Engineering principles for sustainable organic electrode materials

锂离子电池已成为推动现代电子技术进步的主要电化学能量存储系统之一。然而，传统锂离子电池的生产依赖于有限且不可持续来源的过渡金属，如锂和钴，这将不可避免地限制其长期应用。在这个研究项目中，研究人员试图开发新的有机电极材料作为电池中的替代储能介质。这些新型电池材料由碳、氮、氧和硫等丰富的元素组成，可以为可再生能源存储提供更经济、更可持续的途径。这些研究活动与研究生和本科生的培训相结合，以解决电化学，合成化学和机器学习界面的科学挑战。教育目标包括为本科生普通化学课程开发实验室练习，该课程将向学生介绍电化学和环境水质测试之间的联系，并为这些学生提供指导计划，将他们与同行导师联系起来。有机电极材料（OEM）是不可持续来源的过渡金属作为锂离子电池储能介质的有前途的替代品。然而，目前的OEM（主要是氧化还原有机聚合物）遭受（a）差的导电性（需要30%的碳负载），（B）差的循环稳定性（约20%），（b）差的循环稳定性（约20%），（c）差的循环稳定性（约20%），（d）差的循环稳定性（约20%），（e）差的循环稳定性（约20%），（f）差的循环稳定性（约20%），（e）差的循环稳定性（约20%），（f）差的循环稳定性（约20%），（f）差的循环稳定性（约20%），（f）差的循环稳定性（约20%），（f）差的循环稳定性（约20%），（g）差的循环稳定性（约20%），（f）差的循环稳定性（约20%），（g）差的循环稳定性（约2 100个周期），和（c）倾斜/多级电压分布。该研究项目的总体目标是发现，阐明和应用工程原理，以提高原始设备制造商的可充电性。首先，制备了一系列具有强分子间相互作用的新型小分子OEM。原位和非原位光谱研究进行了解电荷存储单元之间的分子间相互作用如何改变作为一个功能的状态的电荷。这些任务将探索互补氢键和π-π堆积改善醌稠合氮杂吩嗪OEM材料的稳定性的假设。据预测，富硫噻唑电荷储存单元之间的额外分子间二硫键可以提高导电性并促进OEM的高速率循环。这些结果和新的基本认识将用于开发新的设计原则，通过修改分子结构来优化OEM的电导率，稳定性和电压分布。在提案的第二部分，该研究项目旨在开发基于机器学习的模型，该模型可以（a）使用从短期高通量测试中收集的数据预测OEM的长期循环寿命，以及（B）基于物理有机描述符推荐新的高度稳定的OEM。这项系统的研究将最终揭示非直观的设计原则，使更多的重点研究工作，而不是广泛的试错筛选。这一奖项反映了NSF的法定使命，并已被认为是值得通过评估使用基金会的智力价值和更广泛的影响审查标准的支持。

Lithium-ion batteries have become one of the leading electrochemical energy storage systems driving the progress of modern electronic technologies. However, the production of conventional lithium-ion batteries relies on finite and unsustainably sourced transition metals, such as lithium and cobalt, which will inevitably restrict their application in the long term. In this research project, the investigators seek to develop new organic electrode materials as alternative energy storage media in batteries. These new battery materials are made of abundant elements, such as carbon, nitrogen, oxygen, and sulfur, and can provide a more economical and sustainable route to renewable energy storage. These research activities are integrated with the training of graduate and undergraduate students in addressing scientific challenges at the interface of electrochemistry, synthetic chemistry, and machine learning. The educational aims include developing a laboratory exercise for an undergraduate general chemistry course that will introduce students to connections between electrochemistry and environmental water quality testing and a mentoring program for these students which connects them with peer tutors. Organic electrode materials (OEM) are promising alternatives to unsustainably sourced transition metals as energy storage media in lithium-ion batteries. Current OEMs (primarily redox organic polymers), however, suffer from (a) poor conductivity (30% carbon loading required), (b) poor cycling stability (ca. 100 cycles), and (c) sloping/multiple-stage voltage profiles. The overall goal of the research project is to discover, elucidate, and apply engineering principles to improve the rechargeability of OEMs. First, a wide array of novel small-molecule OEMs featuring strong intermolecular interactions are prepared. In-situ and ex-situ spectroscopic studies are performed to understand how the intermolecular interactions between charge storage units change as a function of state-of-charge. These tasks will explore the hypotheses that complementary hydrogen bonding and pi-pi stacking improve the stability of quinone-fused aza-phenazine OEM materials. It is predicted that additional intermolecular disulfide bonds between sulfur-rich thiazyl charge storage units can improve conductivity and facilitate high-rate cycling of OEMs. These results and new fundamental understanding will be used to develop new design principles for optimizing the conductivity, stability, voltage profile of OEMs through modification of molecular structure. In the second part of the proposal, the research project seeks to develop machine learning-based models that can (a) predict the long-term cycling life of OEMs using data collected from short-term high-throughput tests and (b) recommend new highly stable OEMs based on physical organic descriptors. This systematic study will ultimately reveal unintuitive design principles that enable more focused research efforts in place of extensive trial-and-error screening.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.