High Graphite Research Articles

Binder-Free Flexible Chickpea Pod Derived Activated Carbon-Carbon Nanofiber Composite for Supercapacitor Application

In the present study, a novel carbon-carbon composite electrode was prepared by embedding activated carbon derived from chickpea pods and evaluated its potential as an electrode for supercapacitors. A simple, single-step electrospinning technique was used for the synthesis of activated carbon-carbon nanofiber composite. The synthesized activated carbon-carbon nanofiber composite electrode is flexible and binder-free with high specific surface area, micro and mesopores, interconnected fiber-to-flake morphology and possess high graphitization. Additionally, rapid electrolyte diffusion has resulted in a low charge transfer resistance due to interconnected morphology. In 6 M KOH electrolyte, composite binder-free electrode shows a specific capacitance of 147 F g−1 at 0.5 A g−1 compared to activated carbon (AC) electrodes that showed a specific capacitance of 120 F g−1 at 0.5 A g−1. It exhibits an energy density of 13 Wh k g−1 at 0.366 W k g−1 power density. It also showed impressive cyclic stability by retaining 93.5% of initial capacitance till 1200 cycles at 1 A g−1. Overall, the study presents an easy-to-use, low-cost, eco-friendly, and flexible electrode for supercapacitors that is free of binder.

Altering Coconut Shell Biomass to High-Ordered Graphitic Carbon with Nickel Catalyzation

Graphite is a carbon-based material potentially utilized in numerous applications, such as electrodes for supercapacitors, lithium-ion batteries, and absorbers for water treatment. Biomass graphite is a beneficial candidate for low-cost yet valuable graphite. In this work, coconut shells, the abundant materials with high carbon contents, were successfully transformed into valuable coconut shell graphite (CSG) using metal catalytic graphitization with nickel as a catalyst at low-temperature conditions of ~1200 °C. Nickel concentration varied between 2 mmol, 3 mmol, and 5 mmol per gram of carbon. The samples were further examined using X-ray diffraction (XRD), Raman Spectroscopy, and Transmission Electron Microscope (TEM). The high graphitization degree of ~ 72 % was confirmed by X-ray diffraction analysis. That was further supported by the high-ordered stacking carbon layer that appeared in HR-TEM images. Meanwhile, Raman spectroscopy confirms that nickel impregnation diminished the structural defect of samples and increased the sp2-carbon bond indicated by its rise of IG/ID. The IG/ID values of CGS and CGS-Ni5mmol are 0.86 and 0.92, respectively.

Heteroatom-doped and graphitization-enhanced lignin-derived hierarchically porous carbon via facile assembly of lignin-Fe coordination for high-voltage symmetric supercapacitors

Lignin-derived carbon materials are widely used as electrode materials for supercapacitors. However, the electrochemical performance of these materials is limited by the surface chemistry and pore structure characteristics. Herein, a novel and sustainable strategy was proposed to prepare heteroatom-doped lignin-derived carbon material (Fe-NLC) with well-developed pore size distributions and enhanced graphitization structure via a facile lignin-Fe coordination method followed by carbonization. During carbonization, Fe3+ in lignin-metal complexes evolve into nanoparticles, which act as templates to introduce porous structures in carbon materials. Also, the lignin-Fe coordination structure endows the material with a higher graphitization during carbonization, thereby improving the structural properties of the carbon materials. Due to the removal of Fe3O4 template, the obtained Fe-NLC possessed reasonable pore distribution and nitrigen/oxygen (N/O) functional groups, which can improve the wettability of materials and introduce pseudocapacitance. Accordingly, Fe-NLC possesses a notable specific capacitance of 264 F/g at 0.5 A/g. Furthermore, a symmetric supercapacitor Fe-NLC//Fe-NLC with a high voltage window (1.8 V) was constructed. The symmetric supercapacitor exhibits a maximum energy density of 15.97 Wh/kg at 450 W/kg, demonstrating well application prospects. This paper proposes a novel approach for preparing carbon materials via lignin-metal coordination to provide an alternative way to explore sustainable and low-cost energy storage materials.

