Solid/electrolyte and cathode/electrolyte interphases in rechargeable ion batteries: Challenges and perspectives

As the world embraces the revolution of electrification and the portability of various devices like electric vehicles, smart electric power grids, and intelligent electronic devices, the need for rechargeable batteries with exceptional energy density, extended cycle life, and utmost operational safety has skyrocketed. The electrodeelectrolyte contact is an important aspect that enables rechargeable ion batteries (RIBs) to function reversibly. While believe that the solid-electrolyte interphase (SEI) controls the cycle life, capacity, and overall safety of batteries, it is known to lower the battery capacity due to the consumption of active ions. However, the cathodeelectrolyte interaction is still largely unexplored. Unlike SEI, little is known about how cathode-electrolyte interphase (CEI) is formed and how it affects battery performance. A typical CEI is considered to be a heterogeneous multicomponent film formed on the cathode surface as a result of electrolyte decomposition. Developing a CEI for high-voltage cathode electrodes is crucial to separating the electrolytes from the active cathode materials and preventing side reactions. In addition to comprehending the thermodynamic characteristics and associated synthetic processes, one of the primary obstacles is establishing and maintaining the CEI layer because of its intricate structure. The utilization of electrolyte additives and cathode heteroatomic doping, among other extensive research efforts aimed at engineering a stable CEI, are discussed. Thus, to improve battery performance, a thorough understanding of SEI performance and CEI formation mechanism is necessary. This review aims to provide a comprehensive insight of recent advancements in the scientific concepts underlying the formation of SEI and CEI. Finally, we delve into the latest developments and future research directions related to SEI/CEI in RIBs.