Regulating Electron Filling and Orbital Occupancy of Anti-Bonding States of Transition Metal Nitride Heterojunction for High Areal Capacity Lithium-Sulfur Full Batteries.

The commercialization of lithium-sulfur (Li-S) battery is seriously hindered by the shuttle behavior of lithium (Li) polysulfide, slow conversion kinetics, and Li dendrite growth. Herein, a novel hierarchical p-type iron nitride and n-type vanadium nitride (p-Fe2 N/n-VN) heterostructure with optimal electronic structure, confined in vesicle-like N-doped nanofibers (p-Fe2 N/n-VN⊂PNCF), is meticulously constructed to work as "one stone two birds" dual-functional hosts for both the sulfur cathode and Li anode. As demonstrated, the d-band center of high-spin Fe atom captures more electrons from V atom to realize more π* and moderate σ* bond electron filling and orbital occupation; thus, allowing moderate adsorption intensity for polysulfides and more effective d-p orbital hybridization to improve reaction kinetics. Meanwhile, this unique structure can dynamically balance the deposition and transport of Li on the anode; thereby, more effectively inhibiting Li dendrite growth and promoting the formation of a uniform solid electrolyte interface. The as-assembled Li-S full batteries exhibit the conspicuous capacities and ultralong cycling lifespan over 2000 cycles at 5.0 C. Even at a higher S loading (20 mg cm-2 ) and lean electrolyte (2.5 µL mg-1 ), the full cells can still achieve an ultrahigh areal capacity of 16.1 mAh cm-2 after 500 cycles at 0.1 C.

Image Encryption Using Quantum 3D Mobius Scrambling and 3D Hyper-Chaotic Henon Map.

In encryption technology, image scrambling is a common processing operation. This paper proposes a quantum version of the 3D Mobius scrambling transform based on the QRCI model, which changes not only the position of pixels but also the gray values. The corresponding quantum circuits are devised. Furthermore, an encryption scheme combining the quantum 3D Mobius transform with the 3D hyper-chaotic Henon map is suggested to protect the security of image information. To facilitate subsequent processing, the RGB color image is first represented with QRCI. Then, to achieve the pixel-level permutation effect, the quantum 3D Mobius transform is applied to scramble bit-planes and pixel positions. Ultimately, to increase the diffusion effect, the scrambled image is XORed with a key image created by the 3D hyper-chaotic Henon map to produce the encrypted image. Numerical simulations and result analyses indicate that our designed encryption scheme is secure and reliable. It offers better performance in the aspect of key space, histogram variance, and correlation coefficient than some of the latest algorithms.

Modulating Zinc Metal Reversibility by Confined Antifluctuator Film for Durable and Dendrite-Free Zinc Ion Batteries.

Aqueous Zn ion batteries are promising systems due to their intrinsic safety, low cost, and non-toxicity, and the Zn corrosion and dendrite growth will cause the poor reversibility of Zn anode. Herein, the porous Zn@C solid, hollow, and yolk-shell microsphere films are developed as Zn anode antifluctuator (ZAAF). The prepared yolk-shell microspheres (Zn@C yolk-shell microsphere [ZCYSM]) film with superior buffering can effectively restrict the deposition of Zn metal in its interior and inhibit the volume expansion during plating/stripping process, thus modulating the Zn2+ flux and enabling stable Zn cycling. As a proof of concept, the ZCYSM@Zn symmetric cells achieve the excellent cyclic stability over 4000 h and cumulative plated capacity of 4 Ah cm-2  at a high current density of 10 mA cm-2 . Concomitantly, the suppressed corrosion reactions and dendrite-free ZAAF significantly improve the durability of full cells (coupled to CaV6 O16 ·3H2 O). Additionally, durable pouch cell and electrochemical neuromorphic inorganic device (ENIDe) are integrated to simulate neural network, providing a strategy for extreme interconnectivity comparable to the human brain.

Utilizing dual functions of LaPO4to enhance the electrochemical performance of LiNi0.87Co0.09Al0.04O2cathode material.

