Rechargeable potassium batteries, including the potassium–oxygen (K–O2) battery, are deemed as promising low-cost energy storage solutions. Nevertheless, the chemical stability of the K metal anode remains problematic and hinders their development. In the K–O2 battery, the electrolyte and dissolved oxygen tend to be reduced on the K metal anode, which consumes the active material continuously. Herein, an artificial protective layer is engineered on the K metal anode via a one-step method to mitigate side reactions induced by the solvent and reactive oxygen species. The chemical reaction between K and SbF3 leads to an inorganic composite layer that consists of KF, Sb, and KSb x F y on the surface. This in situ synthesized layer effectively prevents K anode corrosion while maintaining good K+ ionic conductivity in K–O2 batteries. Protection from O2 and moisture also ensures battery safety. Improved anode life span and cycling performance (>30 days) are further demonstrated. This work introduces a novel strategy to stabilize the K anode for rechargeable potassium metal batteries.

In the past 20 years, research in metal−O 2 batteries has been one of the most exciting interdisciplinary fields of electrochemistry, energy storage, materials chemistry, and surface science. The mechanisms of oxygen reduction and evolution play a key role in understanding and controlling these batteries. With intensive efforts from many prominent research groups, it becomes clear that the instability of superoxide in the presence of Li ions (Li + ) and Na ions (Na + ) is the fundamental root cause for the poor stability, reversibility, and energy efficiency in aprotic Li−O 2 and Na−O 2 batteries. Stabilizing superoxide with large K ions (K + ) provides a simple but elegant solution. Superoxide-based K−O 2 batteries, invented in 2013, adopt the one-electron redox process of O 2 /potassium superoxide (KO 2 ). Despite being the youngest metal−O 2 technology, K−O 2 is the most promising rechargeable metal−air battery with the combined advantages of low costs, high energy efficiencies, abundant elements, and good energy densities. However, the development of the K−O 2 battery has been overshadowed by Li−O 2 and Na−O 2 batteries because one might think K−O 2 is just an analogous extension. Moreover, due to the lower specific energy and the high reactivity of K metal, K− O 2 is often underestimated and deemed unsuitable for practical applications. The objective of this Perspective is to highlight the unique advantages of K−O 2 chemistry and to clarify the misconceptions prompted by the name "superoxide" and the judgment bias based on the claimed theoretical specific energies. We will also discuss the current challenges and our perspectives on how to overcome them.

The development of high-performance organic electrodes for potassium-ion batteries (KIBs) is attracting interest due to their sustainability and low costs. However, the electrolyte systems and moieties that generally proved to be successful in high-performance Li-ion batteries have found relatively little success in KIBs. Herein, two alkynyl-based covalent organic frameworks (COFs) containing 1,3,5-tris(arylethynyl)benzene (TAEB) and dehydrobenzoannulene (DBA) units are utilized as bulk anode materials for KIBs in a localized high-concentration electrolyte. TAEB-COF provides a high capacity value of 254.0 mAh g −1 at ∼100% efficiency after 300 cycles, and DBA-COF 3 provides a capacity of 76.3 mAh g −1 with 98.7% efficiency after 300 cycles. DFT calculations suggest that the alkynyl units of TAEB-COF facilitate the binding of Kions through both enthalpic and geometric driving forces, leading to high reversible capacities.

A redox-active dehydrobenzoannulene (DBA) monomer was used to construct an efficient porous polymer-based anode material for lithium ion batteries (LIBs).