Carbon Anode Materials Research Articles

Boosting sodium storage performance of biomass-derived porous carbon anodes by surface functionalized strategy

In order to enhance the sodium ion storage performance of biomass-derived carbon anode materials, a surface functionalization strategy was employed through a simple acid etching method on porous carbon. The resulting functionalized carbon exhibits a hierarchically porous structure, expanded interlayer spacing, and oxygen-containing functional groups. The redox reactions occurring at the surface between Na ions and carbonyl groups provide additional sites for sodium ion storage, thereby improving cycling capacity and rate capability. Theoretical calculations and electrochemical tests further demonstrate that the functionalized carbon can increase the surface-controlled sodium storage capacity by modifying the transport and adsorption processes of sodium ions. After 200 cycles at a current density of 100 mA g−1, the carbon anode, which was surface-functionalized with an etching time of 6 h, achieve a high reversible capacity of 273 mA h g−1. Furthermore, it displays improved rate performance with a capacity of 194 mA h g−1 at a high current density of 2 A g−1 for sodium-ion batteries. This study introduces an effective and general strategy for the cost-effective and large-scale synthesis of carbon anode materials for sodium-ion batteries.

Revealing sodium storage mechanism of graphitic carbons with various dimensions by a new strategy

Two kinds of graphitic carbon materials without closed pores were obtained by a new strategy in an effort to thoroughly characterize the sodium storage mechanism in the graphitic carbon anodes of sodium-ion batteries. In the first strategy, the interlayer distance is constant, but the defect concentration varies, while in the second strategy, the defect concentration is constant, but the interlayer distance varies and the graphitic crystallites are of different sizes. In situ X-ray diffraction (XRD) analysis was employed to detect the intercalation/de-intercalation process of Na+ ions in these graphitic carbon materials. The results showed that Na+ intercalation in the interlayer space proceeds in two stages at 1.0–0.5 V and 0.5–0 V, contributing to both sloping and plateau capacity profiles. Moreover, the size of the graphene layers in the graphitic crystallites exerts an effect on the slope and plateau capacities in addition to the interlayer distance and defect concentration. Furthermore, the rate performance of a graphitic anode is mainly determined by the defect content, polar groups, and surface area, rather than the interlayer distance. This is due to the influence of defects and polar groups on the diffusion coefficients of Na+ in the insertion/extraction process in the interlayer space and in the Na+ adsorption/desorption process. This work provides new insight for the design of hard carbon anode materials for high-energy-density sodium-ion batteries.

Efficient adsorption and rapid electrochemical degradation of methyl methacrylate (MMA) by three-dimensional nanostructured carbon anode

Methyl methacrylate (MMA) is a widely used oxygen-containing volatile organic compound, functioning as both an organic solvent and additive. Therefore, the advancement of effective methods for MMA removal is of great significance. In this study, three-dimensional nanostructured carbon (CNTs/CC) anode materials were prepared through the in-situ growth of carbon nanotubes (CNTs) on carbon cloth (CC) using chemical vapor deposition (CVD). The prepared material showed outstanding adsorption-electrocatalytic degradation performance towards MMA, with a saturated adsorption capacity of 2033 mg·g−1 and complete degradation achieved after 90 min of electrification at a 100 mg·L−1 MMA concentration. The electrochemically active surface area increased to 29.8 cm2 with an Rs value of 2.35 Ω for the CNTs/CC-2 anode material, leading to enhanced ·OH generation capability and faster degradation rates. The material also exhibited excellent reusability over thirteen cycles of adsorption-electrochemical degradation of MMA, with a degradation efficiency consistently above 92 %. This research provides valuable insights for developing new materials and technologies for MMA degradation.

