Monitoring the Strain Evolution of Lithium‐Ion Battery Electrodes using an Optical Fiber Bragg Grating Sensor

Abstract

More advanced characterization and developmental tools are essential to improve the performance and safety of Li‐ion batteries. Conventional tools have been limited to customized test cell configurations that require special facilities and expensive equipment. As a practical solution for the in situ monitoring of realistic battery cells, we have embedded fiber optic sensors within Li‐ion battery pouch cells to monitor the internal electrode strain and temperature during cycling. Here we report the direct monitoring of strain evolution using implanted fiber‐optic sensors within the individual electrodes in a Li‐ion battery. Reproducible peak shifting and splitting in the implanted fiber optic sensor originate from the accumulated longitudinal and transverse strains associated with the expansion or contraction of the anode electrode. These discoveries demonstrate the feasibility and utility of fiber Bragg grating (FBG) sensors to be used as diagnostic tools in the development of new battery materials and structures.

In Situ Stress Measurement Techniques on Li-ion Battery Electrodes: A Review

“…The shift in the Bragg peak wavelength worked as a function of SOC [45]. More noticeable wavelength shifting in both attached and implanted FBG sensors was observed at the end of the Energies 2017, 10, 591 9 of 19 SOC steps; this phenomenon corresponded to the larger volume change in graphite material when Li-ions were completely intercalated or de-intercalated.…”

“…The shift in the Bragg peak wavelength worked as a function of SOC [45]. More noticeable wavelength shifting in both attached and implanted FBG sensors was observed at the end of the Measurement of the stress evolution of Li-ion battery electrodes has been performed on Li-ion batteries using FBG sensors.…”

“…More noticeable wavelength shifting in both attached and implanted FBG sensors was observed at the end of the Measurement of the stress evolution of Li-ion battery electrodes has been performed on Li-ion batteries using FBG sensors. Bae et al [45] made an FBG sensor attached or built into the graphite anode of a lithium cobalt oxide Li-ion cell to directly detect dimensional changes as shown in Figure 4b. Peak shifting or splitting at the Bragg wavelength was observed with the FBG sensors attached to or implanted within the battery anode at the fully charged state (100% SOC).…”

Hybrid Thermo‐Electrochemical In Situ Instrumentation for Lithium‐Ion Energy Storage

“…Lithium‐ion cells are seeing increased utilisation in portable electronics, electric vehicles and grid storage . This is due to a number of advantages over alternative technologies, such as high energy and power density, low self‐discharge, high output voltage and limited memory effects . However, the market expectations and consumer demands go further requiring better performance.…”

Development of a Polymeric Arrayed Waveguide Grating Interrogator for Fast and Precise Lithium-Ion Battery Status Monitoring

“…Additionally, due to the small fiber diameter of 125 µm, FBG sensors can be integrated in many areas that are usually inaccessible for electric sensors e.g., in a battery system consisting of many densely stacked cells. FBG, applied as external strain sensors for monitoring lithium-ion cells with a flexible casing (also referred to as pouch cells), have been demonstrated several times already [25][26][27]. This observable strain variation during operation is of great interest for an improved state estimation because none of the aforementioned methods used in practice are capable of delivering information about the mechanical behavior of the cells, e.g., swelling due to aging effects.…”