New Highly Graphitized N-Doped Carbon as a Robust Support for Pt Electrocatalysts

For polymer electrolyte membrane fuel cells (PEMFCs), the state-of-the-art electrocatalysts are based on Pt group metals deposited over electroconductive porous carbon support. However, current carbon supports suffer from carbon corrosion during repeated start-stop operations, causing performance degradation. We report a new strategy to produce highly graphitized porous carbon with controllable N-doping that uses low-temperature synthesis (650 ℃) from g-C3N4 carbon-nitrogen precursor with pyrolysis using Mg. The high graphiticity is confirmed by high-intensity 2D Raman peak with low ID/IG (0.57), pronounced graphitic XRD planes, and excellent conductivity. Without further post-treatment, this highly graphitized N-doped porous carbon (GNPC) material combines high pyrrolic-N content with high porosity. Supporting Pt on GNPC exhibits excellent oxygen reduction activity for PEMFC with greatly improved durability as proved by real-time loss measurements of Pt and carbon, the first to surpass the DOE 2025 durability targets for both catalyst and support. The Pt/GNPC prepared at 650 oC shows 32 and 24% drop in mass activity after accelerated durability tests of both electrocatalyst and support, respectively, which are less than DOE target of 40% loss. The atomistic basis for this durability is explained via quantum mechanics-based molecular dynamics simulations. Interestingly, it is found that pyrrolic-N strongly interacts with Pt, making the Pt catalyst more stable during fuel cell reaction. We expect that high porosity robust graphitized materials will lead to many other novel applications for electrocatalysis with durable carbon frameworks.

Ru-Loaded Highly Graphitized Porous Carbon with High Pyrrolic-N Content for Superb Electrochemical Hydrogen Evolution

The performance of electrocatalysts is closely related to their supporting materials since their properties such as heteroatom doping, porosity, graphiticity, and electrical conductivity play a decisive role on catalyst performance. We report here the preparation of N-doped highly graphitized porous network-structured carbon (N-HGC) as a catalyst support for Ru nanoparticles (NPs) catalytically active for hydrogen evolution reaction (HER) using simple pyrolysis of g-C3N4 in the presence of Mg metal. The as-prepared N-HGC shows high graphiticity confirmed by XRD and Raman analyses, high electrical conductivity, and large surface area along with large amount of open mesopores, containing the proper amount of N doping rich with high pyrrolic-N content for homogeneous distribution of Ru NPs. This Ru/N-HGC catalyst shows a remarkably low overpotential of 9.6 mV (vs RHE) at 10 mA/cm2, which is near ideal and far better than state-of-the-art Pt/C. It also illustrates superb stability, maintaining the HER activity for 200 h and 10k CV cycles without any significant degradation. This superb HER performance is attributed to the robust N-HGC support featuring thin carbon structure, high electrical conductivity, suitable porosity, and N pyrrolic doping. The atomistic basis for the low overpotential is explained via Grand Canonical Quantum Mechanics (GC-QM) calculations. These calculations show that the pyrrolic-N in the support strengthens the coupling to Ru NP and weakens the binding of H to Ru NP, improving the rate determining Tafel reaction.

Hydrophobic Conductive Coatings for Fuel Cell Gas Diffusion Layers

Mass transfer of the reactant gases, water management, thermal and electrical conductivity are all highly depending on the properties of the gas diffusion layer (GDL) in polymer electrolyte fuel cells (PEFCs). GDLs are produced in complex and energy demanding processes including high temperature graphitization and are modified using polytetrafluoroethylene (PTFE) to introduce the hydrophobicity needed to efficiently remove water [1]. PTFE is, however, negatively impacts the required electrical conductivity and is facing an uncertain future with the pending restrictions on the use of perfluoroalkyl substances (PFAS) [2], [3]. Therefore, we have investigated the use of electrically conductive polyaniline (PANI) coatings on carbon fiber substrates with modifications to increase hydrophobicity. As substrate, AvCarb carbon paper EP40 was used and PTFE treated EP40T was used as state-of-the-art reference. EP40 was coated through dip-coating or electro-coating using PANI modified with sodium dodecylbenzenesulphonate as additive to adjust hydrophobicity [4]. With this approach, we have been able to show comparable pore volumes and pore surface areas (Figure 1) through mercury porosimetry as well as comparable hydrophobic properties.

