemical process. The designed structure facilitates the preferential electrochemical reduction of copper ions into copper nanocrystals during the discharge process and functions as a catalytically active center to promote multivalence tin sodiation reaction. Furthermore, during the charging process, the presence of copper nanocrystals also facilitates efficient desodiation of NaxSn and further activates to form higher valence state sulfides. As a result, the SnS/Cu2SnS3/RGO composite demonstrates high cycling stability with a high reversible capacity of 395 mAh g-1 at 5A g-1 after 500 cycles with a capacity retention of 85.6%. In addition, the assembled Na3V2(PO4)3∥SnS/Cu2SnS3/RGO sodium ion full cell achieves 93.7% capacity retention after 80 cycles at 0.5 A g-1.

The potassium storage performance of carbon nanosheets derived from heavy oils

As by-products of petroleum refining, heavy oils are characterized by a high carbon content, low cost and great variability, making them competitive precursors for the anodes of potassium ion batteries (PIBs). However, the relationship between heavy oil composition and potassium storage performance remains unclear. Using heavy oils containing distinct chemical groups as the carbon source, namely fluid catalytic cracking slurry (FCCS), petroleum asphalt (PA) and deoiled asphalt (DOA), three carbon nanosheets (CNS) were prepared through a molten salt method, and used as the anodes for PIBs. The composition of the heavy oil determines the lamellar thicknesses, sp3-C/sp2-C ratio and defect concentration, thereby affecting the potassium storage performance. The high content of aromatic hydrocarbons and moderate amount of heavy component moieties in FCCS produce carbon nanosheets (CNS-FCCS) that have a smaller layer thickness, larger interlayer spacing (0.372 nm), and increased number of folds than in CNS derived from the other three precursors. These features give it faster charge/ion transfer, more potassium storage sites and better reaction kinetics. CNS-FCCS has a remarkable K+ storage capacity (248.7 mAh g−1 after 100 cycles at 0.1 A g−1), long cycle lifespan (190.8 mAh g−1 after 800 cycles at 1.0 A g−1) and excellent rate capability, ranking it among the best materials for this application. This work sheds light on the influence of heavy oil composition on carbon structure and electrochemical performance, and provides guidance for the design and development of advanced heavy oil-derived carbon electrodes for PIBs.

N/P/O co-doped porous carbon derived from agroindustry waste of peanut shell for sodium-ion storage

Porous bio‑carbon from agroindustry waste behaves one of the most promising anode materials for sodium-ion batteries (SIBs) because of its high sodium storage capacity, low cost, sustainability, and low charge/discharge voltage platform. Herein, we have developed a new N/P/O co-doped porous hard carbon derived from peanut shell (PSCNP) synthesized via KOH activation, hydrothermal doping combined with carbonization method, using chitosan as nitrogen source, phytic acid as phosphorus source, and peanut shell as carbon and oxygen source. Through seriously regulating the calcination temperature, the optimal PSCNP-800 carbonization at 800 °C can well combine the advantages of the natural rich porous microstructure of peanut shells, large graphite interlayer spacing (0.379 nm), and short diffusion distance for sodium-ion. As an advanced anode for SIBs, the PSCNP-800 delivered a reversible capacity of 248.8 mAh g−1 after 100 cycles at 25 mA g−1. This work could provide a possible idea for the preparation of N/P/O co-doped porous hard carbon from low-cost agroindustry waste as anodes for SIBs.

