Advanced 3D-Printed Potassium Ammonium Vanadate/rGO Aerogel Cathodes for Durable and High-Capacity Potassium-Ion Batteries.

A 3D-printed oxygen-vacancy-rich potassium ammonium vanadate/reduced graphene oxide (KNVO/rGO) microlattice aerogel is designed for the cathode in high-performance K-ion batteries (KIBs). The 3D-printed KNVO/rGO electrode with periodic submillimeter microchannels and interconnected printed filaments is composed of highly dispersed KNVO nanobelts, wrinkled graphene nanoflakes, and abundant micropores. The well-defined 3D porous microlattice structure of the rGO backbone not only provides the interconnected conductive 3D network and the required mechanical robustness but also facilitates the penetration of the liquid electrolyte into inner active sites, consequently ensuring a stable electrochemical environment for K-ion intercalation/deintercalation within the KNVO nanobelts. The 3D-printed KNVO/rGO microlattice aerogel electrode has a high discharge capacity of 109.3 mAh g with a capacity retention rate of 92.6% after 200 cycles at 50 mA g and maintains a discharge capacity of 75.8 mAh g after 2000 cycles at 500 mA g. The flexible pouch-type KIB battery consisting of the 3D-printed KNVO/rGO has good mechanical durability and retains a high specific capacity under different forms of deformation such as bending and folding. The results provide valuable insights into the integration of advanced 3D-printed electrode materials into K-ion batteries and the design of flexible and wearable energy storage devices.