Development of a Monitoring Technique for Damages in Laminated Lithium-ion Batteries using Optical Fiber AE Sensor

Lithium-ion batteries possess high energy density and cause small memory effects. Accordingly, they are widely used in such systems as portable electronic devices and electric vehicles. However, instances of past accidents have raised concerns regarding the safety ng such batteries. To address these concerns, damage detection at an early stage is important. This study proposes use of Acoustic Emission (AE) sensors to monitor damages that occur in laminated-sheet type lithium-ion batteries. Optical are explosion proof and design sensor shape free. Characteristics of AE generation in batteries were first evaluated using sensors. The majority of AE signals were detected at battery potentials exceeding 80% across charge-discharge cycles. , compared to batteries comprising metallic cells, lithium-ion batteries demonstrated reduced AE signal generation. Moreover, batteries, AE signal generation at random intervals was observed. Compared to normal cycles of operation, twice as many AE events were observed for damaged batteries, and AE waveforms with low peak frequencies were detected. Sheet-type sensors were using optical fiber, and their sensitivities were compared against those of conventional sensors. The maximum amplitude AE signals, as detected by the sheet-type sensor, was lower compared to conventional-sensor readings. However, signal over a wide region could be performed using sheet-type sensors. Finally, proposed sheet-type sensors were employed to damage affecting lithium-ion batteries, and AE signal generation was also detected using similar wide sensors. The proposed method could, therefore, be used as a potential tool for monitoring damages caused in sheet-type lithium-ion batteries.