Carbon Anodes For Sodium-ion Batteries Research Articles

One stone two birds: Pitch assisted microcrystalline regulation and defect engineering in coal-based carbon anodes for sodium-ion batteries

Coal-based carbons with abundant resources and low cost are regarded as promising anode materials for sodium‐ion batteries (SIBs). However, their ordered carbon microstructure and abundant surface defects often result in low Na-storage capacity and poor initial coulombic efficiency (ICE). Herein, we propose a simple vapor deposition strategy to synthesize coal-based carbons coated with pitch-based soft carbon layer (PCLC) for potential use as anodes for SIBs. The deposition of pitch-based volatile species allows for an efficient cross-linking reaction between hydroxyl‑containing volatile species and oxygen-rich functional groups of coal, thus generating a disordered inner-phase microcrystalline structure with dominant pseudo-graphitic phase in coal-derived carbon. Meanwhile, the exterior soft carbon coating layer substantially reduces surface defects and increases the electrical conductivity of coal-based carbon. Unlike the pristine lignite coal pyrolytic carbon which exhibited a Na-storage capacity of 290.2 mAh g−1 and ICE of 59.9%, the optimal PCLC (PCLC-1) delivered a higher reversible capacity of 312.2 mAh g−1 and a much-improved ICE of 85.3%. In addition, the PCLC-1 electrode also demonstrated excellent cycle stability with 93.4% retention after 1,000 cycles. When coupled with O3-NaNi1/3Fe1/3Mn1/3O2 cathode, PCLC-1 as an anode in a full cell configuration achieved a high energy density of 220.9 Wh kg−1 with excellent cycling and rate performance. The proposed work offers a unique insight into modulating the microcrystalline structure and surface chemistry of high-performance coal-based carbon anode materials for commercial SIBs.

A fundamental understanding of structure evolution in the synthesis of hard carbon from coal tar pitch for high-performance sodium storage

Coal tar pitches (CTPs) can be used to fabricate low-cost hard carbon anodes in sodium-ion batteries (SIBs) via pre-oxidation methods; however, an in-depth analysis of their synthesis processes is still scarce in literature.

Na Storage Activity or Inertness of P-Configurations in N, P Dual-Doped Carbon Nanofibers: Bulk vs Surface

Heteroatom doping is an effective method to improve the electrochemical properties of hard carbon anodes for sodium-ion batteries. However, the different roles of surface and bulk heteroatoms in Na storage have not been explored much. Herein, N, P dual-doped carbon nanofibers (NP-CNFs) with high doping contents and low surface area are designed to clarify the above issue. It is confirmed that P plays a more crucial role in Na storage compared with N. In addition, surface and bulk P not only possess different configurations but also show distinct Na storage activity. There are only oxidized POx groups on the surface, which are inactive for Na storage but promote the stability of electrochemistry interphase, while in the bulk phase, unoxidized P-C bonds also emerge except POx, which shows preeminently reversible Na storage activity, and the POx groups are activated simultaneously. Furthermore, P-doping changes the reactivity of N-configurations with Na both on the surface and in the bulk phase, exhibiting interesting synergism. As expected, the surface stability, bulk activity, and synergism enable NP-CNFs to achieve superior performance. It could deliver a prominent capacity of 105.6 mAh g-1 at 10 A g-1 after 3000 cycles in half cells and 164.3 mAh g-1 at 1 A g-1 after 200 cycles in full cells.

Dual-Function Presodiation with Sodium Diphenyl Ketone towards Ultra-stable Hard Carbon Anodes for Sodium-Ion Batteries.

