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Uneven deposition and stripping of Lithium (Li) can lead to dendrite growth and instability of solid electrolyte interphase (SEI), which severely prevents the Li metal battery from practical applications. In this paper, atomic layer deposition (ALD) method is used to alter the lithiophilicity of carbon fiber network by depositing ultra-thin conformal ZnO layer at a low mass loading (5.9 ​wt%). The thin layer ZnO by ALD could provide uniform Li nucleation sites and guide Li deposition along the carbon fibers without formation of dendrites, and release Li from top of the electrode without formation of dead Li during dissolution. As a result, the ALD ZnO-modified carbon fiber/Li (ALD/C–Li) composite anode can cycle stably at a large current density as high as 15 ​mA/cm2 giving low overpotential (105 ​mV) and long-running lifespan with stable stripping/plating profiles nearly 500 cycles at 5 ​mA/cm2. Tests of X-ray photoelectron spectroscopy (XPS) combined with argon ion etching show that the ALD/C–Li anode can effectively stabilize the SEI with a negligible increase in thickness after 100th cycle, while that of bare Li electrode doubles under the same cycling conditions. The full cell with LiFePO4 cathode also shows a much low hysteresis at 2 ​C over 300 cycles. The strategy developed in this work provides a novel alternative to Li anodes with long lifespan and opens up a new avenue for Li metal batteries with high energy density and high power density.

The nonuniform nucleation of lithium (Li) leads to dendritic behavior and formation of dead Li, which seriously hinders the practical application of Li metal batteries. Here, atomic layer deposition (ALD) is used to deposit uniform and conformal ZnO coating (at a low content of 5.96%) on carbon fibers to form a free-standing framework Li host material without uncontrollable dendrites. Compared with the liquid deposition process, the ALD method can achieve homogeneous and conformal ZnO coating and excellent lithiophilicity of the carbon fiber, guiding molten Li infusion into the carbon fiber skeleton to obtain the Li/C composite electrode with a flat surface, thereby minimizing the effective current density. More importantly, the converted LiZn alloy will serve as uniform and numerous nucleation sites for Li and guide synchronous growth of the Li metal along carbon fibers, displaying a dendrite-free morphology after large-current and long-term deposition/dissolution cycling. Therefore, the ALD ZnO-modified carbon fiber/Li exhibits significantly better cycle and rate performances than the liquid deposition ZnO-modified carbon fiber/Li composite anode. The electrodes display an ultralong lifespan up to 400 cycles at 3.0 mA/cm2, as well as a high rate performance (with a deposition overpotential of 338 mV at 25.0 mA/cm2) at a high Li deposition areal capacity of 5.0 mA h cm-2.

To better implement super critical carbon dioxide (SC-CO2) fracturing on shale, it is important to investigate effects of SC-CO2 on rock mechanical properties. Because micro-scale mechanical properties determine the overall mechanical response, the determination of micro-scale mechanical properties is necessary. In this paper, continuous stiffness measurement (CSM) and constant loading rate (CLR) mode nanoindentation was performed on shale samples before and after SC-CO2 treatment. With the aid of scanning electron microscope and energy dispersive spectra mapping technique, mechanical strength difference on clay-rich and quartz –rich areas in shale sample can be identified. The results demonstrated that samples treated by SC-CO2 present lower Hardness, Young’s modulus and fracture toughness. The average decrease rates of hardness and Young’s modulus under CSM mode for three sample are 32.01 % and 11.75 %. The hardness, Young’s modulus and fracture toughness under CLR mode for the three samples have decreased at average rates of 29.5 %, 11.0 %, and 11.3 %, respectively. Moreover, the mechanical strength substantially decreases in the clay-rich area because CO2 adsorption and mineral dissolution happen after the SC-CO2 treatment. The change in mechanical properties in quartz-rich area is much smaller because there is little effect on quartz. The close examination of indentation fracture geometry indicate more micro fractures have been generated in the post SC-CO2 treated shale, thus we can expect the capability of SC-CO2 for rock weaken. This study can provide more insights for fracture mechanism in target areas with different mineral distribution, which is beneficial for SC-CO2 engineering applications.

