Hard Carbon Anode Research Articles

Exploring the Impact of Lanthanum on Sodium Manganese Oxide Cathodes: Insight into Electrochemical Performance

This investigation focuses on nominally La‐doped Na0.67MnO2, exploring its structural, electrochemical, and battery characteristics for Na‐ion batteries. X‐ray diffraction analysis reveals formation of composite materials containing three distinct phases: P2‐Na0.67MnO2, NaMn8O16, and LaMnO3. The bond structures of the powders undergo scrutiny through Fourier‐transform infrared and Raman analyses, revealing dependencies on the NaO, MnO, and LaO structures. X‐ray photoelectron spectroscopy and energy‐dispersive X‐ray dot mapping analyses show that the La ions are unevenly dispersed within the samples, exhibiting a valence state of 3+. Half‐cell tests unveil similarities in redox peaks between the cyclic voltammetry analysis of La‐doped samples and P2‐type Na0.67MnO2, with a reduction in peak intensities as La content increases. Electrochemical impedance spectroscopy model analysis indicates direct influences of La content on the half‐cell's resistive elements values. The synergistic effect of composite material with multiple phases yields promising battery performances for both half and full cells. The highest initial capacity value of 208.7 mAh g−1, with a 57% capacity fade, among others, is observed, and it diminishes with increasing La content. Full cells are constructed using an electrochemically presodiated hard carbon anode, yielding a promising capacity value of 184.5 mAh g−1 for sodium‐ion battery studies.

Joule heating for structure reconstruction of hard carbon with superior sodium ion storage performance

Hard carbon anode for sodium ion batteries still remains many challenges including insufficient cycling life and initial Coulombic efficiency (ICE), weak rate capability and poor compatibility in common ester electrolytes. Here, we propose a Joule heating post-treatment including multifield sintering method to reconstruct the structure of hard carbon from thick graphene layers to more disordered vortex layer structure composed of thin and curved graphite-like domains. The molecular dynamics simulation and differential charge density distribution demonstrate the crucial effect of electric field in strengthening the interaction between the polar molecule groups and the graphene layer, leading to the distortion and expanding of graphene layer. This is a universal and highly efficient strategy to modify various hard carbons within minutes. The optimized hard carbon anode exhibits exceptional rate capability and cycling stability with a high retention rate of 88.4% after 15,000 cycles at 10C in ether electrolyte. It also displays remarkably improved reversible capacity, initial Coulombic efficiency ICE of 89.5% and cycling stability in ester electrolyte. It is revealed by in-situ electrochemical impedance spectroscopy and atomic force microscopy that the spontaneous formation of a thin, stable and inorganic substance-rich solid electrolyte interface layer with significantly improved mechanical property is largely responsible for the outstanding sodium-ion transport kinetics and long lifespan.

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.

Heterogeneous carbon coated resin-based hard carbon anode material for high-performance sodium ion batteries

Resin-based hard carbons are promising anode materials for sodium ion batteries (SIBs) due to their high storage capacity and purity. However, the low initial coulombic efficiency (ICE) still hinders their practical application. Crosslinking and high-temperature pyrolysis strategies have been demonstrated to improve ICE effectively, but the complex process and high energy consumption hinder their industrialization. This paper proposes a facile synthesis of resin-based hard carbon with a soft carbon coating strategy to improve ICE. By carbonizing commercial phenolic resin at 1150℃, hard carbon with a reversible capacity of 291.6 mAh g−1 and 82.6 % ICE was obtained. After asphalt-based soft carbon coating, the optimized sample (CHC-1150) with a heterogeneous carbon coating layer of about 8.5 nm displays a high reversible capacity and ICE of 309.8 mAh g−1 and 88.2 %. Moreover, when combined with NaFe1/3Ni1/3Mn1/3O2 cathode, the assembled 18650 cylindrical-type batteries deliver a high ICE of 84.3 %, excellent low-temperature capability and cycling stability. Additionally, the disassembly results after cycling indicate that the soft carbon layer can inhibit the decomposition of electrolytes and avoid sodium plating. These encouraging results suggest that heterogeneous carbon coating should be a promising strategy to promote the electrochemical performance of resin-based hard carbon anode materials for SIBs.