Hard carbon (HC) is a promising anode material for sodium-ion batteries, yet still suffers from low initial Coulombic efficiency (ICE) and unstable solid electrolyte interphase (SEI). Herein, sodium diphenyl ketone (Na-DK) is applied to realize dual-function presodiation for HC anodes. It compensates the irreversible Na uptake at the oxygen-containing functional groups and reacts with carbon defects of five/seven-membered rings for quasi-metallic sodium in HC. The as-formed sodium induces robust NaF-rich SEI on HC in 1.0 M NaPF6 in diglyme, favoring the interfacial reaction kinetics and stable Na+ insertion and extraction. This renders the presodiated HC (pHC) with high ICE of ≈100 % and capacity retention of 82.4 % after 6800 cycles. It is demonstrated to couple with Na3 V2 (PO4 )3 cathodes in full cells to show high capacity retention of ≈100 % after 700 cycles. This work provides in-depth understanding of chemical presodiation and a new strategy for highly stable sodium-ion batteries.

Stabilization residual oxygen reduces sulfur activity in hard carbon anode for sodium-ion batteries

Stabilization residual oxygen reduces sulfur activity in hard carbon anode for sodium-ion batteries

Tailoring Defects in Hard Carbon Anode towards Enhanced Na Storage Performance

Hard carbon (HC) anodes show conspicuously commercialized potential for sodium-ion batteries (SIBs) due to their cost-effectiveness and satisfactory performance. However, the development of hard carbon anodes in SIBs is still hindered by low initial Coulombic efficiency (ICE) and insufficient cyclic stability, which are induced by inappropriate defects in the structure. Herein, we introduce a simple but effective method to tailor the defects in HC by the chemically preadsorbed K + . The soft X-ray absorption spectroscopy at the C K-edges reveals that K + can anchor on the hard carbon via C-O-K bonds, occupying the irreversible reactive sites of Na + . Therefore, the irreversible capacity caused by some C-O bonds can be reduced. Moreover, the preadsorbed K + can induce the rearrangement of carbon layers and lead to a high graphitization structure with fewer defects and large interlayer spacing, which not only improves the structural stability and electrical conductivity of the HC anode but also facilitates fast Na + diffusion. Therefore, the as-obtained optimized anode demonstrates a higher ICE with better cyclic stability and superior rate capacities compared with the anode without preadsorbed K + . This work indicates that K + preadsorbed into hard carbon is a practicable alternative to enhance the Na storage performances of HC anodes for SIBs.

A life cycle assessment of hard carbon anodes for sodium-ion batteries.

Waste management is one of the biggest environmental challenges worldwide. Biomass-derived hard carbons, which can be applied to rechargeable batteries, can contribute to mitigating environmental changes by enabling the use of renewable energy. This study has carried out a comparative environmental assessment of sustainable hard carbons, produced from System A (hydrothermal carbonization (HTC) followed by pyrolysis) and System B (direct pyrolysis) with different carbon yields, as anodes in sodium-ion batteries (SIBs). We have also analysed different scenarios to save energy in our processes and compared the biomass-derived hard carbons with commercial graphite used in lithium-ion batteries. The life cycle assessment results show that the two systems display significant savings in terms of their global warming potential impact (A1: -30%; B1: -21%), followed by human toxicity potential, photochemical oxidants creation potential, acidification potential and eutrophication potential (both over -90%). Possessing the best electrochemical performance for SIBs among our prepared hard carbons, the HTC-based method is more stable in both environmental and electrochemical aspects than the direct pyrolysis method. Such results help a comprehensive understanding of sustainable hard carbons used in SIBs and show an environmental potential to the practical technologies. This article is part of the theme issue 'Bio-derived and bioinspired sustainable advanced materials for emerging technologies (part 2)'.

A Lignosulfonate Binder for Hard Carbon Anodes in Sodium-Ion Batteries: A Comparative Study

