Despite great progress in lithium-sulfur batteries (LSBs), great obstacles still exist to achieve high loading content of sulfur and avoid the loss of active materials due to the dissolution of the intermediate polysulfide products in the electrolyte. Relationships between the intrinsic properties of nanostructured hosts and electrochemical performance of LSBs, especially, the chemical interaction effects on immobilizing polysulfides for LSB cathodes, are discussed in this Review. Moreover, the principle of rational microstructure design for LSB cathode materials with strong chemical interaction adsorbent effects on polysulfides, such as metallic compounds, metal particles, organic polymers, and heteroatom-doped carbon, is mainly described. According to the chemical immobilizing mechanism of polysulfide on LSB cathodes, three kinds of chemical immobilizing effects, including the strong chemical affinity between polar host and polar polysulfides, the chemical bonding effect between sulfur and the special function groups/atoms, and the catalytic effect on electrochemical reaction kinetics, are thoroughly reviewed. To improve the electrochemical performance and long cycling life-cycle stability of LSBs, possible solutions and strategies with respect to the rational design of the microstructure of LSB cathodes are comprehensively analyzed.

Well-controlled core-shell hierarchical nanostructures based on oxyfluoride and hydroxide are for the first time rationally designed and synthesized via a simple solvothermal and chemical precipitation route, in which FeOF nanorod acts as core and porous Ni(OH) 2 nanosheets as shell. When evaluated as electrodes for supercapacitors, a high specific capacitance of 1452 F g −1 can be obtained at a current density of 1 A g −1 . Even as the current density increases to 10 A g −1 , the core-shell hybrid still reserves a noticeable capacitance of 1060 F g −1 , showing an excellent rate capacity. Furthermore, all-solid-state flexible asymmetric supercapacitor based on the FeOF/Ni(OH) 2 hybrid as a positive electrode and activated carbon as a negative electrode shows high power density, high energy density, and long cycling lifespan. The excellent electrochemical performance of the FeOF/Ni(OH) 2 core-shell hybrid is ascribed to the unique microstructure and synergistic effects. FeOF nanorod from FeF 3 by partial substitution of fluorine with oxygen behaves as a low intrinsic resistance, thus facilitating charge transfer processes. While the hierarchical Ni(OH) 2 nanosheets with large surface area provide enough active sites for redox chemical reactions, leading to greatly enhanced electrochemical activity. The well-controllable oxyfluoride/hydroxide hybrid is inspiring, opening up a new way to design new electrodes for next-generation all-solid-state supercapacitors.flexible applications in a wide range of power equipment, electronic products, digital telecommunication systems, and hybrid electric vehicles. [4,6] Furthermore, as a crucial class of energy storage devices, supercapacitors can bridge the gap of power density and energy density between batteries and traditional capacitors. [7][8][9][10] However, fabrication of high-performance supercapacitors is still challenging both in mechanism and structure design of electrode materials.Taking consideration of charge storage mechanism, supercapacitors can be divided into two categories: electric double layer capacitor (EDLC) and pseudocapacitor. EDLC, usually utilizing carbon materials, stores electrochemical energy by absorbing/dislodging [11] and dominates the supercapacitor markets currently. [12] Nevertheless, relatively low specific capacitance of EDLC cannot meet the increasing demand for supercapacitors with higher capacitance and longer cycling life, hindering their further applications. [13][14][15][16][17] Recently, extensive efforts have been dedicated to investigating pseudocapacitors due to their higher specific capacitances depending on fast Faradaic redox reaction. Among these materials, transition metal hydroxides have been actively studied and recognized as promising supercapacitor electrode materials because of their high theoretical specific capacitance. [18][19][20][21] However, it is of urgency to extend the operating potential of these supercapacitors so as to get better electrochemical performance. [22] Nowadays, it has developed a valid approach t...

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