Enhanced Polysulfide Trapping and Conversion by Amorphous-Crystalline Heterostructured MnO2 Interlayers for Li-S Batteries.

The practical application of lithium-sulfur batteries (LSBs) is still hindered by several technical issues, including severe polysulfide shuttling and sluggish redox kinetics, which reduces the sulfur utilization and further results in low energy density. Herein, amorphous-crystalline heterostructured MnO2 (ACM) prepared through a simple calcination process was employed as the functional interlayer to play a double role as effective trapper and multifunctional electrocatalyst for LSBs. ACM not only combines the strong sulfur chemisorption of the amorphous MnO2 (AM) and fast Li+ transportation of the crystalline MnO2(CM) but also accelerates the interface charge transfer at the amorphous/crystalline interfaces. The LSBs with such unique interlayer exhibited an excellent rate performance of 1155.5 mAh·g-1 at 0.2 C and 692.9 mAh·g-1 at 3 C and a low decay rate of 0.071% per cycle over 500 cycles at 0.5 C. Even for a high sulfur loading of 5 mg·cm-2 at 0.1 C, a high capacity retention of 92.3% could also be achieved after 100 cycles. The concept of amorphous-crystalline heterostructures prepared by crystallization regulation might also be used for other electronic devices and catalyst designs.

Enhanced stability of vanadium-doped Li1.2Ni0.16Co0.08Mn0.56O2 cathode materials for superior Li-ion batteries.

Lithium-manganese-based cathode materials have attracted much attention due to its high specific capacity, but the low initial coulomb efficiency, poor rate performance and voltage attenuation during cycling limit its application. In this work, Li1.2Ni0.16Co0.08Mn0.56-x V x O2 samples (x = 0, 0.005, 0.01, 0.02, 0.05) were prepared using the sol-gel method, and the effects of different V5+ contents on the structure, valence state, and electrochemical performance of electrode materials were investigated. The results show that the introduction of high-valence V5+ in cathode materials can reduce partial Mn4+ to active Mn3+ ions for charge conservation, which not only improves the discharge capacity and coulomb efficiency of Li-rich manganese-based cathode materials, but also inhibits the voltage attenuation. The initial discharge capacity of the Li1.2Ni0.16Co0.08Mn0.55V0.01O2 is as high as 280.9 mA h g-1 with coulomb efficiency of 77.7% at 0.05C, which is much higher than that of the undoped pristine sample (236.6 mA h g-1 with coulomb efficiency of 74.0%). After 100 cycles at 0.1C, the capacity retention rate of Li1.2Ni0.16Co0.08Mn0.55V0.01O2 was 92.3% with the median voltage retention rate of 95.6%. This work provides a new idea for high performance of lithium-rich manganese-based cathode materials.

Built-In Electric Field on the Mott-Schottky Heterointerface-Enabled Fast Kinetics Lithium-Sulfur Batteries.

Lithium-sulfur (Li-S) batteries (LSBs) have been considered one of the most potential candidates to substitute traditional Li-ion batteries (LIBs), owing to their high theoretical energy density and low cost. Nevertheless, the shuttle effect and the sluggish redox kinetics of lithium polysulfides (LiPSs) have long been obstacles to realizing stable LSBs with high reversible capacity. In this study, we proposed a metal-semiconductor (Mo and MoO2) heterostructure with the hollow microsphere morphology as an effective Mott-Schottky electrocatalyst to boost sulfur electrochemistry. The hollow structure can physically inhibit the shuttling of LiPSs and accommodate the volume fluctuation during cycling. More importantly, the built-in electric field at the heterointerfacial sites can effectively accelerate the reduction of LiPSs and oxidation of Li2S, thereby reaching a high sulfur utilization. With the assistance of the Mo/MoO2 catalyst, the cell exhibited prominent rate capability and stable long-term cycling performance, showing a high capacity of 630 mA h·g-1 at 4 C and a low decay of 0.073% at 1 C after 500 cycles. Even with high areal sulfur loading of 10.0 mg·cm-2, high capacity and good cycle stability were achieved at 0.2 C under lean electrolyte conditions (E/S ratio of 6 µL·mg-1).

