Graphene Anode Research Articles

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.

(Invited) Structural Lithium-Ion Battery Based on LiFePO4/Reduced Graphene Oxide Composite Cathode and Graphene Anode Prepared via Electrophoretic Deposition on Carbon Cloth

Structural lithium-ion batteries based on binder-free LiFePO4/reduced graphene oxide composite cathode electrode and graphene anode electrode are prepared respectively via electrophoretic co-deposition of LiFePO4, reduced graphene oxide, and carbon black on carbon cloth substrate for the cathode, and graphene oxide and carbon black on carbon cloth substrate for the anode. Following deposition, the electrode materials were dried. The graphene oxide of the anode was reduced to graphene via rapid thermal annealing. Possessing excellent stiffness, strength-to-weight ratio, and good electrical conductivity, the carbon cloth substrate serves multifunctional roles in the battery: as structural reinforcement and mechanical load bearing element and as current collector. Given its good electrical conductivity, high aspect ratio, and high surface area, reduced graphene oxide improves electrical conductivity within the cathode and provides sites for hosting LiFePO4; this enhances reversible Li ion extraction from the host during cycling. Graphene with its good electrical conductivity and high aspect ratio provides sites for insertion of Li ions in the anode; this enhances the aerial lithiation capacity of the battery system. Carbon black enhances conductivity within the two electrodes and reduces interfacial impedance. The electrochemical properties of the electrodes are strongly correlated to their microstructure and phase composition. Electrochemical characterization of the electrodes and their performance in half-cell and full cell configurations are evaluated. Additionally, Li-ion diffusivity within the materials is evaluated with three independent electroanalytical methods, including potentiostatic and galvanostatic and intermittent titration techniques, and electrochemical impedance spectroscopy.

Optimizing Graphene Anode Performance in Lithium‐Ion Batteries: Investigating the Effects of Diverse Thermal Conditions

Herein, the graphene nanoplatelets (GNPs) anode is prepared using a facile, chemical‐free, and scalable approach that combines probe sonication and microwave treatment in an argon condition. The resulting GNPs exhibit a significant number of structural defects (ID/IG: 0.262), which provide abundant active sites to store lithium ions and offer sufficient pathways for the quick transfer of lithium ions and electrons. In lithium‐ion batteries (LIBs), the GNPs anode exhibits an outstanding electrochemical performance, achieving a high reversible 414 mAh g−1 capacity at the high current density of 1 A g−1 after 350 cycles. The anode maintains desirable capacities of 167 and 150 mAh g−1 even at elevated current densities of 4 and 5 A g−1, respectively. Importantly, it exhibits remarkable cycling performance with more than 100% of the initial reversible capacity retention after 350 cycles. The outcomes show noticeably enhanced performance characteristics, suggesting the potential for developing microwave‐treated graphene anode for long‐lasting and high‐performance LIBs.

Interfacial engineering in SnO2-embedded graphene anode materials for high performance lithium-ion batteries

Tin dioxide is regarded as an alternative anode material rather than graphite due to its high theoretical specific capacity. Modification with carbon is a typical strategy to mitigate the volume expansion effect of SnO2 during the charge process. Strengthening the interface bonding is crucial for improving the electrochemical performance of SnO2/C composites. Here, SnO2-embedded reduced graphene oxide (rGO) composite with a low graphene content of approximately 5 wt.% was in situ synthesized via a cetyltrimethylammonium bromide (CTAB)-assisted hydrothermal method. The structural integrity of the SnO2/rGO composite is significantly improved by optimizing the Sn–O–C electronic structure with CTAB, resulting a reversible capacity of 598 mAh g−1 after 200 cycles at a current density of 1 A g−1. CTAB-assisted synthesis enhances the rate performance and cyclic stability of tin dioxide/graphene composites, and boosts their application as the anode materials for the next-generation lithium-ion batteries.

