Anode For Sodium-ion Batteries Research Articles

N, S, Se-Codoped dual carbon encapsulation and Se substitution in pyrite-type FeS2 for high-rate and long-life sodium-ion batteries

The use of metal sulfides as anodes in sodium-ion batteries (SIBs) faces significant challenges due to slow reaction kinetics and extensive shuttling of sodium polysulfides (NaPSs). In response, a selenium-substituted iron disulfide encapsulated in a nitrogen-sulfur-selenium-codoped dual carbon framework (Se-FeS2@NSSC) has been engineered for high-performance SIBs. Selenium substitution within the FeS2 lattice improves electrical conductivity, facilitates favorable redox kinetics that reducing the possibility of NaPSs generation. Moreover, the dual NSSC encapsulation promotes Na+/electron transport and efficiently manages volume expansion during electrochemical processes. Strong interfacial interaction (Fe-S-C bonding) between Se-FeS2 and NSSC further suppress NaPSs shuttling, significantly alleviating the cell failure and thus prolonging its lifespan. Consequently, Se-FeS2@NSSC demonstrates a top-notch performance, achieving a notable capacity of 725 mAh g-1 at 0.5 A g-1, unparalleled rate capability (355.1 mAh g-1 at 30 A g-1), and sustained cyclic stability (89.6 % capacity is retained after 1250 cycles). Theoretical analyses underscore the critical role of selenium in diminishing bulk stress–strain energies, lowering energy barriers for Na+ diffusion, and decreasing Gibbs free energy for conversion reactions, thereby markedly bolstering electrochemical kinetics and overall performance of Se-FeS2@NSSC. The insights gleaned from this research foster advancements in developing next-generation anodes with high capacity and durability, representing a promising response to the existing hurdles in SIBs technology.

Design and preparation of carbon-coated NaZnFe(MoO4)3 composite as novel anode materials for lithium/sodium-ion batteries

The investigation of new anode materials with novel crystal structure and high ionic conductivity is of great significance for potential applications in lithium/sodium-ion batteries. Herein, carbon-coated NaZnFe(MoO4)3 composite was produced by solid state method coupled with the mechanical ball milling technique. The crystal and morphology were accurately confirmed by XRD, XPS and SEM techniques. When tested with lithium-ion batteries, the charging capacity reached an impressive 1005 mA h g−1 during the initial cycle and 840 mA h g−1 after 50 cycles, resulting in a capacity retention of 84.2 %. This performance is 40 % higher than that of the sample without a carbon layer coating. When utilized as an anode for sodium-ion batteries, the carbon-coated NaZnFe(MoO4)3 composite electrode exhibited a remarkable specific capacity of 152 mA h g−1 and a high capacity retention of 74.9 % after 100 cycles at a rate of 100 mA g−1. Furthermore, the charge capacity was measured at 105 mA h g−1 after 500 cycles test conducted at 500 mA g−1, with a capacity retention of 86.0 %. The advantages of polyanionic molybdate NaZnFe(MoO4)3 combined with the simple carbon coating strategy make it possible to application in the next generation of Li/Na secondary batteries.

FeS2/SnS2@C with mosaic-like heterointerface as robust sodium anode

Sodium-ion batteries (SIBs) have been widely researched due to their abundant resource and inherent safety. However, the major challenge for further commercialization of SIBs is the absence of low-priced anode electrodes with high reversible capacity and durability. Herein, a hierarchical heterogeneous structure of FeS2/SnS2@C nanocubes with rich two-dimensional mosaic-like heterointerface and N/S co-doped carbon wrapping is constructed and synthesized, to achieve ultrahigh reversible capacity and long cycling stability as anode of SIBs. Combining x-ray photoelectron spectroscopy, ion diffusion kinetic analysis, and in situ x-ray diffraction, the exquisite hierarchical heterogeneous structure of FeS2/SnS2@C could promote charge/electrons transfer and accelerate ion diffusion kinetics. As expected, the FeS2/SnS2@C anode shows superior reversible capacity (867.5 mA h g−1 at 0.1 A g−1), good rate performance (718.9 mA h g−1 at 5.0 A g−1), and long cycle stability (738.0 mA h g−1 after 1200 cycles at 5.0 A g−1) with Na metal as counter electrode. This work proves that the effectiveness of heterojunction interfaces for promoting Na+ diffusion is highlighted by such capabilities.

