Carbon Anode Materials Research Articles

Sulfur/Oxygen Codoped Porous Hard Carbon Microspheres for High‐Performance Potassium‐Ion Batteries

AbstractPotassium‐ion batteries (KIBs) are very promising alternatives to lithium‐ion batteries (LIBs) for large‐scale energy storage. However, traditional carbon anode materials usually show poor performance in KIBs due to the large size of K ions. Herein, a carbonization‐etching strategy is reported for making a class of sulfur (S) and oxygen (O) codoped porous hard carbon microspheres (PCMs) material as a novel anode for KIBs through pyrolysis of the polymer microspheres (PMs) composed of a liquid crystal/epoxy monomer/thiol hardener system. The as‐made PCMs possess a porous architecture with a large Brunauer–Emmett–Teller surface area (983.2 m2 g−1), an enlarged interlayer distance (0.393 nm), structural defects induced by the S/O codoping and also amorphous carbon nature. These new features are important for boosting potassium ion storage, allowing the PCMs to deliver a high potassiation capacity of 226.6 mA h g−1 at 50 mA g−1 over 100 cycles and be displaying high stability by showing a potassiation capacity of 108.4 mA h g−1 over 2000 cycles at 1000 mA g−1. The density functional theory calculations demonstrate that S/O codoping not only favors the adsorption of K to the PCMs electrode but also reduces its structural deformation during the potassiation/depotassiation. The present work highlights the important role of hierarchical porosity and S/O codoping in potassium storage.

Boosting Fast Sodium Storage of a Large‐Scalable Carbon Anode with an Ultralong Cycle Life

AbstractSodium‐ion batteries (SIBs) are considered to be a promising alternative for large‐scale electricity storage. However, it is urgent to develop new anode materials with superior ultralong cycle life performance at high current rates. Herein, a low‐cost and large‐scalable sulfur‐doped carbon anode material that exhibits the best high‐rate cycle performance and the longest cycle life ever reported for carbon anodes is developed. The material delivers a reversible capacity of 142 mA h g−1 at a current rate up to 10 A g−1. After 10 000 cycles the capacity is remained at 126.5 mA h g−1; 89.1% of the initial value. Density functional theory computations demonstrate that the sulfur‐doped carbon has a strong binding affinity for sodium which promotes sodium storage. Meanwhile, the kinetics analysis identifies the capacitive charge storage as a large contributor to sodium storage, which favors ultrafast storage of sodium ions. These results demonstrate a new way to design carbon‐based SIBs anodes for next‐generation large‐scale electricity storage.

Design advanced carbon materials from lignin-based interpenetrating polymer networks for high performance sodium-ion batteries

Hard carbon materials hold the most promising application among all anode materials for sodium-ion batteries because of the high storage capacity and good cycling stability. However, the low initial Coulombic efficiency limits their further commercialization. Herein, a new carbonization strategy is presented to prepare a cost-effective hard carbon material as anodes for sodium-ion batteries by pyrolyzing the interpenetrating polymer networks (IPNs) made from the mixture of biomass-derivative lignin and epoxy resin. By adjusting heat-treatment temperatures and the lignin/epoxy resin mass ratios, we can adjust the interlayer distance of carbon crystallites and defect sites for Sodium-ion storage, and thus obtain a hard carbon with a high capacity of 316 mAh g−1, a high ICE of 82%, and good rate capability (e.g., 161 mAh g−1 at 300 mA g−1), all of which are superior to or comparable to those state-of-the-art carbons reported in literatures, by the help of a large interlayer distance of 3.95 Å. Besides, a full cell with the configuration of as-prepared hard carbon anode versus air-stable O3-Na0.9[Cu0.22Fe0.30Mn0.48]O2 cathode is further demonstrated, while it presents a high ICE of 80% and an energy density of 247 Wh kganode−1 (vs. hard carbon) with good cycle performance. These excellent properties verify that our synthetic strategy is feasible, scalable and can be extended into the fabrication of various carbon anode materials with anticipative microstructures for the economical SIBs.

