Electrochemical potassium-ion intercalation in Na_xCoO₂: a novel cathode material for potassium-ion batteries

Abstract

Reversible electrochemical potassium-ion intercalation in P2-type Na_xCoO₂ was examined for the first time. Hexagonal Na_0.84CoO₂ platelets prepared by a solution combustion synthesis technique were found to work as an efficient host for K⁺ intercalation. They deliver a high reversible capacity of 82 mA h g^-1, good rate capability and excellent cycling performance up to 50 cycles.