In this paper, via a facile wet coating method, the LaPO4coating layer has been introduced onto the LiNi0.87Co0.09Al0.04O2(NCA) surface while a small part of La3+has also been doped on the surface to realize the dual functions modification of coating and doping. The morphology and structure of the samples were investigated by XRD, SEM and TEM measurements. The chemical compositions of the samples were analyzed via EDS and XPS data. The results showed that the coating of LaPO4and the doping of La3+were successfully achieved on the surface of NCA. Electrochemical tests indicate that the sample modified with 2 wt% LaPO4(L2-NCA) possesses the best electrochemical performance. After 100 cycles, compared with the capacity retention rate of pristine NCA of 87.1%/74.2% at 0.5 C at 25 °C/60 °C, L2-NCA showed better cycling stability, and the capacity retention rate increased to 96.0%/85.1%, respectively. Besides, the rate performance of the modified samples at 1 C, 2 C and 5 C were also significantly improved. These satisfactory results reveal that the surface modification of LaPO4provides a feasible scheme to uprate the performance of Ni-rich cathode materials.

Highly sensitive detection of carbendazim in juices based on mung bean-derived porous carbon@chitosan composite modified electrochemical sensor.

We reported a simple and scalable strategy for the preparation of mung bean-derived porous carbon@chitosan (MBC@CTS) composite, which was used to optimize the glassy carbon electrode (GCE). The MBC@CTS/GCE sensor was applied for the carbendazim (CBZ) detection. For the MBC@CTS composite, MBC with three-dimensional hierarchical structure presented large specific surface area, good adsorbability, and high electrical conductivity, while CTS had good film-forming property, hydrophilicity performance, and adhesion capacity. The MBC@CTS/GCE sensor exhibited wonderful electrochemical detection performance towards CBZ. Under the optimized conditions, the MBC@CTS/GCE sensor showed a linear concentration range from 0.1 to 20 µM with relatively low limit of detection (LOD) of 20 nM. In addition, the fabricated sensor with good reproducibility, stability, and selectivity were successfully applied for the CBZ detection in apple and tomato juices with low relative standard deviation of 2.4 %-4.2% and satisfactory recoveries of 98.8-103.2%.

Rapid determination of methyl parathion in vegetables using electrochemical sensor fabricated from biomass-derived and ß-cyclodextrin functionalized porous carbon spheres.

Porous carbon spheres (PCS) derived from expired sugarcane juice (SJ) and modified with ß-cyclodextrin (ß-CD) were used for the fabrication of SJPCS@ß-CD/GCE sensor with glassy carbon electrode (GCE) to detect methyl parathion (MP). SJPCS with interconnected porous structure exhibits excellent electrical conductivity, strong adsorption property, and high specific surface area, while ß-CD with molecular recognition property achieves the uniform dispersion of SJPCS and promotes the recognition and adsorption of MP molecules. Thanks to the synergistic combination of SJPCS and ß-CD, the SJPCS@ß-CD/GCE sensor exhibited respectable MP determination performance with low limit of detection of 5.87 nM in the MP concentration range of 0.01-10 µM. For the MP detection in vegetables (onion, cabbage, spinach), the fabricated sensor showed good practicability with adequate relative standard deviation of 1.06% to 4.25% and satisfactory recoveries of 96.5 to 100.5%. A promising strategy for the rapid determination of methyl parathion in food products was developed.

A novel electrochemical sensor based on ß-cyclodextrin functionalized carbon nanosheets@carbon nanotubes for sensitive detection of bactericide carbendazim in apple juice.

Carbendazim (CBZ) abuse always causes the over-standard of pesticide residues in agricultural products, which has adverse effects on human health. Herein, a novel electrochemical sensor was firstly fabricated based on the ß-cyclodextrin (ß-CD) functionalized carbon nanosheets@carbon nanotubes (CNS@CNT) for the CBZ determination. CNS@CNT combined large surface area of CNS and excellent electrical conductivity of CNT, which significantly enhanced the electrocatalytic performance. Moreover, ß-CD possessed excellent host-gest supramolecular recognition ability, which could improve the selective recognition and enrichment capability of CBZ. Thanks to the synergistic interaction of CNS@CNT and ß-CD, the ß-CD/CNS@CNT/GCE sensor exhibited a low limit of detection of 9.4 nM in the linear CBZ concentration range of 0.03-30 µM. The fabricated sensor presented favorable stability, high sensitivity (30.86 µA µM-1 cm-2), and reliable reproducibility (RSD = 3.6%). Especially, the ß-CD/CNS@CNT/GCE sensor could show pretty practical feasibility for the detection of CBZ in apple juice with recoveries of 97.1%-99.4%.

Dual functions of zirconium metaphosphate modified high-nickel layered oxide cathode material with enhanced electrochemical performance.

