Hard Carbon Materials Research Articles

Synergistic effect of pore structure and crystalline domains enabling high capacity toward non-aqueous rechargeable aluminum batteries

Rechargeable aluminum batteries (RABs) with low cost and high safety have been regarded as a potential alternative to lithium-ion batteries. Despite the widely used graphite materials, the research on hard carbon with abundant sources and low carbonization temperature is rarely reported. Herein, a series of hard carbon materials with different degrees of graphitization is controllably fabricated through a ball-milling method. It is found that surface-specific area and pore structure are significantly affected by ball-milling time. As a result, the as-optimized product with suitable graphitization degree and pore distribution shows a high capacity (125 mAh·g−1 at 200 mA g−1 after 200 cycles) and excellent cycle stability (82.2 mAh·g−1 at 150 mA g−1 after 500 cycles). Such electrochemical performances can be ascribed to the fact that a proper graphitization degree ensures fast electrons transfer between layers, and multi-pores architectures contribute to accelerating ions migration. This work is expected to guide synthesizing a biomass-derived hard carbon via a facile and low-energy method, which may accelerate the practical application of RABs and facilitates the mass production of cathode carbon materials.

A Multifunctional Coating on Sulfur-Containing Carbon-Based Anode for High-Performance Sodium-Ion Batteries.

A sulfur doping strategy has been frequently used to improve the sodium storage specific capacity and rate capacity of hard carbon. However, some hard carbon materials have difficulty in preventing the shuttling effect of electrochemical products of sulfur molecules stored in the porous structure of hard carbon, resulting in the poor cycling stability of electrode materials. Here, a multifunctional coating is introduced to comprehensively improve the sodium storage performance of a sulfur-containing carbon-based anode. The physical barrier effect and chemical anchoring effect contributed by the abundant C-S/C-N polarized covalent bond of the N, S-codoped coating (NSC) combine to protect SGCS@NSC from the shuttling effect of soluble polysulfide intermediates. Additionally, the NSC layer can encapsulate the highly dispersed carbon spheres inside a cross-linked three-dimensional conductive network, improving the electrochemical kinetic of the SGCS@NSC electrode. Benefiting from the multifunctional coating, SGCS@NSC exhibits a high capacity of 609 mAh g-1 at 0.1 A g-1 and 249 mAh g-1 at 6.4 A g-1. Furthermore, the capacity retention of SGCS@NSC is 17.6% higher than that of the uncoated one after 200 cycles at 0.5 A g-1.

Optimization of Electrochemical Presodiation Parameters of Na‐Ion Full Cells for Stable Solid–Electrolyte Interface Formation: Hard Carbon Rods from Waste Firefighter Suits

Utilizing the synthetic waste of firefighter costumes, rod‐shaped hard carbon materials are effectively produced for the first time with over 99% purity, and their structural properties are evaluated using the appropriate spectroscopic techniques. The galvanostatic cycling tests are performed at different temperatures and the result shows that the capacity and capacity fade values are directly affected by the temperature. The high‐rate consumption of sodium ions during the evolution of the solid–electrolyte interface in the first cycle of the cells is observed and the highest capacity of the half cells is obtained as 410 and 233 mAh g−1 for the first and second cycles, respectively. To compensate for the sodium‐ion loss, an electrochemical treatment presodiation technique is implemented, which is an effective means of compensating for the initial inefficiency. The optimum presodiation condition of electrochemical treatment of anode electrode for the production of Na0.67Mn0.5Fe0.45Ti0.07O2/presodiated hard carbon full cells is investigated. The highest capacity values for C/10 are obtained at 114.9 mAh g−1 for the full cells using the voltage window of 2–4 V. The cost analysis of the battery pack for 90 kW electric‐powered cars is calculated by the BatPaC software and the results are evaluated for possible commercialization.

Sinthesis and Properties of Hard Carbon Materials Made of Molybdenum-Doped Viscose Fiber for Negative Electrodes of Sodium-Ion Batteries

Herein, a method for the preparation of hard carbon via carbonization of chemically modified (molybdenum-doped) commercially available viscose fiber was developed. The effects of a molybdenum dopant on carbonization conditions were studied. The carbonization products retained the fibrous structure and flexibility. The structural features of the synthesized hard carbon materials were investigated, and their relationships to the carbonization temperature and the amount of the molybdenum dopant were analyzed. The texture of materials was studied, and correlations between the specific surface area and porosity, on the one hand, and the synthesis conditions, on the other, were discovered. The usefulness of the products as anode materials for sodium-ion batteries was evaluated. The electrochemical tests, together the extant relevant data, indicate that molybdenum induces the structural rearrangement of the carbon framework upon annealing, accompanied by the growth and ordering of graphite-like nanoclusters. The material prepared at 1050°C exhibited the best electrochemical performances among the synthesized products and the stable cyclability with a capacity of 290 (mA h)/g at a current density of 25 mA/g.