An important factor in the development of sodium-ion batteries (SIBs) is the use of cheap and sustainable materials. Sodium lignosulfonate, a lignin derivative, is demonstrated here as an attractive, “green”, water-soluble, and potentially cost-effective binder for use in hard carbon anodes for SIBs. A comparison of its battery cycling performance is made against other binders including sodium carboxymethyl cellulose and lignin, obtained from the kraft process, as well as sodium alginate, derived from algae. Apart from lignin, which requires processing in N-methyl-2-pyrrolidone, the other three binders are water-soluble. Lignosulfonate shows comparable or better performance, with high capacity retention and stability, when using 1 M NaPF6 in propylene carbonate or ethylene carbonate:diethyl carbonate electrolytes for both half- and full-cells (against a Prussian white cathode). Further improvements are observed when including styrene-butadiene rubber as a co-binder. X-ray photoelectron spectroscopy demonstrates similar solid electrolyte interphase compositions after the initial sodium insertion for both lignosulfonate and carboxymethyl cellulose binders. However, after subsequent cycling, the surface layer composition and thickness are found to be dependent on the binder. For the lignosulfonate-based electrode, the layer appears thicker but comprises a smaller fraction of carbon–oxygen species.

Tailoring a Phenolic Resin Precursor by Facile Pre-oxidation Tactics to Realize a High-Initial-Coulombic-Efficiency Hard Carbon Anode for Sodium-Ion Batteries.

As the leading anode material for sodium-ion batteries (SIBs), hard carbon (HC) still faces the puzzle of low initial Coulombic efficiency (ICE) in achieving commercialization. From the perspective of precursors, the low ICE has been attributed to the large specific surface area and porosity produced by the rapid decomposition of polymers during the carbonization. Therefore, increasing the cross-linking degree of precursors will be an effective shortcut to improve the ICE. Herein, a facile pre-oxidation tactic was successfully employed to tailor the cross-linking degree of phenolic resin precursors to precisely control the specific surface area of the obtained HC. As the pre-oxidation time is increased, the optimal HC with the lowest specific surface area shows an ICE elevated by 22.2% (from 62.5 to 84.7%) compared to the original pre-oxidation HC and delivers a high reversible capacity of 334.3 mAh g-1 at 20 mA g-1. Besides, the pre-oxidation also introduces abundant carbonyl groups, which increase the disorder degree of HC and supply abundant adsorption sites of Na+, thus enhancing the rate performance. When matched with a layered O3-NaNi1/3Fe1/3Mn1/3O2 cathode, the full cell achieves an energy density of ca. 256.2 Wh kg-1 with superior rate performance. This work sheds light on the positive effect of pre-oxidation in elevating the ICE of HC and provides effective guidance to achieve a high ICE for other HC materials.

Biomass seaweed-derived nitrogen self-doped porous carbon anodes for sodium-ion batteries: Insights into the structure and electrochemical activity

Sustainable transformation and efficient utilization of biomasses and their derived materials are environmentally as well as economically compliant strategies. Biomass seaweed-derived nitrogen self-doped porous carbon with tailored surface area and pore structures are prepared through carbonization and activation. The influence of carbonization temperature on morphology, surface area, and heteroatom dopants are investigated to optimize sodium-ion storage capability. Seaweed-derived nitrogen self-doped activated carbon (SAC) as anode materials for sodium-ion batteries exhibits remarkable reversible capacity of 303/192 mAh g−1 after 100/500 cycles at current densities of 100/200 mA g−1, respectively, and a good rate capability. The interconnected and porous conducting nature along with the heteroatom dopant role in creating defective sites and charge stabilization are favorable for ion storage and diffusion and electron transport, indicating the electrodes can offer improved electrochemical performances. In addition, post-mortem analysis of the cycled carbon electrodes through ex-situ tools demonstrates the sodium-ion storage mechanism.

Biomass Derived High Areal and Specific Capacity Hard Carbon Anodes for Sodium-Ion Batteries

Sodium-ion battery (NIB) technology has drawn increased attention for stationary storage applications owing to its potential in facilitating the transition to a world powered by renewables, mainly ...

