In-situ detection of pH and dissolved oxygen in electrolyte of aqueous zinc-ion batteries

Electrode corrosion and electrolyte decomposition in aqueous zinc-ion batteries (AZIBs) have significant impacts on their capacity, stability, and lifespan. Herein, a portable extended gate field-effect transistor (EGFET)-pH & dissolved oxygen (DO) sensor is constructed for in-situ monitoring of these adverse reactions in AZIBs. The EGFET-pH & DO sensor separates the sensitive electrodes from the detection circuitry, which gives the sensor high stability in aqueous solutions and enables its integration into pouch-type AZIBs. The high sensitivity and robustness of the sensor facilitate the real-time investigation of the variations of pH and DO concentration in the electrolyte of AZIBs at different charging voltage ranges, as well as evaluation of the effects of electrolyte additives on the battery performance. This work expands the electrochemical sensing technique for in-situ monitoring of secondary batteries, enhances the understanding of energy storage mechanisms for AZIBs, and provides reliable data support for battery optimization. Aqueous zinc-ion batteries suffer from performance-degrading side reactions. Here, authors develop an extended gate field-effect transistor to monitor the real-time changes of pH and dissolved oxygen in the electrolyte during battery operation.