Unlocking ion Storage Chemistry in Aqueous Batteries via Operando Smartphone Multispectral Techniques

Abstract Real‐time monitoring of the dynamic charging process and state‐of‐charge inside energy storage systems is crucial for ensuring their sustainable operation. Here, a novel computational multispectral imaging reconstruction (MSIRC) strategy is presented using a smartphone for in situ monitoring of the optical states of aqueous batteries via transparent monitoring window, allowing analysis of ion storage chemistry and real‐time capacity variations. Prussian blue and MnO 2 that exhibit significant and subtle color changes during the ion storage process are selected to validate this approach. Time‐domain reconstructed reflectance spectra are capable of selecting the proper wavelength with the largest variation in reconstructed reflectance and precisely monitor the ion storage process of these two materials. This indicates MSIRC's rapidly distinguishing capability between electrodes with unique ion storage mechanisms and great potential in recognizing new materials with unknown mechanisms. Furthermore, the MSIRC technique can perform operando monitoring for several kinds of Zn ion batteries using cathodes with different ion storage mechanisms. These imply the ability of MSIRC to detect the real‐time healthy state of batteries at the device level and judge the inside varying ion storage mechanism.