Bi2O3/Bi@CSs achieved by shock-type heating for fast and long-lasting sodium ion battery

Sodium ion batteries (SIBs) become highly viable post-lithium batteries technologies, thanks to their low manufacturing costs and relatively better low-temperature tolerance. The fatty Na+ demands impregnable anode materials to overcome the critical issues of problematic redox kinetics and unsatisfactory cycling stability. Bi2O3 is widely explored as the anode for SIBs, but suffers from sluggish reaction kinetics and dramatic volume fluctuations. Herein, a peculiar hybrid of Bi2O3/Bi embedded in amorphous carbon sheets (Bi2O3/Bi@CSs) has been designed via a shock-type heating method. The introducing of Bi not only can act as active component to store Na+, but also combined with the amorphous carbon sheets provide favorable reinforcement for structural stability. Synchronously, at the formed Bi2O3/Bi heterogeneous interface, a built-in electric field was generated, significantly promoting the electron/ion transfer. Accordingly, the Bi2O3/Bi@CSs-35 anode achieves an extraordinary rate capability (337.8 mAh g−1 at 100 A g−1), remarkable long-lasting stability for 4000 cycles at 5 A g−1 with a capacity of 345.7 mAh g−1, as well as amazing workableness for 200 cycles at −40 °C. This work unveils new insights for developing fast and long-lasting Bi-based anodes for SIBs and demonstrates promising application at low temperature.

Manipulating micropore structure of hard carbon as high‐performance anode for Sodium-Ion Batteries

Hard carbon (HC) is the most promising anode material for sodium-ion batteries (SIBs), but its low initial coulombic efficiency (ICE) and specific capacity limit its practical application. Herein, a chemical vapor deposition (CVD) strategy is used to address these challenges via filling the micropores of sucrose-based HC with pyrolysis by-products from acetonitrile, thereby reducing the specific surface area of HC microspheres. This approach mitigates the formation of solid electrolyte interphase (SEI) film leading to an enhancement in ICE. Moreover, the conversion of open micropores into closed pores creates additional storage space for sodium ions, effectively extending the specific capacity within the plateau region. Specifically, the HC prepared with a deposition duration of 1 h demonstrates the most favorable electrochemical performance. The optimal HC anode manifests an enhanced specific capacity of 307.6 mAh g−1 with an ICE of 66.01 % and exhibits excellent cycle stability (84.9 % capacity retention after 200 cycles at 100 mAh g−1). This study provides a feasible approach to optimize hard carbon anode materials for SIBs.

Composition and Structure of the solid electrolyte interphase on Na-Ion Anodes Revealed by Exo- and Endogenous Dynamic Nuclear Polarization─NMR Spectroscopy.

Sodium ion batteries (SIB) are among the most promising devices for large scale energy storage. Their stable and long-term performance depends on the formation of the solid electrolyte interphase (SEI), a nanosized, heterogeneous and disordered layer, formed due to degradation of the electrolyte at the anode surface. The chemical and structural properties of the SEI control the charge transfer process at the electrode-electrolyte interface, thus, there is great interest in determining these properties for understanding, and ultimately controlling, SEI functionality. However, the study of the SEI is notoriously challenging due to its heterogeneous nature and minute quantity. In this work, we present a powerful approach for probing the SEI based on solid state NMR spectroscopy with increased sensitivity from dynamic nuclear polarization (DNP). Utilizing exogenous (organic radicals) and endogenous (paramagnetic metal ion dopants) DNP sources, we obtain not only a detailed compositional map of the SEI but also, for the first time for the native SEI, determine the spatial distribution of its constituent phases. Using this approach, we perform a thorough investigation of the SEI formed on Li4Ti5O12 used as a SIB anode. We identify a compositional gradient, from organic phases at the electrolyte interface to inorganic phases toward the anode surface. We find that the use of fluoroethylene carbonate as an electrolyte additive leads to performance degradation which can be attributed to formation of a thicker SEI, rich in NaF and carbonates. We expect that this methodology can be extended to examine other titanate anodes and new electrolyte compositions, offering a unique tool for SEI investigations to enable the development of effective and long-lasting SIBs.