(Invited) Mechanistic Study of Sodium Insertion into Bio-Waste Derived Hard Carbon Anode for Sodium-Ion Batteries

Sodium-ion-batteries (SIBs) are considered one of the most promising next-generation battery systems. [1] Owing to their potential lower cost and higher sustainability compared to the current lithium-based technology, SIBs have the potential to dominate the future stationary storage market filling the gap between energy production and utilization. [2]Currently, hard carbon represents the anode of choice for SIBs. Bio-waste derived hard carbons, in particular, are certainly the most attractive among others in terms of sustainability and cost. [3,4]. Recently, there has been a great interest in the fundamental understanding of the sodiation process. Indeed, several mechanisms have been proposed, however, the unresolved nature of the hard carbon structure hinders a comprehensive description of the sodiation mechanism. [3] Nonetheless, the understanding of the Na uptake and release is crucial for a rational design of improved hard carbon anodes. The most commonly detected sodiation processes have been identified as:ⅰ) inter-lamellae Na-ion intercalation, ⅱ) Na-ion ad-/chemisorption at defects in the graphenic sheets, ⅲ) Nano-clustering of quasi-metallic Na on micropores, and ⅳ) Solid-electrolyte-interphase (SEI) formation, including the related irreversible Na trapping. Besides, their state of charge dependence upon cycling is still widely discussed. [3]In this study, we attempt to elucidate the sodiation processes in a peanut shell-derived hard carbon anode. X-ray based techniques and vibrational spectroscopies are used to probe and clarify the structure/function correlation and the potential dependence of the sodiation processes. In-situ X-ray diffraction (XRD) is performed to evaluate the effect of Na ion intercalation on the interlayer distance among graphenic sheets. The carbon structure changes occurring in the electrode’s bulk and surface a upon sodiation are investigated by in-situ Raman spectroscopy. X-ray absorption (XAS), emission (XES), and photoelectron (XPS) spectroscopies in the soft and tender X-ray regimes are employed to reveal the formation and evolution of the SEI upon cycling, complemented by ex-situ attenuated total reflection Fourier-transform infrared (ATR-FTIR) spectroscopy to identify the chemical species generated. Additionally, resonant inelastic X-ray scattering (RIXS) measurements at the C K-edge provide supplementary information about the Na-insertion mechanism into the anode structure due to its excellent atom-specificity and mapping of the C band structure at different (dis)charge stages.Overall, a direct relation between structural properties of hard carbon and its sodiation mechanism is proposed, paving the way for a rational design of high-performance hard carbon anodes. Reference s : [1] V. Palomares, P. Serras, I. Villaluenga, K. B. Hueso, J. Carretero-Gonzalez, T. Rojo, Energy Environ. Sci. 2012, 5, 5884.[2] S. Roberts, E. Kendrick, Nanotechnol. Sci. Appl. 2018, 11, 23.[3] X. Dou, I. Hasa, D. Saurel, C. Vaalma, L. Wu, D. Buchholz, D. Bresser, S. Komaba, S. Passerini, Materials Today, 2019, 23, 87.[4] D. Saurel, B. Orayech, B. Xiao, D. Carriazo, X. Li, T. Rojo, Adv. Energy Mater. 2018, 8, 1703268.

Insight to defects regulation on sugarcane waste-derived hard carbon anode for sodium-ion batteries