From Powder to Pouch Cell: Setting up a Sodium‐Ion Battery Reference System Based on Na3V2(PO4)3/C and Hard Carbon

At the research level, novel active materials for batteries are synthesised on a small scale, fabricated into electrodes and electrochemically characterised using each group’s established process due to the lack of standards. Recently, eminent researchers have criticised the implementation of e.g. low active material contents/electrode loadings, the use of research‐type battery cell constructions, or the lack of statistically relevant data, resulting in overstated data and thus giving misleading predictions of the key performance indicators of new battery technologies. Here, we report on the establishment of a reference system for the development of sodium‐ion batteries. Electrodes are fabricated under relevant conditions using 9.5 mg/cm² self‐synthesised Na3V2(PO4)3/C cathode active material and 3.6 mg/cm² commercially available hard carbon anode active material. It is found that different types of battery cells are more or less suitable for half‐ and/ or full‐cell testing, resulting in ir/reproducible or underestimated active material capacities. Furthermore, the influence of electrode overhang, which is relevant for upscaling, is evaluated. The demonstrator cell (TRL 4‐5) has been further characterised providing measured data on the power/energy density and thermal behaviour during rate testing up to 15 C and projections are made for its practical limits.

Engineering mesoporous Na4Mn0.9Ni0.1V(PO4)3@NC microspheres cathode towards advanced sodium ion batteries

Currently, the exploitation of robust cathode materials for sodium-ion batteries (SIBs) is of critical urgency. Sodium superionic conductor (NASICON) Na4MnV(PO4)3 (NMVP) owns a decent energy density of 425 Wh kg−1 which has been regarded as a research hotspot in SIBs. Nonetheless, the performance of NMVP is greatly hindered by structural degradation due to Jahn-Teller distortions of Mn3+ and intrinsically limited electronic conductivity. In view of this, a series of Na4Mn1-xNixV(PO4)3@NC (x = 0.04, 0.1 or 0.12) denoted as NMVP, 0.04Ni-NMVP, 0.1Ni-NMVP and 0.12Ni-NMVP are facilely envisaged via the scalable spray-drying approach in this work. Notably, the optimized mesoporous 0.1Ni-NMVP reveals the most excellent cycling durability at high current rate (a capacity of 67.8 mAh g−1 at 5C over 1500 cycles with a capacity retention ratio of 73.7 %). Especially, the full cell based on 0.1Ni-NMVP cathode and commercial hard carbon (HC) anode manifests a satisfied energy density of 295 Wh kg−1 at the power density of 105.6 W kg−1. It is proved that the appropriate Ni-doping could extremely mitigate the Jahn-Teller distortion in MnO6 during cycling and significantly favor the electron/ion transportation. Besides, the N-doped carbon coating could also avoid the aggregation of NMVP microspheres and ameliorate the electronic conductivity. A reversible structural evolution including two-phase and solid-solution reactions during cycling are validated for the 0.1Ni-NMVP upon (de)sodiation based on the in-situ XRD patterns. Furthermore, density functional theory (DFT) calculations suggest the Ni-modification for NMVP leads to the reduced bandgap and boosted electron transfer, which is much beneficial to the expedited electron/ion transportation. This innovative Ni-modification protocol serves an explicit direction for engineering advanced NMVP cathode in SIBs.

Tuning the microstructure of biomass-derived hard carbons by controlling the impurity removal process for enhanced Na ion storage performance

Biomass-derived hard carbons are promising anode materials of sodium-ion batteries (SIBs) due to their low cost, renewability and high specific capacity. However, there are inevitably some impurities in biomasses that may not only affect the purity, but microstructure and electrochemical performance of hard carbons. Although the impurities can be removed by appropriate treatments after carbonization, the microstructure of hard carbons can hardly be changed. In this work, taking ficus macrophylla leaves (FMLs) as the model biomass, the effects of impurities and their removing process on the microstructure and Na ion storage performance of hard carbons are investigated. It is found that the presence of Ca and Si-bearing impurities in FMLs results in more graphite-like structure in hard carbons because of their catalytic graphitization effect. The acid and base washing processes after carbonization can mostly get rid of the inorganic impurities is unable to increase the plateau region capacities associating to Na ion insertion in the interlayer of graphitic microcrystals and Na metal filling in micropores. By contrast, by stepwisely removing the Ca and Si-bearing impurities from raw materials before carbonization, hard carbons with high purity, larger interlayer space and more micropores are produced, which exhibit a high reversible specific capacity of 336 mAh g−1 at 20 mA g−1, a high initial Coulombic efficiency of 93 %, excellent rate capability (245 mAh g−1 at 2 A g−1) and robust cycle stability. This study implies that controlling the impurity removal process can simultaneously tune the microstructure of hard carbon anodes derived from biomasses towards high performance Na ion storage.

Mild and Fast Chemical Presodiation of Na0.44MnO2

This work presents a mild, fast, and scalable approach for chemical presodiation of Na-ion battery cathodes employing a tunnel-type Na0.44MnO2 (NMO) as a model material to demonstrate its sodiation with sodium-phanazine solutions. After presodiation using this approach, there is an 80% increase in specific capacity and a 66% increase in specific energy of NMO in full cells with hard carbon anodes.

