Recent Advances in 3D Array Anode Materials for Sodium-Ion Batteries

Abstract

Lithium-ion batteries have achieved tremendous success in the fields of portable mobile devices, electric vehicles, and large-scale energy storage owing to their high working voltage, high energy density, and long-term lifespan. However, lithium-ion batteries are ultimately unable to satisfy increasing industrial demands due to the shortage and rising cost of lithium resources. Sodium is another alkali metal that has similar physical and chemical properties to those of lithium, but is more abundant. Therefore, sodium-ion batteries (SIBs) are promising candidates for next-generation energy storage devices. Nevertheless, SIBs generally exhibit inferior electrochemical reaction kinetics, cycling performance, and energy density to those of lithiumion batteries owing to the larger ion radius and higher standard potential of Na+ compared to those of Li+. To address these issues, significant effort has been made toward developing electrode materials with large sodiation/desodiation channels, robust structural stability, and high theoretical capacity. As electrode performance is closely related to its architecture, constructing an advanced electrode structure is crucial for achieving high-performance SIBs. Conventional electrodes are generally prepared by mixing a slurry of active materials, conductive carbon, and binders, followed by casting on a metal current collector. Electrodes prepared this way are subject to shape deformation, causing the active materials to easily peel off the current collector during charge/discharge processes. This leads to rapid capacity decay and short cycle life. Moreover, binders and other additives increase the weight and volume of the electrodes, which reduces the overall energy density of the batteries. Therefore, binder-free, three-dimensional (3D) array electrodes with satisfactory electronic conductivity and low ion-path tortuosity have been proposed. In addition to solving the aforementioned issues, this type of electrode significantly reduces contact resistance through the strong adhesion between the array and the substrate. Furthermore, electrolyte infiltration is greatly facilitated by the abundant interspacing between individual nanostructures, which promotes fast electron transport and shortens ion diffusion, thus enabling the electrode reaction. The array structure can also readily accommodate substantial volume variations that occur during repeated sodiation/desodiation processes and release the generated stress. Therefore, it is of great interest to explore binder-free array electrodes for sodium-ion storage applications. This review summarizes the recent advances in various 3D array anode materials for SIBs, including elemental anodes, transition metal oxides, sulfides, phosphides, and titanates. The preparation methods, structure/morphology characteristics, and electrochemical performance of various array anodes are discussed, and future opportunities and challenges from employing array electrodes in SIBs are proposed.

CO2 Etching Modulates Lithium and Sodium Storage Performance of Hard–Soft Carbon Composite-Based Freestanding Thick Electrodes

“…Carbon-based materials are preferred for fabricating all-electrochem-active electrodes. The tortuous atomic structure of hard carbon suffers low electronic/ionic conductivity, which leads to a relatively poor rate capability; in contrast, soft carbon represents the graphitizable nongraphitic carbon with higher electronic conductivity. − Hard carbon has a larger lattice plane distance ( d 002 ) of ∼0.388 nm, which has been proven to be effective for sodium storage, whereas the full performance potential of soft carbons has not been explored and well understood; thus, soft carbon has been extensively investigated as the active material for anion and cation storage, and its lattice plane distance ( d 002 ) is ∼0.344 nm. , Thus, it is significant to adjust the microcrystal structure of carbon materials to fully exploit the advantages when applied to different energy storage systems.…”

Carbon Quantum Dot-Coated VSe2 Nanosheets as Anodes for High-Performance Potassium-Ion Batteries

“…Lithium-ion batteries (LIBs) have been extensively used in electronic equipment, electric vehicles, and hybrid electric vehicles due to their high energy density, environmental protection, and long cycling life. − Sodium-ion batteries (SIBs) and potassium-ion batteries (PIBs) have attracted great attention in recent years thanks to their abundant natural storage (2.36 and 2.09% for sodium and potassium, respectively, compared to 0.0017% for lithium in weight in the Earth’s crust). − PIBs have a lower redox voltage (−2.93 K + /K vs E 0 ) compared to that of SIBs (−2.71 Na + /Na vs E 0 ) and a higher operating voltage and energy density. − Besides, with the weaker Lewis acidity of K + , the smallest solvated K + , and Stokes’ radius (0.36, 0.46, and 0.48 nm for K + , Na + , and Li + , respectively), K + has faster diffusion in the electrolyte, thus improving the electrode kinetic. , Unfortunately, the large radius of K + results in the poor kinetic and unstable structure during the depotassiation/potassiation process, leading to low capacity and inferior cycling life. − To date, the investigation of PIB electrode materials is also less. On the one hand, the anode materials focus on carbon, graphene, and transition-metal composites. − On the other hand, the cathode materials concentrated in Prussian blue and phosphate. , …”

Rational Design Hierarchical SnS2 Uniformly Adhered to Three-Sided Carbon Active Sites to Enhance Sodium Storage

“…With the popularity of portable electronic devices and the growth of the electric vehicle market, lithium-ion secondary batteries have become a practical and effective energy storage solution. − Due to the scarcity of lithium, it is critical to investigate and develop energy storage technologies that can efficiently replace and supplement lithium. , Because of their availability and global distribution, sodium-ion batteries (SIBs) have gotten a lot of interest as a viable replacement. − Unfortunately, the repeated insertion/extraction process of sodium ions exacerbates the decay of cycle life due to the larger radius of sodium compared to lithium ions. Therefore, it is urgent to produce an anode material with a large interlayer distance and a large capacity. − …”

“…Currently, a sequence of anode materials are being exploited, such as traditional graphite materials, , transition metal oxides, , alloy-based materials, , and metal sulfides. − Tin sulfide (SnS 2 ) is considered to be an ideal anode material for SIBs due to its large interlayer distance, low cost, and considerable theoretical specific capacity. − Nevertheless, in addition to the inherent advantages mentioned above, SnS 2 anodes generally suffer from some drawbacks, such as insufficient electronic conductivity, and the large volume change caused by the large Na + during insertion/extraction. , This invariably results in poor rate performance and electrode material cycle stability. , …”

“…22−24 Nevertheless, in addition to the inherent advantages mentioned above, SnS 2 anodes generally suffer from some drawbacks, such as insufficient electronic conductivity, and the large volume change caused by the large Na + during insertion/extraction. 10,23 This invariably results in poor rate performance and electrode material cycle stability. 24,25 Fabrication of nanostructures with various morphologies and synthesis of composite materials (especially with conductive carbon materials) are considered two countermeasures for addressing the aforementioned issues.…”