Promoting Reaction Kinetics and Boosting Sodium Storage Capability via Constructing Stable Heterostructures for Sodium‐Ion Batteries

AbstractConstructing heterostructures containing multiple active components is proven to be an efficient strategy for enhancing the sodium storage capability of anode materials in sodium‐ion batteries (SIBs). However, performance enhancement is often attributed to the unclear synergistic effects among the active components. A comprehensive understanding of the reaction mechanisms on the interfaces at the atomic level remains elusive. Herein, the carbon‐coated Fe3Se4/CoSe (Fe3Se4/CoSe‐C) anode material as a model featuring atomic‐scale contact interfaces is synthesized. This unique heterogeneous architecture offers an adjustable electronic structure, which facilitates rapid reaction kinetics and enhances structural integrity. In situ microscopic and ex situ spectral characterization techniques, along with theoretical simulations, confirm that the heterointerface with strong electric fields promotes Na+ ion migration. Based on solid‐state nuclear magnetic resonance (NMR) analysis, an interface charge storage mechanism is revealed, resulting in the enhanced specific capacity of the anode materials. When employed as an anode in SIBs, the Fe3Se4/CoSe‐C electrode demonstrates excellent rate capabilities (218 mAh g−1 at 7 A g−1) and prolonged cycling stability (258 mAh g−1 at 5 A g−1 after 1000 cycles). This work highlights the significance of heterointerface engineering in electrode material design for rechargeable batteries.

Effect of precursor particle size on the microstructure and Na storage performance of semi-coke derived carbon

The microstructure of carbon-based materials exerts a decisive influence on their Na storage performance. Furthermore, its evolution process may be influenced by the size of precursor particles during the pyrolysis preparation process. In this work, semi-coke has been used as the precursor, and its particle size (median particle sizes of 3, 7, 11, 15, and 19 μm) is investigated for its impact on the microstructure and Na storage performance of the resulting carbon materials (SDC-X, X = 3, 7, 11, 15, or 19). As the size of semi-coke increases from 3 μm to 19 μm, the highly-disordered carbon content of SDC-X decreases from 41.27 % to 30.94 %, while the content of pseudo-graphitic carbon associated with plateau capacity remains nearly constant. When SDC-X are employed as anodes for sodium-ion batteries, the initial coulombic efficiency (ICE) rose from 77.4 % to 82.3 % with the increase of size, primarily due to the increase in the ICE of slope region. However, despite SDC-19 having the highest ICE, its reversible capacity, rate, and cycle performance are inferior compared with the others due to its higher order degree and larger particle size. Therefore, carbon-based materials used as anodes for SIBs require a trade-off between particle size and the electrochemical performance.

Identifying Problematic Phase Transformations in Pb Foil Anodes for Sodium-Ion Batteries

Group IVA elements have aroused attention in sodium-ion batteries (SIBs) due to their Na-storage capability. Among them, Pb is less explored perhaps due to its perceived risks, but its long-standing success in Pb-acid batteries should not be neglected. Together with the well-established recycling procedures, the merits of Pb warrant further investigations as a practical SIB anode. In this work, four intermetallic phases are detected during electrochemical sodiation of Pb, which yields a capacity of ∼460 mAh·g−1 (∼1167 mAh·cm−3) upon the formation of Na15Pb4. When pursuing full capacities, the electrode stops functioning after only 3–4 cycles largely due to electrode physical damage. The reversibility of each phase transformation pair is then assessed to explore the origins of capacity fading. The NaPb/Na9Pb4 transformation shows the worst stability, consistent with the observed structural damage (e.g., cracks and voids). Through bypassing the problematic phase transformations using a partial cycling protocol, the stability of Pb foil anodes is improved, giving 20 cycles with 85% capacity retention. Considering other factors are unoptimized, it is suggested that the Pb-based anodes should not be fully eliminated from the future roadmap of SIBs, as the prospective merits can create value to ensure the management of such materials of concern.

