On-line Electrode Dissolution Monitoring during Organic Electrosynthesis: Direct Evidence of Electrode Dissolution during Kolbe Electrolysis.

Electrode dissolution was monitored in real-time during Kolbe electrolysis along with the characteristic products. The fast determination of appropriate reaction conditions in electro-organic chemistry enables the minimization of electrode degradation while keeping an eye on the optimal formation rate and distribution of products. Herein, essential parameters influencing the dissolution of the electrode material platinum in a Kolbe electrolysis were pinpointed. The formation of reaction products and soluble platinum species were monitored during potentiodynamic and potentiostatic experiments using an electroanalytical flow cell coupled to two different mass spectrometers. The approach opens new vistas in the field of electro-organic chemistry because it enables precise and quick quantification of dissolved metals during electrosynthesis, also involving electrode materials other than platinum. Furthermore, it draws attention to the vital topic of electrode stability in electro-organic synthesis, which becomes increasingly important for the implementation of green chemical processes utilizing renewable energy.

Online Monitoring of Transition-Metal Dissolution from a High-Ni-Content Cathode Material.

The dissolution of transition metals (TMs) from cathode materials and their deposition on the anode represents a serious degradation process and, with that, a shortcoming of lithium-ion batteries. It occurs particularly at high charge voltages (>4.3 V), contributing to severe capacity loss and thus impeding the increase of cell voltage as a simple measure to increase energy density. We present here for the first time the online detection of dissolved TMs from a Ni-rich layered oxide cathode material with unprecedented potential and time resolution in potentiodynamic scans. To this aid, we used the coupling of an electroanalytical flow cell (EFC) with inductively coupled plasma mass spectrometry (ICP-MS), which is demonstrated to be an ideal tool for a fast performance assessment of new cathode materials from initial cycles. The simultaneous analysis of electrochemical and dissolution data allows hitherto hidden insights into the processes' characteristics and underlying mechanisms.