Activated Vacuum Residue for Efficient Oxygen Reduction Reaction in Alkaline Media

As a potential replacement for Pt-based materials, the heteroatom-doped and metal-free porous carbons have always been a crucial challenge in modern electrocatalysis. On the other hand, petroleum waste, particularly, vacuum residue presents as a carbon-rich precursor for the development of porous carbons for electrocatalysis. Herein, the new catalysts were prepared from vacuum residue gained from the local petroleum industry. The porous carbons (PCs) as the catalysts were prepared via a simple single route activation at 800 °C and 2 hours in the presence of phosphoric acid. PC possesses a high surface area at ~2200 m2/g with mixed micro- and meso porosities as well as high graphitization content. Spectroscopic analyses reveal up to ~6 % of phosphorous doping content. PCs were tested against oxygen reduction reaction (ORR) as an important challenge in electrochemistry. The structural features and the differences in the activating agents for the development of the PCs were compared to decipher the importance of the doped heteroatoms’ environment in ORR. The ORR efficiency of the electrocatalysts was compared against the commercial 5% Pt/C under alkaline conditions to show the potential of the vacuum residue-derived PCs as the sustainable utilization of petroleum waste.

Porous carbon materials augmented with heteroatoms derived from hyperbranched biobased benzoxazine resins for enhanced CO2 adsorption and exceptional supercapacitor performance

Porous carbon materials doped with heteroatoms are an excellent alternative for applications in CO2 adsorption and supercapacitors. Herein, we present a new approach to obtain heteroatoms (N, O, and S) doped porous carbon materials using bio-based hyperbranched benzoxazine (RES-HP-BZ) as a precursor. Two types of porous carbon materials, poly(RES-HP-BZ)-700 and poly(RES-HP-BZ)-800, were synthesized through a simple calcination method by carbonization and KOH activation of benzoxazine at temperatures of 700 °C and 800 °C, respectively. The chemical structure, texture properties, and surface chemistry characteristics were validated through FTIR, NMR, SEM, XRD, and XPS, respectively. The resulting poly(RES-HP-BZ)-800 exhibited micro and meso porous characteristics with a high SBET of 841 m2 g−1, pore size of 1.14 nm, and pore volume of 0.70 cm3 g−1. The poly(RES-HP-BZ)-800 also showed a high graphitization degree and electrochemically energetic N-6, N-5, N-Q, O-2, and O-3 heteroatoms, which led to a high capacitance of 523 F g−1 (at 0.5 A g−1) as well as CO2 capture of 4.63 mmol g−1 at 298 K. These newly developed bio-based porous carbons derived from hyperbranched bio-benzoxazine with excellent electrochemical performance make them a promising candidate for eco-friendly supercapacitors.

Electrical Resistance, Stability and Mechanical Properties of PVC Composites Containing Graphite and Semiconductor for Sensor Technologies

This study aimed to obtain a new flexible poly vinyl chloride (PVC) based composite with conductive or semiconductor properties. Additives were graphite and semiconductor zinc oxide (ZnO). A non-ionic surfactant was also firstly used to obtain a homogeneous composite. For the characterization of these new composites; humidification, electrostatic discharge (ESD), electrical resistance, thermal shock measurements, tensile test and morphological and microscopic (SEM) measurements were performed. For the light test, a “Solar simulator” with a 1000 W xenon lamp was used. The electrical resistance and tensile strength of the materials were measured at each test step. According to the data obtained, it was determined that the electrical resistance of the materials with high graphite content, without ZnO, is still stable, while the electrical resistance of the ZnO-doped materials decreases and their conductivity increases considerably in special stimuli such as light. P3G2Z (32% PVC, 60% Graphite, 8% ZnO) was greater than 3 MΩ, with a large change in conductivity after electrostatic discharge, reaching 1078.33 kΩ, with the largest difference observed. It was determined that the resistance of P2G3Z and P1G1Z composite materials under solar radiation decreased approximately 81 and 23 times, respectively. This event proves that the composites become light sensitive semiconductor. As a result, the electrical and mechanical data of flexible, sensitive, conductive and semiconductor new polymers by doping PVC with graphite and ZnO nanoparticles at different rates will make a great contribution to the sensor, actuator, management system control mechanisms, and the robots used in the automotive and defense industries.

Carbon black production characteristics and mechanisms from pyrolysis of rubbers

Pyrolysis is a promising way to treat the waste tires for high value carbon black production. However, the carbon black formation mechanism is still unclear due to the complex decomposition and polymerization reactions during the pyrolysis of tire components. In this study, the production behavior, characters, and mechanism of carbon black from pyrolysis of natural rubber (NR), butadiene rubber (BR), and styrene-butadiene rubber (SBR) were investigated. The yield of carbon black was increased from 20.8%–24.4% to 47.9%–56.7% with the increase of pyrolysis temperature from 1100 to 1300°C. Although the carbon black production yield from NR was lower than that of BR and SBR at 1300°C, the graphitization degree (ID/IG = 2.22), microcrystal length (3.17 nm) and mean particle diameter (90.3 nm) of the carbon black derived from NR were the highest. The volatile evolution, carbon black nucleation mechanisms were revealed by reactive force-field molecular dynamics simulations. The pyrolysis of BR and SBR generated more C2H2, C2H3⋅, long carbon-chains and cyclic molecules than NR, which probably resulted in a higher carbon black yield than NR. With few defect borders, regular stacking and wrapping of the aromatic layers, the carbon black from NR exhibited more ordered nucleation and high graphitization degree.