Identifying the importance of functionalization evolution during pre-oxidation treatment in producing economical asphalt-derived hard carbon for Na-ion batteries

Na-ion batteries (NIBs) are emerging as frontrunners for next-generation energy storage systems, boasting superior safety profiles and promising cost-effectiveness. A crucial hurdle in the commercialization of NIBs lies in developing cost-effective hard carbons (HC) with high carbon yields. This work leverages ultra-affordable asphalt as a precursor, coupled with pre-oxidization to specifically tailor the microstructures of HC, achieving an impressive carbon yield of 63%. Both experimental and theoretical calculation results reveal that the successful introduction of oxidation sites during the pre-oxidation process is a prerequisite for producing non-graphitizable HC with large interlayer spacing. The inclusion of carbonyl groups effectively restricts the movement of carbon atoms during subsequent carbonization, thus hindering the graphitization of carbon layer. Furthermore, abundant ether-oxygen bonds enable the solid-phase carbonization mechanism and prevent the shrinkage of carbon layers, facilitating the crispation of carbon layers. This breakthrough significantly boosts the potential of harnessing low-cost, high-performance HC for NIBs.

Electrochemical Performance of Coal-Based Needle Coke Anode for Lithium Ion Batteries

Lithium-ion capacitors (LICs) with the capability of high energy and high power are considered to be attractive for advanced energy storage applications. However, the design and fabrication of suitable electrode materials with desirab-le properties by a facile approach using cost-effective precursors are still a great challenge. In this work, we have utilized needle cokes, an commercial carbon material with high carbon content and soft carbon structure, as a single carbon source for anode material. A lithium-ion battery fabricated using four kinds of needle cokes exhibits a maximum high energy density of 1357mAhg-1. Systematic characterization analysis demonstrates that unique characteristics of the green coke including large interlayer spacing, turbostratic and disordered microstructures that are composed of surface defects, nanopores or voids, and graphitic domains. That contribute synergistically to the outstanding performance of the needle coke-based LIC. More importantly, anode materials from a single source is an effective way for high value-added utilization of needle coke at the commercial level.

Carbon-decorated hydrated V10O24 nanorods for high-performance lithium-ion battery cathodes

This study reports the successful synthesis of carbon-decorated hydrated V10O24 (HVO@C) nanorods using a facile hydrothermal method. The synthesized material was comprehensively characterized using XRD, FTIR, Raman, TGA/DSC, BET, SEM, and HRTEM to reveal its structure and morphology, and the resulting electrode's electrochemical performance as a lithium-ion battery (LIB) cathode was evaluated for the first time. The HVO@C nanorods exhibited a remarkable initial capacity of 292.5 mAh g−1 at 75 mA g−1 current rate, exceeding most of the reported V2O5-based LIB cathodes. Notably, the HVO@C electrode retained a good capacity retention of 67.1 % and a slower capacity loss rate of 0.26 % after 125 cycles compared to most V2O5-based counterparts with shorter lifespans. This outstanding performance could be due to a synergistic interplay of structural characteristics. The large interlayer spacing within the nanorods facilitated unimpeded Li-ion diffusion, while the short diffusion path minimized transport limitations. Furthermore, the strategic incorporation of carbon coating enhanced electrical conductivity and structural stability, leading to enduring LIB battery performance. These results indicate that in-situ carbon-decorated hydrated V10O24 nanoparticles have great potential as a promising cathode electrode for LIBs with exceptional performance.

Organic and Inorganic Modified Montmorillonite as a Scavenger of Formaldehyde in Modified Urea-Formaldehyde Composites

This research used montmorillonite (K10) modified with Hexadecyltrimethylammonium bromide (HDTMABr), and sulfuric acid (H2SO4). The samples are marked with MMT, OMMT for organic-modified montmorillonite, and AMMT for inorganic-modified montmorillonite. UF resin with a molar ratio FA/U = 0.8 was synthesized in situ with modified and unmodified MMT. X-ray diffraction analysis (XRD), Fourier transform infrared spectroscopy (FTIR), non-isothermal thermogravimetric analysis (TGA), and scanning electron microscopy (SEM) were used to characterize the MMT samples. The degree of activation was determined based on the measurement of specific surface area, which was determined by the Sears method. The sulfite method was used to determine free and released formaldehyde from synthesized urea-formaldehyde/montmorillonite (UF/MMT) composites. SEM analysis showed changes in the OMMT morphology and the formation of a hollow network, affecting the clay's absorption capacity. Measurement of the specific surface area shows that higher values were obtained for AMMT (183 m2/g) compared to OMMT (13.5 m2/g). Despite that, the free and released formaldehyde amount was 0.06% and 4.6% for UF/AMMT and 0.1% and 1.0% for UF/OMMT. The larger interlayer spacing and hydrophobic nature of OMMT make it an effective barrier within the UF resin matrix.