Nanospace confined N,P co-doped carbon foams as anode for highly reversible and high capacity sodium ions batteries

Non-graphitic carbons have shown great potential in sodium ions batteries, however, major hurdle to address is the poor capacity performance. Herein, a facile strategy combining supramolecular chemistry polymerization and nanospace confinement carbonization is proposed to construct interconnected carbon foams with N,P co-doping (MNNPCs) to improve sodium storage performance. Electrochemical impedance spectroscopy (EIS) measurements demonstrate that defined MNNPCs display fast charge transfer at the electrode-electrolyte interface. And the Na+ diffusion coefficient in the MNNPCs electrodes (1.2 × 10−10 cm2 s−1) is about 22 times than that of reference electrode, suggesting excellent sodium ions diffusion kinetics in MNNPCs electrodes. In particular, MNNPCs are capable of delivering superior specific capacity of 394.5 mAh g−1 at 50 mA g−1 after 100 cycles with an initial coulombic efficiency of 58.7%. Such architecture provides a promising structural platform for the preparation of carbon anode materials for high reversible and high capacity sodium ions batteries.

Ex situ solid electrolyte interphase synthesis via radiolysis of Li-ion battery anode–electrolyte system for improved coulombic efficiency

Radiolysis generates artificial solid electrolyte interphase on carbon nanoparticles.

The Non-Ignorable Impact of Surface Oxygen Groups on the Electrochemical Performance of N/O Dual-Doped Carbon Anodes for Sodium Ion Batteries

Oxygen functional groups universally exist in most nitrogen-containing carbon materials, but the influences on structure and sodium storage performance are usually not been well considered. In this work, the carbon nanospheres material with 6.92 at. % of nitrogen and 16.01 at. % of oxygen exhibits high capacity (325 mAh g−1 at 50 mA g−1) and excellent rate performance (114 mAh g−1 at 5 A g−1) as an anode material for sodium-ion batteries. By hydrogen reduction treatment with different time, N/O dual-doped carbon nanospheres with different oxygen content are obtained. According to integrated analysis of structural characterizations and electrochemical performance of these carbon nanospheres, we propose that C–O– will lead to more irreversible capacity and relatively poor cycling performance in long-term cycle due to the irreversible reaction with Na+. However, surface oxygen in C-OH phenol groups, C-O-C ether groups and COOH carboxylic groups can effectively improve capacity by enlarging interlayer distance, increasing active sites, and thus enhancing reaction activity. Our work provides a deep insight about the impact of oxygen functional groups on sodium storage performance and is significant to design advanced carbon anode materials for sodium ion batteries.

3D Amorphous Carbon with Controlled Porous and Disordered Structures as a High‐Rate Anode Material for Sodium‐Ion Batteries

AbstractSodium‐ion batteries (SIBs) have a promising application prospect for energy storage systems due to the abundant resource. Amorphous carbon with high electronic conductivity and high surface area is likely to be the most promising anode material for SIBs. However, the rate capability of amorphous carbon in SIBs is still a big challenge because of the sluggish kinetics of Na+ ions. Herein, a three‐dimensional amorphous carbon (3DAC) with controlled porous and disordered structures is synthesized via a facile NaCl template‐assisted method. Combination of open porous structures of 3DAC, the increased disordered structures can not only facilitate the diffusion of Na+ ions but also enhance the reversible capacity of Na storage. When applied as anode materials for SIBs, 3DAC exhibits excellent rate capability (66 mA h g−1 at 9.6 A g−1) and high reversible capacity (280 mA h g−1 at a low current density of 0.03 A g−1). Moreover, the controlled porous structures by the NaCl template method provide an appropriate specific surface area, which contributes to a relatively high initial Coulombic efficiency of 75%. Additionally, the high‐rate 3DAC material is prepared via a green approach originating from low‐cost pitch and NaCl template, demonstrating an appealing development of carbon anode materials for SIBs.