High-performance asymmetric pseudocapacitor based on NiCo2O4@MnO2 cathode and N-doped graphene anode

The design and fabrication of scalable energy storage systems are crucial for portable applications, demanding advanced materials through large-scale and facile processing. In this report, an asymmetric solid-state pseudocapacitor (ASPC) is assembled using a core–shell NiCo2O4@MnO2 composite and solution-processed nitrogen-doped graphene (N-GP) as the positive and negative electrodes, respectively. With interconnected porous structures, the electrodes based on N-GP and NiCo2O4@MnO2 offer high specific capacitance and rate capability, broad operation voltage, and a binder-free design with no added conductive agent. With these benefits, the ASPC with a PVA-KOH electrolyte exhibits a specific capacitance of 103.3F g−1 at 1 A/g and exceptional energy density of 36.73 Wh kg−1 at a power density of 792 W kg−1. In addition, the specific capacitance retention reaches 90.9 % after 5000 cycles, indicating excellent cycling stability. In the broader context of solid-state supercapacitors based on solution-processed graphene, this ASPC exhibits highly competitive performance, establishing it as a promising candidate for advanced energy storage.

The application of graphene material in the negative electrode of lithium battery

With the development of science and technology, the massive consumption of traditional fossil fuels not only brings serious environmental pollution but also causes an energy crisis. As an indispensable new energy in today’s world, Lithium batteries have many advantages that other types of batteries do not have, such as high energy density, long life, low self-discharge rate advantages, green and environmental protection, etc., and widely used in various fields, such as automotive, medical, aerospace and so on. However, the drawbacks such as low specific capacity and high side reaction of graphite material in traditional lithium batteries limit the application of lithium batteries. Graphene, as a two-dimensional material composed of carbon atoms in a single layer thickness, possesses the advantages of huge surface area, high strength and hardness, good electrical and thermal conductivity, flexibility, and transparency, and has great potential for application in lithium batteries. In this paper, for graphene as the anode material of lithium batteries, its effects on the performance of lithium batteries, including cycling performance, charge/discharge rate, and energy density, are discussed respectively. In addition, this paper also summarizes the latest progress on the application of graphene anode materials in lithium batteries.

Natural tea polyphenol functionalized graphene anode for simultaneous power production and degradation of methyl orange dye in microbial fuel cells.

The microbial fuel cell (MFCs) has dual functions, capable of achieving dye decolorization and synchronous power generation. Despite these advantages, the MFCs have faced challenges related to low electron transfer efficiencies and limited dye treatment capacity in wastewater applications. This work introduces an innovative approach by employing reduced graphene oxide-modified carbon cloth (TP-RGO@CC) anodes, utilizing tea polyphenols as the reducing agent. This modification significantly enhances the hydrophilicity and biocompatibility of the anodes. The MFC equipped with the TP-RGO@CC anode demonstrated a remarkable increase in the maximum power density, reaching 773.9 mW m-2, representing a 22% improvement over the plain carbon cloth electrode. The decolorization rate of methyl orange (50 mg L-1, pH 7) reached 99% within 48 h. Biodiversity analysis revealed that the TP-RGO@CC anode selectively enriched electrogens producing and organic matter-degrading bacteria, promoting a dual mechanism of dye decolorization, degradation, and simultaneous electro-production at the anode. This work highlights advanced anode materials that excel in effective pollutant removal, energy conversion, and biomass reuse.