Sinthesis and Properties of Hard Carbon Materials Made of Molybdenum-Doped Viscose Fiber for Negative Electrodes of Sodium-Ion Batteries

Sinthesis and Properties of Hard Carbon Materials Made of Molybdenum-Doped Viscose Fiber for Negative Electrodes of Sodium-Ion Batteries

Boosting the Initial Coulomb Efficiency of Sisal Fiber-Derived Carbon Anode for Sodium Ion Batteries by Microstructure Controlling

As anode material for sodium ion batteries (SIBs), biomass-derived hard carbon has attracted a great deal of attention from researchers because of its renewable nature and low cost. However, its application is greatly limited due to its low initial Coulomb efficiency (ICE). In this work, we employed a simple two-step method to prepare three different structures of hard carbon materials from sisal fibers and explored the structural effects on the ICE. It was determined that the obtained carbon material, with hollow and tubular structure (TSFC), exhibits the best electrochemical performance, with a high ICE of 76.7%, possessing a large layer spacing, a moderate specific surface area, and a hierarchical porous structure. In order to better understand the sodium storage behavior in this special structural material, exhaustive testing was performed. Combining the experimental and theoretical results, an "adsorption-intercalation" model for the sodium storage mechanism of the TSFC is proposed.

Sulfur-grafted hard carbon with expanded interlayer spacing and increased defects for high stability potassium-ion batteries

Carbon materials have been proven to be an effective anode for potassium-ion batteries (PIBs) due to their high safety, low cost, and environmental benignity. However, the repeated insertion/extraction of K-ions with a larger size into/from electrode at low voltage region will inevitably cause obvious volume expansion, easily resulting in poor cycle stability. Hence, we synthesize S-doped hard carbon material (NSHCM2) using biomass as carbon and thiourea as S sources. Various characterizations demonstrate that the introduced S-heteroatom not only expands the distance between carbon layers, but also creates more defects. The former ensures the free intercalation/deintercalation of K-ions without structure deformation, while the latter can provide numerous active sites to adsorb K-ions, all these together contribute to structure stability and reversible capacity. As a result, the optimized NSHCM2 electrode delivers a high capacity of 294 mAh g−1 at 200 mA g−1 and an ultra-long cycling stability by achieving 220 mAh g−1 at 2000 mA g−1 over 5000 cycles. This simple and high effective synthesis route makes durable and fast potassium storage possible.

Hard Carbons Derived from Phenyl Hyper-Crosslinked Polymers for Lithium-Ion Batteries

Hyper-crosslinked polymers are attracting extensive attention owing to their ease of design and synthesis. Based on the flexibility of its molecular design, a hyper-crosslinked polymer with a π-conjugated structure and its derived carbon were synthesized by the Friedel–Crafts reaction. The polymer and its derived hard carbon material were characterized by FTIR, 13C NMR, Raman, BET, and other characterization tools. The electrochemical properties of both materials as anode electrodes of lithium-ion batteries were investigated. Benefiting from the highly cross-linked skeleton and conjugated structure, the as-prepared carbon materials still had high specific surface area (583 m2 g−1) and porosity (0.378 cm3 g−1) values. The hard carbon (CHCPB) anode possessed the powerful reversible capacity of 699 mAh g−1 at 0.1A g−1, and it had an excellent rate of performance of 165 mAh g−1 at the large current density of 5.0 A g−1. Long-cycle performance for 2000 charge/discharge cycles displayed that the capacity was kept at 148 mAh g−1 under 2 A g−1. This work contributes to a better understanding of the properties of hard carbon materials derived from hyper-crosslinked polymers and how this class of materials can be further exploited in various applications.

High performance potassium-ion and lithium-ion batteries anode based on natural N-doped carbon microspheres

As an inexpensive and renewable anode material with the advantages of less intercalation-induced exfoliation, superior molecularly doping performance, and outstanding rate capacity, hard carbon material attracts extensive attention in lithium-ion batteries (LIBs) and potassium-ion batteries (KIBs). In this work, a series of glucosamine hard carbon microspheres (GCMs) are synthesized through facile and inexpensive hydrothermal and pyrolysis procedures. The obtained hard carbon microspheres as anode material provide favorable dual functionality for both LIBs and KIBs. The electrochemical performance of GCMs electrodes at various carbonation temperatures is fully evaluated. The as-prepared GCM-900 is an admirable anode for LIBs, with good reversible capacity (407.8 mAh/g at 0.1 A/g after 200 cycles) and rate performance. Correspondingly, the GCM-1100 is good for KIBs (269.9 mAh/g at 0.05 A/g and 161.9 mAh/g after 100 cycles at 0.1 A/g).

