多酸-离子液体核壳结构复合材料作为Li-CO2电池正极的应用探索

Li-CO2电池具有较高的放电电位和理论能量密度以及潜在的处理CO2的价值，被认为是下一代新型电池候选者。但是，Li-CO2电池存在着CO2还原和析出反应极化大、Li+和CO2扩散慢、可逆性差和循环容量衰减等问题。特别是CO2还原和析出反应中CO2的活化、还原以及碳酸锂氧化等动力学缓慢的步骤，限制了电池性能的提高。多酸具有优异的多电子氧化还原特性和结构可调性，能够潜在应用于催化这些关键决速步骤，是Li-CO2电池正极材料的候选。但是多酸的导电性或稳定性较差限制了其应用。本项目将选择离子液体和多酸复合制备多酸-离子液体核壳结构复合材料，离子液体为壳能够有效增强多酸稳定性并提供导电性而多酸为核能够提供催化中心。这类材料可以进一步溶解负载在导电和多孔基底上并作为正极材料，有效催化电池反应决速步骤以提高电池性能。本项目将围绕着这类材料研究Li-CO2电池存在着的难点，拓展多酸在该领域的应用。

Li-CO2 battery is considered as one of the candidates for the next generation of new battery, which is due to its high discharge potential, theoretical energy density and potential value in CO2 treatment. However, Li-CO2 battery still faces problems like large reaction polarization, slow diffusion efficiency of Li+ and CO2, poor reversibility and cycle capacity attenuation. Especially for slow rate reactions like the activation or reduction of CO2 and oxidation of lithium carbonate, they are rate-determining steps that limit the increase of battery performances. Polyoxometalates have tunable structures and excellent multi-electron redox properties have potential in catalysis of these rate-determining steps, which might serve as promising candidate as cathode materials for Li-CO2 battery. However, polyoxometalates have bottlenecks like poor conductivity or low stability, which will largely limit their applications as cathode materials. Therefore, this project will select ionic liquid and polyoxometalates to prepare polyoxometalate/ionic liquid core-shell composites, in which ionic liquid as the shell can stabilize polyoxometalate and enhance conductivity while polyoxometalates as the core can provide catalysis centers. This kind of crystalline materials can be further dissolved and loaded onto conductive and porous substrates, which can serve as powerful cathode materials in catalysis of the rate-determining steps. This project will focus on these crystal materials to treat the problems existed in Li-CO2 battery and expand the application area of polyoxometalates in Li-CO2 battery.