B-doped and La_(4)NiLiO_(8)-coated Ni-rich cathode with enhanced structural and interfacial stability for lithium-ion batteries

Ni-rich layered oxides are considered promising cathodes for advanced lithium-ion batteries(LIBs)in the future,owing to their high capacity and low cost.However,the issues on structural and interfacial stability of Ni-rich cathodes still pose substantial obstacles in the practical application of advanced LIBs.Here,we employ a one-step method to synthesize a B-doped and La_(4)NiLiO_(8)-coated LiNi_(0.82)5Co_(0.115)Mn_(0.06)O_(2)(BL-1)cathode with reliable structure and interface,for the first time.The La_(4)NiLiO_(8)coating layer can prevent cathodes from electrolyte assault and facilitate Li+diffusion kinetics.Moreover,B-doping can effectively restrain the pernicious H_(2)-H_(3) phase transition and adjust the orientation of primary particles to a radial alignment,which is obstructive to the arise of microcracks induced by the change of anisotropic volume.Specifically,when tested in pouch cells,the BL-1 cathode exhibits outstanding capacity retention of 93.49%after 500 cycles at 1 C.This dual-modification strategy dramatically enhances the stability of the structure and interface for Ni-rich cathode materials,consequently accelerating the commercialization process of high-energy–density LIBs.

A pure dielectric metamaterial absorber with broadband and thin thickness based on a cross-hole array structure

A pure dielectric metamaterial absorber with broadband and thin thickness is proposed,whose structure is designed as a periodic cross-hole array.The pure dielectric metamaterial absorber with high permittivity is prepared by ceramic reinforced polymer composites.Compared with those with low permittivity,the absorber with high permittivity is more sensitive to structural parameters,which means that it is easier to optimize the equivalent electromagnetic parameters and achieve wide impedance matching by altering the size or shape of the unit cell.The optimized metamaterial absorber exhibits reflection loss below-10 dB in 7.93 GHz–35.76 GHz with a thickness of 3.5 mm,which shows favorable absorption properties under the oblique incidence of TE polarization(±45°).Whether it is a measured or simulated value,the strongest absorbing peak reaches below-45 dB,which exceeds that of most metamaterial absorbers.The distributions of power loss density and electric and magnetic fields are investigated to study the origin of their strong absorbing properties.Multiple resonance mechanisms are proposed to explain the phenomenon,including polarization relaxation of the dielectric and edge effects of the cross-hole array.This work overcomes the shortcomings of the narrow absorbing bandwidth of dielectrics.It demonstrates that the pure dielectric metamaterial absorber with high permittivity has great potential in the field of microwave absorption.

Dynamic targets searching assistance based on virtual camera priority

Background When a user walks freely in an unknown virtual scene and searches for multiple dynamic targets,the lack of a comprehensive understanding of the environment may have a negative impact on the execution of virtual reality tasks.Previous studies can help users with auxiliary tools,such as top view maps or trails,and exploration guidance,for example,automatically generated paths according to the user location and important static spots in virtual scenes.However,in some virtual reality applications,when the scene has complex occlusions,and the user cannot obtain any real-time position information of the dynamic target,the above assistance cannot help the user complete the task more effectively.Methods We design a virtual camera priority-based assistance to help the user search dynamic targets efficiently.Instead of forcing users to go to destinations,we provide an optimized instant path to guide them to places where they are more likely to find dynamic targets when they ask for help.We assume that a certain number of virtual cameras are fixed in virtual scenes to obtain extra depth maps,which capture the depth information of the scene and the locations of the dynamic targets.Our method automatically analyzes the priority of these virtual cameras,chooses the destination,and generates an instant path to assist the user in finding the dynamic targets.Our method is suitable for various virtual reality applications that do not require manual supervision or input.Results A user study is designed to evaluate the proposed method.The results indicate that compared with three conventional navigation methods,such as the top-view method,our method can help users find dynamic targets more efficiently.The advantages include reducing the task completion time,reducing the number of resets,increasing the average distance between resets,and reducing user task load.Conclusions We presented a method for improving dynamic target searching efficiency in virtual scenes by virtual camera priority-based path guidance.Compared with three conventional navigation methods,such as the top-view method,this method can help users find dynamic targets more effectively.

