柔性自修复锂金属电池的构筑及性能研究

Recently, the emerging direction towards the ever-growing market of wearable electronics has nourished progress in building flexible lithium ion batteries (LIBs) that provide power for them. However, current flexible LIBs have disadvantages such as low energy density, easy detachment of electrode materials and even battery break under repeated deformations, which in turn lead to the deterioration of electrochemical performances, leakage of liquid electrolyte and battery failure. Lithium metal is most promising anode material. But, the growth of lithium dendrite and large volume change during charge/discharge processed could reduce safety and stability. This project focuses on the flexible lithium metal batteries (LMBs) based on composite solid electrolyte with self-healing functionality. First, we will explore the flexible cathode with self-healing polymer as binder and study the electrochemical and mechanical performances; Flexible and dendrite-free lithium metal anode supported by porous current collector is under investigation with improving Columbic efficiency; Flexible composite solid electrolyte based on inorganic materials and self-healing polymer will be developed, which shows a great opportunity to reduce interfacial resistance and release the strain with volume change for lithium metal anode; Finally, based on the composite solid electrolyte, we will build the flexible LIBs with high energy-density, good cycling performance, high safety and low cost, for the applicant requirements.

近年来，可穿戴电子产品受到越来越多的关注，为其供电的柔性锂离子电池逐渐成为储能领域的研究热点之一。但是，现阶段柔性锂离子电池能量密度较低，反复变形容易产生活性物质脱落甚至电池破裂，从而导致循环性能下降、有毒电解液泄露和电池失效。锂金属是最理想的负极材料，但在充放电过程中锂枝晶的生长和较大的体积变化会降低其安全性和稳定性。本项目研究基于具有自修复功能的复合固体电解质的柔性锂金属电池。首先，探索采用自修复聚合物作为粘结剂的柔性正极材料的电化学和机械性能；开发多孔集流体支撑的柔性锂金属负极，实现无锂枝晶生长的同时提高库伦效率；将无机材料与自修复聚合物复合制备具备自愈合能力的柔性固体电解质，降低与电极的界面阻抗，缓解锂金属负极体积变化带来的应变；最后，构建基于该复合固体电解质，具有高能量密度、良好循环稳定性、高安全性和低成本的柔性锂金属电池，满足实际应用的需求。

近年来，可穿戴电子产品受到越来越多的关注，为其供电的柔性锂离子电池逐渐成为储能领域的研究热点之一。但是，现阶段柔性锂离子电池能量密度较低，反复变形容易产生活性物质脱落甚至电池破裂，从而导致循环性能下降、有毒电解液泄露和电池失效。锂金属是最理想的负极材料，但在充放电过程中锂枝晶的生长和较大的体积变化会降低其安全性和稳定性。用固体电解质取代传统易燃的有机液态电解液，有望从根本上提高安全性，还有望使用高能锂金属负极，提高锂电池能量密度。本项目研究了一系列用于柔性固态锂金属电池的关键材料，包括柔性固体电解质材料、高稳定性金属锂负极和高负载正极材料等。在固体电解质方面，采用自修复聚合物、Ga掺杂Li7La3Zr2O12粉体和电解液复合的半固态电解质；利用光固化3D打印技术开发高性能柔性全固态聚合物固体电解质材料。其次，在稳定的锂金属负极方面，利用石墨烯多级结构构建与空气和水稳定的锂金属负极；利用Sn纳米层稳定锂枝晶；Zn纳米团簇修饰的三维导电框架用于稳定锂金属负极。最后，本项目开发了柔性、高负载全固态锂金属电池，采用原位固化聚合物电解质和具有垂直通道的正极材料，在正极活性物质3.0 mg cm-2高负载下，实现了室温比容量为154.3 mAh g-1，循环150圈后具有89%容量保持率。此外，通过使用包覆NiCo2O4纳米线阵列的碳布作为基底，开发了柔性且高负载量的锂硫电池。本项目开发的新型关键材料和高性能柔性锂金属电池是整个柔性电池行业发展的大方向，具有极其重要的意义。