No abstract

Lithium−sulfur batteries are promising candidates to satisfy the growing demand for high gravimetric, as well as high volumetric energy density batteries, due to their abundant and cost‐efficient raw‐materials. Consequently, this cell system has become an active subject of academic and industrial research. Therefore, new records for gravimetric, as well as volumetric energy densities have been reported in recent years. To further increase the volumetric energy density of the cells, the electrodes are often densified. Hence, the influence of the cathode density on the performance of lithium−sulfur batteries is still not fully understood. Herein, dry‐processed (DRYtraec) sulfur carbon cathodes with varying electrode densities are tested with ether‐based electrolytes under lean electrolyte (5 μL mg(s)−1) conditions. The electrochemical evaluation reveals that the density does not influence the performance of the cathodes at coin‐cell level as their density is altered upon electrolyte contact due to swelling. To monitor this, dynamic swelling experiments via confocal microscopy are conducted. Subsequently, the findings are transferred to investigate the influence of cathode swelling on the volumetric energy density. The influence of cathode swelling on the volumetric energy density of pouch cells is calculated based on the cathodes investigated at coin‐cell level.

The user demands lithium-ion batteries in mobile applications, and electric vehicles request steady improvement in terms of capacity and cycle life. This study shows one way to compensate for capacity losses due to SEI formation during the first cycles. A fast and simple approach of electrolyte-free direct-contact pre-lithiation leads to targeted degrees of pre-lithiation for graphite electrodes. It uses tailor-made lithium thin films with 1–5 µm lithium films produced by lithium melt deposition as a lithium source. These pre-lithiated graphite electrodes show 6.5% capacity increase after the first cycles in NCM full cells. In this study, the influence of the pre-lithiation parameters—applied pressure, temperature and pressing time—on the pre-lithiation process is examined.

Lithium sulfur (Li−S) batteries represent an interesting technology due to the high theoretical capacity of sulfur and the low cost of the cathode material. Li−S cells with graphite electrodes could be an option for low‐cost stationary energy storage as graphite is cheap and the electrode production process is well established. Unfortunately, in most Li−S electrolytes, graphite is not stable due to solvent co‐intercalation and degrades fast. In this work, a new low density electrolyte based on hexyl methyl ether (HME) and 1,3‐dioxalane (DOL) is presented, which allows to use graphite as anode material for Li−S batteries. In symmetric graphite vs. graphite cells an averaged Coulombic efficiency of 99.94 % per electrode could be reached. For the first time, cycling conditions like voltage window and balancing were optimized for Li−S cells with graphite anodes and the suitability of the concept could be demonstrated in multilayer pouch cells under realistic conditions.

To increase the energy density of today’s lithium batteries, it is necessary to develop an anode with higher energy density than graphite or carbon/silicon composites. Hence, research on metallic lithium has gained a steadily increasing momentum. However, the severe safety issues and poor Coulombic efficiency of this highly reactive metal hinder its practical application in lithium-metal batteries (LMBs). Herein, the development of an artificial interphase is reported to enhance the reversibility of the lithium stripping/plating process and suppress the parasitic reactions with the liquid organic carbonate-based electrolyte. This artificial interphase is spontaneously formed by an alloying reaction-based coating, forming a stable inorganic/organic hybrid interphase. The accordingly modified lithium-metal electrodes provide substantially improved cycle life to symmetric Li||Li cells and high-energy Li||LiNi0.8Co0.1Mn0.1O2 cells. For these LMBs, 7 μm thick lithium-metal electrodes have been employed while applying a current density of 1.0 mA cm–2, thus highlighting the great potential of this tailored interphase.