CAREER: Unveil the Electrical Double Layer Structure in Battery Electrolyte Systems

能源储存对国家的经济、安全和减缓气候变化的承诺来说是一项关键技术。随着大多数行业广泛需求的扩大，从大规模电网存储到电动汽车和消费电子产品，这一点变得越来越重要。虽然锂离子电池(LIB)的创新已经彻底改变了人们的日常生活，但由于电池技术的基本面缺乏突破，该行业遇到了跟上客户日益增长的需求的主要障碍。电双层(EDL)是电极/电解液界面的界面层。它控制着电子转移、离子迁移和溶剂分子的吸附/脱附过程。在电池应用中，EDL显著影响可循环性、电功率、容量保持和安全性等性能。然而，对电池电解液中EDL的基础知识仍然缺乏。本项目旨在揭示LiB电解液体系中EDL的性质和结构，确定这些性质对电池性能的影响，从而指导更安全、更高效、更强大和可靠的电池系统的开发。此外，该项目将作为一个教育载体，1)建立一个强大和可持续的管道，为学术界和工业界提供高质量的电池专家；2)为不同背景的学生和学者创造一个包容和公平的电池研究和教育环境。这个职业项目的目标是开发一个新的现场表征平台，直接探索EDL在典型LiB电解液(高浓度和非水)中潜在的依赖性质和结构。本工作的目的是1)利用静态汞电极的毛细作用表征电致发光性能，2)用变角衰减全反射傅立叶变换红外光谱(ATR-FTIR)来解析电致发光结构，3)将电致发光性能与电池电解液的电化学行为联系起来。这个界面表征平台将能够表征LiB电解质的一系列界面和EDL性质，包括界面自由能、表面过剩离子、零电荷电位(PZC)、表面电荷密度和双电层电容。本课题的研究成果将加速电解液的优化设计，为电极的界面修饰提供新的思路，提高固/液界面的基础知识。该项目中开发的表征方法在LiB电解液以外的更多电池电解液系统中具有变革性。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。

Energy storage is a key technology to the Nation’s economy, safety, and commitment to mitigate climate change. It has been increasingly important with the expanded widespread demand among most industries, spanning from large-scale electrical grid storage to electric vehicles and consumer electronics. While the innovation of lithium-ion batteries (LIB) has revolutionized daily life, the industry is hitting a major obstacle to keep pace with increasing demand of customers due to the lack of breakthrough in fundamentals of battery technology. The electrical double layer (EDL) is the interfacial layer at the electrode/electrolyte boundary. It governs the electron transfer, ion migration, and solvent molecular adsorption/desorption processes. In battery applications, EDL significantly impacts performance like cyclability, power rate, capacity retention, and safety. However, the fundamental knowledge of EDL in battery electrolytes is still lacking. This project aims to unveil the properties and structures of the EDL in LIB electrolyte systems, determine how these properties impact battery performance, and thus guide the development of safer, more efficient, powerful, and reliable battery systems. Moreover, this program will serve as an education vehicle to 1) build a strong and sustainable pipeline that supplies high quality battery experts to academia and industry and 2) create an inclusive and equitable battery research and education environment for students and scholars with diverse backgrounds.The goal of this CAREER project is to develop a novel in-situ characterization platform to directly probe the potential dependent properties and structure of EDL in typical LIB electrolytes (high concentration and nonaqueous). The objective of this work is to 1) characterize EDL properties by electrocapillarity with static mercury electrode, 2) resolve the EDL structure by varied angle Attenuated Total Reflection-Fourier Transform infrared (ATR-FTIR), and 3) bridge the EDL properties to electrochemical behavior of battery electrolytes. This interfacial characterization platform will enable the characterization of a series of interfacial and EDL properties in LIB electrolytes, including interfacial free energy, surface excess of ions, Potential of Zero Charge (PZC), surface charge density, and double layer capacitance. The knowledge derived from this project will accelerate the design optimization of electrolyte, shed light on interfacial modification of electrode, and advance the fundamental knowledge of solid/liquid interface. The characterization approaches developed in this project are transformative in more battery electrolyte systems beyond LIB electrolytes.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.