Plum pudding model inspired KVPO4F@3DC as high-voltage and hyperstable cathode for potassium ion batteries

[Display omitted] •KVPO4F@3DC is first used as high-voltage and hyperstable cathode for potassium ion batteries.•Potassium ion storage capacity of the KVPO4F@3DC composite is intensively examined.•KVPO4F@3DC composite efficiently suppresses the harmful side reactions between electrode/electrolyte. The investigation on the cathode material of potassium ion batteries (PIBs), one of the most promising alternatives to lithium ion batteries, is of great significance. Potassium vanadium fluorophosphate (KVPO4F) with a high working voltage is an appealing cathode candidate for PIBs, while the poor cycling performance and low electronic conductivity dramatically hinder the application. Herein, a plum pudding model inspired three-dimensional amorphous carbon network modified KVPO4F composite (KVPO4F@3DC) is successfully designed in this study to tackle these problems. In the composite, KVPO4F particles are homogeneously wrapped by a layer of amorphous carbon and bridged by cross-linked large area carbon sheets. As the cathode for PIBs, the KVPO4F@3DC composite exhibits a high average operating voltage about 4.10 V with a super-high discharge capacity of 102.96 mAh g−1 at 20 mA g−1. An excellent long cycle stability with a capacity retention of 85.4% over 550 cycles at 500 mA g−1 is achieved. In addition, it maintains 83.6% of its initial capacity at 50 mA g−1 after 100 cycles at 55 °C. The design of KVPO4F@3DC with plum pudding structure provides facilitative electron conductive network and stable electrode/electrode interface for electrode, successfully innovating an ultra-stable and high-performance cathode material for potassium ion batteries.