Anode Material For Sodium-ion Batteries Research Articles

Use of Hydrothermal Carbonization to Improve the Performance of Biowaste-Derived Hard Carbons in Sodium Ion-Batteries.

Over the last years, hard carbon (HC) has been the most promising anode material for sodium-ion batteries due to its low voltage plateau, low cost and sustainability. In this study, biomass waste (spent coffee grounds, sunflower seed shells and rose stems) was investigated as potential material for hard carbon preparation combining a two-step method consisting of on hydrothermal carbonization (HTC), to remove the inorganic impurities and increase the carbon content, and a subsequent pyrolysis process. The use of HTC as pretreatment prior to pyrolysis improves the specific capacity in all the materials compared to the ones directly pyrolyzed by more than 100 % at high C-rates. The obtained capacity ranging between 210 and 280 mAh g-1 at C/15 is similar to the values reported in literature for biomass-based hard carbons. Overall, HC obtained from sunflower seed shell performs better than that obtained from the other precursors with an initial Coulombic efficiency (ICE) of 76 % and capacities of 120 mAh g-1 during 1000 cycles at C with a high capacity retention of 86-93 %.

Poly(p-phenylenediamine)-Coated Metal-Organic Frameworks for High-Performance Sodium-Ion Batteries: The Balance of Capacity and Stability.

Metal-organic frameworks (MOFs) with well-defined porous structures and highly active frameworks are considered as promising electrode materials for sodium-ion batteries (SIBs). However, the structure pulverization upon sodiation/desodiation impacts on their practical application in SIBs. To address this issue, poly(p-phenylenediamine) (PPA) was uniformly coated onto the surface of MIL-88A, a typical Fe-based MOF through in situ polymerization initiated by the metal ions (Fe3+) of MIL-88A. Used as an anode material for SIBs, the PPA-coated MIL-88A, denoted as PPA@MIL-88A, showed significantly improved electrochemical performance. A reversible capacity as high as 230 mAh g-1 was achieved at 0.2 A g-1 even after 500 cycles. MIL-88A constructed with electrochemically active Fe3+ and fumaric acid ligands guarantees the high specific capacity, while the PPA polymer coating effectively inhibits the pulverization of MIL-88A. This work provides an efficient strategy for improving the structure and cycling stability of MOFs-based electrode materials.

A pinning structure via composing laminar rGO with fragmented MoS2 toward fast and stable sodium and lithium-ion storage

The diffusion of lithium ions and sodium ions in the anode materials is the main factor limiting the fast-charging performance of lithium and sodium-ion batteries. Due to the slow diffusion kinetics, taking lithium-ion batteries as an example, lithium ions and electrons accumulate locally in and on the surface of anode materials, especially in the process of fast-charging, resulting in uneven lithiation reaction and enormous transient stress, which leads to poor fast-charging performance. In this work, from the aspect of solving the ion diffusion rate, a capacitive type of energy storage is introduced by designing MoS2/rGO composite materials with pinned structures as fast-charging and stable anode materials for lithium-ion batteries and sodium-ion batteries. Combining the high ion conductivity and structural rigidity of the rGO conductive network with a few-layer MoS2 provides a high ion diffusion rate and capacity. As expected, it can charge to 69 % in 25 min and 44 % in 3.2 min, respectively, providing a high capacity of 214.2 mAh g−1 at 10 A g−1 and a high-capacity retention of 85.31 % after 1, 000 cycles at the current density of 3 A g−1 in sodium-ion batteries. Similarly, the high reversible capacity of 910.5 mAh g−1 is achieved in the lithium-ion batteries, and there is almost no capacity loss after 1, 000 cycles at a high current density of 2 A g−1. This work may provide a reference for designing more fast-charging anode materials with high capacity.

