Fiber Optical Detection of Lithium Plating at Graphite Anodes

• Published in: Advanced materials interfaces Vol. 10; no. 3
• Main Authors: Hedman, Jonas, Mogensen, Ronnie, Younesi, Reza, Björefors, Fredrik
• Format: Journal Article
• Language: English
• Published: Weinheim John Wiley & Sons, Inc 01.01.2023; Wiley-VCH
• Subjects: Anodes; detection; Electrodes; Evanescent waves; Fiber optic sensors; fiber optical sensor; Fiber optics; Graphite; Lithium; Lithium plating; Lithium-ion batteries; Optical measuring instruments; Optical properties; Plating
• ISSN: 2196-7350; 2196-7350
• DOI: 10.1002/admi.202201665

Avoiding the plating of metallic lithium on the graphite anode in lithium‐ion batteries, potentially leading to aging and the formation of dendrites is critical for long term and safe operation of the cells. In this contribution, in operando detection of lithium plating via a fiber optical sensor placed at the surface of a graphite electrode is demonstrated. The detection is based on the modulation of light at the sensing region, which is in direct contact with the graphite particles. This is first demonstrated by the intentional deposition of lithium on a copper electrode, followed by experiments with graphite electrodes in pouch cells where plating is initiated both as a result of over‐lithiation and excessive cycling rates. The plating resulted in a significant loss of light from the fiber, and the findings correlated well with previous experiments on the detection of sodium plating. The modulated light is also found to correlate well with the graphite staging via changes in the optical properties of the graphite during slow (de)intercalation of lithium ions. In a practical application, the fiber optical sensor may provide a battery management system (BMS) with input to optimize the charging procedure or to warn for cell failure. An optical fiber sensor is presented for the detection of lithium plating at the graphite anode in lithium‐ion batteries. The plating, for example, as a result of a too‐high charging rate, significantly modulates the intensity of the light reaching the detector. This can hence serve as a potential warning system for the growth of harmful lithium dendrites.