Iron-doped carbon nanotubes with magnetic enhanced Fe(VI) degradation of arsanilic acid and inorganic arsenic: Role of intermediate iron species and electron transfer

Arsanilic acid (p-AsA), a prevalently used feed additive, is frequently detected in environment posing a great threat to humans. Potassium ferrate (Fe(VI)) was an efficient way to tackle arsenic contamination under acid and neutral conditions. However, Fe(VI) showed a noneffective removal of p-AsA under alkaline conditions due to its oxidation capacity attenuation. Herein, a magnetic iron-doped carbon nanotubes (F-CNT) was successfully prepared and further catalyzed Fe(VI) to remove p-AsA and total As species. The Fe(VI)/F-CNT system showed an excellent capability to oxidize p-AsA and adsorb total As species over an environment-related pH range of 6–9. The high-valent iron intermediates Fe(V)/Fe(IV) and the mediated electron-transfer played a significant part in the degradation of p-AsA according to the probes/scavengers experiments and galvanic oxidation process. Moreover, the situ formed iron hydroxide oxide and F-CNT significantly improved the adsorption capacity for total As species. The electron-donating groups (semiquinone and hydroquinone) and high graphitization of F-CNT were responsible for activating Fe(VI) based on the analysis of X-ray photoelectron spectroscopy (XPS). Density functional theory calculations and the detected degradation products both indicated that the amino group and the C–As bond of p-AsA were main reactive sites. Notably, Fe(VI)/F-CNT system was resistant to the interference from Cl−, SO42−, and HCO3−, and could effectively remove p-AsA and total As species even in the presence of complex water matrix. In summary, this work proposed an efficient method to use Fe(VI) for degrading pollutants under alkaline conditions and explore a new technology for livestock wastewater advanced treatment.

Tuning electrolyte solvation structure with Co-solvent engineering to enable highly reversible and stable Zn-graphite dual-ion batteries

Graphite-based dual-ion batteries (GDIBs) have attracted ever-growing attentions due to its non-transition metal configuration and high working potential. However, the safety concerns associated with the use of organic electrolyte make it unpractical for large-scale energy storage system. Moreover, the anodic limit of aqueous electrolytes, even the improved anodic limit derived from highly concentrated aqueous electrolytes, is not sufficient to support high graphite intercalation voltage. Herein, a co-solvent-induced hybrid aqueous/non-aqueous electrolyte has been proposed to break this bottleneck through regulating the solvation structures around anions. A series of hybrid electrolytes are prepared by controlling dimethyl carbonate (DMC) ratio and the relation between the solvation structures and anion intercalation chemistry is explored, indicating that the mutual interaction between solvent molecules and anions determines the anion intercalation behaviour. The optimized DMC-dominated solvation structures with a mass ratio of DMC to water of 1.2:1 significantly expand the anodic limit of electrolyte up to 2.54 V (vs. Zn/Zn2+). The as-designed Zn-Graphite batteries exhibit an excellent cyclic stability and reversibility (99 % capacity retention after 200 cycles at 200 mA g−1, nearly 98 % Coulombic efficiency). This work provides guidance to achieve the balance between security capability and electrochemical performances through controllable solvation structures.

Gas fluidization of natural graphite flakes

Demand for high purity graphite is expected to greatly increase in the coming decades. Mined graphite is purified to the final purity specification via thermal and/or chemical fluid-solid processes. As fluidized bed electro-thermal purification is a promising technology, the physical characterization and cold-flow fluidization of Canadian natural flake graphite was undertaken to better understand the gas-solid dynamics. Three commercial graphite particle batches were characterized. Mean Sauter diameters of the three particle populations measured by microscopy were 89, 63 and 51 μm. The modified sieve analysis and permeametry yielded similar mean diameters. Particle sphericities were determined to be 0.34, 0.36 and 0.40 respectively. Channelling near the surface occurred near minimum fluidization (vmf) but eventually disappeared with increasing gas velocity. This led to a partial fluidization state before achieving complete fluidization with the delay, which was observed to be up to around 3vmf, being greater for the smaller particles. Minimum fluidization velocity was determined to be 0.063, 0.028 and 0.011 m/s respectively. Complete fluidization was observed at velocities of approximately 0.070, 0.046 and 0.035 m/s respectively. Finally, wall effects due to the presence of a central electrode did not significantly impact overall fluidization characteristics.