Potential difference-induced electrodeposition of defect-rich α-cobalt hydroxide on porous copper (PCu): High-voltage performance of supercapacitor

Designing electrode materials for aqueous battery-type supercapacitors to extend the operating voltage window remains a significant challenge to increase the energy density of aqueous supercapacitors. In this work, a directional electrodeposition method without any additives was employed to deposit α-Co(OH)2 onto a porous copper (PCu) current collector substrate, which involves the fabrication of a supercapacitor electrode material with a cross-linked network structure named α-Co(OH)2@PCu900. The potential difference between copper and cobalt facilitated the formation of a larger interlayer spacing for α-Co(OH)2. In addition, crystals of α-Co(OH)2 with different orientations exert stress on one another, leading to lattice distortion and vacancy formation. The morphology and microstructure of materials were analyzed through techniques such as SEM, HRTEM, XRD, and XPS, confirming the validity of the experimental design. This defect-rich, large interlayer spacing structure facilitates ion intercalation and deintercalation during the charge-discharge process, thereby expanding the operating voltage window. In a three-electrode system, α-Co(OH)2@PCu900 exhibited a potential range from −0.45 V to 0.55 V and demonstrated an areal capacitance of 2580 mF cm−2 and specific capacitance of 600 A g−1 at 2 mA cm−2. The α-Co(OH)2@PCu900 was used as the cathode material and commercial reduced graphene oxide (rGO) was used as the anode material in an asymmetric supercapacitor, and the ASC device exhibited an areal capacitance of 295.3 mF cm−2 and a specific capacitance of 87.89 F g−1. Notably, it retained a high energy density of 0.12 mW h cm−2 (35.27 Wh kg−1) at a power density of 1.7 mW cm−2 (505.95 W kg−1). This method established α-Co(OH)2@PCu900 as a promising supercapacitor electrode material, providing a viable strategy for designing and fabricating functional electrode materials.

Highly-pseudocapacitive origin and design principles of MoS2 for high-performance aqueous zinc-ion storage

Pseudocapacitive storage of Zn2+ in nanostructured molybdenum disulfide (MoS2) is expected to break through the limitations of sulfide in monovalent or multivalent ions storage; however, the deficiency of theoretical guidance and experimental strategies that enable rational design of MoS2 as a kind of cathode material towards aqueous zinc-ion batteries. Herein, we firstly establish guiding theory in order to design pseudocapacitive MoS2-based cathode in the light of the first-principles calculation, and then propose a simple and effective one-pot template-free solvothermal method to synthesize 1T phase-dominated MoS2 cathode with low crystallinity. Through this method, MoS2 cathode delivers an exceptional reversible capacity of 233 mAhg−1 at 0.05 A g−1, especially at 0.1 A g−1, the stability can achieve >150 cycles, and maintains 84 % capacity retention after 2100 cycles at 5 A g−1. Experimental and theoretical analysis show that such extraordinary pseudocapacitive contribution determines by the synergistic effects in the activated and stable metallic phase, abundant lattice defects and larger interlayer spacing in the rag-like MoS2 cathode. The revealed origin of highly pseudocapacitive Zn2+ storage and design principle for MoS2-based cathode facilitate the design of a variety of efficient cathodes.

Ultrahigh Pyridinic/Pyrrolic N Enabling N/S Co-Doped Holey Graphene with Accelerated Kinetics for Alkali-Ion Batteries.

