Carbon Anodes For Sodium-ion Batteries Research Articles

Ball-Milling-Assisted N/O Codoping for Enhanced Sodium Storage Performance of Coconut-Shell-Derived Hard Carbon Anodes in Sodium-Ion Batteries.

Sodium-ion batteries (SIBs) are regarded as cost-effective alternatives or competitors to lithium-ion batteries for large-scale electric energy storage applications. However, their development has been hindered by the high cost of hard carbon (HC) anodes and poor electrochemical performance. To enhance the sodium storage capacity and rate performance of HC, this study accelerated the electrochemical performance of coconut-shell-derived HC anodes for SIBs through N/O codoping using ball milling and pyrolysis. Experimental results demonstrate that the simultaneous introduction of N and O generates a synergistic effect, increasing the surface oxygen-containing functional groups, defects, and interlayer spacing of coconut-shell-derived HC through the codoping of light elements. The excellent strategy has increased the slope capacity and platform capacity of HC, and the synergistic modification of N/O has increased its reversible specific capacity from 272 to 343 mA h g-1 (30 mA g-1), with a retention rate of approximately 92.1% after 100 cycles. In addition, it also exhibits an excellent rate performance, reaching 178 mA h g-1 at 1500 mA g-1. In summary, this study presents an effective strategy for modifying biomass-derived HC.

Multieffect Preoxidation Strategy to Convert Bituminous Coal into Hard Carbon for Enhancing Sodium Storage Performance.

Preoxidation is an effective strategy to inhibit the graphitization of coals during carbonization. However, the single effect of the traditional preoxidation strategy could barely increase surface-active sites, hindering further enhancement of sodium storage. Herein, a multieffect preoxidation strategy was proposed to suppress structural rearrangement and create abundant surface-active sites. Mg(NO3)2·6H2O helps to introduce oxygen-containing functional groups into bituminous coal at 450 °C, which acted as a cross-linking agent to inhibit the rearrangement of carbon layers and promote structural cross-linking during the subsequent thermal carbonization process. Besides, the residue solid decomposition product MgO would react with carbon to create surface-active sites. The obtained coal-based hard carbon contained more pseudographitic domains and sodium storage active sites. The optimized sample could deliver an excellent capacity of 287.1 mAh g-1 at 20 mA g-1, as well as remarkable cycling stability of capacity retention of 96.1% after 200 cycles at 50 mA g-1, and notable capacity retention of 88.9% after 1000 cycles at 300 mA g-1. This work provides an effective and practical strategy to convert low-cost bituminous coal into advanced hard carbon anodes for sodium-ion batteries (SIBs).

(Invited) Novel Q Carbon Anodes for Sodium-Ion Batteries

The main goal of this research is to develop low-cost anodes for sodium-ion batteries. Lack of standard carbon intercalation/insertion anode for sodium-ion batteries has greatly hindered its application. Two types of Q carbons have been studied as a potential anode material for sodium-ion batteries. Q1 carbon exhibits a high initial columbic efficiency of 81% but has a low-capacity retention of less than 60%. Whereas Q2 carbon has a low initial columbic efficiency of 58% but has a high-capacity retention of 81%. Q2 exhibited a stable capacity of 168 mAh/g at a cycling rate of C/3 which is comparable to other high performing hard carbon anodes. This work will discuss in detail about the synthesis procedure, microstructural and electrochemical performance of the Q carbons. This study reports the successful pathway of using Q carbon as a promising anode for sodium ion batteries.ACKNOWLEDGEMENTSThis research was supported by the U.S. Department of Energy, Office of Science, Basic Energy Sciences, Materials Sciences and Engineering Division.

