Search

Nickel–cobalt sulfides and nickel–cobalt hydroxides are outstanding anode materials for lithium-ion batteries (LIBs), but their commercial applications are restricted by poor conductivity and severe cyclic expansion. In this article, we report a structure in which nitrogen-doped carbon layers are compactly coated on nanosheets of (Co0.67Ni0.33)9S8/NiCoLDH that are supported by hollow carbon spheres (HCS). The HCS@(Co0.67Ni0.33)9S8/NiCoLDH@NC was synthesized by hydrothermal reactions and calcination with SiO2 as hard templates. The hollow structure reduces the severe capacity attenuation caused by volume expansion, and the nanosheets covered with carbon have a huge specific surface area and significantly enhanced electrical conductivity. The HCS@(Co0.67Ni0.33)9S8/NiCoLDH@NC exhibits excellent cycle capacity (615 mAh g−1 at 0.2 A g−1 after 150 cycles) and rate performance depending on the structural preponderances and the synergistic interaction between (Co0.67Ni0.33)9S8 and NiCoLDH. This research provides a unique route for the synthesis of anode materials for high-performance LIBs. [ABSTRACT FROM AUTHOR]

As the only vascular tissue that can be directly viewed in vivo, retinal vessels are medically important in assisting the diagnosis of ocular and cardiovascular diseases. They generally appear as different morphologies and uneven thickness in fundus images. Therefore, the single‐scale segmentation method may fail to capture abundant morphological features, suffering from the deterioration in vessel segmentation, especially for tiny vessels. To alleviate this issue, we propose a multi‐scale channel fusion and spatial activation network (MCFSA‐Net) for retinal vessel segmentation with emphasis on tiny ones. Specifically, the Hybrid Convolution‐DropBlock (HC‐Drop) is first used to extract deep features of vessels and construct multi‐scale feature maps by progressive down‐sampling. Then, the Channel Cooperative Attention Fusion (CCAF) module is designed to handle different morphological vessels in a multi‐scale manner. Finally, the Global Spatial Activation (GSA) module is introduced to aggregate global feature information for improving the attention on tiny vessels in the spatial domain and realizing effective segmentation for them. Experiments are carried out on three datasets including DRIVE, CHASE_DB1, and STARE. Our retinal vessel segmentation method achieves Accuracy of 96.95%, 97.57%, and 97.83%, and F1 score of 82.67%, 81.82%, and 82.95% in the above datasets, respectively. Qualitative and quantitative analysis show that the proposed method outperforms current advanced vessel segmentation methods, especially for tiny vessels. [ABSTRACT FROM AUTHOR]

Transition metal chalcogenides (TMCs) are considered to be promising as anode materials for lithium-ion batteries (LIBs) due to their unique physical and chemical properties and high theoretical specific capacity. Nevertheless, the poor rate performance and fast capacity decay seriously affect its practical application in LIBs. In the present study, porous yolk-shell CoS2@FeS2@NC hollow microspheres have been successfully prepared through a simple step-by-step strategy. In addition to shortening the transport length of lithium ions, this unique structure can also successfully alleviate the volume change during charging/discharging. Importantly, the coating of the nitrogen-doped carbon (NC) layer effectively enhances the electrical conductivity of the material and prevents exfoliation of metal particles. The yolk-shell CoS2@FeS2@NC hollow microspheres show high specific capacity (1162.6 mAh g−1) and excellent cycle stability (614 mAh g−1 at 1 A g−1 after 100 cycles) when used as anode material for LIBs. These fascinating electrochemical performances strongly demonstrate that the as-obtained yolk-shell CoS2@FeS2@NC hollow microspheres can be highly applicable in the field of high-performance LIBs electrode materials. [ABSTRACT FROM AUTHOR]