Overview of coals as carbon anode materials for sodium-ion batteries

Abstract Energy storage is an important technology in achieving carbon-neutrality goals. Compared with lithium-ion batteries, the raw materials of sodium-ion batteries are abundant, low-cost, and highly safe. Furthermore, their costs are expected to be further reduced as large-scale applications take off, making them viable for energy storage applications. The primary anode material for sodium-ion batteries is hard carbon, which has a high sodium-ion storage capacity but is relatively expensive, limiting its applications in energy storage. In order to widen the applications of sodium-ion batteries in energy storage and other fields, it is particularly important to develop anode materials that have both high performance and low cost. Coals, with abundant reserves and worldwide availability, can serve as low-cost carbon sources for anode materials. Additionally, coals of different grades of metamorphism have different structural characteristics that can be tailored for the structural characteristics of coal-based anode materials for sodium-ion batteries. Recent research on tailoring coals as the anode materials for sodium-ion batteries is summarized and the recent progress made towards mitigating the existing issues is analysed in this review. Specifically, the impacts of different grades of metamorphism on the sodium-ion storage performance of coal-based anode materials prepared using direct carbonization are discussed in detail. Studies on improving the electrochemical performances of coal-based anode materials through pore and microcrystalline structure controls and surface as well as interface modifications are presented. Finally, the advantages and disadvantages of different preparation methods are identified. To make the industrial applications of coal-based anode materials for sodium-ion batteries more viable, the importance of the de-ashing process is introduced.

Design of the Particle Size and Morphology of Hard Carbon Anode Materials for Sodium-Ion Batteries Through Hydrothermal Carbonization

With sodium-ion batteries (SIBs) finding widespread application, the demand grows for hard carbon, the most popular anode material for SIBs. Hydrothermal carbonization facilitates the production of hard carbon with desired characteristics from various sources. Despite the considerable volume of literature addressing this subject, there is a notable absence of investigations elucidating the relationship between synthesis conditions and the electrochemical characteristics of the product. Here we study systematically the influence of hydrothermal carbonization parameters on hard carbon characteristics and emphasize the potential of hard carbon as an anode material for SIBs. The initial Coulombic efficiency (ICE) is significantly affected by the particle size of the glucose-derived hard carbon, which, in turn, depends on glucose concentration in the initial solution, pH, and stirring regime. By optimizing the hydrothermal carbonization parameters, the ICE up to 91% and a good reversible capacity of ∼300 mAh g−1 in a half cell are achieved. Full cells with Na3(VO)2(PO4)2F cathode material demonstrate ICE of about 80% and reversible capacity of up to 100 mAh g−1 cath. Considering the effective performance of pouch-cell SIB prototypes based on Na3(VO)2(PO4)2F and hard carbon, hydrothermal carbonization of glucose yields hard carbon with the necessary characteristics required for its successful application in SIBs.

Engineering Porous Carbon with Precise Sizes to Promote Surface‐Dominated Storage in Sodium‐Ion Batteries

AbstractAs the sole commercially viable anode material for sodium‐ion batteries, hard carbon currently faces challenges such as slow diffusion kinetics in the low voltage range and low safety due to sodium deposition. In order to deepen the understanding of the pseudocapacitive processes of hard carbon in the high voltage range and enhance sodium storage capacity, this study systematically investigates the electrochemical performance and ion storage of ZIF‐8‐derived porous carbons (ZPCs) of different sizes. We propose a mathematical model based on a spherical particle core‐shell structure, which profoundly reveals the relationship between size and specific surface area, as well as the linear relationship between specific surface area and specific capacity. Moreover, simply by reducing the size of the porous carbon, the specific capacity increased by 86.5 mAh g−1. Dynamic studies reveal that in nano‐porous carbon materials, sodium‐ion storage primarily relies on defect adsorption. Size reduction enhances physical adsorption and surface capacitance response, with ZPC‐80 exhibiting lower resistance and higher diffusion coefficient, indicating that size reduction improves electronic conductivity and charge transfer efficiency, achieving excellent reversible capacity and cycling stability. This work yields a profound insight into the dynamic characteristics of hard carbon anode materials, presenting a new perspective for the design of efficient sodium‐ion batteries.