High-nickel LiNi0.9Co0.1O2 cathode shows an enormous potential in next-generation high energy density lithium-ion batteries. However, its cation mixing and the second hexagon to the third hexagonal of phase transition (H2 - H3) pose severe challenges to its practical and commercial applications. In this work, zirconium metaphosphate is applied to optimize the microstructure near surface zone of LiNi0.9Co0.1O2 cathode material to suppress its cation mixing and the H2 - H3 phase transformation during long cycling process. It is found that single-atom or atomic group plays different roles in doping strategy due to their different thermodynamic properties. Specifically, Zr4+ tends to form a uniform doping to optimize crystal structure, while PO43- group presents a gradient distribution near the surface area and generates Li3PO4 coating layer to enhance the Li+ mass transfer. As a result, the modified LiNi0.9Co0.1O2 cathode shows an improved cycling stability with a high capacity retention of 93.7% after 100 cycles, whereas the bare LiNi0.9Co0.1O2 cathode only delivers a low capacity retention of 81.7%. This work highlights the critical role of thermodynamic properties of doped atoms toward the electrochemical performance and can be extended to other layered cathode materials.

Three-dimensional hierarchical porous carbon coupled with chitosan based electrochemical sensor for sensitive determination of niclosamide.

Herein, a simple, low-cost, environment-friendly strategy was proposed to prepare the composite of three-dimensional hierarchical porous carbon and chitosan, which was applied to modify the glass carbon electrode to fabricate an electrochemical sensor for the determination of niclosamide. The three-dimensional porous carbon with interconnected conductive network, high surface area, and self-generated oxygen-containing functional groups was prepared by salt-templating method with glucose as carbon source and eutectic mixture of LiBr/KBr as both activating and pore-forming agent. During the subsequent ultrasonic process, chitosan with excellent filming property, strong adsorption ability, and good dispersibility was successfully decorated on the obtained porous carbon to further enhance the determination performance of niclosamide. Benefitting from the multi-functional integration of three-dimensional hierarchical porous carbon and chitosan, the fabricated sensor presented a low limit of detection (6.7 nM) in the linear concentration range from 0.01 to 10 µM. Moreover, the fabricated sensor could show good repeatability, reproducibility, stability, and selectivity. Most important, the decent practicability for the detection of niclosamide was obtained in different food samples with low relative standard deviation and satisfactory recoveries. This work provides a very valuable reference for the sensitive determination of niclosamide in food samples.

Fluorinated Carbons as Rechargeable Li-Ion Battery Cathodes in the Voltage Window of 0.5-4.8 V.

Fluorinated carbon (CFx) cathodes have the highest theoretical energy density among lithium primary batteries. However, it is still a huge challenge to be reversible. Here, CFx is proposed as a high-performance cathode material for rechargeable lithium-ion batteries in the extended voltage window of 0.5-4.8 V. Specifically, the fluorinated graphite CF0.88 exhibits an initial specific discharge capacity of 1382 mAh g-1 (2362 Wh kg-1) and a specific discharge capacity of 782 mAh g-1 at the 2nd cycle and maintains a specific discharge capacity of 543 mAh g-1 (508 Wh kg-1) after the 20th cycle. This rechargeable behavior is associated with the conversion of CFx to LiF + C (>1.5 V) and then to Li1+xFC (0.5-1.5 V) during the initial discharge process; Li1+xFC is reversible to LiF + C in the following charge-discharge process (0.5-4.8 V). By extending the voltage window, CFx cathodes can show new electrochemical behaviors. Our research has provided new Li-free cathode materials for rechargeable batteries and insights for improving the performance of a Li/CFx secondary battery.

Unraveling the Reaction Mechanism of FeS2 as a Li-Ion Battery Cathode.

Iron pyrite (FeS2) is a promising lithium-ion battery cathode material because of its low cost and ultrahigh energy density (1671 Wh kg-1). However, its reaction mechanisms are still controversial. In this work, we find that different from the conventional belief that an intermediate phase Li2FeS2 is formed followed by Fe/Li2S composites at the initial discharge, it undergoes a one-step reaction (FeS2 → Fe + Li2S) or a two-step reaction (FeS2 → FeS + Li2S → Fe + Li2S), which depends on the current rate and temperature. In the charge process, it undergoes a two-step reaction: phase transition Fe + Li2S → FeS at about 1.74 V and generation of elemental sulfur (Li2S → S, 2.30 V). FeS is a mackinawite phase that is formed on the interface of Li2S via heteroepitaxial growth. Subsequent cycles involves a combination reaction of FeS and S. The reaction mechanism suggests that FeS2 suffers from the demerits of both FeS and S, such as a large volume change, voltage hysteresis, and polysulfide dissolution. These findings would help us to understand the intrinsic capacity fading of FeS2 and provide guidelines to improve its electrochemical performances.