SnS2 materials have attracted broad attention in the field of electrochemical energy storage due to their layered structure with high specific capacity. However, the easy restacking property during charge/discharge cycling leads to electrode structure instability and a severe capacity decrease. In this paper, we report a simple one-step hydrothermal synthesis of SnS2/graphene/SnS2 (SnS2/rGO/SnS2) composite with ultrathin SnS2 nanosheets covalently decorated on both sides of reduced graphene oxide sheets via C-S bonds. Owing to the graphene sandwiched between two SnS2 sheets, the composite presents an enlarged interlayer spacing of ∼8.03 A for SnS2, which could facilitate the insertion/extraction of Li+/Na+ ions with rapid transport kinetics as well as inhibit the restacking of SnS2 nanosheets during the charge/discharge cycling. The density functional theory calculation reveals the most stable state of the moderate interlayer spacing for the sandwich-like composite. The diffusion coefficients of Li/Na ions from both molecular simulation and experimental observation also demonstrate that this state is the most suitable for fast ion transport. In addition, numerous ultratiny SnS2 nanoparticles anchored on the graphene sheets can generate dominant pseudocapacitive contribution to the composite especially at large current density, guaranteeing its excellent high-rate performance with 844 and 765 mAh g-1 for Li/Na-ion batteries even at 10 A g-1. No distinct morphology changes occur after 200 cycles, and the SnS2 nanoparticles still recover to a pristine phase without distinct agglomeration, demonstrating that this composite with high-rate capabilities and excellent cycle stability are promising candidates for lithium/sodium storage.

Lithium sulfide (Li2S) is considered as an attractive cathode material for Li/S batteries due to its high theoretical specific capacity. In order to overcome its poor conductivity, Li2S is often compounded with carbon materials. However, the composites prepared by the traditional physical mixing method have low loading content, poor dispersion, large particle size of Li2S and lack of binding effects for polysulfides shuttle. Herein, we prepare nano-sized Li2S/graphene aerogel composite by in-situ lithiation of nano-S precursor. The Li2S loading in this composite is high (69.0 wt%) and variable, the nanoscaled particle size (ca. 10 nm) retains well from the elemental S precursor and disperses evenly on the three-dimensional porous graphene aerogel. More importantly, C O S chemical bonding is retained between Li2S and graphene skeleton, thus the dissolution of polysulfide species and the shuttle effect can be effectively suppressed. After the lithiation process, the specific surface area is also unexpectedly increased by a factor of 10, greatly improving the lithium ion transport path, and contributing to an increase in rate performance. As a result, the in-situ lithiated Li2S/graphene aerogel composite exhibits higher specific capacity and stability compared to that via ex-situ infiltration route.

Flexible pressure sensors play an important role in electronic skins (E-Skins), which mimic the mechanical forces sensing properties of human skin. A rational design for a pressure sensor with adjustable characteristics is in high demand for different application scenarios. Here, we present tunable, ultrasensitive, and flexible pressure sensors based on compressible wrinkled microstructures. Modifying the morphology of polydimethylsiloxane (PDMS) microstructure enables the device to obtain different sensitivities and pressure ranges for different requirements. Furthermore, by intentionally introducing hollow structures in the PDMS wrinkles, our pressure sensor exhibits an ultrahigh sensitivity of 14.268 kPa-1. The elastic microstructure-based capacitive sensor also possesses a very low detectable pressure limit (1.5 Pa), a fast response time (

