A long lifespan potassium-ion full battery based on KVPO4F cathode and VPO4 anode

Abstract K-ion batteries are promising alternatives to Li-ion batteries for large-scale energy storage, owing to the abundance of potassium resources and low cost of raw materials. The search and improvement for electrode materials are critical to obtain high safety and high efficiency potassium-ion full batteries. Here we synthesize a well-constructed KVPO4F with primary particles embedded in carbon framework. The as-obtained KVPO4F manifests a high capacity of 103 mAh g−1 (at 20 mA g−1), stable cycle life to 900 cycles (at 1 A g−1) and excellent high-rate capacity of 87.6 mAh g−1 at 5 A g−1. For the first time, we assemble K-ion full batteries based on KVPO4F/VPO4 with a high capacity of 101 mAh g−1 (controlled by cathode), high operating voltage of 3.1 V, and a capacity retention of 86.8% over 2000 cycles.