金属原子插层金属氧化物对锂硫电池的作用机理研究

Li-S battery is considered as one of the most promising batteries with high energy density in the next generation because of its advantages such as high theoretical capacity, high energy density and so on. There are two critical factors that impede the further development of Li-S battery in the current time. The first one is the “shuttling” effect lead by the dissolution of high-valance lithium polysulfides. The second one is the insulation of active material S8 and discharging reduction Li2S2/Li2S. Therefore, it is highly desirable to introduce ideal carriers for S8 to restrain the “shuttling effect” availably and enhance the dynamic process of charging and discharging as well. As the previous research proves, MoO3 can transform from insular to semiconductor after the intercalation of atoms Sn and its biding energy with Li2S4 increases obviously. Here we proposed that MoO3 intercalated wtih various metal atoms can lead to effective improvement of "shuttle" effect and electronic conductivity of Li-S battery. Furthermore, we will systemically study the relationships between constituent and the macroscopic characteristics such as conductivity, band gap and adsorptivity to lithium polysulfide, to achieve the optimal rate and cycle performance of Li-S battery. In addition, the intercalation method will be further applied to other kinds of metallic oxide materials, and the mechanism of intercalation reaction will be explored by DFT theoretical calculation.

Li-S电池具有理论容量高和能量密度大等优势，被认为是最有希望的下一代高能量密度电池之一。目前，高阶多硫化锂的溶解引起的“穿梭”效应和活性物质S8及放电产物Li2S2/Li2S的绝缘性是制约Li-S电池进一步发展的两个关键因数。因此，引入理想的S8载体能够同时有效的抑制“穿梭”效应的发生并增强充放电动力学过程显得迫在眉睫。前期研究表明，金属原子Sn插层后，MoO3从绝缘体变成了半导体，且与Li2S4的结合能有明显增加。本项目拟在此基础上，进一步对MoO3插入不同种类金属原子，实现对Li-S电池“穿梭”效应和电导率的有效改善，阐述原子插层后MoO3材料的微观组分和电导率、带隙、对多硫化锂吸附等宏观特性之间的构效关系，实现Li-S电池倍率和循环性能的最优化。并进一步将插层技术应用到其它种类的金属氧化物材料中；结合DFT理论计算探究插层技术对Li-S电池的作用机理。

随着“双碳”政策越来越受到各国的重视，开发节能和清洁环保的新能源是解决“双碳”问题的关键因素。其中，锂硫电池由于高的能量密度受到了研究者和产业界广泛的关注，得到大电流充放电性能和循环稳定性优越的电极材料是整个锂硫电池研究的关键因数之一。此外，氢气具有比能量密度高、清洁和环保的优势，一直被认为是一种理想的燃料。催化剂是制约电解水产氢效率的关键因数，如何降低能耗是电催化析氢的关键。本项目工作按原计划执行，通过将不同种类金属原子插入到MoO3的展开，探究其物相结构变化和电化学性能之间的构效关系。同时，构建了MoO3/MoO2异质结在锂硫电池中的研究。进一步将原子插层技术推广到电催化氢析出反应中，探究其可能的作用机理。主要研究内容包括:.1.研究不同种类金属原子插入MoO3的范德瓦尔斯层间，探究不同种类金属原子插入后材料的物相结构和电化学性能之间的构效关系；.2.发明了原子插层/硫化的方法，将原子插层的MoO3转化成原子掺杂的MoS2，研究其电催化析氢性能；.3.将金属原子插层MoO3进一步推广到SnS2，探究其电催化析氢性能和可能的作用机理；.4.构建了MoO3/MoO2异质结，探究了异质结相对锂硫电池的作用机理。.本项目深入研究了插层技术在锂硫电池和电催化析氢中的反应机理, 分析了金属原子种类、不同载体和多种金属原子的协同作用对锂硫电池和电催化析氢的影响及作用机理。揭示了插层技术在能源转化与存储领域的应用和普适性规律，为插层技术在能源领域的应用和推广提供了参考和借鉴。