Recent Advances in Electrolytes for Potassium‐Ion Batteries

Abstract

Potassium-ion batteries (KIBs) are considered as the potential energy storage devices due to the abundant reserves and low cost of potassium. In the past decade, research on KIBs has generally focused on electrode materials. However, since electrolytes also play a key role in determining the cell performance, this review summarizes recent advances in KIB electrolytes and design strategies. Specifically, the review includes five parts. First, the organic liquid electrolyte is the most widely used type for KIBs. Its two major components, salts and solvents, have a huge impact on the formation of the solid electrolyte interphase and the performance of KIBs. Changes in salts/ solvents, the introduction of additives, and the concentration increase all have a positive effect on organic liquid electrolytes. Second, the design of water-in-salt electrolytes can effectively widen the narrow electrochemical stability window of aqueous electrolytes. Third, despite the appealing properties, the ionic liquid electrolytes have not been widely applied due to its high cost. Fourth, the solid-state electrolytes have drawn much attention due to high safety, and current research has been working on improving their ionic conductivity at room temperature. Lastly, perspectives are provided to support the future development of suitable electrolytes for high-performance KIBs.

2023 roadmap for potassium-ion batteries

“…By specific alterations, the performance of the electrolyte can be improved. Fluoroethylene carbonate (FEC) is one of the most widely reported and used additive in LIBs [238]. However, the introduction of FEC into EC-based electrolytes demonstrated distinctly different results for PIBs [239,240].…”

Nonfluorinated Antisolvents for Ultrastable Potassium-Ion Batteries

“…Rechargeable potassium-ion batteries (PIBs) offer exciting advantages, such as abundant potassium resources and high operating voltage, and therefore hold great promise for development. − The electrolyte is an indispensable component of a battery that guarantees its efficient cycling. − The solvent and anion coordinate and interact with the cation in the electrolyte competitive ion–dipole or ion–ion interactions. , In typical solvent-derived interfacial chemistry, the component coordinating with the cation (cation inner solvation sheath) preferentially decomposes and forms a solid–electrolyte interphase (SEI) at the anode surface. − The anion-derived, inorganic-rich SEI is an effective guarantee for stable battery operation. − Accordingly, by improving the structure of the inner solvation sheath and enhancing the interaction between anions and cations, the formation of anion-derived, inorganic-rich SEI is facilitated. , In this manner, by shifting the equilibrium of the original electrolyte and improving the interaction between anions and cations, the electrochemical performance of the battery can be enhanced.…”

Free-Standing Carbon Nanofiber Composite Networks Derived from Bacterial Cellulose and Polypyrrole for Ultrastable Potassium-Ion Batteries

“…With the emergence of energy crisis, secondary batteries have attracted the extensive attention of many researchers. As the most important battery system at present, lithium-ion batteries (LIBs) have the advantages of a high capacity, a long cycle life, and a wide application range, but the low reserves and high price limit their continuous application. − With the development of a new energy system, the research on sodium-ion batteries (NIBs) and potassium-ion batteries (KIBs) has become more and more important due to more abundance in the Earth’s crust. − KIBs have a higher reaction voltage than NIBs, improving their energy density. Meanwhile, the suitability of KIBs with graphite can also greatly improve their application potential.…”