ZnO-templated N-doped holey graphene for efficient lithium ion storage performance

Two-dimensional carbon nanomaterials have attracted much attention in the last decade because of their promising applications. Recently, the discovery of N-doped holey graphene (NhG) with plentiful in-plane holes and high N contents as the anode material has opened up exciting opportunities to improved electrochemical performance for the li-ion Battery applications. In this paper, we provide a bottom-up and economic solution-combustion synthesis route for the simple preparation of NhG. The nitrogen content, specific surface area (SSA) and pore size of the as-obtained NhG all increase with the increasing ratio between the oxidizer and fuel. With the increased nitrogen content and SSA, the prepared NhG exhibits higher capacity performance for lithium ion storage, especially for the prepared NhG4, gives rise to the highest initial reversible capacity 1354 mAh g−1 at 0.2 A g−1 as the carbon anode material. The detailed explanation of this “Bottom-up” route to prepare NhG is also provided for its extensive applications.

Nanotube-like hard carbon as high-performance anode material for sodium ion hybrid capacitors

Sodium ion hybrid capacitors (SIHCs) are of great concern in large-scale energy storage applications due to their good energy-and-power characteristic, as well as abundant reserves and low cost of sodium. However, the sluggish faradaic kinetics of anode materials severely limit the overall electrochemical performance of SIHC devices. Herein, we report an application of nanotube-like hard carbon (NTHC) anode material prepared by high-temperature carbonization (1150°C) of polyaniline (PANI) nanotubes for high-performance SIHCs. As a result, the assembled sodium ion half-cell with NTHC shows a high reversible capacity of 419.5 mA h g−1 at 0.05 A g−1 and a good rate performance of 74.6 mA h g−1 at 2.5 A g−1 in a potential window of 0–2 V ( vs . Na/Na+). On this basic, a SIHC using such NTHC as anode and a high-capacity activated carbon (APDC) as cathode is fabricated, which exhibits a high energy density of 133.0 W h kg−1 at 2850 W kg−1 and still remains 100.9 W h kg−1 at 14,250 W kg−1. Within the potential range of 1.5–3.5 V, the SIHCs display an outstanding cycling stability tested at 2 A g−1 with a good capacity retention of 82.5% even after 12,000 cycles.

Synthesis of self N-doped carbonaceous nanorods as stable lithium-ion battery anode materials

It’s meaningful to design and fabricate novel high-performance carbon anode materials for lithium ion batteries (LIBs). Herein, 3-aminophenol-formaldehyde resin/silica nanorods were synthesized via a sol–gel transcription method, using cetyltrimethyl ammonium bromide as the template and pentanol as co-structure directing agent. After carbonization at 600°C and removal of silica, carbonaceous nanorods with N content of 7.87wt% and specific surface area of 551.3m2g−1 were obtained. They showed a stable discharge capacity of 696.7mAhg−1 after 400 cycles. Carbonaceous nanorods (comprising 9.6wt% β-SiC) with N content of 1.22wt% and specific surface area of 1079.1m2g−1 were also obtained at 1400°C. They showed a stable discharge capacity of 457.9mAhg−1 after 400 cycles. The results prove that the synthesized N-doped carbonaceous nanorods are good anode candidates for LIBs.

Cycling Porous Silicon with Lithium Iron Phosphate for High Performance Li-Ion Batteries

Silicon has drawn significant attention as an anode material for lithium ion batteries due to it significant capacity over carbon anode materials. Much of the literature as focused on cycling silicon with lithium-metal as the counter-electrode, which serves as an infinite source of lithium ions. We have recently shown that porous silicon is able to cycle at 1000 mAh/g at 1C for 600+ cycles against a lithium-metal counter-electrode. Here we will present the practical applicability and cycling performance of porous silicon with commercially available lithium-iron phosphate (LFP) cathodes. Having excess anode capacity is the standard widely used in industry with graphite-based lithium ion batteries to prevent lithium plating issue. However, we have observed that our porous silicon exhibits longer cycle life when the cathode capacity is in excess. This is likely due to the large consumption of lithium-ions during the formation of solid-electrolyte interface (SEI) layer. Our experiments will show that two different cycle performance based on either the anode or cathode in excess for the purpose of assembling a full-cell battery. Furthermore, a three-electrode test cell is used to monitor the I-V curves for each electrode independently to determine if lithium plating or other electrode degradation mechanisms occur.

