systems is hindered by the limited reserves and high cost of lithium. [1][2][3] Compared with LIBs, sodium ion batteries (SIBs) enjoy many advantages, such as low costs arising from abundance of sodium as well as potentially wider applications, including grid energy storage. [4][5][6][7] In view of the recent studies in developing promising cathode materials, [8,9] one of the critical challenges in promoting the commercialization of SIBs is the lack of suitable anode materials with high capacities and rate capability as well as long-term cyclic performance. The commercial graphite anode in LIBs cannot host the Na + ions whose diameter is 34% larger than the Li + ions in the commonly used carbonate-based electrolyte system, [10,11] although a recent study demonstrated the feasibility of cointercalation of Na + ions in ether-based electrolyte upon the formation of a ternary intercalation compound. [12] Many efforts have been devoted to investigating carbonaceous materials, such as hard carbon, [13] hollow carbon sphere, [14] carbon fiber, [15] as well as metals/metal chalcogenides, like Sn, [16] SnO x , [17] SnO 2 , [18] Bi 0.94 Sb 1.06 S 3, [19]and Sb, [20] as the potential anode materials. Compared with carbonaceous anodes possessing low storage capacities and unsafely low working potentials, anodes made from metal sulfides have been increasingly explored to achieve superior rate performance and high specific capacities. [21][22][23][24][25] For example, antimony trisulfide (Sb 2 S 3 ) has drawn significant attention because of its attractive reversible theoretical capacity of 946 mAh g −1 by accommodating 12 moles of Na + ions per Sb 2 S 3 mole and the improved cyclic performance owing to the Na 2 S phase serving as the buffer matrix to relieve the volume expansion. [26] So far, many methods have been adopted to successfully fabricate various Sb 2 S 3 -based anodes, such as reduced graphene oxide (rGO)/Sb 2 S 3 , [25] flower-like Sb 2 S 3 , [26] Sb 2 S 3graphite, [27] and rod-shaped Sb 2 S 3 , [28] which demonstrated exceptional reversible capacities and great potential for SIBs. However, the fundamental understanding of the underlying sodiation reaction mechanisms is still lacking and needs to be investigated in order to promote the wide application of the Sb 2 S 3 anodes.Carbon-coated van der Waals stacked Sb 2 S 3 nanorods (SSNR/C) are synthesized by facile hydrothermal growth as anodes for sodium ion batteries (SIBs). The sodiation kinetics and phase evolution behavior of the SSNR/C anode during the first and subsequent cycles are unraveled by coupling in situ transmission electron microscopy analysis with first-principles calculations. During the first sodiation process, Na + ions intercalate into the Sb 2 S 3 crystals with an ultrafast speed of 146 nm s −1 . The resulting amorphous Na x Sb 2 S 3 intermediate phases undergo sequential conversion and alloying reactions to form crystalline Na 2 S, Na 3 Sb, and minor metallic Sb. Upon desodiation, Na + ions extract from the nanocrystalline phases to leave behi...

A dual-phase MoS2 with expanded interlayer distance is fabricated for sodium storage. The dual-phase MoS2 shows significantly improved electrical conductivity and enhanced Na+ diffusivity compared to the common 2H-MoS2.

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SnS2 nanoplatelet electrodes can offer an exceptionally high pseudocapacitance in an organic Na+ ion electrolyte system, but their underlying mechanisms are still largely unexplored, hindering the practical applications of pseudocapacitive SnS2 anodes in Na‐ion batteries (SIBs) and Na hybrid capacitors (SHCs). Herein, SnS2 nanoplatelets are grown directly on SnO2/C composites to synthesize SnS2/graphene‐carbon nanotube aerogel (SnS2/GCA) by pressurized sulfidation where the original morphology of carbon framework is preserved. The composite electrode possessing a large surface area delivers a remarkable specific capacity of 600.3 mA h g−1 at 0.2 A g−1 and 304.8 mA h g−1 at an ultrahigh current density of 10 A g−1 in SIBs. SHCs comprising a SnS2/GCA composite anode and an activated carbon cathode present exceptional energy densities of 108.3 and 26.9 W h kg−1 at power densities of 130 and 6053 W kg−1, respectively. The in situ transmission electron microscopy and the density functional theory calculations reveal that the excellent pseudocapacitance originates from the combination of Na adsorption on the surface/Sn edge of SnS2 nanoplatelets and ultrafast Na+ ion intercalation into the SnS2 layers.