Deciphering the storage mechanism of biochar anchored with different morphology Mn3O4 as advanced anode material for lithium-ion batteries

Biochar is regarded as a promising lithium-ion batteries anode material, owing to its high cost-effectiveness. However, the poor specific capacity and cycling stability have limited its practical applications. A straightforward and cost-efficient solvothermal method is presented for synthesizing Mn3O4/biochar composites in this study. By adjusting solvothermal temperatures, Mn3O4 with different morphology is prepared and anchored on the biochar surface (MKAC-T) to improve the electrochemical performance. Due to the morphological effect of nanospherical Mn3O4 on the biochar surface, the MKAC-180 anode material demonstrates outstanding reversible capacity (992.5 mAh/g at 0.2 A/g), significant initial coulombic efficiency (61.1 %), stable cycling life (605.3 mAh/g at 1.0 A/g after 1000 cycles), and excellent rate performance (385.8 mAh/g at 1.6 A/g). Moreover, electro-kinetic analysis and ex-situ physicochemical characterizations are employed to illustrate the charge storage mechanisms of MKAC-180 anode. This study provides valuable insights into the “structure–activity relationship” between Mn3O4 microstructure and electrochemical performance for the Mn3O4/biochar composites, illuminating the industrial utilization of biomass carbon anode materials.

Characteristics and properties of anode materials for lithium-ion batteries

Lithium-ion secondary batteries (LIBs) are battery systems with high energy densities. They are essential components of todays information-rich, mobile societys portable, entertainment, computing, and telecommunications technology. After 1981, most of the research on anode materials mainly focused on the anode containing Li, such as LiAl alloy, LiC alloy, etc. These materials have high prices, unstable cycling performance, and are difficult to be commercialized. The successful commercialization of LIBs began in 1991 with SONYs manufacturing of petroleum coke-based anode materials. Among them, anode plays a crucial role in LIBs. Anode materials that have been commercialized include carbon, alloys, and lithium titanate. Lithium-ion batteries using carbon anode materials and lithium titanate anode materials can meet the needs of electric vehicles (EVs) and large-scale energy storage applications to a certain extent, and alloy anode materials can promote the energy density of LIBs. The properties of the commercialized anode materials are covered in this paper. Next generation anode materials such as silicon anode materials are also introduced.

Locally Curved Surface with CoN4 Sites Enables Hard Carbon with Superior Sodium‐Ion Storage Performances at −40 °C

AbstractThe impressive electrochemical performance of sodium‐ion batteries at low temperatures has long been recognized as a promising technical advantage. However, the inadequate transport kinetics of Na+ ions and complex interfacial reactions at the hard carbon anode surface hinder the practical implementation of commercial sodium‐ion batteries. Herein, a novel approach to address this issue by introducing a homogenized functional carbon coating layer with a locally curved configuration is proposed. This coating layer is designed to accommodate single CoN4 sites on the surface of commercial hard carbon particles, resulting in enhanced sodium storage performance at low temperatures. The surface‐modified hard carbon anode material (HC‐Z1) demonstrates a commendable rate performance of 220.6 mAh g−1 at 3 A g−1@25 °C and a substantial reversible capacity of 288.7 mAh g−1 with an 89% capacity retention at 0.06 A g−1@‐20 °C. Furthermore, even at a temperature as low as −40 °C, the reversible capacity remains at 270 mAh g−1 at 0.06 A g−1. Extensive characterizations and theoretical calculations provide evidence that the optimized interface between the electrode and electrolyte effectively enhances the desolvation and migration of Na+ ions, particularly at low temperatures.

