High-Performance Potassium-Ion-Based Full Battery Enabled by an Ionic-Drill Strategy

Potassium-ion (K+) batteries (PIBs) show great potential in large-scale energy storage applications owing to their low-cost and high-operating voltage. However, the development of practical PIBs remains hindered by their poor performance rate due to the large ionic radius of the K+ (1.38 angstrom). Herein, we report an ionic-drill strategy using smaller lithium ions (Li+) to open diffusion channels for K+ in the host electrode and enable much faster kinetics of K-ions. To realize this goal, a K+/Li+/PF6- hybrid configuration was rationally designed, and the K-based electrolyte hybridized with 20 atom % Li showed significantly improved diffusion kinetics and discharge capacity. The optimized K+-based full battery exhibited excellent rate performance with a specific capacity of 106 mAh g(-1) at a current rate of 5 C and maintained 84.7 mAh g(-1) up to 25 C. It also showed long-term cycling stability with capacity retention similar to 100% over 500 cycles at 5 C. These results are the best known K+ full batteries. Thus, this work provides an effective strategy to enhance the electrochemical performance of PIBs for potential practical applications. [GRAPHICS] .