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、廉价的储能技术的需求越来越大。由于风能和太阳能的间歇性，固定储能需要电网缓冲，以便在低产时提供电力，例如在夜间太阳能或风平浪静的时候。虽然就能量密度和市场份额而言，锂离子电池仍然是占主导地位的可充电电池技术，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。钾离子电池最近被认为是一种可持续的、国内可用的替代品，因为它的工作电压更高，而且它有希望使用石墨阳极。虽然已经为该系统研究了许多有前景的电极材料，但实际的工程考虑因素，如电池安全和温度依赖性能，仍未得到探索。本项目将提供发生在石墨负极和电解液界面中的化学反应机理和传输的基本知识，这与理解电池性能的安全考虑因素有关，以避免热失控。电化学教育是这个项目的另一个主要目标。PI已经开发出适合大学预科学生进行实验和测试的创造性实验工具包，这些实验和测试传达了电池和电化学反应的关键概念。该项目的技术目标是提高对钾离子(K-ion，K)电池化学的基本了解，以评估温度对电池安全和性能的影响。虽然已经通过实验和计算研究了K嵌入石墨的机理，但这种化学只在室温下进行了研究。PI将在更高的温度下研究这些K离子电池，以了解电极-电解液界面上可能导致热失控的反应的能量学和动力学。计划开展四项研究工作：(1)加速量热法(ARC)分析钾离子电池的热失控行为；(2)研究和表征钾离子电池碳负极固体电解液界面(SEI)层；(3)研究工作温度对电化学性能(如电池老化)和安全性(如K树枝晶形成)的影响；(4)测试电极粘结剂和电解液，通过操纵SEI层来提高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分析来进行，探索SEI、荷电状态和电解液组成的影响。该项目还将通过具有深度剖析的x射线光电子能谱，对碳阳极SEI层进行详细的系统表征。温度研究将通过电化学阻抗谱(EIS)和恒流间歇滴定技术(GITT)等电化学表征方法来确定SEI生长和K扩散系数的模型参数。这些结果将使人们更深入地了解SEI组成与电池安全之间的关系，以及温度对电池性能的影响，从而进一步深入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智力优势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.