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The development of liquid electrolytes receives significant attention within the field of battery research. New concepts are emerging, and one of these groundbreaking ideas is localized high concentration electrolytes (LHCEs). The fundamental characteristic of this type of electrolyte is related to its solvation structure. However, despite the progress made, the solvation process and its relationship towards physicochemical and electrochemical properties are not yet fully understood. A comprehensive understanding of LHCEs and their solvation structure requires further dedicated research and analysis. This concept review offers a thorough examination of the design principles governing LHCEs, elucidates methodologies for investigating solvation structures, connects these insights to interphase chemistry, and explores potential applications in future battery technology.

Accurate measurement of the heat release from a battery fire is vital for risk management, product development and construction of accurate models. Oxygen consumption calorimetry is the most common method for heat release measurements in experimental fire tests. The strength of the method is that it can be applied to unknown compositions of fuel with sufficient accuracy. Despite that this method is used to estimate heat release from battery fires, the method is subject to discussion. In this work, the method is studied in-depth, and potential errors are structured and quantified. Uncertainties associated with self-generated oxygen and internal heat generation, total gas release from the battery and impact on the heat release calculations, as well as the assumed E-factor (i.e., heat release per unit mass of oxygen consumed), are thoroughly discussed. For a Li-ion battery fire, it is concluded that oxygen consumption calorimetry will exclude internal heat generation and underestimate the total heat released from the external flaming fire by up to 10 %. In addition, high rate of combustion reactions can result in that the measured peak heat release rate is underestimated much more, up to 100 %.

In an effort to improve safety and cycling stability of liquid electrolytes, the use of dicarbonates has been explored. In this study, four dicarbonate structures with varying end groups and spacers are investigated. The effect of these structural differences on the physical and ion transport properties is elucidated, showing that the end group has a significant influence on ion transport. The solvation structure and ion transport in the dicarbonates are compared to those of the linear carbonates dimethyl carbonate (DMC) and diethyl carbonate (DEC). Although the carbonate coordination numbers (CN) are similar in the different systems, the CN from the anion is higher in dicarbonate electrolytes. At low salt concentrations, rapid solvent exchange is observed in the DMC- and DEC-containing systems, transitioning to a more correlated ion transport at high salt concentration. In contrast, the exchange of solvents around lithium ions (Li+) is limited in the dicarbonate systems regardless of the salt concentration, with only one carbonate group from each molecule participating in the coordination. In addition, according to the molecular dynamics simulations, Li+ mainly moves together with coordinating dicarbonate molecules and anion(s).