Sb/Sb4O5Cl2/C composite as a stable anode for sodium-ion batteries

One of the most demanding goals in the field of Na-ion batteries is to find an appropriate anode material that delivers high capacities and can endure numerous cycles without structural degradation. Antimony stands out with a theoretical capacity of 660 mAh·g−1 and relatively high electrical conductivity. However, its challenges are pulverization and degradation of its microstructure due to volume changes. In this work, we used a solvothermal reaction to synthesize the composite material Sb/Sb4O5Cl2/C, which is made of Sb with branch-shaped morphology and Sb4O5Cl2 with cuboids-shaped morphology. The mechanism of the (de)sodiation of the composite material was analyzed both through operando and ex-situ measurements: X-ray diffraction, Raman spectroscopy, X-ray absorption spectroscopy, scanning electron microscopy, dilatometry, and online electrochemical mass spectrometry. The results show great mechanical integrity of the electrode, ensured by a lot of space for volume changes in the branch-shaped microstructure, buffered expansion/contraction by the amorphous matrix (sodiated Sb4O5Cl2), and high electronic conductivity, thanks to carbon. The microstructural features and the multistep (de)sodiation mechanism of the Sb/Sb4O5Cl2/C composite result in excellent cycling stabilities.

Multi boron-doping effects in hard carbon toward enhanced sodium ion storage

Hard carbon (HC) has been considered as promising anode material for sodium-ion batteries (SIBs). The optimization of hard carbon’s microstructure and solid electrolyte interface (SEI) property are demonstrated effective in enhancing the Na+ storage capability, however, a one-step regulation strategy to achieve simultaneous multi-scale structures optimization is highly desirable. Herein, we have systematically investigated the effects of boron doping on hard carbon’s microstructure and interface chemistry. A variety of structure characterizations show that appropriate amount of boron doping can increase the size of closed pores via rearrangement of carbon layers with improved graphitization degree, which provides more Na+ storage sites. In-situ Fourier transform infrared spectroscopy/electrochemical impedance spectroscopy (FTIR/EIS) and X-ray photoelectron spectroscopy (XPS) analysis demonstrate the presence of more BC3 and less B–C–O structures that result in enhanced ion diffusion kinetics and the formation of inorganic rich and robust SEI, which leads to facilitated charge transfer and excellent rate performance. As a result, the hard carbon anode with optimized boron doping content exhibits enhanced rate and cycling performance. In general, this work unravels the critical role of boron doping in optimizing the pore structure, interface chemistry and diffusion kinetics of hard carbon, which enables rational design of sodium-ion battery anode with enhanced Na+ storage performance.

Liquid Gallium-Assisted Pyrolysis of MOF Affording CNT Non-Hollow Frameworks in High Yields for High-Performance Sodium-Ion Battery Anode.

Carbon materials have great potential for applications in energy, biology, and environment due to their excellent chemical and physical properties. Their preparation by carbonization methods encounters limitations and the carbon loss during pyrolysis in the form of gaseous molecules results in low yield of carbon materials. Herein a low-energy (600°C) and high-yield (82wt.%) carbonization strategy is developed using liquid gallium-assisted pyrolysis of metal-organic frameworks (MOFs) affording the N-doped carbon nanotube (CNT) non-hollow frameworks encapsulating Co nanoparticles. The liquid gallium layer offers protection against air, promotes heat transfer, and limits the escape of small carbonaceous gaseous molecules, which greatly improve the yields of the pyrolysis reaction. Experimental and theoretical results reveal that the synergistic interaction between CNTs and N/O-containing groups gives a non-hollow framework composed of N/O-enriched and open CNTs (NOCNTF-15, 15 denotes the 15mm thickness of the liquid gallium layer during the pyrolysis) with high specific capacity (185mAhg-1 at 10Ag-1) and ultra-stable cyclability (stable operation at 10Ag-1 and 50°C for 20000 cycles). This study provides a unique approach to carbonization that facilitates the practical application of low-cost CNTs and other MOFs-derived carbon materials in high-performance sodium-ion batteries (SIBs).