Boron–Phosphorus Codoped Coral-like Hard Carbon Anodes for Sodium Ion Storage

Hard carbon materials have the advantages of low price, environmental friendliness, and good electrical conductivity but have the disadvantages of unsatisfactory sodium storage capacity and low long-cycle stability. The use of heteroatom doping and structural design can significantly improve the sodium storage properties of carbon materials. In this paper, a boron–phosphorus doped hard carbon material (CABP) was designed by using citric acid as the carbon source. The rich pore structure of CABP also provides fast transport channels for Na+, while the efficient doping of B and P atoms can distort the graphitic layer and generate more active sites and defects. The CABP carbon material therefore exhibits excellent electrochemical properties. It can obtain pretty good capacities of 246.8 mA h g–1 after 400 cycles at 0.1 A g–1. Moreover, it was able to maintain 161.9 mA h g–1 after 5000 cycles at 5 A g–1. This work provides a new route for the facile preparation of high-performance heteroatom-doped carbon materials and an idea for the preparation of diatom-doped materials for energy storage.

From waste to resources: transforming olive leaves to hard carbon as sustainable and versatile electrode material for Li/Na-ion batteries and supercapacitors

Over the last few years, biomass-derived hard carbon materials are drawing more and more attention because of their high abundance, cost breakdown, high performance, and fast regeneration. In this context, the synthesis of hard carbon from olive leaves, a widely available by-product of table olive and olive oil industries, is here reported and its performance, as a sustainable electrode material for Li-ion batteries (LIBs), Na-ion batteries (NIBs), and supercapacitors (SCs), are evaluated. According to the information acquired by structural characterization, a disordered structure is confirmed for the synthesized hard carbon. When tested as anode for LIBs and NIBs, electrodes based on Na-CMC green binder show discharge capacities of 331.0 mAh/g and 265.4 mAh/g at 1C (with minor irreversibility), respectively, with promising cycling stability. In SC application, the electrode delivers a high specific capacitance of 169.6 F/g at 0.5 A/g and remarkable capacity retention of 96.7% after more than 20,000 cycles at 10 A/g. As a result, this work confirms the possibility to use olive leaves-derived hard carbon material for the low-cost, environmental-friendly fabrication of electrodes with high energy and power capabilities.

Sustainable and scalable fabrication of high-performance hard carbon anode for Na-ion battery

Sustainable and green manufacturing of hard carbon (HC) material in a low-cost way is the key issue in promoting its industrial applications in Na-ion batteries (SIB). Nowadays, most synthesis ways to prepare HC need the help of chemical reagents to improve its Na-ion storage performance. Herein, we firstly developed a completely green biological fermentation technology to prepare HCs on a large scale using cheap and renewable carbon sources of various biomass starch. Pre-treatment by bio-fermentation can effectively modify the carbon precursor for facile pyrolysis to fabricate starch-based HCs, and make its internal microstructure with larger interlayer spacing, more disordered structure and abundant closed micropores. Finally, a case of cornstarch-based hard carbon exhibits a high reversible capacity of 335 mA h g−1 at a current density of 30 mA h g−1 and high rate performance with a reversible capacity of 140.6 mA h g−1 even at a high current of 5 A g−1 as well as long cycling stability. In-situ Raman spectra, ex-situ SAXS and ex-situ XPS tests during discharge and charge process reveal the pore filling mechanism of quasi-metallic Na in hard carbon anode. Such a “bread-making”strategy is a facile and scalable route to fabricate various starch-based hard carbons with improved performance, demonstrating a very practically promising application for industrial manufacture.

Is There a Ready Recipe for Hard Carbon Electrode Engineering to Enhance Na-Ion Battery Performance?