Knowledge and Attitudes toward Genetic Testing for Autism Spectrum Disorders among Parents of Affected Children in Taiwan.

The prevalence of autism spectrum disorders (ASD) in Taiwan has been increasing, and genetic testing for ASD has been available and provided to parents of children diagnosed with ASD in Taiwan. However, there is still limited understanding of Taiwanese parents' knowledge of and attitudes toward such testing. Therefore, the present study addressed this gap by assessing the attitudes toward as well as actual and perceived knowledge of ASD genetic testing among Taiwanese parents of children diagnosed with ASD. A sample of 443 parents of children with ASD recruited from 236 public schools in Taiwan completed a paper-and-pencil survey. Although parents generally held favorable attitudes toward ASD genetic testing, they had deficient knowledge of such test (with only a 31.4% average correct rate on the actual knowledge scale). Tailored health education materials should be developed to improve the knowledge of ASD genetic testing among parents with affected children in Taiwan.

Rich Heterointerfaces Enabling Rapid Polysulfides Conversion and Regulated Li2S Deposition for High-Performance Lithium-Sulfur Batteries.

The practical uses of lithium-sulfur batteries are greatly restricted by the sluggish reaction kinetics of lithium polysulfides (LiPSs), leading to low sulfur utilization and poor cyclic stability. Using the heterostructure catalysts is an effective way to solve the above problems, but how to further enhance the conversion efficiency and avoid the surface passivation by the insulative Li2S has not been well investigated. Herein, a heterostructure catalyst with rich heterointerfaces was prepared by modifying Mo2N microbelt with SnO2 nanodots. The formed rich interfaces with high accessibility act as the profitable nucleation sites guiding the Li2S 3D growth, which avoids the catalyst surface passivation and facilitates the LiPS conversion. The introduction of SnO2 nanodots also enhances the LiPS adsorption. Thus, the assembled battery with the above catalyst as the cathode additive shows a high capacity of 738.3 mAh g-1 after 550 cycles at 0.5 C with an ultralow capacity decay of 0.025% per cycle. Even with high sulfur loading of 9.0 mg cm-2, good cyclic stability is also achieved at 0.5 C with a low E/S ratio of 5 µL mgs-1. This work shows an effective way to enhance the LiPS conversion kinetics and guide Li2S deposition in Li-S batteries.

Accelerating the activation of Li2MnO3 in Li-rich high-Mn cathodes to improve its electrochemical performance.

Li-rich high-Mn oxides, xLi2MnO3·(1 - x)LiMO2 (x ≥ 0.5, M = Co, Ni, Mn…), have attracted extensive research interest due to their high specific capacity and low cost. However, slow Li2MnO3 activation and poor cycling stability have affected their electrochemical performance. Herein, to solve these problems, morphology regulation and LiAlF4 coating strategies have been synergistically applied to a Li-rich high-Mn material Li1.7Mn0.8Co0.1Ni0.1O2.7 (HM-811). This dual-strategy successfully promotes the activation process of the Li2MnO3 phase and thus improves the electrochemical performance of HM-811. Theoretical computation indicates that the LiAlF4 layer has a lower Li+ migration barrier than the HM-811 matrix, so it could boost the diffusion of Li+ ions and promote the activation of the Li2MnO3 phase. Benefiting from the morphology regulation and LiAlF4 coating, the HM-811 cathode shows a high initial charge capacity of >300 mA h g-1. In addition, the modified HM-811 could deliver superior electrochemical performance even at a low temperature of -20 °C. This work provides a new approach for developing high performance cathode materials for next-generation Li-ion batteries.

Facile synthesis of porous Co3O4 nanoflakes as an interlayer for high performance lithium-sulfur batteries.