Physicochemical investigation on the hard carbon interface in ionic liquid electrolyte

An investigation of the solid electrolyte interphase (SEI) on hard carbon (HC) anodes in aprotic sodium batteries was carried out by post-mortem analyses. Electrodes cycled in 1-ethyl-3-methylimidazolium bis(fluorosulfonyl)imide (EMIFSI), and N-trimethyl-N-butylammonium bis(fluorosulfonyl)imide (N1114FSI) ionic liquid electrolytes have been collected and studied: benchmark electrodes cycled in commercial organic solutions were examined for comparison purpose. The SEI composition and morphology of post-mortem HC electrodes were analyzed by X-ray Photoelectron Spectroscopy (XPS) and focused ion beam scanning electron microscopy (FIB-SEM) analysis. Overall, the HC electrodes cycled in carbonate-based electrolyte have shown thicker SEI mainly composed of organic compounds, whereas in ILs electrolytes they have shown thinner layer richer in inorganic species, such as NaF, Na2CO3, N-containing species, and “small” sulfide-based compounds, these improving the SEI interfacial properties towards the Na+ migration kinetics. Focusing on ILs based cell formulations, anodes cycled in the EMIFSI-based electrolyte shows several cracks on its surface.

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

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

Structural and chemical analysis of hard carbon negative electrode for Na-ion battery with X-ray Raman scattering and solid-state NMR spectroscopy

This study explores the structural changes of hard carbon (HC) negative electrodes in sodium-ion batteries induced by insertion of Na ions during sodiation. X-ray Raman spectroscopy (XRS) was used to record both C and Na K-edge absorption spectra from bulk HC anodes carbonized at different temperatures and at several points during sodiation and desodiation. Comparing the π∗/σ∗ regions in the C K-edge spectra sp2/sp3 hybridization ratio of material was determined. Higher carbonization temperatures led to increased order in graphitic structure and shorter ▪ bond lengths. Sodiation caused a decrease in graphitic layer order due to inserted Na ions. Complementary operando solid state 23Na nuclear magnetic resonance (ssNMR) studies confirmed the structural changes, while showing pore filling mechanism, which is not observed in ex situ measurements, primarily at higher carbonization temperatures. XRS analysis of Na K-edge spectra revealed systematic variations in the solid electrolyte interface (SEI) composition during cycling. Changes in XRS spectra were attributed to both SEI composition alterations, accompanied by the insertion/adsorption of Na ions at defect sites within the carbon structure.

Rational Design of Flexible, Self-Supporting, and Binder-Free Prussian White/KetjenBlack/MXene Composite Electrode for Sodium-Ion Batteries with Boosted Electrochemical Performance.

Due to their cost-effectiveness, abundant resources, and suitable working potential, sodium-ion batteries are anticipated to establish themselves as a leading technology in the realm of grid energy storage. However, sodium-ion batteries still encounter challenges, including issues related to low energy density and constrained cycling performance. In this study, a self-supported electrode composed of Prussian white/KetjenBlack/MXene (TK-PW) is proposed. In the TK-PW electrode, the MXene layer is coated with Prussian white nanoparticles and KetjenBlack with high conductivity, which is conducive to rapid Na+ dynamics and effectively alleviates the expansion of the electrode. Notably, the electrode preparation method is uncomplicated and economically efficient, enabling large-scale production. Electrochemical testing demonstrates that the TK-PW electrode retains 74.9% of capacity after 200 cycles, with a discharge capacity of 69.7 mAh·g-1 at 1000 mA·g-1. Furthermore, a full cell is constructed, employing a hard carbon anode and TK-PW cathode to validate the practical application potential of the TK-PW electrode.

The buckwheat-derived hard carbon as an anode material for sodium-ion energy storage system

Biomass-derived hard carbon (HC) has attracted much attention as a promising electrode material for sodium-ion batteries (SIBs) due to its unique properties such as high porosity, large surface area and adjustable pore size distribution. This work presents the results of electrochemical studies of HC derived from buckwheat seeds. The HCs were preoxidized at 300 °C and synthesized using a pyrolysis method in the range 600–1400 °C. It was found that the electrochemical characteristics of the HC anodes are strongly dependent on the morphology and structure. Furthermore, the positive effect of preoxidation on the porosity of HC was confirmed. Although all buckwheat-derived HC-based anodes showed stable cyclability over 100 cycles with CE of approximately 97–98 %, the preoxidized HCs pyrolyzed at 1400 °C achieved the highest reversible capacity of 330.23 mAh g−1 with excellent stability. Additional study using “single particle” measurement of HC1400 and HCox1400 showed that the preoxidation may significantly contribute to the improvement of the mass transfer.