Facile wet mechanochemistry coupled K2FeO4 activation to prepare functional coal-derived hierarchical porous carbon for supercapacitors

The high power characteristics of supercapacitors (SC) are attractive for grid scale energy storage. The core to achieve the large scale application of SC lies in the preparation of high performance electrode materials. Herein, a facile wet mechanochemistry (WMC) coupled K2FeO4 activation is used to fabricate O/N/S doped coal-derived hierarchical porous carbon (CHPC). K2FeO4 generates high-energy sputtering O2 under mechanical force to impact precursor, leading to an increase in lattice defects, and full exposure of active sites, which facilitates activation of precursor and coupling of heteroatoms. Furthermore, K2FeO4 has the pore forming ability of K-based component and the catalytic graphitization effect of Fe-based component, which could synergistically regulate pore structure and graphitization of CHPC. Experimental exploration combined with density functional theory calculation showed that the unique micro-mesopores structure of CHPC provides a fast ion transport channel and a large ion accessible specific surface area (SSSA). Meanwhile, the high heteroatom doping and graphitization synergistic promote ion storage (high adsorption energy, Eads) and electron transport. The specific capacitance (C) of optimized CHPC900 can obtain 335 F g−1 under 0.5 A g−1. The C retention is 96.2% after 10,000 cycles at 1 A g−1. CHPC900//CHPC900 delivers remarkable energy/power characteristics (9.9 Wh kg−1 of 125 W kg−1).

Gram-scale synthesis of graphene quantum dots via energetic material deflagration for bioimaging application

Graphene quantum dots, which possesses unique photoluminescence property, have received enormous attention for bio-sensor, photovoltaic devices and bioimaging application. However, synthesizing high-quality of GQDs remains a formidable obstacle in terms of the two conventional methods since the “top-down” method usually requires expensive raw materials while the “bottom-up” method suffers from incompatibility between quality and production. Thus, developing new strategies to trade-off these issues is promising for GQDs production. Here, we reported an ultrafast deflagration strategy by igniting Al and pentafluoropyridine mixture to prepare high-quality of carbon nanomaterials (CNs) with high graphitization, reaching a high yield of ∼3 g. Combining with a subsequent Hummer's exfoliation and dialyze method, the CNs materials were successfully exfoliated into the uniform-dispersed graphene quantum dots (D-GQDs) with size of 1∼2 nm. The as-prepared D-GQDs derivatives shows remarkable optical properties and it is successfully applied in fluorescence imaging of HeLa cells. Our results in this study highlighted the high efficiency of deflagration technique to prepare functional carbon-based nanomaterials, and proposed a facile and fast strategy for gram-scale synthesis.

Low temperature multi-catalytic growth and growth mechanism of carbon nanotubes on carbon fiber surfaces

In order to reduce the etching effect of the catalysts to carbon fibers caused by high temperature during the chemical vapor deposition (CVD) process, four multi-element catalysts, Fe–Co, Fe–Ni, Co–Ni and Fe–Co–Ni, were used to realize the low temperature growth of carbon nanotubes (CNTs) on carbon fibers at 350 °C–400 °C. The results show that the growth state of CNTs has a great relationship with the type of catalysts. The catalytic efficiency of Fe–Co catalysts is low, but the graphitization degree of CNTs is relatively high. The Fe–Co–Ni catalysts has high catalytic efficiency but low graphitization degree of CNTs. The tensile strength of carbon fiber/CNTs reinforcements prepared by Fe–Ni catalysts at 400 °C is the highest, reaching 3.99 GPa, which is 11.14% higher than that of desized fiber. The melt drop phenomenon of the catalysts was found by TEM, indicating the formation of the liquid phase catalysts during the growth of CNTs. This phenomenon can change the diffusion mode of carbon atoms in the catalyst and significantly reduce the growth activation energy of CNTs, so that CNTs can grow at lower temperatures. Based on the detailed analysis of the CVD process, a low temperature growth model of CNTs on carbon fibers was proposed.

Catalytic Graphitization of Biocarbon for Lithium-Ion Anodes: A Minireview.

