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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.

Lithium ion batteries are generally considered to be the technology of choice for hybrid electric and full electric vehicles. However, further enhancement in the energy and power densities of lithium ion batteries is necessary to fulfill the requirements imposed by automotive applications [1, 2]. High voltage LiNi0.5Mn1.5O4 spinel (LNMO) appears to be a very promising cathode-active material in combination with state-of-the-art graphite anodes. This is due, in part, to its low cost, high theoretical specific capacity (147 mAh g–1) and high nominal operating voltage (4.7 V vs. Li/Li+). However, there are severe performance limitations that need to be overcome before commercialization can be contemplated. LNMO/Li half-cells typically show high cycling stability, even at elevated temperatures [3]. Full-cells made of LNMO cathode and graphite anode suffer from capacity fading upon cycling. In recent years, several degradation mechanisms have been identified and correlated with the overall performance. Major issues arise from electrolyte decomposition [4, 5] accompanied by formation of gaseous species [6] and manganese dissolution [7]. In this study, we focus on the in situ gas analysis of LNMO based full-cells during charge and discharge. Two different cell systems, LNMO/graphite and LNMO/LiFePO4, are investigated. In the LNMO/graphite system both electrodes contribute to the gassing processes. By using delithiated LiFePO4 as anode, gas evolution on LNMO can be studied separately, because no gaseous byproducts are formed on LiFePO4. The evolving gases were studied using an analysis setup allowing for in situ investigation by means of mass spectrometry (DEMS: differential electrochemical mass spectrometry). A visualization of forming gas bubbles and a quantitative estimation of the formed gas volume in the cell was achieved by in operando neutron imaging. Mechanistic insights into the decomposition processes were gained by correlating the cell potential to the pattern of the evolving gases. The influence of other electrochemical parameters, like constant voltage steps, charge/discharge current rate and formation processes (i.e., pre-aging of the electrodes at different temperatures), on the gassing behavior and gas composition was also investigated. These effects and their impact on the cycling stability are discussed. References: [1] J. Vetter, P. Novak, M. R. Wagner, C. Veit, K. C. Moller, J. O. Besenhard, M. Winter, M. Wohlfahrt-Mehrens, C. Vogler, A. Hammouche, Journal of Power Sources 2005, 147, 269-281. [2] M. Winter, R. J. Brodd, Chem. Rev. 2004, 104, 4245-4269. [3] B. Markovsky, Y. Talyossef, G. Salitra, D. Aurbach, H. J. Kim, S. Choi, Electrochemistry Communications 2004, 6, 821-826. [4] D. Aurbach, B. Markovsky, G. Salitra, E. Markevich, Y. Talyossef, M. Koltypin, L. Nazar, B. Ellis, D. Kovacheva, Journal of Power Sources 2007, 165, 491-499. [5] L. Yang, B. Ravdel, B. L. Lucht, Electrochemical and Solid State Letters 2010, 13, A95-A97. [6] M. Onuki, S. Kinoshita, Y. Sakata, M. Yanagidate, Y. Otake, M. Ue, M. Deguchi, Journal of the Electrochemical Society 2008, 155, A794-A797. [7] N. P. W. Pieczonka, Z. Liu, P. Lu, K. L. Olson, J. Moote, B. R. Powell, J.-H. Kim, The Journal of Physical Chemistry C 2013, 117, 15947-15957.