Regulating the active hydroxyl group of starch: Revealing the evolution of hard carbon structure and sodium storage behavior

The active hydroxyl group of starch has a crucial effect in regulating the microstructure of hard carbon anodes for sodium-ion batteries. By optimizing the chemical structure of starch and controlling the pyrolysis process, high-performance hard carbon materials can be obtained. These active hydroxyl groups are primarily located on the terminal and ring structures of glucose units, exerting significant influence on the formation and performance of hard carbon. Our results demonstrate that low-temperature oxidation treatment effectively modifies the terminal hydroxyl groups in precursor materials, facilitating chain cross-linking and leading to a more robust hard carbon structure. This cross-linking effect helps suppress excessive foaming during pyrolysis, thereby enhancing the stability of the hard carbon structure. Furthermore, by modifying the hydroxyl group on the ring structure of precursors, we can control the pyrolysis process, promote pore closure, and further improve the low plateau capacity of hard carbon anode materials from 153.95 to 219.58 mAh g −1. This study offers novel insights into harnessing and understanding starch's active hydroxyl groups in preparing hard carbon materials—a significant contribution towards optimizing their performance as anode materials.

Modifying lignite-derived hard carbon with micron carbon tubes to improve sodium-ion storage

Lignite is a feasible raw material for the development of hard carbon anodes for sodium-ion batteries because of its high abundance and cheap cost. However, the existence of more defects in lignite-derived carbon, leads to unsatisfactory electrochemical performance as the anode of sodium-ion batteries, such as the initial Coulombic efficiency (ICE) and capacity retention rate. In this work, we introduce a preparation process of lignite-derived hard carbon using carbonized lignite and oleic acid (C9H16O2) as precursors. The micron carbon tubes (MCTs) generation on the hard carbon surface can provide additional Na+ active sites and reduce the defects, which effectively enhances the specific capacity and ICE of the anode. Benefiting the MCT modification, the hard carbon anode has a high reversible capacity of 244.8 mAh g−1 and ICE of 76.72%, which is respectively 30% and 10% higher than that of the bare hard carbon anode, this is of significance for the practical application of coal-based hard carbon in sodium-ion batteries.

Sub-minute carbonization of polymer/carbon nanotube films by microwave induction heating for ultrafast preparation of hard carbon anodes for sodium-ion batteries

Hard carbons (HCs) are excellent anode materials for sodium-ion batteries (SIBs). However, the carbonization and granulation of HC powders involve complex processes and require considerable energy. Here, we developed a facile method for manufacturing HC anodes for SIBs via a novel microwave induction heating (MIH) process for polymer/single-walled carbon nanotube (SWCNT) films. Numerical simulations solving electromagnetic field and heat transfer problems revealed the MIH mechanism; the electric current induced by the applied microwave enables direct Joule heating of the SWCNT networks in the composite film. Consequently, the composite films could be heated to the target temperatures (800–1400 °C) and free-standing HC/SWCNT anodes could be prepared by applying MIH for only 30 s. Comparative analyses confirmed that ultrafast MIH is a reliable technique for producing HC anodes and can replace conventional carbonization processes which require a high-temperature furnace. Moreover, the HC/SWCNT anodes prepared by the ultrafast MIH were successfully applied to the SIB full cells. Finally, the feasibility of MIH for scalable roll-to-roll production of HC anodes was verified through local heating tests using a circular sheet larger than a resonator.

Demineralization activating highly-disordered lignite-derived hard carbon for fast sodium storage

Lignite, as one of the coal materials, has been considered a promising precursor for hard carbon anodes in sodium-ion batteries (SIBs) owing to its low cost and high carbon yield. Nevertheless, hard carbon directly derived from lignite pyrolysis typically exhibits highly ordered microstructure with narrow interlayer spacing and relatively unreactive interfacial properties, owing to the abundance of polycyclic aromatic hydrocarbons and inert aromatic rings within its molecular composition. Herein, an innovative demineralization activating strategy is established to simultaneously modulate the interfacial properties and the microstructure of lignite-derived carbon for the development of high-performance SIBs. Demineralization process not only creates numerous void spaces in the matrix of lignite precursor to assist aromatic hydrocarbon rearrangement, thereby reducing the ordering and expanding interlayer spacing, but also exposes more interfacial oxygen-containing functional groups to effectively increasing the sodium storage active sites. As a result, the optimal demineralized lignite-derived hard carbon (DLHC 1300) delivers a high reversible capacity of 335.6 mAh g−1 at 30 mA g−1, superior rate performance of 246.3 mAh g−1 at 6 A g−1 and nearly 100 % capacity retention after 1100 cycles at 1A g−1. Furthermore, the optimized DLHC 1300 material functions as an outstanding anode in sodium ion full cells. This work significantly advances the development of low-cost, high-performance commercial hard carbon anodes for SIBs.