Carbonaceous materials hold great promise for K-ion batteries due to their low cost, adjustable interlayer spacing, and high electronic conductivity. Nevertheless, the narrow interlayer spacing significantly restricts their potassium storage ability. Herein, hierarchical N, S co-doped exfoliated holey graphene (NSEHG) with ultrahigh pyridinic/pyrrolic N (90.6at.%) and large interlayer spacing (0.423nm) is prepared through micro-explosion assisted thermal exfoliation of graphene oxide (GO). The underlying mechanism of the micro-explosive exfoliation of GO is revealed. The NSEHG electrode delivers a remarkable reversible capacity (621 mAhg-1 at 0.05 Ag-1), outstanding rate capability (155 mAhg-1 at 10 Ag-1), and robust cyclic stability (0.005% decay per cycle after 4400 cycles at 5 Ag-1), exceeding most of the previously reported graphene anodes in K-ion batteries. In addition, the NSEHG electrode exhibits encouraging performances as anodes for Li-/Na-ion batteries. Furthermore, the assembled activated carbon||NSEHG potassium-ion hybrid capacitor can deliver an impressive energy density of 141 Whkg-1 and stable cycling performance with 96.1% capacitance retention after 4000 cycles at 1 Ag-1. This work can offer helpful fundamental insights into design and scalable fabrication of high-performance graphene anodes for alkali metal ion batteries.

Monitoring and Law Analysis of Secondary Deformation on the Surface of Multi-Coal Seam Mining in Closed Mines

A large number of mines have been closed due to resource depletion, failure to meet safety production requirements, and other reasons. To effectively ensure the safety of the ecological environment above these closed mines along with the safety of engineering construction, it is necessary to monitor the secondary deformation of closed mines. Based on TerraSAR-X, Sentinel-1A data, and InSAR technology, this study obtained high-density secondary surface deformation data on the Jiahe Coal Mine and Pangzhuang Coal Mine in the western Xuzhou area. Combining mining geological data, we analyzed the spatiotemporal variation patterns and mechanisms of secondary deformation in multi-seam mining of closed mines. It was found that when mining multiple seams involves large interlayer spacing, the secondary deformation pattern shows a “W” shape. In this situation, the deformation can be divided into five stages: subsidence, uplift, re-subsidence, re-uplift, and relative stability. This study provides technical support for the evaluation and prevention of secondary deformation hazards in closed mines.

Optimisation of Mo doping to form NiCoMo ternary sulphides for high performance charge storage.

Multi-component synergy and the rational design of structures are effective methods for preparing electrode materials for high-performance energy storage devices. Transition metal-based hydroxides offer advantages such as a large specific surface area, large interlayer spacing, multiple redox states, and high theoretical capacity, making them commonly used as positive materials for supercapacitors. However, challenges like low conductivity and severe agglomeration limit their practical application. This study focuses on the preparation of Ni, Co, and Mo ternary transition metal hydroxides by incorporating the Mo element to optimize their structure. Furthermore, sulfide ions were utilized in an ion exchange process to replace hydroxides, resulting in the formation of NiCoMo ternary sulfide electrode materials. By adjusting the amount of Mo added, a spherical nanoneedle-shaped N2C1MS0.2-2 electrode material was successfully synthesized. This electrode exhibited a specific capacity of 2094 F g-1 at a current density of 1 A g-1. In addition, an asymmetric supercapacitor was assembled with activated carbon as the negative electrode and N2C1MS0.2-2 as the positive electrode, which had an energy density of 46.2 W h kg-1 at a power density of 800 W kg-1, a capacity retention of 89.7% and a coulombic efficiency of 97.8% after 10 000 cycles. This study provides a reference for the design and preparation of ternary sulphide electrode materials.

Engineering VOx structure by integrating oxygen vacancies for improved zinc-ion storage based on cation-doping regulation with electric density.