Electrochemical Synthesis of Nano-Structured Si and Graphene Composite for Li Ion Battery

The application of lithium-ion batteries is widespread across a variety of sectors, such as portable electronic gadgets, mobile phones, new electric car batteries, and many others. Silicon–Graphene (SiG) anodes are among the sophisticated anode materials that have been used in lithium-ion batteries. These anodes have been widely researched because of their high capacity, strong operating potential, environmental friendliness and great abundance. SiG anodes have shown a lot of promise as a potential anode material for lithium-ion batteries [1]. This is due to the fact that they have solved many issues that were present in Si anodes, including particle pulverization, shedding and failures of electrochemical performance during lithiation and delithiation. Nevertheless, there are still certain issues that need to be improved, such as low initial discharge efficiency, poor conductivity and poor cycle performance. This research focuses on presenting a unique approach that may be used to address the issues associated with Si anode materials. An electrodeposition method that only needs a single unit operation, is applied in the process of constructing composites of SiG from G-1M SiCl4 in [BMIm]Tf2N ionic liquid (IL) [2]. In SiG composites, both silicon and graphene have been seen to have a layered structure (Fig.1 a). The SiG anode displays a specific charge/discharge capacity of 1133/ 2272 mAhg-1 at the first cycle and it drops to 676/ 737 mAhg-1 at the conclusion of 100 cycle at 0.2C (Fig.1b), which demonstrates a robust cycle ability at a moderate rate. The present work will thus discuss on the development of SiG composite by electrochemical method for its utility as negative electrode material in Li ion battery.

Cost-Effective Milled Silicon and Exfoliated Graphene Anode for High-Performance Li-Ion Batteries

Lithium-ion batteries play a significant role in modern electronics and electric vehicles. However, current lithium-ion battery chemistries are unable to satisfy the increasingly heightened expectations regarding energy demand and reliability. To boost the overall energy density while ensuring the safety of Li batteries, researchers have focused on developing the battery materials [1]. Silicon has an ultrahigh theoretical capacity and has been regarded as the best choice for next-generation lithium-ion battery anodes, but it also suffers from dramatic expansion during cycling [2]. Hence mitigating volume expansion is one of the main challenges towards developing a successful Si based anodes. Herein, a facile air-controlled electrospray method to directly deposit silicon/graphene (Si/Gr) onto current collectors was described. This method is inspired by an electrospinning process and possesses all the advantages that electrospinning has such as low cost, easy scaling up, and simultaneous solvent evaporation during the spraying process. Cost-effective silicon/graphene (Si/Gr) composite electrodes have been investigated for the multiple benefits of Gr in providing mechanical integrity to buffer the silicon volume expansion while maintaining electronic contact with Si to provide a Li-ion transport pathway and to form a uniform solid electrolyte interface (SEI) layer. Our results revealed a superior battery performance including a capacity of 1000 mAh/g at 2C rates and minor capacity loss during long cycling. The details of synthesis, characterization, and lithium-ion battery results of the hybrid anodes will be presented.

Investigation of Heteroatom Doped Graphene Anode for High-Capacity Alkali Metal-Ion Batteries