Sodiation and Delithiation of Li4Ti5O12 for the Synthesis of Spinel-Type Sodium Titanium Oxide as an Anode Material for Sodium-Ion Batteries

Spinel-type sodium titanium oxide, Na3LiTi5O12 (NTO) has a structure analogous to that of Li4Ti5O12 (LTO) and is a promising anode material for sodium-ion batteries exhibiting good cyclability. However, the synthesis of NTO using LTO is a tedious process and requires more than nine iterated procedures, which involves the reductive insertion of Na+ in a glovebox, followed by oxidation using water, and subsequent extraction of Li+. Therefore, in this study, a efficient method was developed for the conversion of LTO to NTO. The conversion ratio of sodiated LTO to NTO during water oxidation was determined from the quantity of Li+ released into water, which was evaluated using ion chromatography. The results revealed that the conversion ratio was approximately 53 mol% at 273 K but decreased to 45 mol% at 303 K confirming its temperature dependence. Moreover, the sodiation of LTO could be accelerated via stirring, ultrasonication, and heating to 323 K. NTO was successfully produced via five treatment cycles using a method without using the glovebox. The half-cell employing the obtained NTO afforded a capacity of 125 mA h g−1, and stable cyclability for up to 200 cycles, with a retention ratio of 97.6% and a coulombic efficiency of 99.8%.

SnSe Nanosheet Array on Carbon Cloth as a High-Capacity Anode for Sodium-Ion Batteries.

Binder-free electrodes offer a great opportunity for developing high-performance sodium-ion batteries (SIBs) aiming at the application in energy storage devices. Tin selenide (SnSe) is considered to be a promising anode material for SIBs owing to its high theoretical capacity (780 mA h g-1). In this work, a SnSe nanosheet array (SnSe NS) on a carbon cloth is prepared using a vacuum thermal evaporation method. The as-prepared SnSe NS electrode does not have metal current collectors, binders, or any conductive additives. In comparison with the electrode of SnSe blocky particles (SnSe BP), the SnSe NS electrode delivers a higher initial charge capacity of 713 mA h g-1 at a current density of 0.1C and maintains a higher charge capacity of 410 mA h g-1 after 50 cycles. Furthermore, the electrochemical behaviors of the SnSe NS electrode are determined via pseudocapacitance and electrochemical impedance spectroscopy measurements, indicating a faster kinetic process of the SnSe NS electrode compared to that of the SnSe BP. Operando X-ray diffraction measurements prove that the SnSe NS exhibits better phase reversibility than the SnSe BP. After the cycles, the SnSe NS electrode still maintains its particular structure. This work provides a feasible method to prepare SnSe nanostructures with high capacity and improved sodium ion diffusion ability.

Hierarchical porous titanium dioxide nanosheets with surface-engineering for exceptional sodium storage performance

Structural reconstruction derived from surface engineering has substantially improved fast and high-efficient charge storage for sodium-ion batteries. Here, a surface engineering strategy including phosphorus doping and nitrogen-doped carbon coating simultaneously realizes surface structural reconstruction and establishes a conductive network, which significantly enhances Na+ storage kinetics of TiO2. Expectedly, functionalized TiO2 nanocrystals with phosphorus doping and nitrogen-doped carbon coating present expedited electron and Na+ transfer and enhanced structural stability during Na+ insertion/extraction, fueled by the enhanced surface electrochemical reactivity and unique hybrid structure. Therefore, surface-engineered two-dimensional (2D) TiO2 nanosheets achieve exceptional Na+ storage performance including the ultralong cycling stability with reversible capacities of 223 mAh/g at 5C for 10,000 cycles at 5C, 212 mAh/g at 10C for 20,000 cycles, and 203 mAh/g at 20C for 5000 cycles, as well as an ultrahigh rate capability of 181 mAh/g up to 50C. This functionalizing strategy fueled by surface engineering paves a new way for achieving high-performed anode materials for sodium-ion batteries.

