Harnessing Fiber Bragg Grating Sensor Enabled Multi‐Physical Monitoring in the Pursuit of an Ideal Operating Voltage Window for Ni–Zn Batteries

Nickel-zinc (Ni-Zn) batteries have high-power densities and unrivalled potential for cost-effectiveness and sustainability. However, reliability concern quickly arises from their delicately balanced operational window, characterized by significantly different reduction and oxidation mechanisms at the electrode-electrolyte interfaces. Accurately identifying and utilizing the ideal faradaic reactions, while avoiding degradative side reactions, is key to them reaching their full market potential. Here we show that by continually monitoring the real-time strain and temperature evolution of commercial Ni-Zn batteries during cycling with fiber Bragg grating (FBG) sensors, critical insights can be gained. Utilizing systematic cycling with varying charge cutoff voltages, specifically between 1.85 V and 1.90 V, we track volumetric deformation and temperature changes at the cell level with signature indications of charge storage mechanisms. Evidence shows that while applied voltages of 1.88 V during cell charging initially appear unremarkable, repeated cycling with this voltage gives rise to nonreversible reactions. This contrasts sharply voltages of 1.875 V were found to safely avoid such mechanisms, indicative of the anticipated operational mode and cell capacity. The demonstrated monitoring strategy offers a multidimensional, scalable sensing framework for Ni-Zn batteries and next generation battery management systems and suggest potential for integration with more intelligent or AI powered prognostics.