The C─S/C═S Bonds Synergistically Modify Porous Hollow‐Carbon‐Nanocages Anode for Durable and Fast Sodium‐Ion Storage

AbstractSulfur doping in carbonaceous anode is a popular method to improve the sodium storing performance. Regulating the C/S bond effect of carbon atom with doped sulfur atom could understand and develop superior carbonaceous anode for sodium‐ion batteries. Therefore, this study designed porous hollow carbon nanocages with synergistically‐doped C/S bonds (C‐S/C = S) by secondary‐sulfidation. The secondary‐sulfidation is conducive to the different bond formation of sulfur atom with carbon skeleton and adjust the structure via removed other groups. Thus, the C‐S/C = S anode with synergistically C‐S and C = S bonds delivered a reversible capacity of 307 mAh g‐1 at 1.0 A g−1 with initial coulomb efficiency of 80.15%, a stable cycle life of 2000 cycles, and a fast charge capability of 186 mAh g−1 at 20.0 A g−1 in sodium‐ion batteries. Through characterization and simulation results, the doped C‐S/C = S bonds creates more active sites and ion diffusion channels in carbon skeleton for enhancing the fast and durable kinetics of sodium‐ion. This work provides deep insights into C/S bonds effect of carbon anode material for developing fast charge stability sodium‐ion batteries.

Pore structure and oxygen content design of amorphous carbon toward a durable anode for potassium/sodium‐ion batteries

AbstractBoth sodium‐ion batteries (SIBs) and potassium‐ion batteries (PIBs) are considered as promising candidates in grid‐level energy storage devices. Unfortunately, the larger ionic radii of K+ and Na+ induce poor diffusion kinetics and cycling stability of carbon anode materials. Pore structure regulation is an ideal strategy to promote the diffusion kinetics and cyclic stability of carbon materials by facilitating electrolyte infiltration, increasing the transport channels, and alleviating the volume change. However, traditional pore‐forming agent‐assisted methods considerably increase the difficulty of synthesis and limit practical applications of porous carbon materials. Herein, porous carbon materials (Ca‐PC/Na‐PC/K‐PC) with different pore structures have been prepared with gluconates as the precursors, and the amorphous structure, abundant micropores, and oxygen‐doping active sites endow the Ca‐PC anode with excellent potassium and sodium storage performance. For PIBs, the capacitive contribution ratio of Ca‐PC is 82% at 5.0 mV s−1 due to the introduction of micropores and high oxygen‐doping content, while a high reversible capacity of 121.4 mAh g−1 can be reached at 5 A g−1 after 2000 cycles. For SIBs, stable sodium storage capacity of 101.4 mAh g−1 can be achieved at 2 A g−1 after 8000 cycles with a very low decay rate of 0.65% for per cycle. This work may provide an avenue for the application of porous carbon materials in the energy storage field.

In Situ Defect Engineering in Carbon by Atomic Self-Activation to Boost the Accessible Low-Voltage Insertion for Advanced Potassium-Ion Full-Cells.

Enhancing the low-potential capacity of anode materials is significant in boosting the operating voltage of full-cells and constructing high energy-density energy storage devices. Graphitic carbons exhibit outstanding low-potential potassium storage performance, but show a low K+ diffusion kinetics. Herein, in situ defect engineering in graphitic nanocarbon is achieved by an atomic self-activation strategy to boost the accessible low-voltage insertion. Graphitic carbon layers grow on nanoscale-nickel to form the graphitic nanosphere with short-range ordered microcrystalline due to nickel graphitization catalyst. Meanwhile, the widely distributed K+ in the precursor induces the activation of surrounding carbon atoms to in situ generate carbon vacancies as channels. The graphite microcrystals with defect channels realize reversible K+ intercalation at low-potential and accessible ion diffusion kinetics, contributing to high reversible capacity (209mAhg-1 at 0.05Ag-1 under 0.8V) and rate capacity (103.2mAhg-1 at 1Ag-1). The full-cell with Prussian blue cathode and graphitic nanocarbon anode maintains an obvious working platform at ca. 3.0V. This work provides a strategy for the in situ design of carbon anode materials and gives insights into the potassium storage mechanism at low-potential for high-performance full-cells.

