Beyond conventional electrolytes in potassium-based batteries: Tailoring solvation structures, interfaces and electrolyte functions

Potassium-based batteries (PBBs) are considered one of the most promising energy storage systems due to their abundant reserves and low cost. However, their development is greatly constrained by the undesirable bulk-phase solvation structure of electrolytes and electrode-electrolyte compatibility. It is significant to understand the design principles and modification strategies for potassium-based battery electrolytes. In recent years, a new generation of potassium metal/ion batteries has emerged featuring specially designed electrolytes. To achieve high-performance potassium metal/ion batteries, how to tune solvation structures and electrolyte types for both electrode interface behavior and bulk ion transport kinetics within the electrodes is crucial. In this review, we begin by discussing relatively common electrolyte modification strategies currently employed in PBBs and summarize corresponding design principles (electrolyte descriptors). Building upon this foundation, we analyze the mechanisms underlying how modified electrolytes enhance electric double layers and improve anode/cathode interfaces. Finally, electrolyte design in the aspect of molecular design, suspensions, and phase separation and future development directions are concluded.