本征可弹性拉伸锂离子全电池制备及其结构与性能实时分析

Some of the wearable and implantable devices put forward a new demand of elastic stretchability on the lithium batteries, e.g. some devices which are attached to the joints or integrated into the clothing. However, the large deformation during the stretch will significantly change the microstructure of the batteries, proposing much higher challenges compared with flexible batteries. At present, there have been some reports on stretchable batteries, but most of them focused on the methods to achieve stretchability. Only a small amount of them tried to improve the intrinsic elasticity of each component. No studies have been carried out to integrate these elastic materials in all parts. The stretchable batteries obtained are still facing problems inducing fast capacity fading, low active materials loading etc. In particular, the related fundamental research is missing. The knowledge on the relationship between its structure and performance of the battery during the stretch is absent. The method to maintain the same ion and electron transfer rate during the stretch is absent. Therefore, the applicant plans to design and prepare the conductive polymer elastomer, electrode binder, polymer electrolyte and other elastic materials through controlling the polymer chain sequence. Stretchable battery will be achieved with all of its compounds having intrinsic elasticity. The real-time, in-situ analysis methods on the battery structure and performance during the stretch will be established for the first time to carry out the fundamental research as mentioned above. Intrinsically elastic stretchable battery will be achieved with stable performance. This work will promote the development of stretchable batteries and high-capacity batteries which are suffering from the large electrode volume change during the charge and discharge process. It also has scientific significance in understanding the relationship between lithium battery structure and performance.

可穿戴、可植入设备中，一些贴合于关节、整合到衣物内等器件对锂电池提出了可弹性拉伸新需求。然而，拉伸大形变会显著改变电池微观结构，相比柔性电池提出了更高挑战。目前已有可拉伸电池报道，但多侧重于可拉伸性的实现方法，提高各部件本征弹性研究较少，缺失各部位弹性材料一体化研究。所得电池仍存在容量衰减明显、负载低等问题。特别是相关基础研究欠缺，缺少电池发生拉伸大形变时对结构与性能关系的认知，离子、电子传导速率如何在拉伸时维持稳定的研究等。因此，申请者希望通过聚合物链序列结构调控、统一设计导电聚合物弹性体、电极粘结剂、聚合物电解质等弹性材料，在实现电池各部件本征弹性的同时得到一体化全电池；首次建立拉伸过程中结构与性能实时、原位分析方法，实现上述基础问题的研究，获取本征可弹性拉伸、性能稳定全电池。对可拉伸电池、充放电时体积变化显著的高比能电池发展有积极促进作用，对认知锂电池结构与性能关系有重要科学意义。

可穿戴、可植入设备中，一些贴合于关节、整合到衣物内等器件对锂电池提出了可拉伸新需求，现代单兵作战由于电子化装备的增多需随身佩戴高能量储能电源，对其实现可穿戴化、舒适化也提出了新的需求。目前已有可拉伸电池报道，但多通过宏观结构设计实现宏观拉伸形变，提高各部件本征弹性研究较少，缺失各部位弹性材料一体化研究。电池外部形变会显著改变电池微观结构，进而导致导电、导离子网络失去完整性，电极与集流体之间也易发生剥离，均会导致电池在拉伸过程中性能显著下降。因此，本项目研究了通过聚合物链序列结构调控、统一设计本征可弹性聚合物材料，获得可拉伸导电聚合物集流体、电极粘结剂、聚合物电解质等，在实现电池各部件本征弹性的同时得到一体化可拉伸全电池。采用了可逆加成断裂链转移自由基乳液聚合法，制备了苯乙烯与丙烯酸丁酯的三嵌段聚合物弹性体，与纳米碳管共混制备得到了可实现100%拉伸形变，电导率为10mS/cm的弹性导电集流体，解决金属集流体不可拉伸的问题；制备了苯乙烯与聚丙烯酸甲酯嵌段聚合物弹性粘结剂，与弹性集流体相结合实现了可拉伸电极，可完成100%形变，在1C倍率以下电池性能与采用金属集流体电池性能一致，100次100%形变后电极性能无变化。制备了苯乙烯与丙烯酸甲酯双向梯度共聚物，实现可90%拉伸形变的聚合物电解质, 室温离子电导率达0.288mS/cm。集流体、弹性电极粘结剂、聚合物电解质采用多嵌段链序列结构，均通过聚苯乙烯相形成物理交联点，通过后处理物理交联，实现全电池各部件的一体化，在电池拉伸过程中有助于界面的稳定性，最终获得了柔性及可拉伸锂离子全电池，研究了拉伸过程中各材料结构与性能关系。并且，为解决可穿戴锂离子电池的安全性，还制备了可拉伸全固态聚合物电解质，可实现50%弹性形变，室温电导率达0.465mS/cm，实现了可室温工作的柔性全固态电池制备。为提高可穿戴储能设备的能量密度，首次将硅基材料用于柔性及可拉伸电极制备，获得了硅基可拉伸电极。本项目研究对可拉伸电池、充放电时体积变化显著的高比能电池发展有积极促进作用，对认知锂电池结构与性能关系有重要科学意义。