Affiliation:
1. State Key Laboratory for Physical Chemistry of Solid Surfaces Collaborative Innovation Center of Chemistry for Energy Materials and Department of Chemistry College of Chemistry and Chemical Engineering Xiamen University 361005 Xiamen China
2. Innovation Laboratory for Sciences and Technologies of Energy Materials of Fujian Province (IKKEM) 361005 Xiamen China
3. College of Energy Xiamen University 361005 Xiamen China
4. Contemporary Amperex Technology Co., Ltd. 352100 Ningde China
5. School of Engineering Westlake University 310024 Hangzhou China
Abstract
AbstractThe aging of lithium‐ion batteries (LIBs) typically accompanies the degradation of electrolyte, but the relationship between them remains unclear. Therefore, quantifying residual electrolyte in batteries at different states of health (SOH) is a crucial issue. Here, we have developed a comprehensive characterization method to quantitatively analyze the electrolyte salts, solvents, and additives in commercial pouch cell, achieving quantification of all electrolyte compositions with high accuracy. Compared to the reported external standard method used in gas chromatography‐mass spectrometry (GC‐MS), we developed an internal standard method, which offers higher accuracy and reliability, with the maximum error decreased from 9.54 % to 3.48 %. Moreover, the quantitative accuracy of the calibration curves remains unchanged after 2 months. Multi‐instruments analysis is also utilized for the extraction and quantitative analysis of electrolyte in practical battery systems, achieving less than 5 % quantification error for all compositions. With our proposed method, it becomes possible to determine the absolute amounts of all electrolyte compositions, rather than obtaining limited information such as concentration or relative content. It is believed that this protocol of quantifying electrolyte compositions in commercial cells could serve as a baseline for further studies to reveal the relationship between electrolyte degradation and battery aging.