Yuxin Zhang1,Anyang Hu1,Luxi Li2,Feng Lin1
Virginia Tech1,Argonne National Laboratory2
Yuxin Zhang1,Anyang Hu1,Luxi Li2,Feng Lin1
Virginia Tech1,Argonne National Laboratory2
The X-ray fluorescence microscopy (XFM) is a powerful technique that possesses the following advantages: (1) simultaneous detection of multiple elements with high sensitivity, favorably in the sub-ppm range; (2) sufficient spatial resolution; (3) capability of <i>in situ</i> measurements under operating conditions and (4) large-area scanning (µm to mm) to ensure statistical representativeness. It is widely applied in the biological and medical areas while receiving less attention in rechargeable batteries. Herein, using the aqueous batteries as a platform, we systematically demonstrate the application of XFM in the battery field. The ex-situ measurements can inform the degradation issues of traditional cathode materials (LiFePO<sub>4</sub>, LiMn<sub>2</sub>O<sub>4,</sub> and LiNi<sub>0.8</sub>Mn<sub>0.1</sub>Co<sub>0.1</sub>O<sub>2</sub>) in different electrolytes and quantify the dissolved transition metals (TM) during electrochemical cycling, establishing the correlation between TM dissolution and electrochemical performance. On the other hand, the in-situ experiments can unravel the spatiotemporal evolution of TM in the electrodes and electrolytes upon cycling. Therefore, we are able to use the home-designed in situ cell to directly investigate the electrode-electrolyte interfacial reactions. For example, the evolution of the diffusion layer formed by TM dissolution can be visualized under different electrochemical protocols, and the dissolution/redeposition dynamics of TM can be revealed at the single-particle resolution and electrode-scale statistical analysis. The present work shows the capabilities of XFM in the rechargeable battery field and potentially serves as a guideline for future XFM-related studies.