Synergistic effect of holey graphene and CoSe2-NiSe2 heterostructure to enhance fast Na-ion transport

Inspired by the “Barrel principle” and based on the working principle of the “rocking chair”. We propose two shortboards that “bulk diffusion rate” and “ion reaction rate”, which affect the fast charging of sodium ion batteries (SIBs). The holey reduced graphene oxide (HrGO) with abundant nanopores provides longitudinal diffusion channels, enabling rapid Na+ diffusion along this direction, which solves the shortboard of bulk diffusion rate. Additionally, heterojunctions are considered a viable approach for enhancing fast Na+ storage performance by providing more storage sites and accelerating the kinetics of Na+ reaction, which solve the shortboard of ion reaction rate. Herein, we construct HrGO combined with CoSe2-NiSe2 heterojunctions has been rationally fabricated to synergistically enhance the ionic and electronic diffusion kinetics. As expected, the CoSe2-NiSe2/HrGO anode in SIBs shows an excellent fast-charging performance (392.4mAh/g at 15 A/g), surpassing most Co/Ni-based selenide anodes. Additionally, the assembled CoSe2-NiSe2/HrGO||NVP full cell delivers a high specific capacity of 116.1 and 95.4mAh/g at 0.1 and 20C, respectively, coupled with 97.8 % capacity retention rate for 100 cycles. Furthermore, we elucidate the mechanism of Na+ storage and fast transport through electrochemical kinetic analysis, in situ and ex situ characterizations, density functional theory (DFT) calculations, and distribution of relaxation times (DRT). Importantly, this study provides theoretical insights into accelerating rapid Na+ transfer.

Linking the size of hard carbon particles with electrochemical response in sodium ion storage

Hard carbon is considered to be one of the most promising anodes for sodium-ion batteries (SIBs) owing to its high capacity and abundant resources. However, the role of particle size on sodium ion storage is unclear, which leads to low capacity and initial coulombic efficiency (ICE) in practical application. In this work, a series of hard carbons with different particle sizes were prepared by an “up to down” strategy using simple grinding and ball-milling method to investigate the effect of particle size on electrochemical response of sodium ion storage. The particle size of hard carbon has negligible effect on initial specific capacity. However, it has a strong effect on the ICE and rate capability. The ICE reduces as the particle size decreases, but the rate performance in reverse. Moreover, impedance analysis and electrochemical kinetics show huge differences for different particle sizes. In-situ Raman technique was also adopted to further illustrate the sodium ion storage mechanism of hard carbon, and an “adsorption-intercalation-pore filling” mechanism is proposed. This work could provide a new perspective for the design of hard carbon materials with suitable structure for efficient sodium ion storage, helping to develop high performance SIBs.

Revealing the sodium storage mechanism of cellulose separator-derived hard carbon anode materials for sodium-ion batteries

Hard carbon (HC) shows significant promise as a material for sodium-ion batteries (SIB). Cellulose-derived carbon is considered one of the most promising high-performance anode materials for sodium-ion batteries. In this study, waste cellulose separator-derived HC anode materials were rationally developed using the pre-oxidation-carbonization pyrolysis method. The as-prepared HC possessed advantageous characteristics for Na+ storage, including a unique fibrous structure, a reasonable space layer, and a small specific surface area (SSA). The optimal sample demonstrated a substantial reversible capacity of 361.29 mAh/g at 0.1C, an impressive high-rate performance with a reversible capacity of 272.93 mAh/g at 10C, and an initial coulombic efficiency of 84.85 %. Following 500 cycles at 1C, the capacity retained 96.38 % of its initial value. The sodium storage process was identified as the “adsorption-insertion-pore filling mechanism” through ex-situ XRD and in-situ Raman experiments. Moreover, the as-prepared HCs demonstrated better rate and cycle capability when evaluated as anodes in full-cell sodium-ion batteries (SIBs). This research provides valuable insights into the rational design of high-performance HC anodes for SIBs and other applications.

Open‐Shell Resonance of Germanium‐Alkyne Porous Organic Radical Polymer for Boosting Sodium‐Ion Storage

AbstractPorous organic polymers (POPs) as electrode materials for sodium‐ion batteries (SIBs) are attracting increasing attention. However, the application of porous organic radical polymers (PORPs) with unique properties in SIBs is still in an infancy. Herein, two 3D germanium‐based POPs with conjugated diacetylene units (Ge‐DA) and acetylene units (Ge‐A) are designed and synthesized. Carbon radicals in Ge‐DA are verified by electron paramagnetic resonance and the resonance structure is calculated by density functional theory, showing a lower lowest unoccupied molecular orbital (LUMO) energy level (−5.46 eV) and a narrow energy gap (ca. 1.64 eV). In contrast, Ge‐DA as an anode for SIBs shows superior electrochemical properties to that of Ge‐A counterpart, including a higher specific discharge capacity of 349 mAh g−1 at 200 mA g−1, excellent cyclability with a capacity of 112 mAh g−1 at 5 A g−1 for at least 5000 cycles and high rate performance of 135 mAh g−1 at 20 A g−1, proving that the different electronic structures of the diacetylene and monoacetylene units affect the properties of materials.