Co-Intercalation Batteries (CoIBs): The Use of TiS2 As Electrode for Solvent Co-Intercalation in Sodium-Ion Batteries

With the rising demand for lithium-ion batteries (LIBs), sodium-ion batteries (SIBs) have become an attractive alternative with the promise of improved safety, reduced cost, and lower environmental impact.1 However, the larger ion size of sodium cation has major consequence on the battery chemistry, which provides several challenges and opportunities for designing electrode materials and electrolyte solutions.2 Graphite is the currently most used anode material in LIBs. However, its use in SIBs, with traditional carbonate-based electrolytes, results in very poor specific capacities due to unfavorable thermodynamic processes.3 A strategy around this problem is to choose different solvents: Ethers and in particular glymes can exhibit a co-intercalation behavior into the graphite structure by forming ternary graphite intercalation compounds.4, 5 Although the co-intercalation of solvent molecules with sodium cation leads to a large increase in the graphite framework, the cycle life and rate capability of the reaction are excellent.Regardless of this, there is a lack of evidence for a comparable reaction with other electrode materials. Hence, it would be of interest to identify a cathode material that operates via this same mechanism. A battery based on solvent co-intercalation at both electrodes can have minimized charge-transfer resistances due to the absence of desolvation steps, and great cycle life. Thus, such a system can show high power density over many cycles. It has also been shown that stripping of the solvation shell can be the rate limiting step for battery operation, especially at subzero temperatures.6 Such a solvent co-intercalation battery (CoIB) could therefore be more energy efficient compared to other batteries or could enable a better low-temperature performance.Transition metal dichalcogenides (TMDs) have emerged as promising anode materials owing to their low cost, high electric conductivity, good thermal stability and environmental friendliness. Among them, titanium sulphide (TiS2), with a two-dimensional framework, exhibits several advantages such as a high conductivity (compare to other metal oxides), a larger interlayer distance (0.569 nm) compared to graphite (0.335 nm) and high stability. 7 Several papers have reported on the use of TiS2 as an anode material for SIBs, and observed that the voltage profiles and electrochemical behaviour of the system is highly dependent on the choice of electrolyte. However, this has seldomly been explicitly stated and the cause of the electrolyte dependence has never been investigated. By using operando and in-situ techniques such as Operando XRD and dilatometry, Na-diglyme complexes were showed to co-intercalate, similar as graphite, into TiS2. In contrast, no signs of solvent co-intercalation are observed in cyclic ethers and conventional carbonate-based electrolytes – where instead the redox reaction with TiS2 results in the formation of different NaxTiS2 compounds.As we identified TiS2 as “co-intercalation electrode” in glyme-based electrolytes it served to create the first ever solvent co-intercalation battery (CoIB – pronounced Co-IB) which was done by pairing TiS2 (positive electrode) with graphite (negative electrode).8 This work could enable the development of highly energy efficient batteries with minimum charge transfer resistances and References I. Hasa, S. Mariyappan, D. Saurel, P. Adelhelm, A. Y. Koposov, C. Masquelier, L. Croguennec and M. Casas-Cabanas, J. Power Sources, 2021, 482, 228872. P. Adelhelm, P. Hartmann, C. L. Bender, M. Busche, C. Eufinger and J. Janek, Beilstein Journal of Nanotechnology, 2015, 6, 1016-1055. B. Jache and P. Adelhelm, Angew. Chem., 2014, 126, 10333-10337. B. Jache, J. O. Binder, T. Abe and P. Adelhelm, Physical Chemistry Chemical Physics, 2016, 18, 14299-14316. M. Goktas, C. Bolli, J. Buchheim, E. J. Berg, P. Novák, F. Bonilla, T. f. Rojo, S. Komaba, K. Kubota and P. Adelhelm, ACS applied materials & interfaces, 2019, 11, 32844-32855. S. S. Zhang, K. Xu and T. R. Jow, Journal of Power Sources, 2003, 115, 137-140. Q. Yun, L. Li, Z. Hu, Q. Lu, B. Chen and H. Zhang, Adv. Mater., 2020, 32, 1903826. G. A. Ferrero, G. Avall, K. A. Mazzio, Y. Son, K. Janssen, S. Risse and P. Adelhelm, Adv. Energy Mater., 2022, 2202377. an improved low temperature performance, where the charge transfer can become rate limiting. Figure 1

Design and Synthesis Strategy of MXenes-Based Anode Materials for Sodium-Ion Batteries and Progress of First-Principles Research.