Heterostructures have broad potential application in energy conversion material and optoelectronic device since of novel interface effect and enhanced electron transport dynamics at heterointerfaces. Herein, we report a heterostructured SnS/SnO2/spherical graphene composite, in which ultrafine SnS/SnO2 nanoparticles with heterostructures are sandwiched between multi-layers of graphene sheets, exhibiting a hollow spherical architecture as a whole. Detailed electrochemical studies indicate that the molar ratio of SnS to SnO2 has great influence on the charge transport efficiency. Theoretical calculation reveals that SnS and SnO2 exhibit different work functions and the Fermi level shift is affected by the SnS/SnO2 molar ratio, thus the hybrid with the ratio close to 1.0 owns the most adsorbed lithium ions, which leads to the highest specific charge-transfer kinetics and lowest ion-diffusion resistance than other samples. Electrochemical tests show that the composite with appropriate composition delivers the best lithium storage rate performance (620 and 312.7 mAh g−1 at 1 C and 10 C). A much stable and high reversible specific capacity of 850 mAh g−1 is obtained after 200 cycles at 0.1 C. The appropriate molar ratio of nano-heterostructures and the novel sandwich hollow spherical composite structure are attributed to the excellent electrochemical performances.

A novel two-step method is developed for the facile preparation of hollow nano-spherical boron nitride (BN). BN nanospheres prepared by the traditional chemical vapor deposition reaction of ammonia and trimethyl borate were hollowed out. The average size of solid BN nanospheres precursor was ~ 130 nm. Boron nitride phase, morphology, and surface functionalization characterization along with the measurement of O content, and surface functionality were used to illustrate the final differences among various cavitating BN nanospheres treated with different gas flows at a higher temperature. Several possible formation mechanisms for the BN cavitating structures were proposed. This work provides direction for the controllable preparation of hollow-type BN particles.

The reunion of Sn is always a troublesome issue when it’s used as the energy storage materials, on the one hand it comes from the preparation process due to its low melting point, and on the other hand it comes from the Li-Sn alloying process because of its natural tendency of migration. The Sn/SnO2/spherical graphene composite prepared by one-step low temperature hydrothermal reduction method can effectively solve this problem. In the composite, Sn/SnO2 tiny nanoparticles with average diameter of 5 nm distribute evenly between multilayers of graphene sheets presenting a hollow spherical structure. The introduction of SnO2 can effectively restrain the agglomeration of Sn nanoparticles during alloying process since an amorphous Li2O matrix is formed to separate the adjacent active particles. The sandwich graphene hollow sphere skeleton effectively buffers the volume expansion of Sn/SnO2 and further restricts their migration and agglomeration. Due to the above advantages, the nano-Li2O generating from the decomposition of SnO2 can contact closely with excessive nano-Sn in restricted area, promoting facile conversed conversion reaction. Therefore, the composite exhibits high reversible capacity and excellent cycle performance. A stable and high specific capacity of 843.8 mAh g−1 is obtained after 100 cycles at 0.1 C.

Energy efficiency has become the main concern of IC technology. Tunnel FET (TFET) is recognized to possess the superiority of energy efficiency over MOSFET at ultralow voltage, while variability might limit the voltage reduction and thus the energy saving. Recently, device source doping gradient (SDG) is found to be the dominant variation source in TFET. In this paper, for the first time, with the awareness of SDG variation, the energy efficiency of TFET-based circuits with different activity factors ( $\alpha $ ) is comprehensively reassessed and the device optimization strategy is provided. It is found that the superiority of energy efficiency of TFET will significantly decrease especially for the more active circuit due to the inherent tradeoff between SDG variation and nominal SDG. Based on the quantitative relationship between SDG variation and nominal SDG extracted from the experimental devices, the optimal design of tunnel junction abruptness to maximize the circuit energy efficiency is obtained, leading to significant energy efficiency improvements of TFET-based circuit over MOSFET even for circuit with high $\alpha $ . This paper provides helpful device design guidelines for TFET with device variability awareness from the perspective of circuit energy efficiency.