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.

Ultra-Fast-Charging, Long-Duration, and Wide-Temperature-Range Sodium Storage Enabled by Multiwalled Carbon Nanotube-Hybridized Biphasic Polyanion-Type Phosphate Cathode Materials.

Sodium-ion batteries (SIBs) represent a promising energy storage technology with great safety. Because of their high operating potential, superior structural stability, and prominent thermal stability, polyanion-type phosphates have garnered significant interest in superior prospective cathode materials for SIBs. Nevertheless, the disadvantages of poor intrinsic electronic conductivity, sluggish kinetics, and volume variation during sodiation/desodiation remain great challenges for satisfactory rate performance and cycle stability, which severely hinder their further practical applications. In this work, by adjusting the amounts of pretreated multiwalled carbon nanotubes (CNT) added intentionally at the beginning of the preparation, biphasic polyanion-type phosphate materials (marked as NFC) are synthesized through a one-pot solid state reaction methodology, which are composed of CNT-interwoven Na3V2(PO4)2F3 (NVPF) and a small amount of Na3V2(PO4)3 (NVP). Benefiting from the improved electronic conductivity and unique composition and structure, the optimized sample (labeled as NFC-2) illustrates exceptional cycle stability and remarkable rate performance. The discharge capacities of the NFC-2 electrode are 114.8 and 78.6 mAh g-1 tested at 20 and 5000 mA g-1, respectively. Notably, such an electrode still gives out 75.7% capacity retention upon 10 000 cycles at 5000 mA g-1. In situ X-ray diffraction analysis demonstrates that the NFC-2 cathode has outstanding structural reversibility during charge/discharge cycles. More importantly, such a biphasic material has achieved impressive electrochemical performance within a wide operating temperature range of -20-50 °C. When temperature is decreased to -20 °C, the NFC-2 electrode still delivers an initial discharge capacity of 102.4 mAh g-1 and exhibits a remarkable capacity retention of 97.8% even after 500 cycles at 50 mA g-1. In addition, the sodium-ion full cell assembled by integrating NFC-2 cathode and hard carbon anode shows a satisfying energy density of 431.3 Wh kg-1 at 20 mA g-1 with a better long-term cycle performance. The synergistic effect among high energy NVPF, conductive CNT, and stable NVP may lead to the great improvement in the electrochemical sodium storage performance of the NFC-2 sample. Such biphasic polyanion-type phosphate materials will inject new ideas into the material design for SIBs with excellent electrochemical performance and further promote practical applications of this advanced energy storage technology.

Regulating Pseudo-Graphitic Domain and Closed Pores to Facilitate Plateau Sodium Storage Capacity and Kinetics for Hard Carbon.

Hard carbon anode demonstrates exceptional potential in sodium-ion batteries due to their cost-effectivenss and superior plateau capacity. However, the proximity of the plateau capacity to the cut-off voltage of battery operation and the premature cut-off voltage response caused by polarization at high rates greatly limit the exploitation of plateau capacities, raising big concerns about inferior rate performance of high-plateau-capacity hard carbon. In this work, a facile pre-oxidation strategy is proposed for fabricating lignin-derived hard carbon. Both high-plateau capacity and sodiation kinetics are significantly enhanced due to the introduction of expanded pseudo-graphitic domains and high-speed closed pores. Impressively, the optimized hard carbon exhibits an increased reversible capacity from 252.1 to 302.0 mAh g-1, alongside superior rate performance (174.7 mAh g-1 at 5 C) and stable cyclability over 500 cycles. This study paves a low-cost and effective pathway to modulate the microstructure of biomass-derived hard carbon materials for facilitating plateau sodium storage kinetics.

Achieving High-Performance Na3V2(PO4)2F3 Cathode Material through a Bifunctional N-Doped Carbon Network.

