The formation of a stable solid electrolyte interphase (SEI) is a prerogative for functional lithium metal batteries. Herein, the formation and evolution of such SEI in contact with glyme‐based electrolytes is investigated under open circuit voltage and several constant current cycles. An important conclusion of the study is that LixSy species are nonbeneficial SEI components, compared to the Li3N counterpart. In addition, chemical (X‐ray photoelectron spectroscopy, XPS) and electrochemical (impedance spectroscopy) evolution of SEI under galvanostatic conditions are comprehensively tracked.
In the presented study, a sulfur infiltrated ultra-microporous carbon aerogel as a composite cathode for lithium sulfur batteries is developed and investigated.
A stable solid‐electrolyte interphase (SEI) is of crucial essence for realization of lithium (Li) metal batteries. This article provides an overview of attempts undertaken to understand the nature of the natural SEI, including growth behavior at the open circuit potential and under cycling conditions as well as underlying causes of instabilities. Additionally, the influence of features such as morphology and composition of the SEI and electrolyte properties on the charge transport and transfer mechanism, resulting in distinct growth behavior and overall stability, is elaborated. Finally, it will be discussed how already at the fundamental stage of research, it is crucial to take into account the implications that progressing from coin‐cell level to more realistic cell and cycling conditions has on SEI properties and stability.
For lithium-sulfur batteries, porous carbon/sulfur composite cathodes are the primary solution to compensate the non-conductive nature of sulfur. The composition and structure of this class of cathodes are crucial to the electrochemical performance, achieved energy density and the stability of the cell. Electrochemical impedance spectroscopy is employed to investigate and correlate the electrochemical performance of lithium-sulfur batteries to the composition and microstructure of differently fabricated carbon/sulfur composite cathodes. A transmission line model is applied to identify different underlying electrochemical processes appearing in the impedance response of a range of porous carbon/sulfur cathodes. The integration of a lithium ring serving as a counter electrode coupled with advanced wiring has allowed an artifact-free recording of the cathode impedance at different states of charge with the aim to investigate the evolution of impedance during discharge/charge and the kinetics of charge transfer depending on the infiltration method and the utilized carbon host. It is shown that impedance response of this class of cathodes is highly diverse and the plausible underlying processes are discussed in details. To this end, quasi-solid-state and various polysulfide-based charge transfer mechanisms are identified and their time constants are reported.
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