Exchange coupling interaction in sintered magnetic materials is generally isotropic. In this study, the anisotropic exchange coupling interaction was found in sintered oblate cylindrical SrFe₁₂O₁₉ (SrM) specimens obtained by the SrM nanopowders synthesized via a hydrothermal method. According to Henkel plots, the exchange coupling interaction between hard–hard magnetic grains was found in both as-pressed and sintered specimens. However, the exchange coupling interaction can only be found in the in-plane direction but not in the out-of-plane direction for the sintered specimens. By building a model of a grain configuration, this anisotropy of the exchange coupling interaction was ascribed to the vertically arranged plate-like SrM grains with micrometers in width but nanometers in thickness, which was confirmed by morphologies of cross sections in fractured specimens.

Lithium-sulfur (Li-S) batteries with the merits of high theoretical capacity and high energy density have gained significant attention as the next-generation energy storage devices. Unfortunately, the main pressing issues of sluggish reaction kinetics and severe shuttling of polysulfides hampered their practical application. To overcome these obstacles, various strategies adopting high-efficient electrocatalysts have been explored to enable the rapid polysulfide conversions and thereby suppressing the polysulfide shuttling. This review first summarizes the recent progress on electrocatalysts involved in hosts, interlayers, and protective layers. Then, these electrocatalysts in Li-S batteries are analyzed by listing representative works, from the viewpoints of design concepts, engineering strategies, working principles, and electrochemical performance. Finally, the remaining issues/challenges and future perspectives facing electrocatalysts are given and discussed. This review may provide new guidance for the future construction of electrocatalysts and their further utilizations in high-performance Li-S batteries.