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Lithium (Li) metal holds great potential for pushing practical energy densities beyond state-of the art Li-ion batteries. However, parasitic problems including Li dendrite formation can result in separator piercing, subsequent short-circuit and ultimately thermal runaway. Here we propose an innovative interlayer strategy that is guided by continuum simulations in 1D and 3D, which shows that materials with low Li nucleation overpotentials and high surface areas can enable spatially controlled plating of Li. This insight inspires an interlayer consisting of highly lithiophilic germanium nanowires (Ge NWs) coated on one side of a carbon cloth (CC). This anode geometry effectively unlocks Li infilling by a "bottom-up" motif during stripping/plating cycles. As a result, dendrite formation is eliminated, with the GeCC interlayer acting as a controlling Li reservoir during stripping/plating cycles. Ultra-stable symmetric cell performance up to 2500 h was achieved, with low overpotentials at high current density (2 mA cm−2) and plating capacity (2 mA h cm−2). Furthermore, aggressive higher current density (4 mA cm−2) and plating capacity (4 mA h cm−2) conditions were enabled by this approach. The high performing GeCC interlayer modified Li metal anodes were tested with LiFePO4 and NMC cathodes, facilitating greatly enhanced cyclic stability compared to control cells. [ABSTRACT FROM AUTHOR]

Rechargeable magnesium (Mg) batteries are promising candidates for the next generation of energy storage systems due to their potential high-energy density, intrinsic safety features and cost-effectiveness. Among the various electrochemical couples, the combination of an Mg anode with a sulfur (S) cathode stands out as an attractive option, as it offers a remarkable theoretical volumetric energy density exceeding 3,200 Wh L–1 . However, owing to the unique properties of Mg-ion electrolytes, Mg polysulfides and the surface passivation of Mg metal anodes, the development of Mg–S batteries is facing multiple challenges. In this review, recent advancements in designing efficient electrolytes for Mg–S battery systems are summarized. Apart from electrolytes, we also discuss the progress made in fabricating new S cathode composites, Mg anodes and functional separators, focusing on their roles in addressing the critical issues of the Mg–S systems. Finally, it is worth pointing out that the collaborative research combining experimental investigations and theoretical modelling could provide deeper insights into the mechanisms of Mg–S battery systems and promote their development. Overall, the comprehensive insights about the S-redox reaction, polysulfide shuttle problems and degradation mechanism in Mg–S batteries are discussed, which is of profound importance for creating solutions to enhance the overall performance of Mg–S batteries. This review aims to providing an overview of the current state of the research to stimulate innovative thoughts on the fundamental guidelines for facilitating development of Mg–S batteries. [ABSTRACT FROM AUTHOR]

A good understanding of the limiting processes in rechargeable magnesium batteries is key to develop novel high‐capacity/high‐voltage cathode materials. Thereby, the performance of magnesium‐ion batteries can strongly depend on the morphology of the intercalation cathode. Moreover, high mass loadings are essential for commercialization. In this work the influence of different mass loadings are studied in addition to the impact of the particle size distribution of the active material. Therefore, a detailed continuum model is developed, which is able to describe the complex intercalation of magnesium into a Chevrel phase (CP) cathode. The model considers the thermodynamics, kinetics and interplay of the two energetically different intercalation sites of Mo6S8, which results from its unique crystal structure, as well as the impact of the desolvation on the electrochemical reactions and possible ion agglomeration. Ideal combinations of mass loading and electrolyte concentration as well as the desired CP particle size are determined for the state‐of‐the‐art magnesium tetrakis(hexafluoroisopropyloxy)borate Mg[B(hfip)4]2 electrolyte. [ABSTRACT FROM AUTHOR]

The performance of rechargeable magnesium batteries is strongly dependent on the choice of electrolyte. The desolvation of multivalent cations usually goes along with high energy barriers, which can have a crucial impact on the plating reaction. This can lead to significantly higher overpotentials for magnesium deposition compared to magnesium dissolution. In this work we combine experimental measurements with DFT calculations and continuum modelling to analyze Mg deposition in various solvents. Jointly, these methods provide a better understanding of the electrode reactions and especially the magnesium deposition mechanism. Thereby, a kinetic model for electrochemical reactions at metal electrodes is developed, which explicitly couples desolvation to electron transfer and, furthermore, qualitatively takes into account effects of the electrochemical double layer. The influence of different solvents on the battery performance is studied for the state‐of‐the‐art magnesium tetrakis(hexafluoroisopropyloxy)borate electrolyte salt. It becomes apparent that not necessarily a whole solvent molecule must be stripped from the solvated magnesium cation before the first reduction step can take place. For Mg reduction it seems to be sufficient to have one coordination site available, so that the magnesium cation is able to get closer to the electrode surface. Thereby, the initial desolvation of the magnesium cation determines the deposition reaction for mono‐, tri‐ and tetraglyme, whereas the influence of the desolvation on the plating reaction is minor for diglyme and tetrahydrofuran. Overall, we can give a clear recommendation for diglyme to be applied as solvent in magnesium electrolytes. [ABSTRACT FROM AUTHOR]

The choice of electrolyte has a crucial influence on the performance of rechargeable magnesium batteries. In multivalent electrolytes an agglomeration of ions to pairs or bigger clusters may affect the transport in the electrolyte and the reaction at the electrodes. In this work the formation of clusters is included in a general model for magnesium batteries. In this model, the effect of cluster formation on transport, thermodynamics and kinetics is consistently taken into account. The model is used to analyze the effect of ion clustering in magnesium tetrakis(hexafluoroisopropyloxy)borate in dimethoxyethane as electrolyte. It becomes apparent that ion agglomeration is able to explain experimentally observed phenomena at high salt concentrations. [ABSTRACT FROM AUTHOR]