By controlling the interlayer spacing and the porosity through pyrolysis and microwave activation, sugarcane-derived hard carbon materials have been prepared to deepen the understanding of Na + storage mechanism in sodium-ion batteries. • High performance hard carbons are successfully synthesized from sugarcane. • Reversible Na-storage capacity of 323.6 mAh g −1 is obtained. • A capacity retention up to 96.7 % after 500 cycles at 50 mA g −1 is achieved. • Pyrolysis promotes graphitization, increasing plateau capacity. • Microwave activation provides enhanced porosity with larger sloping capacity. A great deal of attention has been paid on developing plant-derived hard carbon (HC) materials as anodes for sodium-ion batteries (SIBs). So far, the regulation of HC has been handicapped by the well-known ambiguity of Na + storage mechanism, which fails to differentiate the Na + adsorption and Na + insertion, and their relationship with the size of d -interlayer spacing and structural porosity. Herein, bagasse-derived HC materials have been synthesized through a combination of pyrolysis treatment and microwave activation. The combined protocol has enabled to synergistically control the d -interlayer spacing and porosity. Specifically, the microwave activation has created slit pores into HC and these pores allow for an enhanced Na + adsorption with an increased sloping capacity, establishing a strong correlation between the porosity and sloping capacity. Meanwhile, the pyrolysis treatment promotes the graphitization and it contributes to an intensified Na + insertion with an increased plateau capacity, proving that the plateau capacity is largely contributed by the Na + insertion between interlayers. Therefore, the structural regulation of bagasse-derived HC has provided a proof on positively explaining the Na + storage with HC materials. The structural changes in the pore size distribution, specific surface area, d -interlayer spacing, and the electrochemical properties have been comprehensively characterized, all supporting our understanding of Na + storage mechanism. As a result, the HC sample with an optimized d -interlayer spacing and porosity has delivered an improved reversible capacity of 323.6 mAh g −1 at 50 mA g −1 . This work provides an understanding of Na + storage mechanism and insights on enhancing the sloping/plateau capacity by rationally regulating the graphitization and porosity of HC materials for advanced SIBs.

The recent progress of pitch-based carbon anodes in sodium-ion batteries

Abstract Sodium-ion batteries (SIBs) have attracted significant attentions as promising alternatives to lithium-ion batteries for large-scale energy storage applications. Here carbon materials are considered as the most competitive anodes for SIBs based on their low-cost, abundant availability and excellent structural stability. Pitch, with high carbon content and low cost, is an ideal raw precursor to prepare carbon materials for large-scale applications. Nevertheless, the microstructures of pitch-based carbon are highly ordered with smaller interlayer distances, which are unfavorable for Na ion storage. Many efforts have been made to improve the sodium storage performance of pitch-based carbon materials. This review summarizes the recent progress about the application of pitch-based carbons for SIBs anodes in the context of carbon's morphology and structure regulation strategies, including morphology adjustment, heteroatoms doping, fabricating heterostructures, and the increase of the degree of disorder. Besides, the advantages, present challenges, and possible solutions to current issues in pitch-based carbon anode are discussed, with the highlight of future research directions. This review will provide a deep insight into the development of low-cost and high-performance pitch-based carbon anode for SIBs.

Coffee-Ground-Derived Nanoporous Carbon Anodes for Sodium-Ion Batteries with High Rate Performance and Cyclic Stability

Here, we evaluate the suitability of natural biowaste-derived carbon anodes for sodium-ion batteries (NIBs). Specifically, we utilize eco-friendly, renewable, low-cost coffee grounds (CGs) as precu...

Hydrothermally assisted transformation of corn stalk wastes into high-performance hard carbon anode for sodium-ion batteries

Transforming biomass wastes such as corn stalks into electrochemical functional materials not only reduces environmental concerns associated with biomass combustion, but also provides low-cost new-energy products. Herein, a hydrothermally assisted route without using any chemicals is used to transform corn stalk wastes into high-performance hard carbon anode materials for rechargeable sodium-ion batteries, in which hydrothermal temperature is importantly optimized to eliminate the inorganic impurities and control the oxygen-containing functional group, thus finally achieving high-quality hard carbon with superior electrochemical performance. Structural properties, sodium storage performance and reaction kinetic of the resultant materials are carefully investigated by coupling X-ray diffraction, Raman spectroscopy, X-ray photon spectroscopy, and galvanostatic technique. Experimental results suggest that the optimized product prepared from hydrothermally treated corn stalk wastes delivers a high reversible capacity of 270 mAh g−1 at 0.2C, excellent high-rate capability with 172 mAh g−1 at 10C, and outstanding long-term cycling performance with capacity retention of 96.7% after 100 cycles. The result in this work indicates that hydrothermal treatment is an effective strategy to eliminate inorganic impurities from biomass wastes and promote electrochemical performance of resultant hard carbon anode for sodium-ion batteries.