The drastic growth of Li-ion batteries (LIBs) in global electronic market and low crustal abundance of Li demands for more abundant alternatives such as sodium and potassium having similar electrochemical properties. Sodium-ion battery (SIB) and potassium-ion battery (PIB) can be used “side-by-side” to LIB which can help battery technology progress efficiently. 1Graphite has been a commercial anode in LIB due to its low cost, high abundance, high electrical conductivity, with a theoretical storage capacity (LiC6) of 372 mAh g-1. In contrast the utilization of graphite in SIBs and PIBs is challenging. This is due to the large radius and unstable graphite-intercalation compounds (NaC64) giving very low theoretical capacity of 30 mAh g-1. In PIBs, graphite exhibits a theoretical capacity of 279 mAh g-1 but suffers from poor stability due to huge volume expansion (60%) in fully potassiated state (KC8). Thus, focus is now shifted on to class of amorphous carbon materials such as hard carbon, soft carbon, graphene etc. with variations in micro-structures, larger interlayer spacing, and defect rich sites promoting enhanced capacity and stability even at high current densities. 2 In my presentation I will be discussing about the synthesis of heteroatom doped graphene with high charge storage and stability for LIB, SIB and PIB compared to graphite. The heteroatom doped graphene exhibits nearly 1000 mAh g-1 (LIB), 380 mAh g-1 (SIB) and 379 mAh g-1 (PIB) at a low current density of 25 mAg-1. Additionally, the elastic nature of ultrathin graphene nanosheets aids in attaining long term cyclability at 1 A g-1 with high-capacity retention of 83% for 300 cycles (LIB), 73% for 400 cycles (SIB) and 91% for 600 cycles (PIB). The enhanced stability in case of PIB, is attributed to optimizing solid electrolyte interphase (SEI) components and improving interfacial reaction kinetics at high current densities. Choice of high concentrated electrolyte (HCE) over conventional KPF6 in EC:DEC determines the nature of SEI and thereby helps in achieving cycling stability. The stability in SEI is characterized via voltage profile and understanding chemical composition by ex-situ X-ray photoelectron spectroscopy. Robust SEI in HCE is due to difference in anion structure studied by Raman spectroscopy.Furthermore, the charge-discharge mechanism, alkali ion diffusion kinetics and structure-activity relationship of electrode materials was investigated using various techniques like cyclic voltammetry profiles at different scan rates and Galvanostatic intermittent titration technique (GITT). Additionally, deeper insights into the fundamental understanding of interfacial and bulk behavior were provided with the help of in-situ Raman spectroscopy and in-situ potentiostatic electrochemical impedance spectroscopy (PEIS) analysis. The investigation of peak area and shift in D (defect) and G (graphitic) band analyzed from in-situ Raman studies helped in understanding the evolution and reversibility of alkali ion storage behavior during charging and discharging. PEIS analysis gave us a thorough understanding of the evolution of stable SEI on charging-discharging and after cycling, which helps us to understand the long-term stability in LIB, SIB and PIB.

Crumpled graphene with graded interlayer spacing for high-rate Na+ storage

In electrode preparation, graphene-based electrodes usually form a uniaxially oriented stacking structure, which limits the Na+ diffusion in graphene electrodes for sodium-ion batteries (SIBs). In this work, a crumpled graphene (CG) anode with graded interlayer spacings was synthesized, and CG exhibits high-rate performance for SIBs. The CG has a folding microstructure like a paper clip that facilitates rapid adsorption/desorption of Na+ on its surface so that the diffusion kinetics of Na+ could be improved. The x-ray absorption fine structure and transmission electron microscope proved the mechanism of Na+ co-adsorption and explained the reason for its high-rate performance. When the three-dimensional CG is used as the anode of SIBs, it has a high-rate performance of 146 mAh g−1 with the current density increasing to 1 A g−1, and CG still maintained about 79 mAh g−1 after 1000 cycles at 0.5 A g−1 with good structural stability.

Advancements in anode and cathode nanomaterials for high-performance Li-ion batteries

Commercially, lithium-ion batteries are the most popular batteries for electric devices, while energy density and stability have become more important for electric vehicles. Therefore, there is an increased interest in producing advanced lithium-ion batteries with a greater range of electric storage capability and improved electron transfer efficiency. Over the past few years, nanotechnology has been widely applied to enhance the physical properties of materials through the application of surface treatments or the modification of nanostructures. The significant development potential of nanotechnic applications for lithium-ion batteries is the reason for this discussion. There have been several advancements in graphene, carbon nanotubes, silicon-based and other metal-based anodes, lithium cobalt oxide, lithium iron phosphate, and nickel-based cathodes, their fabrication processes and understanding of mechanisms, as well as trends for further improvement of those previously discovered. These advancements have led to the development of batteries with greater capacity and greater performance, better stability, quicker charging times, and a longer cycle life.