Phenolic Resin Derived Hard Carbon Anode for Sodium-Ion Batteries: A Review

Phenolic Resin Derived Hard Carbon Anode for Sodium-Ion Batteries: A Review

In-situ capture defects through molecule grafting assisted in coal-based hard carbon anode for sodium-ion batteries

Sodium-ion batteries is not essential but also potential to support energy storage system due to the low cost. It's worth noting that low price and high carbon production helps coal extraordinary promise as hard carbon precursor. However, low initial coulombic efficiency (ICE) and practical Na+ storage specific capacity barrier their application owing to lots of defects. Herein, a grafting method is proposed to decrease defects, introducing glucose with simple one step carbonization process. Utilizing the reaction between glucose and coal reduces the defects, which generates a high ICE with less irreversible sodium ion consumption. Meanwhile the expanded carbon layer spaces enable the fast sodium ions transfer, leading to an optimized sodium storage performance. The grafted glucose obviously decreases the defects during the carbonization process and contributes extra sodium storage capacity. The optimal CG0.1 exhibits higher reversible capacity of 293 mAh∙g−1 and ICE of 84 % than pristine coal pyrolytic carbon (250 mAh∙g−1 and 79 %). Besides, it also delivers outstanding capacity retention with 95.3 % and 95.8 % after 1000 cycles at 0.3 A∙g−1 (240 mAh∙g−1) and at 1 A∙g−1 (207 mAh∙g−1).

One-Step Construction of Closed Pores Enabling High Plateau Capacity Hard Carbon Anodes for Sodium-Ion Batteries: Closed-Pore Formation and Energy Storage Mechanisms.

Closed pores play a crucial role in improving the low-voltage (<0.1 V) plateau capacity of hard carbon anodes for sodium-ion batteries (SIBs). However, the lack of simple and effective closed-pore construction strategies, as well as the unclear closed-pore formation mechanism, has severely hindered the development of high plateau capacity hard carbon anodes. Herein, we present an effective closed-pore construction strategy by one-step pyrolysis of zinc gluconate (ZG) and elucidate the corresponding mechanism of closed-pore formation. The closed-pore formation mechanism during the pyrolysis of ZG mainly involves (i) the precipitation of ZnO nanoparticles and the ZnO etching on carbon under 1100 °C to generate open pores of 0.45-4 nm and (ii) the development of graphitic domains and the shrinkage of the partial open pores at 1100-1500 °C to convert the open pores to closed pores. Benefiting from the considerable closed-pore content and suitable microstructure, the optimized hard carbon achieves an ultrahigh reversible specific capacity of 481.5 mA h g-1 and an extraordinary plateau capacity of 389 mA h g-1 for use as the anode of SIBs. Additionally, some in situ and ex situ characterizations demonstrate that the high-voltage slope capacity and the low-voltage plateau capacity stem from the adsorption of Na+ at the defect sites and Na-cluster formation in closed pores, respectively.

