Long-run in-operando NMR to investigate the evolution and degradation of battery cells

TL;DR

This paper presents a new NMR-compatible battery cell design and demonstrates its effectiveness in long-term in-operando studies, revealing microstructural evolution and potential pathways for lifetime prediction and degradation mitigation.

Contribution

Development of a reliable, gas-tight cylindrical battery container with optimized coil for long-term NMR studies of batteries over hundreds of cycles.

Findings

Successful long-term NMR measurements over 2000 hours.

Observation of Li microstructure evolution, including mossy and dendritic formations.

Potential for identifying degradation mechanisms and improving battery lifespan strategies.

Abstract

Nuclear magnetic resonance (NMR) investigations of electrochemical systems require gas-tight and non-metallic cell housings. This contribution reports on the development and evaluation of a cylindrical battery container in combination with a numerically optimized saddle coil that is suitable for NMR investigations of battery cells over hundreds of charge-discharge cycles. The reliability of the new cell container design and its long-time gas-tight sealing are shown by rate capability comparisons to standard housings with LiCoO$_{2}$ (LCO) vs. Li-metal electrodes as well as a charge-discharge experiment of a LCO vs. graphite batteries over more than 2000 hours. To demonstrate the performance of the entire NMR setup, long-run in-operando measurements on a Li-metal vs. graphite cell are presented. The NMR data reveal the formation and evolution of mossy and dendritic Li microstructures over a period of 1000 h. Analyzing the measured rate of microstructure growth could help to identify dendrite mitigation strategies, such as enhanced cell pressure or additives, and could enable a method for battery lifetime prediction.