Real-Time In-situ Optical Analysis Technique to Detect Electrolyte Colour Change in Li-ion Pouch Cells

Authors

S. Sattar, Coventry University

Summary

The widespread adoption of lithium-ion batteries in areas such as portable electronics and the automotive industry has increased the demand for effective diagnostic tools to monitor their performance and ensure safety. The colour change of the electrolyte in lithium-ion batteries has been identified as a promising yet understudied indicator of the State of Health [1]. In addition to this, the colour-related ageing patterns in electrolytes have the potential to correlate to other failure events such as thermal degradation, parasitic reactions caused by contamination, cyclic ageing, and electrolyte degradation, which can improve battery safety standards [2]– [4]. This research discusses the design, development, and verification of a tool that can be used to provide a new source of real-time in-situ diagnostic data for Li-ion cells, potentially allowing identification of cell failure, characterization of cell ageing (for example, for second life application), further research, development and understanding of electrolyte degradation mechanisms [5], [6]. The approach developed to achieve this utilizes micro-scale photodiodes combined with an RGB LED, which will be tested inside various proportions of electrolytes to provide real-time colour shades of the aged electrolytes. The underlying notions discussed in this research can help to enable the future integration of such colour-sensing technologies into Li-ion pouch cells.