Synthesis strategies and obstacles of lignocellulose-derived hard carbon anodes for sodium-ion batteries

In this perspective, we present an overview of the research and advancement of lignocellulose-derived hard carbon anodes and their pivotal role in the commercialization of sodium-ion batteries. Hard carbon anodes, sourced from lignocellulosic biomasses, exhibit considerable promise due to their widespread availability, economical viability, and environmentally friendly attributes with zero carbon-dioxide emissions. Given the intricate compositions and composite nature of lignocellulosic materials, it becomes imperative to prioritize factors crucial for the fabrication of hard carbon anodes that exhibit enhanced sodium-ion storage capabilities. Thus, our study offers an extensive overview of the structure and performance nuances of hard carbon anodes derived from cellulose, hemicellulose, and lignin. Furthermore, it delves into the fundamental principles governing synthesis methodologies and confronts the challenges inherent in producing lignocellulose-derived hard carbon anodes tailored specifically for sodium-ion batteries.Graphical

Comparison and optimization of biomass-derived hard carbon as anode materials for sodium-ion batteries

Hard carbon made from biomass-based precursors has many advantages as anode for sodium-ion batteries such as low cost and sustainability. In this work, three different hard carbon materials derived from bamboo, wood and coconut shell with the same particle size are screened, combining acid etching and carbonization at 1200 °C, to compare the sodium ion storage performances. The anode material originated from bamboo shows the highest specific capacity among them. Subsequently, the hard carbon from bamboo is optimized by the same process, but changing the carbonization temperature ranging from 1000 °C to 1400 °C. Among the hard carbon materials, the bamboo-derived one prepared at 1300 ℃ exhibits excellent electrochemical performances at a current density of 30 mA g−1, with a high reversible specific capacity of 303.8 mAh/g and an initial coulombic efficiency of 83.7 %. After 150 cycles, a capacity retention of 94.7 % is achieved at a current density of 300 mA g−1. This work provides a potential hard carbon anode for sodium-ion batteries to realize large-scale energy storage due to the cheap sources of bamboo.

Effect of precursor morphology of cellulose-based hard carbon anodes for sodium-ion batteries

Hard carbon with different microstructures and physicochemical properties can be obtained based on the precursor used, and these properties have a direct impact on the electrochemical performance. Herein, two different precursors from a single source of waste cotton textiles have been prepared to be either cotton snippets retaining the original fiber structure of cotton or a microfibrillated cellulose, which has a very different morphology and surface area. Both the cotton snippet (CS) and the microfibrillated cellulose (MFC) have been carbonized to prepare hard carbons MFC-C and CS-C, and their electrochemical performance is evaluated in sodium-ion batteries (NIBs). Physicochemical properties in terms of a higher interlayer spacing of 3.71 Å and a high defect ratio (ID/IG) of 1.10 resulted in CS-C having a relatively higher specific capacity of 240 mAh g-1 in comparison to 199 mAh g-1 in MFC-C when cycled at 50 mA g-1. In addition, ex-situ MAS (magic angle spinning) NMR (nuclear magnetic resonance) spectroscopy on the solid electrolyte interphase (SEI) layer of CS-C revealed a lesser amount of conductive SEI layer on its surface compared to MFC-C, mainly composed of NaF and an additional FSI-derived Na complex, suggested to be Na2 [SO3-N-SO2F]). In contrast, MFC-C revealed a greater amount of SEI-related compounds, which is interpreted as a thicker SEI layer resulting in a long Na+ diffusion pathway and slower Na+ reaction kinetics. This study provides insight into the effect of microstructural differences arising from different cellulose precursors on the electrochemical performance, thereby aiding in the fabrication and optimization of hard carbon anodes for sodium-ion batteries.

Study of stable sodium ion storage in porous carbon derived from puffball biomass