A high-performance sodium-ion battery enhanced by macadamia shell derived hard carbon anode

Hard carbon anode materials for sodium-ion batteries (SIB) have usually been tested in half-cells by cycling between 0–2V, and is believed to exhibit low rate capability. However, we find that the specific capacity, the rate performance, and the cycling performance may all be severely underestimated with the traditional half-cell cycling evaluation method, due to premature truncation of part II of the capacity (part I is “sloping”, part II is “plateauing”, while part III is Na metal deposition). Here we introduce a sodium-matched SIB full-cell architecture, with newly developed hard carbon derived from macadamia shell (MHC) as anode and Na[Cu1/9Ni2/9Fe1/3Mn1/3]O2 (NCNFM) as the cathode material, with anode/cathode areal capacity ratio of 1.02–1.04. Our carefully balanced full-cells exhibit a cell-level theoretical specific energy of 215Whkg−1 at C/10 and 186Whkg−1 at 1C based on cathode-active and anode-active material weights, and an outstanding capacity retention of 70% after 1300 cycles (∼2000h). Traditional half-cell test (THT) of MHC using superabundant Na metal counter electrode shows only 51.7mAhg−1 capacity at 1C, and appears to die in no more than 100h due to low open-circuit voltage slope and large polarization. A revised half-cell test (RHT) which shows much better agreements with full-cell test results, delivers a specific capacity of 314mAhg−1, with an initial Coulombic efficiency of ∼91.4%, which is comparable to that of graphite anode in lithium-ion batteries.

Low-Cost and High-Performance Hard Carbon Anode Materials for Sodium-Ion Batteries.

As an anode material for sodium-ion batteries (SIBs), hard carbon (HC) presents high specific capacity and favorable cycling performance. However, high cost and low initial Coulombic efficiency (ICE) of HC seriously limit its future commercialization for SIBs. A typical biowaste, mangosteen shell was selected as a precursor to prepare low-cost and high-performance HC via a facile one-step carbonization method, and the influence of different heat treatments on the morphologies, microstructures, and electrochemical performances was investigated systematically. The microstructure evolution studied using X-ray diffraction, Raman, Brunauer–Emmett–Teller, and high-resolution transmission electron microscopy, along with electrochemical measurements, reveals the optimal carbonization condition of the mangosteen shell: HC carbonized at 1500 °C for 2 h delivers the highest reversible capacity of ∼330 mA h g–1 at a current density of 20 mA g–1, a capacity retention of ∼98% after 100 cycles, and an ICE of ∼83%. Additionally, the sodium-ion storage behavior of HC is deeply analyzed using galvanostatic intermittent titration and cyclic voltammetry technologies.

Passivated Lithium Metal As Anode Materials for Advanced Battery Applications

Lithium (Li) metal electrodes are widely regarded as the promising anodes since their energy densities far exceed those of lithium-intercalated carbon anode materials. However, Li metal anodes are plagued with dendrite formation and electrolyte incompatibility that limits their lifespan and stability within any battery systems that employ them. A promising way to resolve those limitations involves the use of passivating layers to protect the surface of Li metal. This study will explore the mechanism behind the formation of Li dendrite and the passivation of the Li metal surface; it will also discover how coating Li metal with Li ion-conducting layers would effectively protect it from attacks by solvents, contamination, and active species in the electrolyte. Here, we demonstrate the facile method to protect the surface of Li metal with precise structural control. Utilizing symmetric Li-Li cell configuration, the protected Li exhibited stable cycling with minimal polarization at current density of 10 mA cm-2; it also demonstrated over 300% longer cycle life than unprotected Li metal. In addition, a full-cell system using sulfur cathode confirmed an improved capacity retention with our protected Li metal over the cell with bare Li metal for over 300 cycles. The improvement in cycle life and the suppression of lithium dendrite growths through the passivation of Li metal electrodes reveal a new direction for the advancement of Li metal anode in rechargeable batteries.

The mechanism of the sodiation and desodiation in Super P carbon electrode for sodium-ion battery

The sodiation and desodiation of sodium (Na) into the Super-P carbon anode material were investigated using electrochemical analyses, high-resolution transmission electron microscopy (HRTEM), and neutron powder diffraction (NPD). In the sodiated Super-P carbon, sodium is stored both in the graphite interlayer space of carbon nano-particles and pores between the particles. Sodium metal clusters found in micro-pores between the carbon particles are responsible for the large irreversible capacity of the Super-P electrode. The graphite interlayer distance increases on sodiation from 3.57 Å to two distinct values of ∼3.84 and 4.41 Å. The mechanism of the process is discussed.

