Nanowhisker filled solid polymer electrolytes

纳米晶须填充固体聚合物电解质

• 批准号: 1310196
• 负责人: Janna Maranas
• 金额: $ 48万
• 依托单位: Pennsylvania State Univ University Park
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2013
• 资助国家: 美国
• 起止时间: 2013-06-01 至 2017-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1310196&HistoricalAwards=false
• 关键词: Nanowhisker; filled; solid; polymer; electrolytes

TECHNICAL SUMMARYPolymer electrolytes are safer, cleaner, and more flexible than liquid electrolytes currently used in Li batteries. They are an attractive possibility for use with Li metal electrodes because they are stiffer than liquid electrolytes. For this purpose, PEO-based electrolytes are not stiff enough to prevent dendrite formation, which limits use of Li metal. They also do not have high enough conductivity to be practical. Unfortunately, stiffness and conductivity are inversely related because Li motion is coupled to polymer motion, and any attempt to improve conductivity through faster polymer motion results in decreased stiffness. This project is based on the idea that tunnel-like polymer/salt structures promote fast Li motion, recently demonstrated using single-crystal electrolytes. It will harness this motion with a set of high aspect ratio nanofillers based on cellulose nanowhiskers, which are hypothesized to promote the tunnel structures. These fillers offer controllable surface chemistry, degree of functionalization and aspect ratio, thus forming an ideal model system. Building on prior work, particular attention will be paid to the eutectic composition, at which improved electrical conductivity and mechanical properties are established in metal alloys. At this composition, the analogous metal alloys form large-scale structures with the two crystal phases in alternating lamellae. The formation of such structures for polymer electrolytes has not been investigated. The project will use cyclic thermal treatments as a means to produce similar patterns in polymer/salt eutectics, which will extend the tunnel-like structures further from the filler surface. The ideal electrolyte would have fillers, and thus Li conduction pathways, aligned along the direction normal to the electrodes. It is established that cellulose nanowhiskers can be aligned using magnetic fields, electric fields, and shear, and the project will investigate all three for effectiveness at alignment without disrupting polymer/salt pattering extending from the filler surface. The project will promote understanding of the roles of surface chemistry and aspect ratio on interaction of nanoscale fillers with polymer/salt systems, the factors controlling polymer eutectic structures, and the best ways to control filler alignment in polymer/salt mixtures. NON-TECHNICAL SUMMARYPolymer electrolytes are safer, cleaner, and more flexible than liquid electrolytes currently used in the Li batteries in cell phones and laptop computers. They are an attractive possibility for use in vehicles, where Li ion battery technology is already used. Polymer electrolytes are attractive for this application because they allow technical advancements that extend the charge lifetime from 100 to 400 miles per charge. Polymer electrolytes are not currently feasible with these technical advancements, nor can they attain power discharge sufficient for vehicle applications. These two required improvements are currently mutually exclusive: attempts to enable longer charge lifetime will reduce power and vice versa. The science in this project will decouple the objectives of long lifetime and high power. It is based on unique features of polymer/Li salt mixtures that occur near inorganic surfaces. It will use very small fillers, which provide more surface area, and alter the surface chemistry and filler alignment to obtain optimal results. The results of this work will allow scientists to work on increasing power and lifetime independently, thus promoting advancement of the alternative energy technology of Li ion batteries. The U.S. is a world leader in scientific research, yet struggles to fill jobs in the sciences, technology, engineering and mathematics. The United InnoWorks Academy is a national organization that seeks to narrow this disconnect by introducing STEM concepts in a fun way to kids in the critical period where they are deciding what they like and what they are good at. The program is specifically designed towards students who, at age 11, may have already decided that they are not good at math and science. InnoWorks is a student-run organization in which professors, graduate students and undergraduate students raise funds, develop curriculum, and prepare and run summer camps. This project will start a Penn State Chapter, thus showing kids that science is fun.

技术概述：聚合物电解质比目前锂电池中使用的液体电解质更安全、更清洁、更灵活。它们与锂金属电极一起使用是一种有吸引力的可能性，因为它们比液体电解质更硬。为此，peo基电解质的硬度不足以防止枝晶的形成，这限制了锂金属的使用。它们也没有足够高的电导率来实现。不幸的是，硬度和导电性呈负相关，因为锂离子的运动与聚合物的运动是耦合的，任何通过更快的聚合物运动来提高导电性的尝试都会导致硬度的降低。该项目基于隧道状聚合物/盐结构促进快速锂运动的想法，最近用单晶电解质证明了这一点。它将利用一组基于纤维素纳米晶须的高纵横比纳米填料来利用这种运动，这被认为是促进隧道结构的假设。这些填料提供可控的表面化学，功能化程度和纵横比，从而形成一个理想的模型体系。在先前工作的基础上，将特别关注共晶成分，在此基础上，金属合金的导电性和机械性能得到改善。在这种成分下，类似的金属合金在交替的片层中形成两种晶相的大尺度结构。聚合物电解质的这种结构的形成尚未被研究过。该项目将使用循环热处理技术在聚合物/盐共晶中产生类似的图案，这将使隧道状结构从填料表面进一步延伸。理想的电解质应该有填充物，因此锂离子的传导路径沿着与电极垂直的方向排列。纤维素纳米晶须可以通过磁场、电场和剪切来排列，该项目将研究这三种排列的有效性，而不会破坏从填料表面延伸出来的聚合物/盐图案。该项目将促进对表面化学和纵横比在纳米级填料与聚合物/盐体系相互作用中的作用的理解，控制聚合物共晶结构的因素，以及控制聚合物/盐混合物中填料排列的最佳方法。与目前用于手机和笔记本电脑的锂电池的液体电解质相比，聚合物电解质更安全、更清洁、更灵活。锂离子电池技术已经在汽车上得到了应用，因此它们在汽车上的应用具有很大的吸引力。聚合物电解质在这种应用中很有吸引力，因为它们允许技术进步，将每次充电的充电寿命从100英里延长到400英里。随着这些技术的进步，聚合物电解质目前还不可行，它们也无法获得足够的车辆应用的功率放电。这两项改进目前是相互排斥的：尝试延长充电寿命会降低功率，反之亦然。这个项目中的科学将解耦长寿命和高功率的目标。它是基于聚合物/锂盐混合物在无机表面附近的独特特征。它将使用非常小的填料，提供更多的表面积，并改变表面化学和填料排列，以获得最佳结果。这项工作的结果将使科学家们能够独立地提高功率和寿命，从而促进锂离子电池替代能源技术的进步。美国在科学研究方面处于世界领先地位，但却难以填补科学、技术、工程和数学领域的空缺。联合创新工学院是一个全国性组织，旨在通过以有趣的方式向处于决定自己喜欢什么和擅长什么的关键时期的孩子们介绍STEM概念，缩小这种脱节。这个项目是专门为那些在11岁时可能已经认为自己不擅长数学和科学的学生设计的。InnoWorks是一个由学生运营的组织，教授、研究生和本科生在其中筹集资金、开发课程、筹备和运营夏令营。这个项目将启动一个宾夕法尼亚州立大学的分会，从而向孩子们展示科学是有趣的。