Multifunctional Integration of Double-Shell Hybrid Nanostructure for Alleviating Surface Degradation of LiNi0.8Co0.1Mn0.1O2 Cathode for Advanced Lithium-Ion Batteries at High Cutoff Voltage.

Ni-rich LiNi0.8Co0.1Mn0.1O2 (NCM811) cathode is considered to be among the most promising candidates for high-energy-density lithium-ion batteries (LIBs). However, both capacity fading and structural degradation occur during long-term cycling, which extremely limit the commercial applications of NCM811, especially at a high cutoff voltage (>4.3 V). Here, we design a double-shell hybrid nanostructure consisting of a Li2SiO3 coating layer and a cation-mixed layer (Fm3̅m phase) to improve its electrochemical performance. Consequently, the Si-modified NCM811 electrode shows outstanding cycling stability with a 95.2% capacity retention at 4.3 V after 100 cycles and 87.3% at a 4.5 V high cutoff voltage after 100 cycles. This designed double-shell hybrid nanostructure alleviates side reactions, structural degradation, and internal cracking, effectively enhancing the surface structural stability. This efficient strategy provides a valuable step toward further commercial applications of the LiNi0.8Co0.1Mn0.1O2 cathode and enriches the fundamental understanding of layered cathode materials.

Statistical model of the efficiency for spatial light coupling into a single-mode fiber in the presence of atmospheric turbulence.

The average efficiency of spatial light coupling into a single-mode optical fiber is widely used but cannot estimate the signal-to-noise ratio (SNR) and bit error rate (BER) in free-space optical communication. We provide a statistical model for coupling efficiency and derive the exact expression of the probability density function (PDF). The simulation results confirm that the model is reasonable in the condition of different turbulence intensities and wavefront compensation terms, which is also consistent with our outdoor experiment. We also estimate the average SNR and BER using the PDF. The model is quite useful in a satellite-to-ground laser communication downlink.

Manipulative attack using the phase retrieval algorithm for double random phase encoding.

A novel attack scheme is proposed based on a phase retrieval algorithm. In the scheme, the attacker interferes with the user's normal communication through wiretapping the channel and falsifying the ciphertext and quickly cracks the system by gathering information. The difference of this attack scheme from previous schemes is the dispensability of certain assumptions, which results in a higher value of practical application and further significance of the research. In this paper, the double random phase encoding is taken as an example to verify the validity of the scheme. The results show that our proposed scheme is feasible and efficient.

Experimental investigation of radiation effect on erbium-ytterbium co-doped fiber amplifier for space optical communication in low-dose radiation environment.

High power erbium-ytterbium co-doped fiber amplifier (EYDFA) has been radiated to the dose of 50 krad at the dose rate of 40 rad/s. Some key parameters have been measured to investigate the radiation effect on the EYDFA for space optical communication. Considering the dose of 50 krad is big enough to the most of low-dose radiation environment, these experimental results will be a good reference for the low-dose inter-satellite optical communication designers.

Deficiencies of the cryptography based on multiple-parameter fractional Fourier transform.

Methods of image encryption based on fractional Fourier transform have an incipient flaw in security. We show that the schemes have the deficiency that one group of encryption keys has many groups of keys to decrypt the encrypted image correctly for several reasons. In some schemes, many factors result in the deficiencies, such as the encryption scheme based on multiple-parameter fractional Fourier transform [Opt. Lett.33, 581 (2008)]. A modified method is proposed to avoid all the deficiencies. Security and reliability are greatly improved without increasing the complexity of the encryption process.

Wavelet transforming characteristic of a lens.

Based on the wave-front filtering concept of wavelet optics, which we proposed, here we consider that the wave fronts of a light wave are filtered by the lens when the wave fronts pass through the lens. After filtering, the weight of the light field is redistributed, and a Gaussian frequency-modulated complex-valued wavelet function is introduced with the weight function. Subsequent analysis indicates that the lens has a wavelet-transforming characteristic and that the introduction of a Gaussian frequency-modulated complex-valued wavelet function conforms to the actual lens.