SnS is widely studied as anode materials since of its superior structural stability and physicochemical property comparing with other Sn-based composites. Nevertheless, the inconvenience of phase morphology control and excessive consumption of sulfur sources during synthesis hinder the scalable application of SnS nanocomposites. Herein, we report a facile in-situ sulfuration strategy to synthesize sandwiched spherical SnS/sulfur-doped graphene (SnS/S-SG) composite. An ultra-low sulfur content with approximately stoichiometric ratio of Sn:S can effectively promote the sulfuration reaction of SnO2 to SnS and simultaneous sulfur-doping of graphene. The as-prepared SnS/S-SG composite shows a three-dimensional interconnected spherical structure as a whole, in which SnS nanoparticles are sandwiched between the multilayers of graphene sheets forming a hollow sphere. The sandwiched sphere structure and high S doping amount can improve the binding force between SnS and graphene, as well as the structural stability and electrical conductivity of the composite. Thus, a high reversibility of conversion reaction, promising specific capacity (772 mAh g−1 after 100 cycles at 0.1 C) and excellent rate performance (705 and 411 mAh g−1 at 1 C and 10 C, respectively) are exhibited in the SnS/S-SG electrode, which are much higher than that of the SnS/spherical graphene synthesized by traditional post-sulfuration method.

Low reversion of lithium oxide (Li2O) and the tin (Sn) coarsening causing irreversible capacity loss is the main reason for the poor cycle performance in tin dioxide (SnO2) based composites. In this research, a novel sandwiched spherical tin dioxide/graphene with a three-dimensional interconnected closed pore structure is synthesized. The microstructural characterization shows that the spherical graphene with submicron sized diameters interconnects with each other forming an interconnected flexible conductive network, whereas a large number of SnO2 nanoparticles (approximately 5 nm) are limited homogeneously in between the interlayers of the sphere-like graphene shell. The sandwich structure of the SnO2/graphene and the closed graphene sphere can provide double protection for the SnO2. When it is used as an anode material for energy storage, the generated Li2O can remain in close contact with Sn to make the conversion reaction (SnO2 + 4Li+ + 2e- ↔ Sn + Li2O) highly reversible in situ and the reversibility even does not diminish markedly after 100 cycles. A high reversible specific capacity of 914.8 mA h g-1 is expressed in the sandwiched spherical SnO2/graphene composite at 100 mA g-1 after 100 cycles, which is significantly higher than that of a SnO2/graphene aerogel with an open pore structure.

Three-dimensional (3D) interconnected spherical graphene framework-decorated SnS nanoparticles (3D SnS@SG) is synthesized by self-assembly of graphene oxide nanosheets and positively charged polystyrene/SnO2 nanospheres, followed by a controllable in situ sulfidation reaction during calcination. The SnS nanoparticles with diameters of ∼10–30 nm are anchored to the surface of the spherical graphene wall tightly and uniformly. Benefiting from the 3D interconnected spherical graphene framework and subtle SnS nanoparticles, the generated Li2S could keep in close contact with Sn to make possible the in situ conversion reaction SnS + 2Li+ + 2e– ↔ Sn + Li2S. As a result, the 3D SnS@SG as the anode material for lithium ion batteries shows a high initial Coulombic efficiency of 75.3%. Apart from the irreversible capacity loss of 3D spherical graphene, the initial Coulombic efficiency of SnS in the 3D SnS@SG composite is as high as 99.7%, demonstrating the almost complete reversibility of Li2S in this system. Furth...

