Electrolyte design for next-generation batteries

Electrolytes, serving as the ion transfer media, fundamentally determine key battery performance metrics including energy density, rapid charging capability, and cycle life. Consequently, the development of advanced electrolytes has attracted significant research and industrial interest. However, constructing high-performance electrolytes remains challenging due to the complex interdependencies among bulk electrolyte properties, electrode-electrolyte interfacial compatibility, interfacial stability, mechanical stresses, and performance under extreme conditions. Current commercial systems thus necessitate innovative design strategies to overcome these multifaceted constraints and achieve harmonized electrochemical, thermal, and mechanical functionalities. This review systematically analyzes design strategies of three mainstream electrolytes: solid, semi-solid, and liquid electrolytes. Additionally, the discovery of new electrolytes is facilitated by applying machine learning, artificial intelligence, and advanced in situ characterization techniques. This review also introduces special electrolytes, including delocalized electrolytes, all-in-one electrodes, and asymmetric electrolytes, and emphasizes their role in expanding the electrochemical window and achieving high-voltage applications.