Improvement and Development Prospects of Carbon Anode Materials for Lithium-ion Batteries

Improvement and Development Prospects of Carbon Anode Materials for Lithium-ion Batteries

Hybrid hard carbon framework derived from polystyrene bearing distinct molecular crosslinking for enhanced sodium storage

AbstractExploiting high‐performance yet low‐cost hard carbon anodes is crucial to advancing the state‐of‐the‐art sodium‐ion batteries. However, the achievement of superior initial Coulombic efficiency (ICE) and high Na‐storage capacity via low‐temperature carbonization remains challenging due to the presence of tremendous defects with few closed pores. Here, a facile hybrid carbon framework design is proposed from the polystyrene precursor bearing distinct molecular bridges at a low pyrolysis temperature of 800°C via in situ fusion and embedding strategy. This is realized by integrating triazine‐ and carbonyl‐crosslinked polystyrene nanospheres during carbonization. The triazine crosslinking allows in situ fusion of spheres into layered carbon with low defects and abundant closed pores, which serves as a matrix for embedding the well‐retained carbon spheres with nanopores/defects derived from carbonyl crosslinking. Therefore, the hybrid hard carbon with intimate interface showcases synergistic Na ions storage behavior, showing an ICE of 70.2%, a high capacity of 279.3 mAh g−1, and long‐term 500 cycles, superior to carbons from the respective precursor and other reported carbons fabricated under the low carbonization temperature. The present protocol opens new avenues toward low‐cost hard carbon anode materials for high‐performance sodium‐ion batteries.

Needle coke anodes for potassium-ion batteries: Storage mechanism and interfacial evolution in soft carbon

Needle coke has attracted much attention as soft carbon anode material for potassium-ion batteries (PIBs) owing to its high crystallinity and conductivity. However, limited research has been conducted on the storage mechanism and the functional and structural evolution of the solid electrolyte interphase (SEI) in ester and ether based electrolytes. This work investigates the potassium ion storage mechanisms of soft carbon anodes in three electrolytes: KPF6 EC/DEC, KPF6 DME, and KFSI DME, and reveals that K+ stored in the KPF6 EC/DEC electrolyte could be through an “adsorption-intercalation” mechanism. Whereas K+ stored in the DME-based electrolytes is believed to undergo a “co-intercalation/adsorption-intercalation” process. Interfacial analyses indicate that the SEI formed in the EC/DEC electrolyte inhibits co-intercalation of potassium ion and solvent, which preserves sufficient space to accommodate potassium ion. Conversely, the [K-DME]+ solvation co-intercalation in DME-based electrolytes compromises the structural integrity, and results in a persistent capacity decline. This work offers novel insights into potassium ion storage in ester and ether-based electrolytes, and provides theoretical support for the fabrication of high-performance soft carbon anodes.

Dual Activation for Tuning N, S Co-Doping in Porous Carbon Sheets Toward Superior Sodium Ion Storage.

Porous carbon has been widely focused to solve the problems of low coulombic efficiency (ICE) and low multiplication capacity of Sodium-ion batteries (SIBs) anodes. The superior energy storage properties of two-dimensional(2D)carbon nanosheets can be realized by modulating the structure, but be limited by the carbon sources, making it challenging to obtain 2D structures with large surface area. In this work, a new method for forming carbon materials with high N/S doping content based on combustion activation using the dual activation effect of K2SO4/KNO3 is proposed. The synthesized carbon material as an anode for SIBs has a high reversible capacity of 344.44mAhg-1 at 0.05Ag-1. Even at the current density of 5Ag-1, the capacity remained at 143.08mAhg-1. And the ICE of sodium-ion in ether electrolytes is ≈2.5 times higher than that in ester electrolytes. The sodium storage mechanism of ether/ester-based electrolytes is further explored through ex-situ characterizations. The disparity in electrochemical performance can be ascribed to the discrepancy in kinetics, wherein ether-based electrolytes exhibit a higher rate of Na+ storage and shedding compared to ester-based electrolytes. This work suggests an effective way to develop doubly doped carbon anode materials for SIBs.

