Fiber Optical Detection of Lithium Plating at Graphite Anodes

Abstract

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.

Thermo-luminescent optical fibre sensor for Li-ion cell internal temperature monitoring

“…The Biot number (𝐵 𝑖 ) can be calculated to evaluate if there is a difference between the internal and external temperatures. The Biot number is defined as: ( 10 ) where ℎ is the global thermal transfer coefficient (0.5 W/m/K), 𝐿 𝑐 the characteristic length, in our case half of the cell thickness (1 mm), 𝜆 𝑏 the thermal conductivity (0.5W/m/K).…”

“…Among the different sensor technologies, optical fibre sensors have been developed [8,9] due to their fast response, their compact size, which allows their integration in multiple environments, and their immunity to electromagnetic fields. This kind of sensor has already proved its worth in monitoring the internal parameters of Li-ion cells [10][11][12][13][14][15][16][17][18][19][20][21][22].…”

Revealing How Internal Sensors in a Smart Battery Impact the Local Graphite Lithiation Mechanism

“…These systems enable real-time measurements of crucial cell parameters, such as temperature [26][27][28][29][30][31][32] , strain 28,33 , gas pressure, and chemical composition 34,35 . Correlating the evolution of these parameters with physicochemical degradation mechanisms 36 is the key to enhancing the safety and lifetime of batteries through triggering self-healing functionalities or optimizing working conditions based on advanced BMS 37,38 .…”

Novel Li‐Ion Battery Diagnostics; Detection of Redox Peaks Utilising Plasmonic Fibre Optic Sensors and Evaluation of Interference on Cell Function

“…Research and development across a variety of fibre optic based battery diagnostic techniques includes utilising tilted fibre Bragg gratings [20] and Rayleigh scattering [17] for temperature [19] and strain measurements, [21] attenuated total reflection [22] for state of charge estimation and lithium plating detection [23] and fluorescent based sensors for oxygen measurement and tracking ionic transport. [24] A 'lab on fibre' approach could also allow the utilisation of other optical techniques inside relatively unmodified cells, such as Raman spectroscopy to detect structural and compositional change [25] and colorimetry [26,27] for state of charge estimation.…”