Ion-Catalyzed Synthesis of Microporous Hard Carbon Embedded with Expanded Nanographite for Enhanced Lithium/Sodium Storage.

Hard carbons attract myriad interest as anode materials for high-energy rechargeable batteries due to their low costs and high theoretical capacities; practically, they deliver unsatisfactory performance due to their intrinsically disordered microarchitecture. Here we report a facile ion-catalyzed synthesis of a phenol-formaldehyde resin-based hard-carbon aerogel that takes advantage of the chelation effect of phenol and Fe3+, which consists of a three-dimensionally interconnected carbon network embedded with hydrogen-rich, ordered microstructures of expanded nanographites and carbon micropores. The chelation effect ensures the homodispersion of Fe in the polymer segments of the precursor, so that an effective catalytic conversion from sp3 to sp2 carbon occurs, enabling free rearrangement of graphene sheets into expanded nanographite and carbon micropores. The structural merits of the carbon offer chances to achieve lithium/sodium storage performance far beyond that possible with the conventional carbon anode materials, including graphite and mesocarbon microbeads, along with fast kinetics and long cycle life. In this way, our hard carbon proves its feasibility to serve as an advanced anode material for high-energy rechargeable Li/Na batteries.

Lithium Ion Capacitor with Massive Power Density Using Electrodes from Silicon Oxycarbide and Activated Carbon Derived from Zalacca Salacca Peels

Although batteries have been successfully employed in light-duty vehicles (hybrid and fully electric cars), batteries still find it is hard to satisfy power-hungry platforms such as trucks, trams, and buses. Conventional lithium ion batteries (LIB) could provide power density less than 3 kW/kg with relatively moderate energy density. On the other side, supercapacitors (SCs) that are known to provide power density of more than 10 kW/kg have a very low energy density of less than 1 Wh/kg and thus, SCs could not be used solely as energy storage. However, employing anode from LIB and electrode from SC together in a single system would benefit both high energy and power density, which system is-so called lithium ion capacitor (LIC). To date, so many attempts have been done to investigate the best anode material combination with activated carbon (AC) to obtain high performance LIC. The anode materials that are commonly utilized in LIB such as graphite, hard carbon, Li4Ti5O12 (LTO), Fe3O4, SnO2, and silicon based material have been extensively studied for LIC. Graphite that is known as an ubiquitous anode material in LIBs provided relatively high energy density of c.a. 100 Wh/kg and maximum power density of less than 2 kW/kg in LIC. Among all, LTO application was found to be the least desirable material for LIC since it provided relatively low maximum energy and power density, which was merely less than 40 Wh/kg and 2 kW/kg, respectively, due to its low conductivity and high voltage plateau at around 1.5 V. Grphene has been used to reinforce rate capability of Fe3O4 and it demonstrated promising energy density as high as 86 Wh/kg. However, the maximum power density of the enhaced electrode material was only 2.6 kW/kg. Higher power LIC can be achieved by harnessing hard carbon anode material, which displayed maximum power density of about 50 kW/kg. However, the high power density of hard caron in LIC was compensated by extremely low energy density of less than 2 Wh/kg. Herein, we investigate the electrochemical performance of LIC by using silicon oxycarbide (SiOC) as the anode and the AC from biomass (Zalacca salacca) peels as the cathode to provide massive power while maintaining the energy density relatively high. SiOC showed an outstanding rate capability performance indicated by relatively high discharge capacity of over than 200 mAh/g at current density of 80 A/g. The excelent rate capability was attributed to the fast lithium diffusion in SiOC, which was represented by high lithium diffusion coefficient (DLi+) of 5.1 × 10-6 cm2/s. Meanwhile, the AC derived from biomass is promising since its surface area (c.a. 2600 m2/g) and capacitance (163.7 F/g) was significantly higher than that of commercial AC. Combination of SiOC and AC derived from Zalacca salacca in a single unit of LIC could be used to provide a massive power density of 155kW/kg while maintained relatively high energy density of 25 Wh/kg. Moreover, the resulting LIC demonstrated highly stable cycle retention at high C-rate. After reaching equilbrium state, the cycle retention of LIC at 50C was 99.4% after more than 40,000 cycles. At higher C-rate of 100C, the cycle retention of the LIC was 99% even after more than 75,000 cycles. The present study indicates that LIC design based on SiOC and AC from Zalacca salacca peels is suitable for energy storage in high-duty platforms such as trucks, trams, and buses.