A Promising Approach towards the Commercialization of Lithium Sulfur Batteries: Prelithiated Graphene

AbstractLithium‐sulfur (Li‐S) batteries are a promising candidate technology for high‐energy rechargeable batteries due to their advantages of abundant materials and inherently high energy. However, the practical applications of Li‐S batteries are challenged by several obstacles, including the low sulfur utilization and poor lifespan, which are partly attributed to the shuttle of lithium polysulfides and lithium dendrite growth during cycling.[1] The shuttling of polysulfide ions between the electrodes in a Li‐S battery is a major technical issue triggering the self‐discharge and limiting the cycle life.[2] A stable lithium anode is essential for maintaining the good cycle stability of Li‐S batteries in practical applications.[3] To address these lithium related issues, various carbon materials, including graphite and graphene, have been investigated as suitable lithium hosts to use as anode materials for Li‐S batteries.[4] In this study, prelithiated graphite and graphene‐based anode materials are obtained by galvanostatic charging method to improve the performance of Li‐S batteries and compare the electrochemical properties especially in terms of capacity retention and rate capability. According to the results, graphene showed better performance due to its high lithium storage capacity and fast lithium‐ion diffusion rate. Inductively Coupled Plasma Emission Spectrometer (ICP‐OES) results showed that the Li+ content of the graphite, graphite/graphene, and graphene electrodes measured as 26.5, 33.2, and 45.6 wt%, respectively after the lithiation process. 1 Ah pouch cell was assembled with prelithiated graphene anode showing an energy density of about 400 Wh kg−1 in the first cycle and protected its specific capacity of 60 % after 100 cycles in a liquid‐based Li‐S battery system.

Highly Pseudocapacitive Storage Design Principles of Heteroatom‐Doped Graphene Anode in Calcium‐Ion Batteries

AbstractPseudocapacitive storage of multivalent ions, especially Ca2+, in heteroatom‐doped carbon nanomaterials is promising to achieve both high energy and power densities, but there is the lack of pseudocapacitive theories that enable rational design of the materials for calcium‐ion batteries. Herein, the general design principles are established for the anode materials of the batteries via density functional theory calculations and experimental verifications of a series of heteroatom‐doped graphene as an efficient pseudocapacitive anode. A novel descriptor Φ is proposed to correlate the intrinsic properties of dopants with the pseudocapacitive storage properties of the carbon‐based anode. The design principle and descriptor have the predictive ability to screen out the best dual‐doped graphene anode with 10 times higher Ca2+ storage capability than that of sole‐doped one, and exceed the current best Ca2+ storage anode materials.

Catalytic synthesis of 3D graphene nanostructures from biomass-based activated carbon with excellent lithium storage performance

3D multilayer graphene anode materials have shown great potential for energy storage devices due to their extraordinary structural stability combined with unique electrochemical characteristics. Herein, a facile strategy is proposed to synthesize 3D multilayer graphene nanostructures (M-GNS, M refers to graphitization catalyst) via microwave catalytic graphitization incorporated with liquid oxidation and thermal reduction using biomass-based activated carbon. The role of various graphitization catalysts on the characteristics and lithium storage performance of GNS were systematically investigated. Transmission electron microscopy results show that the use of Co led to the formation of multilayer graphene nanostructures with lower thickness compared to Ni and Fe. Various characterization techniques showed that the degree of graphitization in Co-graphitized activated carbon was lower, and the sample was dominated by smaller graphitic structures. When used as lithium-ion battery anode material, Co-GNS delivered superior rate capability (357 mAhg−1 at 5 Ag−1 after 1000 cycles with a capacity retention of ~94 %), and ultrahigh charge capacity (1695 mAhg−1 at 0.1 Ag−1), mainly owing to its thinner multilayer nanostructure.

