Energy Storage The development of efficient electrochemical energy storage systems is of prime importance for future energy management, which will be increasingly based on renewable energy sources. Aqueous rechargeable alkali-ion batteries are particularly attractive for large-scale implementations given their environmentally friendly components and low cost. However, their low-temperature performance requires improvements, which can be achieved by optimizing the electrolyte's ionic conductivity and freezing point. Using dimethyl sulfoxide as the electrolyte additive, Nian et al. develop a new practical electrochemical system with electrolyte that freezes below −130°C. As a result, the battery operates with sufficient ionic conductivity even at −50°C. The reasons for such an ultra-low freezing point are analyzed by means of spectral characterization and molecular dynamics simulation. Angew. Chem. Int. Ed. 10.1002/anie.201908913 (2019).