新型锂电用复合聚合物电解质的多功能特性和作用机理研究

Aiming at the key problem of poor cycling performance caused by the instability of electrode of the new-type lithium/lithium-ion electrochemical devices, this project presents a new idea to eliminate or suppress the influence factors on the electrode stability fundamentally through the design of the materials and interface property that endow polymer electrolyte with multi-functional characteristics. The researches are no longer limited to the traditional approach of exploring electrodes. Graphene oxide (GO), acting as ion conducting promtor, is incorporated into composite polymer electrolytes to improve the ionic conducitivity and electrode-electrolyte interfacial energy storage. On this basis,for aqueous rechargable lithium-ion battery, the electrochromic redox polymer electrolyte is used to self-eliminate oxygen by the reaction during the working of battery, and also to reduce the dissolution of the electrode. For lithium-sulfur battery, the design of topology for physical or chemical structure of polymer electrolytes is in favor of small ion transport, while not conducive to the migration or diffusion of large ions, so that the phenomenon of shuttle polysulfide ions can be suppressed. The process of interfacial energy storage，as well as the role of multi-functional characteristies and mechanisms of composite polymer electrolytes for the new-type lithium/lithium-ion electrochemical devices will be clarified. In summary, the present proposal is reasonably worked out and supported by the pilot explorations. The innovative technical routes have considered the demands of practical usage. In this context, the proposal is coupled with high feasibility.

针对新型锂电体系因电极不稳定而导致循环性能差的关键难题，本项目提出通过材料和界面设计赋予聚合物电解质多功能特性，从根本上消除或抑制影响电极稳定性因素的新思路，而不再局限于仅仅围绕电极展开研究的传统做法。拟采用氧化石墨烯作为离子促进剂，制备复合型聚合物电解质，提高聚合物电解质离子导电率和电极/固态电解质界面储能。在此基础上，对于水系锂离子电池，将引入具有电致氧化还原特性的聚合物电解质，与氧气反应实现电池工作中自行除氧，并减少电极的溶解；对于锂硫电池，将设计有利于小离子传输而不利于大离子迁移扩散的聚合物电解质物理或化学拓扑结构，抑制聚硫离子的飞梭现象。阐明电极/电解质界面储能过程，揭示新型锂电用复合聚合物电解质的多功能特性和作用机理，为新型锂电的开发拓展新途径。本项目研究思路和工作方案具有较扎实的理论依据和前期探索支撑，创新性明显，同时充分考虑了材料应用的需求，可行性较高。

复合聚合物电解质结合了有机材料和无机材料的各自特性，是聚合物电解质最重要的类型之一，符合当今聚合物电解质朝高性能、多功能和复合化的发展趋势。针对新型锂电存在的电极不稳定和循环性能差等关键难题，探索赋予复合聚合物电解质高离子电导率、高储能容量以及离子选择性是本项目主要研究工作。本项目旨在通过材料和界面设计赋予复合聚合物电解质多功能特性，发展从根本上消除或抑制影响电极稳定性因素的新思路，而不再局限于仅仅围绕电极展开研究的传统做法。在上述研究目标下，从复合聚合物电解质的基本组分的合成和结构调控出发，主要开展氧化石墨烯填料-聚合物基体界面超支化聚合物的合成和结构设计，进一步利用高分子加工手段，如溶液共混、以及冷冻干燥法、紫外光固化法等新型材料制备手段制备高离子导电复合聚合物电解质。以调控聚合物电解质中的氧化石墨烯在电极界面分布为目的，对电极-电解质界面的储能行为开展详细的表征和机理研究，研究复合聚合物电解质的储能特性。以调控复合聚合物电解质的孔隙结构为目的，对在复合体系中的离子传导行为开展研究，并以锂硫电池为模型，开展抑制聚硫离子飞梭效应的研究，进而调控复合聚合物电解质的离子选择性。项目最终揭示了复合聚合物电解质的若干多功能特性和作用机理，对进一步拓展聚合物电解质的基础和应用研究具有指导意义。