Mechanistic Elucidation of Thermal Runaway in Potassium-Ion Batteries

太阳能和风能等可再生能源的使用增加，导致对研究高效和廉价的能源储存技术的需求日益增加。由于风能和太阳能的间歇性，静态储能是电网缓冲的一个要求，以在低生产时间提供电力，例如在太阳能夜间或风平静时。虽然锂离子电池在能量密度和市场份额方面仍然是主要的可充电电池技术，但锂的稀缺性使其过于昂贵，无法用于固定规模的电网存储。钾离子电池最近作为可持续的、国内可用的替代品受到越来越多的关注，因为它具有更高的工作电压和石墨阳极的前景。虽然许多有前途的电极材料已经研究了这个系统，实际的工程考虑，如电池的安全性和温度依赖性的性能仍然没有探索。该项目将提供石墨阳极和电解质界面中发生的化学反应机制和运输的基础知识，这些知识与理解电池性能的安全考虑因素有关，以避免热失控。电化学教育是该项目的另一个主要目标。PI开发了适合大学预科学生的创新实验套件，用于传达电池和电化学反应中的关键概念的实验和测试。该项目的技术目标是提高对钾离子（K离子，K+）电池化学的基本理解，以评估温度对电池安全性和性能的影响。虽然K+嵌入石墨的机制已经通过实验和计算研究进行了研究，但这种化学反应迄今为止仅在室温下进行了研究。PI将在较高温度下研究这些K离子电池，以了解可能导致热失控的电极-电解质界面反应的能量学和动力学。本论文的主要研究内容包括：（1）对K离子电池进行加速量热分析，探讨其热失控行为;（2）对K离子电池碳负极固体电解质界面层进行研究和表征;（3）研究工作温度对电池电化学性能的影响（4）测试电极粘合剂和电解质，以通过操控SEI层来增强K离子电池系统的安全性和性能。热失控的机理研究将通过循环电极的ARC分析来研究，探索SEI、充电状态和电解质成分的影响。该项目还将涉及通过X射线光电子能谱法和深度分析对碳阳极的SEI层进行详细的系统表征。SEI生长和K+扩散系数的模型参数的确定，将通过温度研究，通过电化学表征方法，如电化学阻抗谱（EIS）和恒电流间歇滴定技术（GITT）进行。这些结果将加深对SEI成分与电池安全性之间的关系以及温度对电池性能的影响的理解，从而进一步了解碱金属离子电池系统。该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Increased use of renewable energy sources such as solar and wind results in a growing need for research addressing efficient and inexpensive energy storage technologies. Due to the intermittent nature of wind and solar, stationary energy storage is a requirement for grid buffering to provide electricity during low production times, such as during the night for solar or when the winds are calm. While lithium-ion batteries remain the predominant rechargeable battery technology in terms of energy density and market share, the scarcity of lithium makes it too expensive to be used for stationary scale grid storage. Potassium-ion batteries have recently seen increased interest as a sustainable, domestically available alternative, in terms of its higher operating voltage and its promise with a graphite anode. While many promising electrode materials have been researched for this system, practical engineering considerations such as battery safety and temperature dependent performance remain unexplored. This project will provide fundamental knowledge of the chemical reaction mechanisms and transport occurring in the graphite anode and the electrolyte interface that relates to the understanding of the safety considerations of the performance of the battery to avoid thermal runaways. Electrochemistry education is the other primary goal for this project. The PI has developed creative experimental kits for outreach that are appropriate for pre-college students for experiments and tests that convey key concepts in batteries and electrochemical reactions. The technical goal of this project is to improve the fundamental understanding of potassium-ion (K-ion, K+) battery chemistry to evaluate temperature effects on battery safety and performance. While the mechanism of K+ intercalation into graphite has been investigated through experimental and computational studies, this chemistry has only been studied so far at room temperature. The PIs will study these K-ion batteries at higher temperatures to understand the energetics and kinetics of reactions at the electrode-electrolyte interface that may lead to thermal runaway. Four research tasks are planned: (1) accelerating rate calorimetry (ARC) analysis of K-ion batteries to probe thermal runaway behavior; (2) investigation and characterization of K-ion battery carbon anode solid electrolyte interface (SEI) layer; (3) study the effect of operating temperature on electrochemical performance (e.g. cell ageing) and safety (e.g. K dendrite formation); and (4) test electrode binders and electrolytes, to enhance K-ion battery system safety and performance by manipulation of the SEI layer. Mechanistic studies of thermal runaway will be investigated by ARC analysis of the cycled electrodes, exploring the influence of SEI, state of charge, and electrolyte composition. This project will also involve detailed systematic characterization of the SEI layer for carbon anodes via x-ray photoelectron spectroscopy with depth profiling. Determination of model parameters for SEI growth and K+ diffusion coefficients, will be carried out by the temperature study, via electrochemical characterization methods such as electrochemical impedance spectroscopy (EIS) and galvanostatic intermittent titration technique (GITT). These results will generate deeper understanding of the relationship between SEI composition and battery safety, and the influence of temperature on cell performance, providing further insight into alkali metal-ion battery systems.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.