Low reversion of lithium sulfide and defects causing irreversible capacity loss are the primary causes of low Coulombic efficiency in tin sulfide/graphene-based composites. Herein, we synthesized a SnS/graphene composite via a novel lithiation-assisted exfoliation and reduction method using SnS2, n-butyllithium, and graphene oxide as raw materials. The experimental results reveal that lithium from the insertion agent combine with the oxygen-containing groups on graphene oxide; this can help in the reduction of hexagonal SnS2 to orthorhombic SnS during calcination and simultaneous pre-occupancy of the edge and defect sites of graphene; thus, additional lithium ion consumption during the initial several lithiation processes is diminished. Microstructural characterizations indicate that the exfoliated SnS nanosheets with a dramatically decreased lateral size (50–100 nm) are uniformly decorated on the surface of lithium-integrated graphene sheets. Consequently, the as-prepared SnS/graphene composite exhibits a significantly high SnS ultilization with a 77.5% initial Coulombic efficiency, which is the highest value reported in the current literature. Moreover, an excellent reversibility of conversion reaction (SnS + 2Li+ + 2e− ↔ Sn + Li2S) and a high reversible capacity of 1016.4 mA h g−1 after 100 cycles are expressed in this composite electrode, demonstrating its importance as an anode material for energy storage.

Doping modification is usually used to improve the ionic conductivity of sulfide solid electrolytes, but its effects on the interface between the electrolyte/lithium (Li) metal seem not sufficiently studied and understood. In this work, the advantages and disadvantages of sulfide electrolyte doped with MoS2, ZnS, FeS2, SnS2 and SiS2 are systematically studied. The ab initio molecular dynamics (AIMD) calculations and experiments show that MoS44- can preferentially replace the P2S74- in Li7P3S11, thereby broadening Li+ channels and creating Li vacancies to promote ion conduction. However, the doping of MoS2 can lead to the introduction of Mo metal into the solid electrolyte/Li interface layer (SEI), resulting in the reduction of the SEI’s interface energy and migration rate of Li atoms at SEI, as well as the accumulation of electrons, thereby accelerating the thickening of the SEI and growth of Li dendrites. The doping results of different sulfides show that the critical current density is positively related to the resistivity of the doping element. The doping of non-metallic silicon will not cause a decrease in the critical current density. This work provides an important reference for the selection of solid electrolyte dopants and the construction of electrolyte/Li interface.

Layer-controlled MoS2/graphene aerogels (MoS2/GA) composites are synthesized by a facile hydrothermal route, in which few-layer (5–15 layers) MoS2 nanosheets with high crystalline are decorated on the surface of graphene nanosheets homogeneously and tightly. The number of the MoS2 layers can be easily controlled through adjusting the amount of molybdenum source in the reaction system. Moreover, the growth mechanism of the lay-controlled MoS2/GA composites is proposed. The three-dimensional MoS2/GA with macroporous micro-structure not only shortens the transportation length of electrons and ions, but also restrains the re-stacking of MoS2 effectively, stabilizing the electrode structure during repeated charging/discharging processes. Electrochemical tests demonstrate that this few-layer MoS2/GA composite exhibits a high reversible capacity of 1085.0 mAh g−1 at current density of 100 mA g−1, as well as extraordinarily high cycling stability and rate capability.

Hierarchical ultrathin nanostructure MnO 2 on graphene sheets are first prepared through ultrasonic-assisted co-precipitation method. The possible growth mechanism of the nanocomposite is discussed by monitoring the early growth stages. It is shown that the formation of the hierarchical structure MnO 2 follows a typical self-assembly and Ostwald ripening process. The dispersion of nanoscale thin MnO 2 flakes with thicknesses of about 5–10 nm on the graphene helped to increase the contact area of MnO 2 with electrolyte, reduce the diffusion and migration length of the ions and increase the electrochemical utilization of MnO 2 . Electrochemical characterization demonstrate that the hierarchical MnO 2 /graphene are capable of delivering specific capacitance of 216 F g −1 at the current density of 1 A g −1 . A capacity retention of 89.3% can be maintained after 2000 continuous charge–discharge cycles. The method provides a facile and straightforward approach to synthesize hierarchical of MnO 2 onto the graphene and may be readily extended to the preparation of other classes of hybrids based on graphene sheets for technological applications.