MXenes-based materials are considered to be one of the most promising electrode materials in the field of sodium-ion batteries due to their excellent flexibility, high conductivity and tuneable surface functional groups. However, MXenes often have severe self-agglomeration, low capacity and unsatisfactory durability, which affects their practical value. The design and synthesis of advanced heterostructures with advanced chemical structures and excellent electrochemical performance for sodium-ion batteries have been widely studied and developed in the field of energy storage devices. In this review, the design and synthesis strategies of MXenes-based sodium-ion battery anode materials and the influence of various synthesis strategies on the structure and properties of MXenes-based materials are comprehensively summarized. Then, the first-principles research progress of MXenes-based sodium-ion battery anode materials is summarized, and the relationship between the storage mechanism and structure of sodium-ion batteries and the electrochemical performance is revealed. Finally, the key challenges and future research directions of the current design and synthesis strategies and first principles of these MXenes-based sodium-ion battery anode materials are introduced.

Fabrication of Internal Electric Field Sns/Sb2S3 with Engineered Porous Structure for Fast Kinetics Sodium Ion Storage

Benefiting from the abundance and low cost of sodium, sodium-ion batteries show great potential as lithium-ion batteries in application of large-scale energy storage. However, anode material graphite with high theoretical capacity 372 mAh g-1, low charge-discharge plateau potential and good cyclability, widely applied in lithium-ion batteries, exhibited poor electrochemical performance. The larger radius of Na-ion compared to Li-ion hinders the mass and ion transfer during charge-discharge cycling. Thus, anode material with large abundance, stability and high conductivity is crucial for the development and further application of sodium-ion batteries.Sodium-ion batteries have the potential to benefit greatly from metallic sulfide anodes, which offer high theoretical capacities. Unfortunately, the practical use of these anodes is limited by poor electrochemical performance, as sulfides tend to expand significantly in volume and Na+ ions exhibit sluggish kinetics during cycling. We have developed a facile and scalable approach to synthesizing a SnS/Sb2S3 heterostructure that is porous and bimetallic, with an additional sulfur and nitrogen co-doped carbon matrix encapsulation (SnS/Sb2S3@SNC). The PAN precursor is mixed homogeneously with SnSbx and S with a ball milling process. The sulfur evaporates from the mixture and reacts with the SnSbx alloy, leading to the formation of bimetallic sulfides SnS/Sb2S3. As a result, voids are generated, which in turn contributes to the development of a porous structure. At the same time, the PAN is carbonized, generating a S, N co-doped carbon matrix. SnS and Sb2S3 are two highly promising anode materials for sodium-ion batteries, with high theoretical specific capacity of 1022 mAh g-1 and 947 mAh g-1, respectively. Moreover, bimetallic sulfides possess different bandgap make them ideal components for generating a strong internal electric field on the hetero-interface, which allows to improve the charge carrier transport and interface reaction kinetics. The porous nature of the structure can contain the volume expansion of sulfides during cycling, thereby ensuring superior structural stability. The distinctive heterostructure, in combination with the S, N co-doped carbon matrix, enables fast-charge transport and accelerate Na-ion storage kinetics.The SnS/Sb2S3@SNC anode demonstrates impressive electrochemical performance, with high capacities of 425 mAh g-1 at 200 mA g-1 after 100 cycles, and 302 mAh g-1 at 500 mA g-1 after 400 cycles. Additionally, the SnS/Sb2S3 @SNC anode exhibits remarkable rate capability, with a capacity of over 200 mAh g-1 at a high current density of 5000 mA g-1. Figure 1

Rational Design of Bismuth Metal Anodes for Sodium-/Potassium-Ion Batteries: Recent Advances and Perspectives

