In-situ monitoring of charge and discharge process in supercapacitor with a micro-cavity Mach-Zehnder interferometer and a fiber Bragg grating

Abstract

Supercapacitors are promising energy storage devices. However, efficient monitoring of charge and discharge process remains challenging. Current methods are limited by large size, high cost and complex manufacturing processes, restricting their practical application. To address this issue, a low-cost and easily fabricated micro-cavity Mach-Zehnder interferometer (MZI) combined with a Fiber Bragg grating (FBG) is proposed for real-time, in-situ monitoring of charge and discharge process in supercapacitor. The MZI sensor has a ultrahigh refractive index sensitivity of −21833 nm/RIU. In cyclic voltammetry(CV) test, a charge sensitivity of 11.49 nm/C is obtained. Furthermore, the temperature sensitivities of MZI and FBG are 1.64 nm/℃ and 0.011 nm/℃ respectively, measured in an electrolyte environment. This innovative approach enables precise and instantaneous measurement of critical parameters like capacitance and temperature throughout energy storage and release cycles. The proposed compact, flexible and low-cost fiber MZI sensor offers a highly promising solution for in-situ supercapacitor monitoring.