The demand for electrochemical energy storage is increasing rapidly due to a combination of decreasing costs in renewable electricity, governmental policies promoting electrification, and a desire by the public to decrease CO2 emissions. Lithium-ion batteries are the leading form of electrochemical energy storage for electric vehicles and the electrical grid. Lithium-ion cell anodes are mostly made of graphite, which is derived from geographically constrained, non-renewable resources using energy-intensive and highly polluting processes. Thus, there is a desire to innovate technologies that utilize abundant, affordable, and renewable carbonaceous materials for the sustainable production of graphite anodes under relatively mild process conditions. This review highlights novel attempts to realize the aforementioned benefits through innovative technologies that convert biocarbon resources, including lignocellulose, into high quality graphite for use in lithium-ion anodes.

Astonishing performance improvements of dry-film graphite anode for reliable lithium-ion batteries

The electric vehicle (EV) market now requires advanced graphite anodes that can enable both high loading and quick charging. However, meeting these requirements simultaneously is challenging because of uneven electrochemical reactions and Li-plating on the surface of graphite anodes during fast-charging. In this study, high current density graphite anodes (≈6 mA cm−2) were fabricated through a solvent-free dry-electrode process using homogeneously dispersed polytetrafluoroethylene fibrils (2.0 wt% in electrode). This approach significantly improved the mechanical properties and electrochemical performance of graphite anodes during charge/discharge cycles. Dry-processed graphite anodes outperformed conventional wet-processed electrodes in terms of rate performance and capacity retention. Furthermore, LiNi0.6Co0.2Mn0.2O2 (NCM)/graphite coin-type full cells are rapidly charged at a 3C-rate to induce Li-plating on the graphite surface. Thus, dry-processed graphite anodes exhibited less Li-plating than wet-processed anodes, implying that dry-processed electrodes are capable of fast-charging even under high-loading conditions. In addition, dry-processed graphite anodes retain 88.2 % capacity retention after 300 cycles, indicating a stable full-cell operation. Consequently, this research highlights the dry-electrode process as an innovative technique for electrode manufacturing, with the potential to reduce battery production costs while improving electrochemical performance during fast-charging.

Regulation of waste-derived hierarchically porous carbon for optimizing the sulfur cathode host of Li[sbnd]S batteries

Porous carbon matrixes have been widely recognized as the simple and effective host materials for encapsulating sulfur and enhancing electronic conductivity in lithium sulfur batteries. Herein, a waste honeycomb is used to prepare in-situ N-doping hierarchically porous carbon materials by systematically regulating the simultaneous activation/carbonation temperature. The high-temperature is conducive to promoting the porous structural formation and high graphitization of carbon materials. As the increased carbonation temperature, the N-heteroatom doping content decreases and the graphitization degree increases gradually. The carbon material prepared at 900 °C shows the abundant hierarchically porous structure with high specific surface area of 1932.9 m2 g−1 and large pore volume of 1.292 cm3 g−1, hence can well accommodate the sulfur and capture the soluble polysulfides by the porous adsorption and bonding effect of in-situ doped nitrogen atoms. Besides, the improved graphitization endows the carbon material with a high electronic conductivity, boosting the fast electron transport. Due to these structural merits, the optimized porous carbon/sulfur composite cathode shows a high initial discharge capacity of 969.3 mAh g−1 at 0.2C. Even at high current rate of 1.0C, the relatively high discharge reversible capacity of 492.2 mAh g−1 is still maintained after 500 cycles.

Laser-Triggered High Graphitization of Mo2C@C: High Rate Performance and Excellent Cycling Stability as Anode of Lithium Ion Batteries.

Fast electron/ion transport and cycling stability of anode materials are key factors for achieving a high rate performance of battery materials. Herein, we successfully fabricated a carbon-coated Mo2C nanofiber (denoted as laser Mo2C@C) as the lithium ion battery anode material by laser carbonization of PAN-PMo12 (PAN = Polyacrylonitrile; PMo12 = H3PMo12O40). The highly graphitized carbon layer in laser Mo2C@C effectively protects Mo2C from agglomeration and flaking while facilitating electron transfer. As such, the laser Mo2C@C electrode displays an excellent electrochemical stability under 5 A g-1, with a capacity up to 300 mA h g-1 after 3000 cycles. Furthermore, the extended X-ray absorption fine structure results show the existence of some Mo vacancies in Mo2C@C. Density functional theory calculations further prove that such vacancies make the defective Mo2C@C composites energetically more favorable for lithium storage in comparison with the intact Mo2C.