Sodium-ion batteries (SIBs) and potassium-ion batteries (PIBs) have drawn widespread attention for application in large-scale accumulation energy because of their plentiful resources and lower cost. However, the lack of anodes with high energy density and long cycle lifetimes has hampered the progress of SIBs and PIBs. Bismuth (Bi), an alloying-type anode, on account of its high volumetric capacity and cost advantage, has become the most potential candidate for SIBs and PIBs. Nevertheless, Bi anodes undergo significant volume strain during the insertion and extraction of ions, resulting in the crushing of structures and a volatile solid electrolyte interface (SEI). As a result, the tactics to boost the electrochemical properties of Bi metal anodes in recent years are summarized in this study. Recent advances in designing nanostructure Bi-based materials are reviewed, and the reasonable effects of architectural design and compound strategy on the combination property are discussed. Some reasonable strategies and potential challenges for the design of Bi-based materials are also summarized. This review aims to provide practical guidance for the development of alloying-type anode materials for next-generation SIBs and KIBs.

Development of Lithium/Sodium-Ion Battery Electrodes Based on Solvent Engineered Tin(II) Oxide Nanomaterials

With the global economy pushing towards a greener and cleaner energy future for the world, renewable energy storage technologies must continue to develop and improve to allow for a seamless transition from the ways of the past to a carbon neutral future. To this end, renewable battery technology and in particular the capacity of the anode must be improved. Furthermore this improvement must be made across various battery technologies (Lithium/Sodium-ion) and be cost-effective to allow for its widespread implementation and use worldwide.In this work, Tin(II) Oxide (SnO)/single wall carbon nanotube (SWCNT) composite electrodes are analysed as a possible alternative dual anode material for both lithium (LIB) and sodium-ion batteries (NIB). The LIB is limited by the current commercial anode material of graphite with a relatively low theoretical capacity of 372 mAh g-1 whilst NIBs use hard carbon with a capacity of roughly 300 mAh g-1. Alloy/de-alloy materials are envisioned to be a suitable candidate for next generation LIBs/NIBs due to their large specific capacities (875mAh g-1/ 847 mAh g-1 for SnO respectively) although major drawbacks concern the poor cycling life associated with the volume change and the associated irreversible capacity. To overcome such issues the downsizing of materials and the fabrication of composites which incorporate both lithium active and inactive material are viewed as promising solutions. Nanostructured metal oxides, forming an inactive oxide matrix are appealing candidates.Through the implementation of a solvent engineered wet chemistry synthesis, various layered SnO microparticles are produced with several morphologies well-suited to energy storage applications. This synthesis method is facile, scalable and is favourable in comparison to hydrothermal synthesese normally used to synthesise nanomaterials. While SWCNTs are themselves not suited towards energy storage applications, their incorporation in the electrodes allows them to act as a conductive additive at a lower weight loading than other conventional carbon sources (carbon black/graphite), presenting a more effective strategy to form an effective electrical percolation network while also removing the need for polymer binders/copper current collector.The optimised morphology of SnO produces a high capacity, high rate and stable anode for LIB technology. An initial coloumbic efficiency (ICE) in excess of 80% is recorded and a stable cycling capacity of 815 mAh g-1 at 0.5C after 300 cycles is also achieved, demonstrating its long term stability. A maximum capacity of 980 mAh g-1 is recorded at 0.1C, whilst high rate capacities of 775, 671 and 364 mAh g-1 are recorded at 1,2 and 5C respectively. Furthermore a full-cell is composed with a NMC cathode to demonstrate a potential full-cell real world device. As an NIB anode, a maximum capacity of 568 mAh g-1 was recorded at 0.05C, whilst a low ICE of 50% proves an issue under further investigation. Furthermore a cycling capacity of 595 mAh g-1 is recorded after 50 cycles at 0.1C, dropping to 360 mAh g-1 at 100 cycles which is still in excess of that recorded for hard carbon in NIBs.A high capacity, scalable and cost effective anode has been developed that is interchangeable between LIBs/NIBs and exceeds the performance of the current commercial anodes. Reference s : [1] S. Jaśkaniec, S. R. Kavanagh, S. Ryan, J. Coelho, C. Hobbs, A. Walsh, D. O. Scanlon and V. Nicolosi, npj 2D Mater. Appl., 2021, 5, 27. [2] J. H. Shin and J. Y. Song, Nano Converg., 2016, 3(1), 9. [3] F. Zhang, J. Zhu, D. Zhang, U. Schwingenschlögl and H. N. Alshareef, Nano Lett., 2017, 17, 1302–1311.

