Beyond divalent copper: A redox couple for sodium ion battery cathode materials

Abstract

A P2-layered oxide using copper as the active redox metal has been discovered. It has a composition of Na 2/3 Cu 1/3 Mn 2/3 O 2, and can withstand a thousand cycles, maintaining 61% of its original capacity.We demonstrate that copper can enable not only high voltage, but also excellent stability. This work opens up a new avenue of oxide design for high energy, cost effective battery systems.