金属磷化物-多级孔石墨化碳的可控合成及其多重增强硫储锂性能研究

本项目提出磷酸树脂鳌合金属离子，经同步磷化/石墨化/活化联用技术可控合成“金属磷化物-多孔石墨化碳”纳米复合物作为单质硫多重协同增强载体。运用原位TEM等多种分析手段对“金属磷化物-多孔石墨化碳”进行系统的物理表征和生长机制研究，获得其形貌、组成和结构的调控方法及规律。发展了一种通用的“原位还原-热熔”单质硫负载策略，实现硫纳米晶在“金属磷化物-多孔石墨化碳”的均匀分布和高负载量，通过该载体优良的导电性促进单质硫电子传递，开放多级孔结构缓冲体积膨胀，化学吸附、催化和物理限域作用抑制穿梭效应，获得高性能锂硫电池正极材料。重点研究“硫/金属磷化物-多孔石墨化碳”的储锂电化学性能和稳定性及构效关系，揭示金属“磷化物-多孔石墨化碳”多组分和多功效增强单质硫储锂电化学性能的本质及多重增强效应机理，为高容量和长循环锂硫电池正极材料的设计提供理论指导。

Metal phosphides provide effective polysulfide immobilization for inhibiting the shuttle effect in Li-S batteries. We aim to synthesize metal phosphides on hierarchical porous graphitized carbon (MP-HPGC)" from phosphoric acid resin chelated with metal ions through a synchronous phosphidising-graphitization-activation strategy, for use as a host material for sulfur. The growth mechanisms and characterization of MP-HPGC will by studied by in situ TEM, SEM, XRD etc. A high content of sulfur nanocrystals will be uniformly deposited on MP-HPGC by a general "in situ Reduction-Hot Melting" loading strategy. The MP-HPGC substrate aims to improve electron transfer with elemental sulfur, provide opened hierarchical pores, buffer volume expansion, aid chemical adsorption and catalysis, and provide anchorage of polysulfides to inhibit the shuttle effect. Lithium storage of S/MP-HPGC as a cathode, along with study of its morphology and composition and electrochemical performance will be reported. Finally, clarification of the collective enhancement mechanisms of "multiple effects" and "multiple components" on sulfur enhancement, will provide guidance for design and synthesis of high-performance cathode materials for Li-S batteries.