LCA and C-LCC Indicator as Tools for Sodium-Ion Batteries’ Eco-Design

Sodium-ion batteries are considered promising alternatives to lithium-ion technology; however, the diffusion on a commercial scale is hindered by the struggle to identify materials with high electrochemical performances. Studies available in the literature are mainly focused on electrochemical performance and neglect aspects related to the environmental sustainability. In fact, the current state-of-the-art (presented in this study) shows that life cycle assessment (LCA) studies related to the production processes of electrode materials for Na-ion batteries are still very limited. The LCA methodology applied during the development of a technology phase can constitute a valid support for an eco-oriented design and, therefore, to the choice of solutions characterized by a lower environmental impact with the same electrochemical performance. In this context, a life cycle-based environmental–economic assessment was performed to evaluate the environmental impacts of the production process of cathode and anode materials for sodium-ion batteries. The study is focused on the cathodic active material Na0.66MnO2, considering two synthesis paths, and the anodic material consisting of tin (Sn) and Sn-carbon nanofiber (Sn-Cn) active material, binder, and other additives. Results illustrate the environmental performance of the different materials and constitute a useful input for their selection within an eco-design view.

Vanadium Nitride Nanoparticles Grown on Carbon Fiber Cloth as an Advanced Binder-Free Anode for the Storage of Sodium and Potassium Ions.

The escalating demand for sustainable and high-performance energy storage systems has led to the exploration of alternative battery technologies for lithium-ion batteries. Sodium-ion batteries (SIBs) and potassium-ion batteries (PIBs) have emerged as promising candidates because of their abundant Na/K resources, inexpensive costs, and similar chemistries to lithium-ion batteries. However, inherent challenges, such as large ionic radii, sluggish kinetics, and serious volume expansion, necessitate the development of robust and efficient anode materials for SIBs and PIBs. Vanadium nitride has attracted increasing attention as a viable anode due to its high electronic conductivity and potential capacity. In this study, we report on a flexible electrode for SIBs and PIBs that creates binder-free anodes by synthesizing vanadium nitride nanoparticles grown directly on carbon fiber cloths (VN/CFC). The unique architecture and binder-free nature of this anode ensure a robust electrode-electrolyte interface and enhance its electron/ion transport kinetics. The results demonstrate that the material exhibits an outstanding specific discharge capacity of 227 mAh g-1 after undergoing 1000 cycles at a current density of 2 A g-1 for SIBs. An electrochemical analysis indicated that the excellent performance of the material is attributed to the bind-free structure of carbon fiber cloth and the fast kinetics of surface pseudo-capacitive contribution. Furthermore, the material continues to demonstrate an impressive performance, even for PIBs, with a specific discharge capacity of 125 mAh g-1 after 1000 cycles at a current density of 1 A g-1. This study provides a new perspective for designing and developing advanced binder-free anodes for the storage of sodium and potassium ions, paving the way for high-performance energy storage applications.

Significantly Improving the Initial Coulombic Efficiency of TiO2 Anode for Sodium-Ion Batteries.

Titanium dioxide (TiO2) can serve as a candidate anode material for sodium-ion batteries (SIBs) with the merits of their low cost, abundance, and environment friendliness. However, its low initial Coulombic efficiency (ICE) and sluggish sodium-ion diffusion greatly limit its further practical applications. Herein, we report a one-step prepotassiation strategy to modify commercial TiO2 by a spontaneous chemical reaction using potassium naphthalene (K-Nt). Prepotassiation effectively compensates for the irreversible Na loss and induces a homogeneous, dense, and robust artificial solid electrolyte interphase (SEI) on its surface. The well-distributed artificial SEI suppresses the excessive electrolyte decomposition, contributing to rapid interfacial kinetics and stable Na+ insertion/extraction. Therefore, such modified commercial TiO2 anodes demonstrate significantly improved ICE (72.4%) and outstanding rate performance (176.4 mAh g-1 at 5 A g-1). This simple and efficient method for promoting ICEs and interfacial chemistry also demonstrates universality and practical value for other anodes in SIBs.

