Monitoring internal stress variation of solid-state batteries by fiber Bragg grating

Fiber Bragg grating is utilized as an in situ stress sensor for two representative categories of solid-state electrodes. In the active material-only micron-Si electrode, a large stress variation of 63.9 MPa was detected due to the substantial volume change of Si. In addition, a staged stress change was recorded by FBG in the S composite solid-state electrode, which was undetectable by the load cell, indicating the necessity of the embedded stress sensor.