亲硫阵列电极的构筑及锂/硫电池研究

Lithium-sulfur battery (Li-S) has been regarded as one of the most promising energy storage system due to its high energy density, abundant resources of sulfur. However, the main problems of Li-S battery involve the insulating nature of sulfur/lithium sulfides, the shuttling effect of soluble lithium polysulfide (LiPS) intermediates, which cause serious loss of active material and fast capacity decay. In order to entrap sulfur and LiPS, and suppress the shuttling effect thereby increasing the lifespan of Li-S battery, the proposed approach is to build array electrodes with tunable surface chemistry based on combining conductive carbon material with polar inorganic material. By which, the sulfur electrode can have both high affinity towards sulfur and LiPS, thus increase the stability of the battery. In the project, the interaction between different inorganic material, solvent molecule and LiPS will be elucidated by EC-QCM, XPS and DFT calculation; then the inorganic array electrode will be grown on carbon materials like carbon nanotubes, graphene. The design of the electrode is threefold: the carbon material has high conductivity and high affinity towards sulfur; the polar surface of the inorganic material has strong affinity towards LiPS; the array structure the integral conductive and wettability of the sulfur electrode; With the combination of these features, the Li-S battery can achieve controlled distribution and deposition of sulfur species which in turn guarantee high capacity and cycling stability. Thirdly, with further modification of the electrode with electron/ion conductive network, the Li-S battery can realize high rate performance and high stability. The completion of the study can understand the relationship between electrode structure, surface chemistry and electrode reactivity, which will build the foundation for better electrode design.

锂硫电池有原料来源广泛，理论容量高等优点，但是充放电产物均为电子不良导体，中间产物锂多硫离子易溶解，造成容量快速衰减。为固定单质硫和多硫离子，减少穿梭效应，提高电池循环稳定性，申请人提出：利用过渡金属化合物（氧化物、硫化物及磷化物）的强极性表面与碳材料弱极性表面的复合和调控，实现对多硫离子和单质硫的特异性吸附,从而提高锂硫电池的性能。首先采用电化学石英晶体微天平，XPS和DFT等手段明确过渡金属化合物不同晶面与多硫离子的作用机理；然后发展原位合成方法，在纳米碳基底（如碳纳米管和石墨烯）上生长纳米金属化合物阵列，利用纳米碳吸附单质硫，利用极性表面吸附多硫离子，利用阵列化改善体系导电性和浸润性，从而充分改善充放电产物在电极中的分布，提高硫的利用率；进而在硫电极表面构筑导电网络，获得高性能的锂硫电池。本研究将有助于理解电极结构、表面性质和电极反应动力学的关系，为提高电池性能提供依据。

锂硫电池有原料来源广泛，理论容量高等优点，但是充放电产物均为电子不良导体，中间产物锂多硫离子易溶解，造成容量快速衰减。为固定单质硫和多硫离子，减少穿梭效应，提高电池循环稳定性，我们基于锂硫电池在硫正极材料、锂金属负极保护、固态电解质方面进行了系统的研究，取得了一系列的成果。.在硫正极方面我们设计了纳米金属化合物阵列，多壳结构，单分散氮碳材料等作为正极材料，利用阵列化改善体系导电性和浸润性，利用纳米碳吸附单质硫，利用极性表面吸附多硫离子，从而充分改善充放电产物在电极中的分布，提高硫的利用率；进而在硫电极表面构筑导电网络，获得高性能的锂硫电池。相关成果发表在ACS Applied Energy Materials、Inorganic Chemistry Frontiers、Energy & Fuels等期刊上。.在锂金属负极保护方面我们基于设计三维导电骨架促进锂均匀沉积、多组分协同作用和设计人工SEI膜等方面进行了一系列的探究，取得了较为卓越的成绩。相关成果发表在Advanced Materials、Advanced Functional Materials、Energy Storage Materials等期刊上。.在固态电解质设计方面我们基于超支化分子设计以及有机无机复合方面进行了一系列的探索，所制备的固态电解质均表现出了在室温下大于10-4 S/cm的离子电导率以及大于5 V的电化学稳定窗口。相关成果发表在Advanced Materials，Chemical Communication、Chinese Chemical Letters等期刊上。.设计并制备的电极材料合成工艺简单，电化学性能优异，为锂硫电池的发展和商业化应用提供了材料和科学基础。