Utilization of PET derived hard carbon as a battery-type, higher plateau capacity anode for sodium-ion and potassium-ion batteries

Trash to Treasure is a less energy-intensive approach for upcycling plastic waste into value-added products to generate sustainable, cost-effective, eco-friendly materials. The carbonization of polyethylene terephthalate (PET) via a single-step process into hard carbon (HC) delivers a high-performing anode material for sodium-ion batteries (SIBs) and potassium-ion batteries (PIBs). Direct pyrolysis of PET waste increases the interlayer spacing with partially closed slit-shaped micro and mesopores that significantly improves the lower potential plateau-based capacity to 68% of the total capacity, validating a battery-type anode material. The HC carbonized at 1000℃ delivers a reversible capacity of 337 mAh/g with capacity retention of 88% after 100 cycles at 30 mAh/g. The HC exhibits 80% capacity retention even after 1000 cycles at a 1C rate and is promising for fast cycling-high power density applications. In PIBs, the HC carbonized at 800℃ performs the best and shows a reversible capacity of 305 mAh/g, with a battery-type low voltage plateau contribution of 32%. The charge storage mechanism in SIBS and PIBs follows a three-stage storage mechanism, i.e., adsorption, intercalation, and pore-filling.

Yolk-shell FeSe2@CoSe2/FeSe2 heterojunction as anode materials for sodium-ion batteries with high rate capability and stability

Sodium-ion batteries are promising candidates for large-scale grid storage systems and other applications. Their foremost advantage derives from superior environmental credentials, enhanced safety as well as lower raw material costs than lithium-ion batteries. It is still challenging to explore desirable anode material. In this study, FeSe2@CoSe2/FeSe2, with a yolk-shell structure was prepared by ion exchange and selenisation. The FeSe2@CoSe2/FeSe2 prepared as anode material for sodium-ion batteries exhibits excellent rate capability due to the synergistic effect of bimetallic selenides and the interfacial effect of the heterostructure. Moreover, it delivers high performance (510 mAh g−1 at 0.2 A g−1), superior rate capability (90% retention at 5 A g−1), and good long-time cycling stability (78% capacity retention after 1800 cycles at a high current density of 2 A g−1). The optimized sodium-ion full cell with FeSe2@CoSe2/FeSe2 as the anode and Na3V2(PO4)3 as the cathode still demonstrates excellent performance. Namely, a capacity of 272 mAh g−1 (at 1 A g−1) within the operating voltage from 1 to 3.8 V can be obtained. This work illustrates the potential of bimetallic selenides with heterostructures for performance enhancement of sodium-ion batteries.

The Emeraldine salt PANI/SnO2 nanocomposite anode materials for sodium-ion batteries with enhanced initial coulombic efficiency

Tin oxide is promising candidate as an anode material for sodium-ion batteries. High volume change and the low electrical conductivity of SnO2 material during sodiation and de-sodiation affect negatively the electrochemical performance of sodium-ion batteries. Instead of their traditional carbon composites, the Emeraldine salt PANI/SnO2 nanocomposite to alleviate the high volume change (pulverization) and improve conductivity of SnO2 material is synthesized with an emulsion polymerization method by in situ polymerization of aniline on the SnO2 surface. The the Emeraldine salt PANI not only exhibits high flexibility to alleviate the high volume change of SnO2 nanoparticles, but also enhances the conductivity of electrons and sodium ions. Furthermore, the Emeraldine salt PANI coating enhanced the coulombic efficiency of SnO2 electrode. Therefore, Emeraldine salt Polyaniline coating is a promising buffer material for relieving a high volume change and enhancing coulombic efficiency, especially in the first cycle, and anode durability with the high electrochemical performance for sodium-ion batteries.