Aqueous zinc-ion batteries (ZIBs) have attracted enormous attention for future energy-storage devices owing to their high theoretical capacity and environmental friendliness. However, obtaining cathodes with a high specific capacity and fast reaction kinetics remains a huge challenge. Herein, Cu-VOx material with a thin sheet microsphere structure composed of nanoparticles was prepared by a simple hydrothermal reaction, which improved reaction kinetics and specific capacity. Pre-embedding Cu2+ into V2O5 to introduce abundant oxygen vacancies extended the interlayer distance to 1.16 nm, weakened the effect of the V-O bonds, and improved the electrical conductivity and structural stability. At the same time, the influence of different valence metal ions (M = K+, Cu2+, Fe3+, Sn4+, Nb5+, and W6+) pre-embedded in V2O5 was studied. Benefiting from a large interlayer spacing, high electrical conductivity, and excellent structural stability, the Cu-VOx electrode demonstrated a high specific capacity of 455.9 mA h g-1 at 0.1 A g-1. Importantly, when the current density was increased to 6 A g-1, the Cu-VOx electrode still achieved a high specific capacity of 178.8 mA h g-1 and maintained a high capacity retention of 76.5% over 2000 cycles.

Impact resistance of polyurethane elastomer enhanced by organic montmorillonite with interlayer anchored polymer chains

AbstractThe development of materials with excellent impact resistance is essential for safety protection. Polyurethane elastomer (PUE) is widely used in impact protection; however, it has low dynamic compressive strength and poor energy absorption efficiency under high‐speed impact, limiting its in‐depth application in the protection field. Herein, an organic montmorillonite (MMT) with interlayer anchored polymer chains, named M@NH3+, was synthesized via the dual modification of MMT involving surface grafting and cation intercalation by macromolecular amino silane, which was used to enhance the impact resistance of PUE. Based on the uniform dispersion of M@NH3+ within the PUE matrix, the strong bonding at the polymer‐filler interface and the synergistic action between M@NH3+ lamellae, PUE‐M@NH3+ composite exhibited excellent mechanical properties and energy absorption capacity. Compared with pure PUE, the elastic modulus (+98.3%), static compressive strength (+37.0%), dynamic compressive strength (+35.4%) and impact energy absorption (+50.8%) of PUE‐2wt%M@NH3+ were significantly improved, which shows that it has potential applications in the field of high‐speed impact protection.Highlights Organic MMT with interlayer anchored polymer chains was prepared. The large interlayer spacing of M@NH3+ facilitates its dispersion within the matrix. The interconnected M@NH3+ lamellae can collaboratively disperse impact stress. The impact energy absorption of PUE composite has been remarkably improved.

Coal-derived flaky hard carbon with fast Na+ transport kinetic as advanced anode material for sodium-ion batteries

Hard carbon (HC) has demonstrated a significant potential in anode for sodium-ion batteries (SIBs) due to its superior electrochemical properties. Coal is considered a promising hard carbon precursor due to its high carbon yield. However, the widespread adoption of coal-derived HC faces challenges such as limited storage capacity and decreased rate performance, primarily attributed to the dense structure of coal. In this study, a molten salt-assisted approach was developed to adjust the microstructure of coal-derived HC. The dense coal is etched into a flaky structure by molten salt, which is conducive to the diffusion and transport of sodium ions. The optimized HC materials possess large interlayer spacing and abundant pseudo-graphitic domains, exhibiting a remarkable reversible capacity of 303.6 mA h g−1 at 30 mA g−1 and 82.1 mA h g−1 at 500 mA g−1. Besides, a full cell with the configuration of as-prepared coal derived HC versus Na3V2(PO4)2O2F (NVPOF) is presented with a high initial coulombic efficiency of 76.15 % and capacity of 100.7 mA h g−1. The results indicate that our synthesis strategy is feasible for the application of coal derived carbon materials in SIBs.