Carbon-coated silicon/graphite oxide composites as anode materials for highly stable lithium-ion batteries.

Silicon (Si) has been widely investigated as an anode material for lithium-ion batteries (LIBs) due to its high theoretical capacity. However, the huge volume expansion and low electrical conductivity limit its practical application to some extent. Here, we prepared silicon/reduced graphene oxide/amorphous carbon (Si/G/C) anode materials for lithium-ion batteries using a facile synergistic cladding layer. The protective effect of different carbon layers was explored and it was found that ternary composites have excellent electrochemical properties. In this work, the surface of Si was first modified using ammonia, and the positively charged Si was tightly anchored to the graphene sheet layer. In contrast, amorphous carbon was used as a reinforcing coating for further coating to synergistically build up the cladding layer of Si NPs with graphene oxide. The ternary composite (Si/G/C) material greatly ensures the structural integrity of the composites and shows excellent cycling as well as rate performance compared to Si/reduced graphene oxide and Si/carbon composites. For the Si/G/C composite, at a current density of 1 A g-1, it can be stably cycled over 267 times with 70% capacity retention (only 0.0711% capacity reduction per cycle).

Structural design of biomass-derived hard carbon anode materials for superior sodium storage via increasing crystalline cellulose and closing the open pores

Through the two-step acid treatment and two-stage heat treatment method proposed in this study, the properties of almond shells were efficiently modulated and transformed into hard carbon materials rich in closed pores and oxygen-containing groups.

Scalable synthesis of N/S co-doped hard carbon microspheres as a high-performance anode material for sodium-ion batteries

Hard carbon is a promising anode material for sodium-ion batteries (SIBs) due to its abundance. However, it exhibits low reversible capacity and slow kinetics if inappropriate microstructural features are developed during synthesis. Herein, N/S co-doped phenolic resin-based hard carbon microspheres are prepared by a scalable strategy, and the electrochemical performance is assessed both in half cells and full cells. We demonstrate that the expanded interlayer spacing, the increased active sites, and the enhanced capacitive behavior result in the enhanced reversible capacity and promoted kinetics for Na+ storage. The sample with appropriate doping amount exhibits an initial charge capacity of 536.8 mAh g−1 at 50 mA g−1 and maintains 445.9 mAh g−1 after 1000 cycles at a current density of 1 A g–1 in a Na-metal half cell. Coupled with a carbon-coated Na4Fe3(PO4)2P2O7 (NFPP) cathode, the full cell exhibits a capacity of 92.5 mAh g−1 after 90 cycles, with a capacity retention of 91.6%. This work provides a facile and scalable method for synthesizing high-performance hard carbon anode materials for SIBs.

N/S co-doped carbon electrode material made from saponin pod skin for sodium ion battery with high performance

Waste biomass material derived carbon has become an important energy storage material which is easily available, inexpensive and environmentally friendly. However, it is a major challenge to develop ultra-high specific capacity and stable anode materials based on biomass carbon materials (BCMs). In this work, saponin pod skin was doped with thiourea through a simple hydrothermal process, followed by being sintered in one step to obtain simultaneously N and S elements co-doped porous carbon anode material for sodium ion batteries (SIBs). The active sites and layer spacing of the original pure BCM have been altered, which are conducive to the promotion of ion/electron transport. The half battery (Na/electrolyte/C) has a specific capacity of 259 mAh g‐−1 at 0.1 A g−1 maintaining a specific capacitance of 238 mAh g−1 after 250 cycles, meanwhile it could reach a potential capacity of 239 mAh g−1 at 1.0 A g−1 which maintaining a specific capacity of 120 mAh g−1 after 1000 cycles. This research provides new strategy for the development of novel biomass-derived carbon materials as anode materials for high-performance SIBs.