Hard carbon (HC) materials are commonly used as anode materials in Na-ion batteries. In most of the cases, their electrochemical performance is correlated only to their physicochemical properties, and the impact of the electrode additives (binders–conductive agent) and electrolyte is often neglected. In this work, a systematic study is performed to understand the role of electrode/electrolyte engineering on HC initial Coulombic efficiency (iCE), specific capacity, and cycle stability. Four HCs obtained by pyrolysis of several biopolymers, i.e., cellulose (HC-Cell), chitosan (HC-Chs), chitin (HC-Cht), and lignin (HC-Lig), are used. The binder was found to have an important impact on the electrochemical performance, with PVDF resulting in better performance than CMC. The carbon black additive had no significant impact on CMC-based electrochemical performance while it boosted the electrochemical performance of PVDF-based electrodes. For an optimized formulation (PVDF/carbon black), the best HC performance in NaPF6 in 1 EC:DEC was delivered by HC-Cell (83% iCE, 332 mAh g–1 at C/10, and 97% retention). This was attributed to its large graphene interlayer space, high purity, and low surface area. HC-Cht and HC-Chs exhibited similar good electrochemical performance (∼280 mAh g–1) whereas the use of HC-Lig resulted in low iCE and capacity fading overcycling due to the high level of impurities in its structure. This could be overcome by changing the electrolyte salt, by using NaClO4 (76% retention) instead of NaPF6 (52% retention). Based on the obtained results, the electrochemical performance could be correlated with the HC physicochemical properties and binder/conductive additive. It could be demonstrated that careful electrode engineering combined with proper electrolyte selection and tuned HC properties allowed all investigated materials achieving reasonable iCE (up to 83%), high specific capacity (∼280 to 332 mAh g–1), and high-capacity retention (72–97% after 50 cycles).

Regulation of surface oxygen functional groups and pore structure of bamboo-derived hard carbon for enhanced sodium storage performance

Hard carbon materials with long low-voltage plateau have been used as the anode materials for sodium ion batteries which are considered to be one of the most potential large-scale energy storage systems. Herein, carbonyl groups and closed micropores are introduced into bamboo-derived hard carbon materials simultaneously to enhance the sodium ion storage performance. The carbonyl groups are demonstrated to enhance the reversible Na adsorption in the sloping region and closed micropores are beneficial to sodium ion storage in the low-voltage plateau region. Moreover, the introducing carbonyl groups improve the reversible sloping capacity not at the expense of increasing specific surface area and deteriorating the initial Coulombic efficiency. The hard carbon carbonized at 1300 °C delivers a high reversible specific capacity of 348.5 mAh g−1 at a current density of 30 mA g−1 with a charge/discharge Coulombic efficiency of 84.1 %, and keeps a specific capacity of 295.9 mAh g−1 with a capacity retention of 91.6 % at a current density of 300 mA g−1 after 500 cycles. This work provides a novel strategy to precisely regulate the microstructure for biomass-derived hard carbon for superior sodium ion storage performance.

Comprehensive study on improving the sodium storage performance of low-defect biomass-derived carbon through S or N doping

As a promising alternative to graphite, biomass hard carbon has attracted widespread attention in sodium-ion batteries (SIBs). Heteroatom doping can overcome the inherent shortcomings of hard carbon materials, such as low reversible capacity and poor rate performance. Herein, in this paper, a simple and efficient one-step synthesis method is adopted to pyrolyze the mixture of jute fiber carbon with urea (JFCN) or sulfur powder (JFCS) from high to low carbonization temperatures, and determines that high-performance doping is only suitable for relatively low temperatures. Benefiting from the low-defect and ordered structure doped by proper S or N under these temperatures, initial Coulombic efficiency and electrochemical stability of hard carbon materials have been significantly improved. Meanwhile, S doping is a more effective way than N doping, the former shows an ultrahigh reversible capacity exceeding 410 mAh g−1 after 100 cycles at 0.1 A g−1 and a remarkable rate performance of 234.3 mAh g−1 at 2.0 A g−1. Impressively, JFCN exhibits greater rate performance in ether electrolytes, while JFCS shows better stability in ester electrolytes. This work provides a broad application prospect for hard carbon materials to achieve low cost and high capacity as practical SIBs.

Recent advances for SEI of hard carbon anode in sodium-ion batteries: A mini review.

The commercialization of sodium-ion batteries has been hampered by the anode’s performance. Carbon-based anodes have always had great application prospects, but traditional graphite anodes have great application limitations due to the inability of reversible insertion/de-insertion of sodium ions in them, while hard carbon materials have the high theoretical capacity, low reaction potential has received extensive attention in recent years. Nevertheless, the low first cycle Coulomb efficiency and rapid capacity decline of hard carbon materials limited its application. SEI has always played a crucial role in the electrochemical process. By controlling the formation of SEI, researchers have increased the efficiency of sodium-ion battery anodes, although the composition of SEI and how it evolved are still unknown. This paper briefly summarizes the research progress of hard carbon anode surface SEI in sodium-ion batteries in recent years. From the perspectives of characterization methods, structural composition, and regulation strategies is reviewed, and the future development directions of these three directions are suggested. The reference opinions are provided for the reference researchers.