Resilient Yolk–Shell Silicon–Reduced Graphene Oxide/Amorphous Carbon Anode Material from a Synergistic Dual‐Coating Process for Lithium‐Ion Batteries

AbstractA dual‐coating process was developed to prepare a unique yolk–shell silicon–reduced graphene oxide/amorphous carbon (YS‐Si@rGO/a‐C) anode material. The nanostructured Si composite anode material consists of Si cores, evenly wrapped with a first coating of graphene oxide constructed through electrostatic self‐assembly, and a shell of a second reinforced coating of graphene oxide/amorphous carbon, integrated by using an economic hydrothermal carbonization process. Thermal reduction and HF etching were then applied to reduce graphene oxide into graphene and to create the required void space to endow the hybrid material with sufficient mechanical strength and to buffer against stresses induced by volume changes of the Si nanoparticles. The obtained YS‐Si@rGO/a‐C composite anode material has structural integrity together with conductive 3D‐network beneficial to its electrochemical performance, attributed to the synergy of electrostatic self‐assembly and hydrothermal carbonization. As a result, the composite anode has a superior initial coulombic efficiency of 76 %, surpassing other published Si/G composite anodes, as well as an initial cycle reversible capacity of 1668 mAh g−1 at 0.4 A g−1 and a capacity retention of 75 % after over 100 cycles, when compared with the yolk–shell structured Si@a‐C anode.

Poly(anthraquinonyl sulfide) cathode for potassium-ion batteries

Potassium-ion batteries (KIBs) are a promising sustainable energy storage technology due to the high abundance and low cost of potassium. Carbon anode materials for KIBs have seen great successes, but the development of cathode materials is yet to catch up. In this study, poly(anthraquinonyl sulfide) (PAQS) is evaluated as a cathode material for KIBs. It exhibits a high reversible capacity of 200mAh/g, which is the highest value for a potassium storage cathode material. The cell shows two slopes averaged at 2.1 and 1.6V vs. K+/K. It shows a good cycling performance with the capacity retention of 75% after 50cycles at a rate of C/10. These preliminary results indicate that PAQS is a promising cathode material for KIBs.

A New Strategy to Mitigate the Initial Capacity Loss of Lithium Ion Batteries

Electrode materials and electrolyte choices largely dictate the design parameters and the type of lithium-ion battery (LIB) that can be optimized and eventually utilized. Certainly all three components (anode, electrolyte, and cathode) must work in harmony to produce the highest possible energy density achievable for an LIB-based energy storage device. Balancing the electrochemical performance characteristics of the cathode and anode active materials is critical for maximizing the power/energy density of a LIB. Hard carbon (non-graphitizable) anode materials, like tin, tin oxide, silicon and silicon oxide, have a high theoretical capacity (>550 mAh/g depending on their structural and chemical properties) but unfortunately they also exhibit a large initial capacity loss (ICL), which overrides the true reversible capacity in a full cell. Overcoming the large ICL of hard carbon in a full-cell lithium-ion battery (LIB) necessitates a new strategy wherein a sacrificial lithium source additive such as Li5FeO4 (LFO) is used on the cathode side. Full batteries using hard carbon coupled with LFO/LiCoO2 (LCO) are currently under development at our laboratory. We find that the reversible capacity of a cathode containing LFO can be increased by 24%. Furthermore, the cycle performance of full cells with LFO additive is improved from <90% to >95%. We believe that the LFO can not only address the irreversible capacity loss of the anode, but can also provide the additional lithium ion source required to mitigate the lithium loss caused by side reactions. In addition, we have explored the possiblity to achieve higher capacity on hard carbon, whereby the energy density of full cells can be increased from ca. 300 Wh/kg to >400 Wh/kg .