The pursuit of affordable anode materials for sodium-ion batteries (SIBs) has become imperative in light of the rising energy demand in modern society. Hard carbon (HC), a highly promising candidate for SIBs, has garnered interest among researchers. In this study, we present a novel approach involving the thermal treatment of low-cost puffball (PB) at various temperatures to produce cost-effective porous carbon, which holds great potential as an anode material for SIBs. The carbon derived from the treated puffball biomass showcases distinctive morphological features, including carbon tubes and plentiful balloon-like porous structures. This morphological structure can prevent the agglomeration and stacking of carbon materials, which can effectively increase the active sites and energy storage channels. The resulting puffball biomass-derived carbon exhibits a reversible capacity of 205.05 mAh g−1 at 100 mA g−1. Even after 600 cycles at a current density of 2 A g−1, the discharge capacity remains as high as 146.98 mAh g−1. These findings emphasize the remarkable performance and cycling stability of the carbon material. Significantly, the puffball biomass-derived carbon exhibited an impressive initial Coulomb efficiency of 57.6%, which is a noteworthy achievement. Moreover, we employed in situ XRD to investigate its energy storage mechanism in sodium-ion batteries. When integrated into a complete cell with Na3V2(PO4)3 (NVP) and bulking materials, the carbon anode exhibited impressive multiplicative performance and maintained good cycling stability. These findings not only provide new insights into the design of carbon anodes for sodium-ion batteries but also emphasize their exceptional attributes such as excellent initial coulombic efficiency, impressive rate capability, and cost-effectiveness for sodium storage.

Deciphering Electrolyte Dominated Na+ Storage Mechanisms in Hard Carbon Anodes for Sodium-Ion Batteries.

Although hard carbon (HC) demonstrates superior initial Coulombic efficiency, cycling durability, and rate capability in ether-based electrolytes compared to ester-based electrolytes for sodium-ion batteries (SIBs), the underlying mechanisms responsible for these disparities remain largely unexplored. Herein, ex situ electron paramagnetic resonance (EPR) spectra and in situ Raman spectroscopy are combined to investigate the Na storage mechanism of HC under different electrolytes. Through deconvolving the EPR signals of Na in HC, quasi-metallic-Na is successfully differentiated from adsorbed-Na. By monitoring the evolution of different Na species during the charging/discharging process, it is found that the initial adsorbed-Na in HC with ether-based electrolytes can be effectively transformed into intercalated-Na in the plateau region. However, this transformation is obstructed in ester-based electrolytes, leading to the predominant storage of Na in HC as adsorbed-Na and pore-filled-Na. Furthermore, the intercalated-Na in HC within the ether-based electrolytes contributes to the formation of a uniform, dense, and stable solid-electrolyte interphase (SEI) film and eventually enhances the electrochemical performance of HC. This work successfully deciphers the electrolyte-dominated Na+ storage mechanisms in HC and provides fundamental insights into the industrialization of HC in SIBs.

Revealing the closed pore formation of waste wood-derived hard carbon for advanced sodium-ion battery

Although the closed pore structure plays a key role in contributing low-voltage plateau capacity of hard carbon anode for sodium-ion batteries, the formation mechanism of closed pores is still under debate. Here, we employ waste wood-derived hard carbon as a template to systematically establish the formation mechanisms of closed pores and their effect on sodium storage performance. We find that the high crystallinity cellulose in nature wood decomposes to long-range carbon layers as the wall of closed pore, and the amorphous component can hinder the graphitization of carbon layer and induce the crispation of long-range carbon layers. The optimized sample demonstrates a high reversible capacity of 430 mAh g−1 at 20 mA g−1 (plateau capacity of 293 mAh g−1 for the second cycle), as well as good rate and stable cycling performances (85.4% after 400 cycles at 500 mA g−1). Deep insights into the closed pore formation will greatly forward the rational design of hard carbon anode with high capacity.

Invasive alien plant biomass-derived hard carbon anode for sodium-ion batteries

In the context of rampant growth of invasive plants, finding suitable ways for resource utilization has become the optimal choice for invasive plant management. In the field of energy storage, sodium-ion batteries have been limited by the lack of appropriate anode materials, and hard carbon stands out as the most promising candidate. Therefore, this study focuses on the preparation of biomass-derived carbons from three invasive plant species, namely Spartina alterniflora Loisel., Solidago canadensis L., and Erigeron canadensis L., through high-temperature carbonization. The resulting biomass carbons are then subjected to cleaning and activation processes to prepare sodium-ion anode materials. The internal structure of the materials was characterized using SEM, TEM, XRD, XPS, Raman spectroscopy, and BET. The materials exhibited a significant amount of pore structures, with interlayer spacing around 0.37 nm, which is larger than the original graphite interlayer spacing. The plant anode materials were assembled into full batteries for cyclic charge/discharge tests. The results show that all three anode materials have good multiplicative performance and excellent cyclable charge/discharge. After 100 cycles at a current of 50 mA in the voltage range of 0–3.0 V, the reversible capacities of the three materials reached 245.3, 207.19, and 227.12 mAh/g, respectively. Among them, the material derived from Spartina alterniflora maintained a capacity of 141.63 mAh/g even after 1000 cycles at a current of 200 mA, demonstrating the best capacity performance.

