P2- and P3-KxCoO2 as an electrochemical potassium intercalation host

Abstract

P2-/P3-K _xCoO ₂ electrodes deliver a reversible capacity of 60 mA h g ⁻¹ with multiple reversible phase transitions including potassium/vacancy orderings.

Abstract

Reversible and topotactic potassium intercalation of P2- and P3-K _xCoO ₂ electrodes is studied in non-aqueous K cells for the first time. They deliver a highly reversible capacity of 60 mA h g ⁻¹ in the voltage range 2.0–3.9 V accompanied by reversible phase transitions including potassium/vacancy orderings. The electrochemical properties and structural change of P2-K _xCoO ₂ are compared to those of O2-Li _xCoO ₂ and P2-Na _xCoO ₂.