Multi-band reflectance spectroscopy of carbonaceous lithium iron phosphate battery electrodes versus state of charge

R. Norris; K. Iyer; V. Chabot; P. Nieva; A. Yu; A. Khajepour; J. Wang

doi:10.1117/12.2040655

7 March 2014 Multi-band reflectance spectroscopy of carbonaceous lithium iron phosphate battery electrodes versus state of charge

R. Norris, K. Iyer, V. Chabot, P. Nieva, A. Yu, A. Khajepour, J. Wang

Author Affiliations +

Proceedings Volume 8982, Optical Components and Materials XI; 898214 (2014) https://doi.org/10.1117/12.2040655
Event: SPIE OPTO, 2014, San Francisco, California, United States

Abstract

This study aims to expand the body of knowledge about the optical properties of battery cathode materials. Although some studies have been conducted on the optical properties of Lithium Iron Phosphate (LiFePO₄), to the authors’ knowledge, this is the first study of its kind on electrodes extracted from commercially available LiFePO₄ batteries. The use of Vis/NIR and FTIR spectroscopy provides for a methodology to study the optical properties of LiFePO₄ and may allow for the characterization of other properties such as particle size and the proportions of _LiFePO4versus FePO₄ material. Knowledge of these properties is important for the development of a mechanism to measure the state-of charge (SOC) in lithium ion batteries. These properties are also important in a host of other applications including battery modeling and materials characterization. Cylindrical LiFePO₄ batteries (from A123 Systems Inc.) were acquired from the commercial market and charged to 10 different states between 30% and 80% of their nominal capacity using a constant-current, constant-voltage (CCCV) cycling method. Visual inspection of the extracted electrodes shows that the LiFePO_4/C-cathodes display subtle changes in color (shades of grey) with respect to SOC. Vis/NIR measurements support the visual observation of uniform intensity variations versus SOC. FTIR measurements show an absorbance signature that varies with SOC and is distinct from results found in the literature for similar LiFePO₄-based material systems, supporting the uniqueness of the absorbance fingerprint.

Citation Download Citation

R. Norris, K. Iyer, V. Chabot, P. Nieva, A. Yu, A. Khajepour, and J. Wang "Multi-band reflectance spectroscopy of carbonaceous lithium iron phosphate battery electrodes versus state of charge", Proc. SPIE 8982, Optical Components and Materials XI, 898214 (7 March 2014); https://doi.org/10.1117/12.2040655

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