A new type of morphological instability in Sn/2D graphene anodes

A new type of morphological instability in Sn/2D graphene anodes

Synthesis and characterization of CNT@SnO2 decorated graphene anodes for Li-ion batteries as free-standing and flexible

Synthesis and characterization of CNT@SnO2 decorated graphene anodes for Li-ion batteries as free-standing and flexible

Work function tuning of directly grown graphene via ultraviolet–ozone treatment for electrode application in organic photovoltaic devices

Graphene is an efficient electrode material for flexible optoelectronic devices because of its high transmittance and electrical conductivity. A graphene film directly grown using plasma-enhanced chemical vapor deposition is suitable for electrode applications because it can be prepared on a glass substrate at relatively low temperatures without a transfer process from a metal catalyst. However, to obtain efficient optoelectronic devices using graphene electrodes, surface modification is necessary. Herein, we tuned the work function of a graphene electrode using ultraviolet (UV)-O3 treatment. The power conversion efficiency of organic photovoltaic devices was significantly increased by the UV-O3 treatment of the graphene anode. To investigate the origin of the improved device performance, the interface between the graphene anode and tetraphenyldibenzoperiflanthene (DBP) donor layer was analyzed via in situ ultraviolet photoelectron spectroscopy. The energy offset between the Fermi level of graphene and the highest occupied molecular orbital level of DBP was significantly reduced because of the increased work function. The results indicate that the electronic structure modification of graphene is of significant importance for fabricating efficient optoelectronic devices.

Reconfiguration of the electronic structure of metal phosphide for ultrahigh energy density hybrid supercapacitors

Nanostructured mixed transition metal phosphides are promising battery-type materials for supercapacitor applications due to their advantageous morphology and electronic properties. In the present study, we constructed a porous NiFeP/MoO2@Co3O4 core–shell heterostructure grown on nickel foam using a hydrothermal route, phosphorization treatment and atomic layer deposition. The resulting NiFeP/MoO2@Co3O4 cuboids were characterized by a lower charge transfer resistance, rich electroactive sites and shorter ion diffusion paths for redox reactions. It is discovered that the excellent supercapacitive performance of NiFeP/MoO2@Co3O4 cuboids was obtained not only because of the rich active sites via the formation of multiple components but also due to the strong electronic interaction between Co and Ni/Fe/Mo species. Benefiting from the rich active sites of NiFeP, the designed NiFeP/MoO2@Co3O4 exhibited a specific capacity of 1531.1 C g−1 and a high durability, with a retention rate of 90.8% after 20,000 cycles, outperforming previously reported metal-phosphide-based materials. A hybrid device was also constructed with a NiFeP/MoO2@Co3O4 cathode and a graphene anode, delivering a maximum energy density of 71.3 W h kg−1 at a power density of 2100.3 W kg−1 with exceptional capacity retention after 10,000 cycles. These results suggest that the proposed novel strategy has great potential for the improvement of smart nanostructures for advanced supercapacitors.

High-Capacitance γ-rGO/MXene Cathode and Rapid Na+-Transfer Dynamics Sodium Titanate Anode for a Quasi-Solid-State Sodium-Ion Capacitor

Sodium-ion capacitors (SICs) bear the advantages of secondary batteries and supercapacitors and are regarded as promising energy-storage devices. However, the matching of the respective Na+-transfer kinetics of the anode and the cathode and the low energy density are still a challenge. Herein, to achieve a high-capacity cathode, 2D V2C MXene nanosheets were introduced into γ-ray-reduced graphene oxide (γ-rGO), and the γ-rGO/V2C MXene foam (GMF) was fabricated. The GMF provides a high specific capacitance of 391.4 mF cm–2 (130.5 F g–1) at a high current density of 60 mA cm–2 (20 A g–1). Meanwhile, the structure-directing strategy combining multiple nanocarbon composites accelerates the Na+-transfer kinetics of sodium titanate (NTO). The as-fabricated CNT film-supported sodium titanate nanowires encapsulated by the graphene (CNTF@NTO-G) anode deliver a specific capacity of 109 mA h g–1 at a high current density of 10 A g–1. As a result, the assembled quasi-solid-state SIC displays an energy density of 5.61 mW h cm–3 (56.1 W h kg–1) at a power density of 1 W cm–3 (10 kW kg–1) with excellent cycle stability (87.3% capacitance retention after 10,000 cycles).