Na3V2(PO4)2F3 (NVPF) is emerging as a popular cathode for sodium-ion batteries owing to its stable structure, high operating voltage, and large energy density. However, its practical application is hindered by its low conductivity. In addition, due to the loss of fluorine during synthesis, Na3V2(PO4)3 (NVP) impurity is often easily generated, resulting in a decrease in actual operating voltage. Herein, a bifunctional carbon network composed of an N-doped carbon layer and carbon bridge is constructed around NVPF particles. Through pyrolysis of polydopamine (PDA), the NVPF particles are covered in situ by an N-doped carbon layer, and the carbon bridge generated by polytetrafluoroethylene (PTFE) is also coated with N-doped carbon. Besides, PTFE also serves as a fluorine supplement to ensure that pure NVPF is obtained. As a result, the bifunctional N-doped carbon network-modified NVPF delivers a high reversible capacity (125.7 mA h g-1 at 0.2 C) and appreciable cycle stability (92.7% at 1 C over 300 cycles, and 89.8% at 10 C over 1500 cycles). When assembled into a full cell with a commercial hard carbon anode, it displays a discharge median voltage of up to 3.62 V at 0.2 C. Furthermore, it achieves a high energy density of 373.7 W h kg-1 at a power density of 461.2 W kg-1, with an excellent specific energy retention of 78.2% after 200 cycles. Therefore, this modification method is expected to be extended to other fluorine-containing materials with poor electrical conductivity.

Machine learning-assisted thermomechanical coupling fabrication of hard carbon for sodium-ion batteries

This study conducts an extensive investigation into the application of hard carbon in sodium-ion batteries. More than 100 hard carbon samples are meticulously synthesized by precisely controlling temperature and pressure, and their microstructure and performance are comprehensively evaluated. This research introduced innovative standardized parameters, including degree of graphitization, degree of crystallinity and degree of defect, which can be universally applied to the field of amorphous carbon materials. Furthermore, the utilization of machine learning facilitates rapid prediction and screening of high-performance hard carbon materials. As a result, a fully optimized hard carbon anode is successfully developed. At a current density of 0.03 A g−1, the material demonstrates a reversible capacity of 375 mAh g−1 and an initial coulombic efficiency of 92.3 %. At a high current rate of 2 A g−1, it delivers a capacity of 250 mAh g−1. The investigation further provides robust evidence for the pore-filling mechanism of Na clusters by in situ spectroscopic studies. This study not only introduces novel approaches for controlling and quantifying the microstructure of hard carbon but also demonstrates a case study of efficient material development by machine learning.

Extended Plateau Capacity of Hard Carbon Anode for High Energy Lithium-Ion Batteries.

Hard carbon materials have shown promising potential for sodium-ion storage due to accommodating larger sodium ions. However, as for lithium-ion storage, the challenge lies in tuning the high lithiation plateau capacities, which impacts the overall energy density. Here, hard carbon microspheres (HCM) are prepared by tailoring the cross-linked polysaccharide, establishing a comprehensive methodology to obtain high-performance lithium-ion batteries (LIBs) with long plateau capacities. The "adsorption-intercalation mechanism" for lithium storage is revealed combining in situ Raman characterization and ex situ nuclear magnetic resonance spectroscopy. The optimized HCM possesses reduced defect content, enriched graphitic microcrystalline, and low specific surface area, which is beneficial for fast lithium storage. Therefore, HCM demonstrates a high reversible capacity of 537mAhg-1 with a significant low-voltage plateau capacity ratio of 55%, high initial Coulombic efficiency, and outstanding rate performance (152mAhg-1 at 10Ag-1). Moreover, the full cell (HCM||LiCoO2) delivers outstanding fast-charging capability (4min charge to 80% at 10C) and impressive energy density of 393Whkg-1. Additionally, 80% reversible capacity can be delivered under -40°C with competitive cycling stability. This work provides in-depth insights into the rational design of hard carbon structures with extended low-voltage plateau capacity for high energy LIBs.

Biomass-Derived Hard Carbon for Sodium-Ion Batteries: Basic Research and Industrial Application.

Sodium-ion batteries (SIBs) have significant potential for applications in portable electric vehicles and intermittent renewable energy storage due to their relatively low cost. Currently, hard carbon (HC) materials are considered commercially viable anode materials for SIBs due to their advantages, including larger capacity, low cost, low operating voltage, and inimitable microstructure. Among these materials, renewable biomass-derived hard carbon anodes are commonly used in SIBs. However, the reports about biomass hard carbon from basic research to industrial applications are very rare. In this paper, we focus on the research progress of biomass-derived hard carbon materials from the following perspectives: (1) sodium storage mechanisms in hard carbon; (2) optimization strategies for hard carbon materials encompassing design, synthesis, heteroatom doping, material compounding, electrolyte modulation, and presodiation; (3) classification of different biomass-derived hard carbon materials based on precursor source, a comparison of their properties, and a discussion on the effects of different biomass sources on hard carbon material properties; (4) challenges and strategies for practical of biomass-derived hard carbon anode in SIBs; and (5) an overview of the current industrialization of biomass-derived hard carbon anodes. Finally, we present the challenges, strategies, and prospects for the future development of biomass-derived hard carbon materials.