anodes. These new anodes promise an almost 100% increase in practical energy density compared to those of conventional LIB counterparts. [3][4][5][6][7][8][9] While developing cathodes for the next-generation batteries has made a significant progress, relatively fewer research efforts have thus far been devoted to Li metal anodes because of the formation of Li dendrites which is considered a critical drawback instigating devastating safety issues of batteries. [10] Along with recent studies on Li plating behaviors, there have been renewed interests in developing Li metal anodes. [11][12][13] In particular, the dendrite-free Li metal anode was made possible by rationally designing the electrolyte composition and electrode morphologies. [14,15] Nevertheless, the current Li metal anodes are far from being viable because of several reasons. Namely, (1) the dendritic Li emerges when the current density raises above the percolation value; (2) the Coulombic efficiencies (CEs) of Li metal anodes are too low to maintain good cyclic stability of batteries; and (3) the design of Li metal anodes is still inadequate, making it difficult to integrate into the existing LIB configurations, such as pouch and cylindrical cells. [12] Most of the strategies currently exercised for dendrite-free Li metal anodes usually fail to resolve all the above mentioned issues. For example, the all-solid-state Li-metal battery requires certain prestress to reduce the interfacial resistance between the solid-state electrolyte and the electrode, but such a prestress is difficult to apply on pouch cells. [16,17] The feasibility of artificial solid electrolyte interphase (SEI) protection on Li foil remains doubtful because the Li foil alone cannot be used as current collector in practical cells due to its hostless nature and huge volume changes during the repeated cycles. [11,18] Among all potential strategies, the incorporation of conductive substrates to function as both the Li host and current collector is considered an ideal approach for further development of practical Li metal anodes. [19] The growth of Li dendrites at high current densities was mitigated by means of reduced local current densities using conductive substrates. [12] Moreover, the conductive substrates also functioned as the current collector, which is compatible with the existing LIB configurations. While copper has been widely studied as the matrix material for hosting Li metal, carbon is considered a more promising candidate than copper Carbonaceous materials are widely employed to host Li for stable and safe Li metal batteries while relatively little effort is devoted to tailoring the surface properties of carbon to facilitate uniform Li plating. Herein, the correlation between Li plating behavior and the surface characteristics of electrospun porous carbon nanofibers (PCNFs) is systemically elucidated through experiments and theoretical calculations. It is revealed that the neat carbon surface suffers from severe lattice mismatch with Li metal, hindering uniform Li plating....

Hierarchical MoS2/C microspheres are synthesized via a facile hydrothermal method, which enable reversible and fast Na storage.

Advanced wearable strain sensors with high sensitivity and stretchability are an essential component of flexible and soft electronic devices. Conventional metal-and semiconductor-based strain sensors are rigid, fragile, and opaque, restricting their applications in wearable electronics. Graphene-based percolative structures possess high flexibility and transparency but lack high sensitivity and stretchability. Inspired by the highly flexible spider web architecture, we propose semitransparent, ultrasensitive, and wearable strain sensors made from an elastomer-filled graphene woven fabric (E-GWF) for monitoring human physiological signals. The highly flexible elastomer microskeleton and the hierarchical structure of a graphene tube offer the strain sensor with both excellent sensing and switching capabilities. Two different types of E-GWF sensors, including freestanding E-GWF and E-GWF/polydimethylsiloxane (PDMS) composites, are developed. When their structure is controlled and optimized, the E-GWF strain sensors simultaneously exhibit extraordinary characteristics, such as a high gauge factor (70 at 10% strain, which ascends to 282 at 20%) in respect to other semitransparent or transparent strain sensors, a broad sensing range up to 30%, and excellent linearity. The E-GWF/PDMS composite sensor shows a unique reversible switching behavior at a high strain level of 30−50%, making it a suitable material for fast and reversible strain switching required in many early warning systems. With a view to real-world applications of these sensors and switches, we demonstrate human motion detection and switch controls of light-emitting-diode lamps and liquid-crystal-display circuits. Their unique structure and capabilities can find a wide range of practical applications, such as health monitoring, medical diagnosis, early warning systems for structural failure, and wearable displays.

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