Multi-Method Li Plating Characterization of a Commercial 26 Ah Li-Ion Pouch-Cell

TL;DR

This study compares various electrochemical, optical, microscopic, and spectroscopic methods for detecting lithium plating on commercial Li-ion pouch cells, highlighting their effectiveness, speed, and suitability for different analysis needs.

Contribution

It provides a comprehensive classification and comparison of multiple Li plating detection techniques on commercial cells, including a round robin validation across laboratories.

Findings

Optical methods are fast and easy for Li detection.

Spectroscopic methods offer sensitive confirmation of Li plating.

Multimodal approaches enhance detection reliability.

Abstract

Lithium (Li) plating on graphite is a significant degradation mechanism in Li-ion batteries. While numerous experimental techniques have been used to study Li plating in laboratory cells, investigations of commercial high-energy cells often rely on electrochemical methods. Here we present and classify various methods for detecting Li plating on a commercial A123 pouch cell. In a round robin study across multiple battery research laboratories, Li-plated graphitic electrode material was analyzed using electrochemical, microscopic, and spectroscopic methods capable of detecting metallic Li deposits. After cell opening, their overall distribution on the anode surface was examined using a flatbed scanner to ensure comparability of the samples. Optical and electron microscopy provided detailed surface and, in combination with a focused ion beam, subsurface structure and morphology. Spectroscopic methods confirmed the presence and onset of plated Li with varying sensitivity. Moreover, spectroscopic and imaging techniques were combined correlatively where possible. Availability and measurement duration of each technique was compared. Optical methods are fast and easy to use; thus, they are recommended for most samples, with spectroscopic confirmation reserved for reference samples. This multimodal study demonstrates a range of methods that can be used alone or in combination to qualitatively or quantitatively detect Li-plating.