High-Energy Ball Milling Promoted Sulfur Immobilization for Constructing High-Performance Na-Storage Carbon Anodes.

Sulfur (S) doping is an effective method for constructing high-performance carbon anodes for sodium-ion batteries. However, traditional designs of S-doped carbon often exhibit low initial Coulombic efficiency (ICE), poor rate capability, and impoverished cycle performance, limiting their practical applications. This study proposes an innovative design strategy to fabricate S-doped carbon using sulfonated sugar molecules as precursors via high-energy ball milling. The results show that the high-energy ball milling can immobilize S for sulfonated sugar molecules by modulating the chemical state of S atoms, thereby creating a S-rich carbon framework with a doping level of 15.5 wt %. In addition, the S atoms are present mainly in the form of C-S bonds, facilitating a stable electrochemical reaction; meanwhile, S atoms expand the spacing between carbon layers and contribute sufficient capacitance-type Na-storage sites. Consequently, the S-doped carbon exhibits a large capacity (>600 mAh g-1), a high ICE (>90%), superior cycling stability (490 mAh g-1 after 1100 cycles at 5 A g-1), and outstanding rate performance (420 mAh g-1 at a high current density of 50 A g-1). Such excellent Na-storage properties of S-doped carbon have rarely been reported in the literatures before.

Hard carbon anodes for sodium-ion batteries: Dependence of the microstructure and performance on the molecular structure of lignin

Hard carbon is currently believed to be the most promising anode material for commercial sodium-ion batteries. However, the sodium-ion storage mechanism of hard carbons remains ambiguous due to the unclear relationship between their microstructures and sodium-ion storage performance. This work reports several hard carbons with different pore structures by the carbonization of different lignin precursors, and further studies the relationship between their microstructures and sodium-ion storage performance. Corn cob lignin, pine lignin, and acetylated pine lignin with different molecular structures were selected as the precursors for the preparation of hard carbons. It is found that hard carbon prepared by corn cob lignin has the highest closed pore volume, resulting in the highest plateau capacity. The formation of closed pores is due to the formation of micropores at low pyrolysis temperatures. The micropores then transform into closed pores at high carbonization temperatures. N2 adsorption/desorption, CO2 adsorption/desorption, and small-angle X-ray scattering are used to analyze the pore architectures of the obtained hard carbons, and a method for calculating the closed pore volume is proposed. It is found that the plateau capacity is positively correlated with the closed pore volume.

Engineering of the microstructures of enzymatic hydrolysis lignin-derived hard carbon anodes for sodium-ion batteries

Hard carbon is considered as the most commercially applicable anode for sodium-ion batteries. Lignin has the characteristics of sustainable, low cost, high carbon content (>60%) and abundant oxygen functional groups, which is expected to be used as a promising candidate precursor for low-cost hard carbons. The structure and electrochemical performances of hard carbons could be regulated by adjusting carbonization temperature. The microstructure and electrochemical performance of LDHC anode are highly dependent on the carbonization temperature. Increasing carbonization temperature could reduce specific surface area and improve initial coulombic efficiency. The slope and plateau capacity of the LDHC anode could also be adjusted by changing the carbonization temperature. The LDHC prepared at 1200 °C showed the best sodium-ion storage performance, with an initial coulombic efficiency of 78.9% and a reversible sodium-ion storage capacity of 284.7 mAh g−1.