The "shuttle effect" of long-chain polysulfides and the low conductivity of elemental sulfur lead to the inferior cycling stability of lithium-sulfur batteries and imped their practical applications. Herein, Co3O4 nanoflakes with uniform macro pores distribution were synthesized via facile oil bath and calcination methods. Coupled with super P and coated on common polypropylene separators, they were expected to hinder the migration of lithium polysulfides (LiPSs) and accelerate the redox kinetics of polysulfides. Coin cells assembled with the Co3O4-super P interlayer exhibited a capacity of 760 mA h g-1 at 1 C, maintained 598 mA h g-1 after 350 cycles, and the decay rate of discharge capacity was only about 0.062% per cycle. Such high performance can be attributed to the synergistic effects between polar Co3O4 and conductive super P. The facile fabrication method and high performance make the Co3O4-super P interlayer a feasible material to apply in lithium-sulfur batteries.

In Situ Construction of Spinel Coating on the Surface of a Lithium-Rich Manganese-Based Single Crystal for Inhibiting Voltage Fade.

Layered lithium-rich transition-metal oxides (LRMs) have been considered as the most promising next-generation cathode materials for lithium-ion batteries. However, capacity fading, poor rate performance, and large voltage decays during cycles hinder their commercial application. Herein, a spinel membrane (SM) was first in situ constructed on the surface of the octahedral single crystal Li1.22Mn0.55Ni0.115Co0.115O2 (O-LRM) to form the O-LRM@SM composite with superior structural stability. The synergetic effects between the single crystal and spinel membrane are the origins of the enhancement of performance. On the one hand, the single crystal avoids the generation of inactive Li2MnO3-like phase domains, which is the main reason for capacity fading. On the other hand, the spinel membrane not only prevents the side reactions between the electrolyte and cathode materials but also increases the diffusion kinetics of lithium ions and inhibits the phase transformation on the electrode surface. Based on the beneficial structure, the O-LRM@SM electrode delivers a high discharge specific capacity and energy density (245.6 mA h g-1 and 852.1 W h kg-1 at 0.5 C), low voltage decay (0.38 V for 200 cycle), excellent rate performance, and cycle stability.

A gradient screening approach for retired lithium-ion batteries based on X-ray computed tomography images.

Accurate and efficient screening of retired lithium-ion batteries from electric vehicles is crucial to guarantee reliable secondary applications such as in energy storage, electric bicycles, and smart grids. However, conventional electrochemical screening methods typically involve a charge/discharge process and usually take hours to measure critical parameters such as capacity, resistance, and voltage. To address this issue of low efficiency for battery screening, scanned X-ray Computed Tomography (CT) cross-sectional images in combination with a computational image recognition algorithm have been employed to explore the gradient screening of these retired batteries. Based on the Structural Similarity Index Measure (SSIM) algorithm with 2000 CT images per battery, the calculated CT scores are closely correlated with their internal resistance and capacity, indicating the feasibility of CT scores to sort retired batteries. We find out that when the CT scores are larger than 0.65, there is high potential for a secondary application. Therefore, this pioneering and non-destructive CT score method can reflect the internal electrochemical properties of these retired batteries, which could potentially expedite the battery reuse industry for a sustainable energy future.

In situ synthesis and electrochemical performance of MoO3-x nanobelts as anode materials for lithium-ion batteries.

MoO3-x nanobelts with different concentrations of oxygen vacancies were synthesized by a one-step hydrothermal process. XPS test results show that oxygen vacancies are distributed from the exterior to the interior of the MoO3-x nanobelts. As an anode material for lithium-ion batteries, MoO3-x-10 releases excellent rate capacitance. It can maintain a high specific capacitance of about 500 mA h·g-1 at a high current density of 1000 mA·g-1. In the aspect of cycling stability, MoO3-x-10 can retain a high specific capacity of 641 mA h·g-1 after cycling for 50 times at 100 mA·g-1 and 420 mA h·g-1 after cycling for 100 times at 500 mA·g-1. The coexistence of oxygen vacancies and low-valence Mo ions is conducive to the intercalation/de-intercalation of Li ions and to promoting redox reactions. It has been proved to be a significantly effective way in which oxygen vacancies can improve the integrated performance of MoO3-x nanobelts as anode materials.