Transport-induced-charge (TIC) phenomena, in which the concentration imbalance between cations and anions occurs when more than two chemical potential gradients coexist within an ultrathin dimension, entail numerous nanofluidic systems. Evidence has indicated that the presence of TIC produces a nonlinear response of electroosmotic flow to the applied voltage, resulting in complex fluid behavior. In this study, we theoretically investigate thermal effects due to Joule heating on TIC phenomena in an ultrathin nanopore by computational fluid dynamics simulation. Our modeling results show that the rise of local temperature inside the nanopore significantly enhances TIC effects and thus has a significant influence on electroosmotic behavior. A local maximum of the solution conductivity occurs near the entrance of the nanopore at the high salt concentration end, resulting in a reversal of TIC across the nanopore. The Joule heating effects increase the reversal of TIC with the synergy of the negatively charged nanopore, and they also enhance the electroosmotic flow regardless of whether the nanopore is charged. These theoretical observations will improve our knowledge of nonclassical electrokinetic phenomena for flow control in nanopore systems.

By combining of one-dimensional porous boron nitride nanofibers (BNNFs) with polyvinyl alcohol (PVA) via a freeze-drying method, a new type of BNNFs/PVA composite foam has been successfully obtained. The composite foam shows a honeycomb network structure containing a large number of pores. The BNNFs, with the characteristics of high aspect ratio, large pore volume, high specific surface area and good flexibility, act as a bridge connecting matrix to improve the flexibility of the composite foam. With the increasing of contents of BNNFs, the composite foam displays enhanced specific surface area. The addition of BNNFs also leads a tendency to change the foam from hydrophilic to hydrophobic. The BNNFs/PVA composite foams show excellent oil-water separation performance with absorption capacities for silicon oil and pump oil in the range of 1979∼6110 wt%. Moreover, the addition of BNNFs significantly improves the adsorption capacity of the composite foam for cationic dyes due to the hydrogen bonding and electrostatic interaction between BNNFs/PVA composite and cationic dyes. The high specific surface area of composite foam is also beneficial for the CO2 gas adsorption. The developed BNNFs/PVA composite foam has shown a great potential in the field of environmental remediation.

Lithium-sulfur (Li–S) batteries have been recognized as one of the most promising lithium-ion power sources. However, their commercial application is greatly hindered by the incompletely used active materials and unsatisfactory cyclability. Herein, a novel well-honeycombed porous graphene framework (3D-G) was developed using a PMMA-sphere-assisted vacuum filtration method, and used as an advanced sulfur host for enhancing Li–S battery performance. The unique well-honeycombed porous graphene framework not only enhances the electronic conductivity of Li–S cathodes, but also provides numerous active sites for sulfur adsorption. Moreover, the ultrafine sulfur uniformly embedded into the well-honeycombed porous graphene framework increases the utilization of active materials. Benefiting from these synergistic features, 3D-G/S cathodes exhibit excellent electrochemical performance, such as long-cycling stability with a ultra-low capacity fading of 0.099% per cycle over 200 cycles at a high current density, holding great promise for development of practically viable Li–S batteries.

Controlling the particle sizes of electrode materials has long been recognized as an effective way to improve the cycle stability and rate property of both lithium-ion battery (LIB) and sodium-ion battery (SIB). In this paper, a simple one-step hydrothermal process for the preparation of composites with size-tunable tin disulfide on reduced graphene oxide (SnS2/RGO) is reported. These novel material allow to comprehensively study the effect of particle sizes on electrochemical properties for LIB and SIB anodes. The structure, morphology, phase compositions, and Li+/Na+ storage behaviors of three different SnS2/RGO composites obtained at heat-treatment times of 12, 24 and 48 h are characterized systematically. The electrochemical reaction kinetics is demonstrated by differential charge capacity plots and apparent ion diffusion coefficients. Surface capacitive and diffusion-controlled capacitive contributions to lithium/sodium ions storage are also compared. The results show that the small-sized nanoarchitecture can promote both the charge and ions transfer and thus improve the pseudocapacitor contribution. The reversible capacity maintains at 1211 mAh g−1 for LIB after 200 cycles and 841 mAh g−1 for SIB after 100 cycles, respectively, which is superior to most of the previous reports. This work is expected to provide a profound understanding of composite anodes with controllable dimensions and fast kinetics.