Epitaxial growth of Cu2-xSe on Cu (220) crystal plane as high property anode for sodium storage

Three-dimentional (3D) transition metal selenides with sufficient channels could produce significant superiority on enhancing reaction kinetics for sodium-ion batteries. However, the thorough exploration of 3D architecture with a facile strategy is still challenging. Here we report that a polycrystalline Cu2-xSe film was epitaxial grown on (220) facets-exposed Cu by direct selenization of a nanoporous Cu skeleton, which is obtained by dealloying rolled CuMn@Cu alloy foil. Density functional theory calculation result shows strong adsorption energy for Se atoms on Cu (220) planes during selenization reaction, rendering a low energy consumption. By virtue of this core-shell 3D nanoporous architecture to offer abundant active sites and endow fast electron/ion transportation, the nanoporous Cu2-xSe@Cu-0.15 composite electrode exhibits remarkable sodium-ion storage properties with high reversible capacity of 950.6 µAh/cm2 at 50 µA/cm2, suprior rate capability of 457.6 µAh/cm2 at 500 µA/cm2, as well as an ultra-long stability at a high current density. Mechanism investigation reveals that the electrochemical reaction is a typical conversion-type reaction with different intermediates. This novel electrode synthetic strategy provides useful instructions to design the high-performance anode material for sodium-ion batteries.

Synergistic Engineering of Architecture and Composition in Bimetallic Selenide@Carbon Hybrid Nanotubes for Enhanced Lithium‐ and Sodium‐Ion Batteries

AbstractDeveloping sustainable and affordable anode materials that are capable of delivering high performance in both lithium‐ion batteries (LIBs) and sodium‐ion batteries (SIBs) remains a significant challenge. Bimetallic selenide@carbon hybrids are considered as one of the most promising anode materials in LIBs and SIBs due to their high electronic conductivity, high specific capacity, and fast reaction kinetics. Herein, a series of bimetallic selenide@carbon hybrid nanotubes are successfully prepared as anodes of LIBs or SIBs based on the dual regulation of component and micro‐nanostructure. The selenization strategy plays a key important role in determining the composition, microstructure, and electrochemical energy storage properties of anode materials. As a consequence, the ZnSe/CoSe2@NPC NTs(I)‐600 exhibit a reversible capacity of 1328.3 mAh g−1 at 0.1 A g−1 and superior rate capability (269.1 mAh g−1 at 10 A g−1) towards Li+ storage. Meanwhile, ZnSe/CoSe2@NPC NTs(II)‐700 achieve 354.1 mAh g−1 at 0.1 A g−1 and ultralong cycling stability (97.6% of capacity retention after 40 000 cycles at 10 A g−1) used as anode materials in SIBs. This study provides a feasible strategy to fabricate selenide‐based composites as anode materials for high‐performance LIBs and SIBs via architecture engineering and composition tailoring.

Revealing sodium storage mechanism of hard carbon anodes through in-situ investigation of mechano-electrochemical coupling behavior

Hard carbon (HC) is considered a promising anode material for sodium-ion batteries due to its relatively low price and high specific capacity. However, HC still suffers from unclear reaction mechanisms and unsatisfactory cycling stability. The study of mechano-electrochemical coupling behavior by in-situ measurement techniques is expected to understand the sodium storage and degradation mechanisms. In this paper, the strain and stress evolution of HC anodes at different sodiation/desodiation depths and cycles are investigated by combining electrochemical methods, digital image correlation, and theoretical equations. The observation by monitoring the in-situ strain evolution during the redox process supports the “adsorption-intercalation/filling” mechanism in reduction and the “de-filling/de-intercalation-desorption” mechanism in oxidation. Further studies have demonstrated that the strain and stress of the electrode show periodic changes accompanied by a continuous accumulation of residual stress during cycles, explaining the capacity degradation mechanism of HC from a mechanical perspective. In addition, when the higher current density is applied, the electrodes experience greater strain and stress associated with the Na+ insertion rate. This work clarifies the Na-storage mechanism and the mechano-electrochemical coupling mechanism of HC anodes by in-situ strain measurement, which helps optimize and design the anode materials of sodium-ion batteries from the perspective of interface microstructure and multi-field coupling, such as in situ integrated interface structure design.