Pre-oxidation modification of bituminous coal-based hard carbon for high-quality sodium ion storage

Bituminous coal, with its moderate anthracene content, high reactivity, and ease of modulation, stands out as a favorable choice as a precursor for hard carbon. However, due to the highly condensed aromatic rings in bituminous coal, it tends to form highly graphitized structures after high-temperature carbonization. Therefore, pretreatment of bituminous coal is necessary to suppress the graphitization process. Here, we combine pre-oxidation techniques with high-temperature carbonization to produce a cost-effective, high carbon yield, and superior performance coal-based hard carbon. When utilized as anode for sodium-ion batteries, the prepared coal-based hard carbon exhibits a high reversible capacity of 313.5 mAh g−1, along with excellent rate capability and long cycling stability.

Facile one-pot synthesis of bismuth microspheres@N-doped porous carbon composite anodes for high power density and ultralong-life sodium-ion batteries

Facile one-pot synthesis of bismuth microspheres@N-doped porous carbon composite anodes for high power density and ultralong-life sodium-ion batteries

Pitch-based carbon anode for high-energy and long-life sodium-ion battery

Pitch-based carbon generally demonstrate remarkable electrochemical performance for sodium-ion batteries (SIBs). In this paper, the medium temperature pitch is successively subjected to heat treatment under high pressure, extraction of toluene to remove soluble matter, and carbonization of toluene insoluble matter, to prepare the anode material, named pitch toluene insoluble anode (PTIA). The PTIA is characteristic of the coral-like morphology distributed with 100−200 nm pore channels and 2−3 nm mesopores for electrolyte immersion, and the disordered carbon structure is interwoven with graphitic carbon for sodium-ion insertion/desertion and electron transmission. In the PTIA half battery, the reversible specific capacity reaches 276.9 mAh g−1 at 0.1 A g−1 after 300 cycles with a coulombic efficiency of 99.22%. Importantly, the PTIA exhibits good compatibility with vanadium sodium phosphate (NVP) cathode materials, enabling a battery PTIA//NVP to achieve a capacity density of 154 mAh g−1, an energy density of 246.7 Wh kg−1 and a power density of 4800 W kg−1 for 1000 cycles at a current density of 3 A g−1 (16−18 C). The battery has a certain working efficiency at -10−70°C.

CoO nanoparticles anchored on porous pinecone-derived activated carbon as anodes for high-performance lithium and sodium-ion batteries

In this work, a new nanocomposite system based on CoO nanoparticles (NPs) anchored on pinecone-derived activated carbon (PAC), denoted as CoO(x)@PAC, is synthesized by facile ball-milling and sonication processes followed by annealing. H3PO4 is employed as an activation agent to activate the porous carbon derived from pinecone. The loading amount of CoO is varied to obtain the optimum electrochemical performances. Among the nanocomposites, the CoO(20)@PAC delivers a discharge capacity of 886 mA h g−1 after 100 cycles at a current density of 100 mA g−1 when employed as an anode in lithium-ion batteries (LIBs). At higher current rate of 1000 mA g−1, the anode provides an enhanced discharge capacity of 456.6 mA h g−1 after 200 cycles with 99 % capacity retention compared to the 4th cycle capacity. In sodium-ion batteries (SIBs), the CoO(20)@PAC anode delivers a discharge capacity of 290 mA h g−1 at 50 mA g−1. The same nanocomposite anode provides a discharge capacity of 120 mA h g−1 after 900 cycles at a current density of 500 mA g−1. The CoO(20)@PAC nanocomposite shows a great potential as an anode for both LIBs and SIBs, due to its higher capacity, exceptional rate capability, longer cycle life, and a Coulombic efficiency exceeding 99 %.