All-solid-state lithium batteries have been recognized as the next generation energy storage/conversion devices for many high-power and safe applications. Li7P3S11 glass ceramics, as a promising solid electrolyte, has shown a high application possibility. Although the synthesis of Li7P3S11 by wet-chemical method is more controllable and can be well matched with the existing battery preparation processes, the chemical reaction mechanism of such a liquid-phase reaction process is not fully understood, and also its ionic conductivity is lower than that obtained by solid-state methods. In this paper, we have clarified that the liquid-phase reaction is mainly the process of lone-pair electrons of Li2S to attack the bridged S on P2S5 to obtain compounds with different element ratios, which is explored by recording different reaction times and adjusting different proportions of the phase transitions in acetonitrile (ACN) solvent. The only precipitate phase is found to be Li3PS4·ACN, which can react with soluble phases with higher P content such as Li2P4S11, Li4P4S12 and so on to obtain Li4P2S7 for the formation of Li3PS4·ACN and Li4P2S7·ACN (molar ratio 1:1) in the liquid phase. Finally, Li7P3S11 is formed by the equimolar reaction of above two compounds during the calcination. XPS and Raman results indicate that the low conductivity of liquid-phase synthesized Li7P3S11 solid electrolyte may be induced by the residual Li4P2S6, which is caused by the inadequate contact and coverage of gel-like Li4P2S7 with solid Li3PS4, resulting in the desulfurization reaction of Li4P2S7 during the heat-treatment.

Low reversion of Li2S and the Sn aggregation causing irreversible capacity loss are the primary cause of poor cycle performances in tin sulfide-based composites. These problems can be mitigated by confining SnS nanoparticles in sandwiched hollow-spherical graphene skeleton (Sandwich-SnS/GS), in which a large number of tiny SnS nanoparticles are inserted in between the interlayers of the sphere-like graphene shell with homogeneous distribution, while the spherical graphene interconnects each other forming a three-dimensional interconnected conductive network. This novel spherical graphene skeleton can immobilize the SnS and the lithiated products (Sn and Li2S) and suppress the local accumulation of metallic Sn at the largest extent, thus prompting the close contact of Sn/Li2S and their in-situ reverse transformation into SnS. In addition, the closed graphene sphere could inhibit the shuttle of lithium polysulfides derived from Li2S during charging, promote reversible transformation between Li2S and S8, providing an additional capacity contribution and ensuring the sustained capacity of the whole electrode without distinct decay. Thus, a high and stable reversible specific capacity of 756.7 mA h g−1 is retained in the Sandwich-SnS/GS composite after 200 cycles at 100 mA g−1, significantly higher than those of traditional hollow sphere and sandwich-like lamellar composite structures.

A hybrid antenna consisting of a patch cavity and a metal grating is designed in this work. This antenna can effectively localize and enhance the intensity of the electric field inside a quantum well photodetector (QWP). The optical properties of the designed antenna are theoretically investigated, and it is found that the electric field can be increased by a factor of ∼104 in the infrared region (6–10 μm) and ∼105 in the terahertz (THz) region (100 μm). These enhancements can greatly improve the performance of QWPs. In the THz region, it is theoretically estimated that the hybrid antenna can increase the working temperature of the detector to 195 K, and the noise equivalent power is theoretically estimated to be as low as ∼10−18 W/Hz0.5 at T = 4 K and ∼10−15 W/Hz0.5 at room temperature, T = 300 K. These results are of great significance for applications of QWPs.