Chemical Grafting-derived N, P Co-doped Hollow Microporous Carbon Spheres for High-Performance Sodium-ion Battery Anodes

Microstructure design combined with high-level heteroatoms doping has been considered the leading approach for preparing the high-performance carbon anodes for sodium-ion batteries (SIBs). Herein, a hollow porous carbon sphere (NP-HPCS) that exhibits a high N, P co-doping level (6.05 at% for N, 5.19 at% for P) and a large microporous specific area (339 m2 g−1) is reported. The microporous and N, P co-doping synergistic construction of the NP-HPCS was achieved by a high-efficiency chemical grafting of hexachlorocyclotriphosphazene (HCCP) onto polydopamine (PDA) shell, accompanied by the in situ micellar transformation of pore-forming agent F127 in the grafting process. The as-prepared NP-HPCS used as an anode for SIBs delivers a superior rate capacity (~101 mAh g−1 at 20 A g−1) and an excellent long cycle performance (~120 mAh g−1 after 5000 cycles at 5 A g−1). The kinetics analysis and density functional theory (DFT) calculations were carried out to further analyze the superior sodium storage performance of NP-HPCS. Our work suggests an effective way to develop high-performance carbon anode materials for SIBs.

Boosting the sodium storage performance of coal-based carbon materials through structure modification by solvent extraction

High-performance carbon anodes for sodium-ion batteries (SIBs) were synthesized with bituminous coal as precursor through solvent extraction and carbonization. The solvent extraction endows the coal-based carbon a hierarchical pore structure and enlarged interlayer distance, which can shorten the charge diffusion distance, alleviate the volume variation, and improve the ion diffusion rate. As a result, the modified coal-based electrodes exhibit impressive cycling stability (92% capacity retention after 7000th cycle at 2 A g−1) and excellent rate capability (79 mA h g−1 at 10 A g−1).

Effect of Vapor Carbon Coating on the Surface Structure and Sodium Storage Performance of Hard Carbon Spheres

Hard carbons have received considerable attention as anode materials for sodium‐ion batteries (SIBs). However, it is still a challenge to improve the plateau capacity and initial coulombic efficiency (ICE) of hard carbons. Herein, a facile vapor carbon‐coating method is used to modify the surface structure of carbon spheres (CS) via the pyrolysis of polypropylene (PP), aiming to seal the exposed pores through a high‐quality carbon layer. CS@2%PP exhibits highly improved sodium storage performance compared to that of the pristine CS, which delivers a plateau capacity of 220 m Ah g−1 and an ICE of 81%. Further investigations show that the improved sodium storage performance of CS@2%PP can be mainly attributed to the reduced structural defects on the surface, lower specific surface area (11.5 m2 g−1), and increased closed pores (12.5%) via carbon coating. The results prove that the surface vapor carbon coating is a facile route to improve the plateau capacity and ICE of hard carbon anodes in SIBs.

Valorizing low cost and renewable lignin as hard carbon for Na-ion batteries: Impact of lignin grade

Lignin, the second most abundant biopolymer and rich in aromatic entities, is a by-product of paper industry and mainly burned to produce energy. Its commercialization for high-value added products remains largely unexplored today. Herein, we explored the preparation of hard carbon anodes for sodium-ion batteries using the two most common lignin grades, i.e, lignin kraft and lignin sulphonate. The lignin kraft hard carbon (LK-HC) shows small specific surface area (1.8 m2 g−1) and a dense random-like morphology while the latter lignin sulphonate hard carbon (LS-HC) presents a high surface area (180 m2 g−1) and spherical particles containing macropores. Their electrochemical performances vs. Na+ revealed a steady capacity of 181 mAh g−1 over cycling for LK-HC, as compared to a capacity of 205 mAh g−1 for LS-HC which fades after 30 cycles due to an impurity-driven growth of a blocking solid electrolyte interphase (SEI). To circumvent this issue, an efficient washing procedure was successfully implemented enabling to obtain (LSW-HC) carbons which deliver a high and stable capacity (284 mAh g−1) along efficiency (78.1%).