Synergistic effect and heterointerface engineering of cobalt/carbon nanotubes enhancing electromagnetic wave absorbing properties of silicon carbide fibers

To improve the synergistic effect between dielectric and magnetic loss is a practical and effective way in optimizing electromagnetic wave absorbing materials.The composites of metal particles and carbon ligands derived from metal organic frameworks have gained wide attention.In this study,Co particles and multiwalled carbon nanotubes(CNT)were successfully synthesized covering the surface of silicon carbide(SiC)fibers,and the morphology,interfaces and electromagnetic wave absorption performance were explored.For sample SiC@Co/CNT,the minimum reflection loss value can reach-70.22 dB at 11.21 GHz with the thickness of 2.12 mm.The effective absorbing bandwidth can reach up to 6.03 GHz with the thickness of 1.71 mm,which covers the entire Ku band.It brings more interfaces between Co particles and CNTs as well as SiC fibers and Co/C nanosheets.The interfacial polarization has been hugely enhanced,and the microwave absorbing properties have been improved.This article reports on the impedance matching of magnetic and non-magnetic components and the heterointerface engineering,which can be effective strategy and inspiration to illustrate the relationship between components,structures and functions of electromagnetic wave absorbing materials.

AR assistance for efficient dynamic target search

When searching for a dynamic target in an unknown real world scene,search efficiency is greatly reduced if users lack information about the spatial structure of the scene.Most target search studies,especially in robotics,focus on determining either the shortest path when the target’s position is known,or a strategy to find the target as quickly as possible when the target’s position is unknown.However,the target’s position is often known intermittently in the real world,e.g.,in the case of using surveillance cameras.Our goal is to help user find a dynamic target efficiently in the real world when the target’s position is intermittently known.In order to achieve this purpose,we have designed an AR guidance assistance system to provide optimal current directional guidance to users,based on searching a prediction graph.We assume that a certain number of depth cameras are fixed in a real scene to obtain dynamic target’s position.The system automatically analyzes all possible meetings between the user and the target,and generates optimal directional guidance to help the user catch up with the target.A user study was used to evaluate our method,and its results showed that compared to free search and a top-view method,our method significantly improves target search efficiency.

Unveiling the impact of residual Li conversion and cation ordering on electrochemical performance of Co-free Ni-rich cathodes

The residual Li and Li^(+)/Ni_(2)+cation mixing play essential roles in the electrochemical properties of Ni-rich cathodes.However,a general relationship between the residual Li conversion,cation mixing,and their effects on the Li^(+)kinetics and structural stability has yet to be established,due to the presence of cobalt in the cathode.Here,we explore the synergistic impact of the residual Li conversion and cation ordering on a Co-free Ni-rich cathode(i.e.,LiNi0.95Mn0.05O_(2)).It discloses that the rate capability is mainly affected by residual Li contents and operating voltage.Specifically,residual Li can be electrochemically converted to cathode electrolyte interphase(CEI)below 4.3 V,thus inducing high interphase resistance,and decomposes to produce CO_(2)-dominated gas at 4.5 V,causing temporary enhancement of Li^(+)diffusivity but severe surface degradation during cycling.Moreover,the cycling performance of Co-free Ni-rich cathode is not only determined by Li^(+)/Ni_(2)+cation-ordered superlattice,which enhances the structural stability as it functions as the pillar to impede lattice collapse at a highly charged state,but also by the robust CEI layers which protect the bulk from electrolyte attack under 4.3 V.These findings promote an in-depth understanding of residual Li conversion and Li^(+)/Ni_(2)+cation ordering on Co-free Ni-rich cathode.