Effect of sulfur doping on structural reversibility and cycling stability of a Li2MnSiO4 cathode material.

Based on the existing calculation reports, sulfur doping is an effective approach to alleviate the structure collapse of Li2MnSiO4 during cycling. Herein, we investigate the feasibility and limitations of S doping in Li2MnSiO4 by experiment. In our work, the solid solubility of S is confirmed and exceeding the threshold results in MnS impurity. The existence state and site of the S element in a Li2MnSiO4 crystal structure is also confirmed. It is found that S doping significantly improves the structural reversibility and cycling stability. Compared with a pristine sample, a 1mol% S doped sample exhibits a much higher initial coulombic efficiency (88.3%), excellent capacity retention (98% at 10th cycles for instance) and enhanced rate performance. Moreover, the 1mol% S doped sample can retain a discharge capacity of 137 mA h g-1 after 30 cycles while the pristine sample only has 61.6 mA h g-1. This study confirms the effectivity of S doping in suppressing the structural distortion in Li2MnSiO4.

Topochemical synthesis and photocatalytic activity of 3D hierarchical BaTiO3 microspheres constructed from crystal-axis-oriented nanosheets.

Novel BaTiO3 hierarchical porous microspheres were achieved by using H2Ti2O5·H2O (HTO) hierarchical microspheres as a precursor template via a facile solvothermal method. Interestingly, the BaTiO3 microspheres were constructed with two-dimensional (2D) nanosheets, which were composed of many order nanocrystals with crystal-axis-orientation. The special hierarchical structure, which is both macroporous and mesoporous, exhibits a large specific surface area and a high total pore volume. The photocatalytic performance of BaTiO3 hierarchical microspheres for degradation of methyl orange (MO) under UV-light irradiation was tested, its apparent rate being up to 0.10183 min-1, almost 23 times higher than that for nanoscale BaTiO3 particles. The attractive photocatalytic properties are considered to benefit from the effective features of hierarchical BaTiO3 microspheres, such as the ultrathin thickness of nanosheets and their ordered interconnected macro-mesoporous structure and intrinsic photocatalytic activity. This study offers an in situ topochemical conversion route to synthesis of other titanium-based perovskite hierarchical nanostructures, and thus opening the door for the synthesis of other titanium-based functional materials and expanding their potential application.

[Resistance mechanisms of Spodoptera exigua (Hübner) to fenvalerate and alpha-cypermethrin].

By using synergist bioassay and biochemical analysis, this paper approached the resistance mechanisms of Spodoptera exigua (Hübner) to fenvalerate and alpha-cypermethrin. The synergistic ratios of piperonyl butoxide (PBO), o, o-diethyl-o-phenyl-thiophosphate (SV1), triphenyl phosphate (TPP), and diethyl maleate (DEM) between fenvalerate-resistant strain (Fen-R) and susceptible strain were 10.2, 7.8, 12.5, and 1.1, and those between alpha-cypermethrin resistant strain (Cyp-R) and susceptible strain were 21.6, 15.5, 8.6, and 1.2, respectively. Significant synergisms of PBO, SV1, and TPP to fenvalerate and alpha-cypermethrin were observed, implying that multifunctional oxidase and carboxylesterase were involved in the resistance to fenvalerate and alpha-cypermethrin. The carboxylesterase activities in the fourth instar larvae of Cyp-R and Fen-R strains were 1.9 and 2.2 folds of the corresponding susceptible strains, respectively, but no differences were found in the glutathione-S-transferase activities between the resistant and susceptible strains, which indicated that carboxylesterase played an important role in the resistance of S. exigua to fenvalerate and alpha-cypermethrin, while glutathione-S-transferase contributed little to the resistance. There were no significant differences in the Na-K-ATPase activities between the resistant and susceptible strains, but the inhibition of fenvalerate and alpha-cypermethrin on Na-K-ATPase was higher in the susceptible strains than in the resistant strains, indicating the decreased sensitivity of Na-K-ATPase in resistant strains.