Phosphorus/sulfur co-doped hard carbon with a well-designed porous bowl-like structure and enhanced initial coulombic efficiency for high-performance sodium storage

Hard carbon with high specific capacity and cost-effective characteristics has emerged as a critical material in the study of sodium-ion batteries (SIBs) anodes. However, their unsatisfactory initial coulombic efficiency (ICE) and ineluctable structural deformation during long-cycling work seriously hinder their application in practice. Here, phosphorus/sulfur co-doped hard carbon with a porous bowl-like structure (denoted as P/S-HCB) is developed to achieve high performance. The experimental data show that the doping of S increased the interlayer spacing of graphite in the surface/subsurface region, the doping of P promoted the formation of C-S-P and P-O bonds, which can contribute to abundant structural defects and redox reaction sites that not only improves structural stability but also contributes to the capacitive process under high rate. The as-fabricated P/S-HCB electrode demonstrates outstanding Na-ion storage performance regarding high ICE of 88.71%, the high-reversibility capacity of about 450 mA h g−1 after 140 cycles at 0.2 A g−1, extraordinary rate capability of 216.3 mA h g−1 at 10 A g−1, and long-term cycling stability of 276 mA h g−1 after 3000 cycles at 10 A g−1. These results show a novel approach to developing advanced hard carbon materials for sodium storage.

Shock-formed carbon materials with intergrown sp3- and sp2-bonded nanostructured units

Studies of dense carbon materials formed by bolide impacts or produced by laboratory compression provide key information on the high-pressure behavior of carbon and for identifying and designing unique structures for technological applications. However, a major obstacle to studying and designing these materials is an incomplete understanding of their fundamental structures. Here, we report the remarkable structural diversity of cubic/hexagonally (c/h) stacked diamond and their association with diamond-graphite nanocomposites containing sp3-/sp2-bonding patterns, i.e., diaphites, from hard carbon materials formed by shock impact of graphite in the Canyon Diablo iron meteorite. We show evidence for a range of intergrowth types and nanostructures containing unusually short (0.31 nm) graphene spacings and demonstrate that previously neglected or misinterpreted Raman bands can be associated with diaphite structures. Our study provides a structural understanding of the material known as lonsdaleite, previously described as hexagonal diamond, and extends this understanding to other natural and synthetic ultrahard carbon phases. The unique three-dimensional carbon architectures encountered in shock-formed samples can place constraints on the pressure-temperature conditions experienced during an impact and provide exceptional opportunities to engineer the properties of carbon nanocomposite materials and phase assemblages.

Strengthen Synergistic Effect of Soft Carbon and Hard Carbon Toward High-Performance Anode for K-Ion Battery.

Synergistic effect of soft carbon and hard carbon has been proven to be useful for obtaining excellent anode materials for potassium ion battery, which is determined by the mixing degree of precursors. Inspired by the formation of proteins in biology, peptide bonds are used to connect the precursors of the two sort of carbon to prepare soft-hard hybrid carbons with stronger synergistic effects. The hard carbon domain with nanometer size is so highly distributed in the soft carbon that the synergistic effect between two sorts of carbon is significantly enhanced. After the optimization, the diffusion coefficient of as-prepared hybrid carbon (CSHC3-6-1200) is 10 times larger than that of corresponding carbon synthesized by physical method. Consequently, CSHC3-6-1200 can maintain a specific capacity of 71.6 mAh g-1 at a high current density of 1600 mA g-1. It is believed that this new preparation route may bring a new perspective to the development of soft and hard composite carbon material anodes with high power density and ultralong service life.

Hard carbon derived for lignin with robust and low-potential sodium ion storage

Hard carbon as the anode materials is the key for the development of sodium ion batteries (SIBs). However, low initial Coulomb efficiency (ICE) and specific capacity still hinder the development of hard carbon materials. Herein, hard carbon materials derived from lignin were prepared by controlling carbonization temperature, and the resulting hard carbon were used in SIBs. The storage mechanism of SIBs was discussed. In addition, the effect of carbonization temperature on the structure and chemical performance of hard carbon was investigated. As a result of its optimized microstructure, such as lower specific surface area, larger space of the interlayers and fewer defects, hard carbon from lignin carbonized at 1600 ℃ (LDHC-1600) exhibits ICE of 81.2 %, and reversible discharge capacity of 303 mA h g−1, and the ratio of low potential plateau to total capacity is 74.75 % (226.5 mA h g−1). The mechanism revealed that sodium ions are adsorbed in the slope region and the intercalation and filling mechanism in the plateau region are also verified. This study provides a type of biomass carbon anode material from lignin for application of SIBs.