Taking the Positive with the Negative

Abstract

In this issue of Joule, Haoshen Zhou, Shaohua Guo, and colleagues reveal a layered transition metal oxide cathode material that can sequentially intercalate alkali cations and anions, together contributing a capacity exceeding the traditionally defined theoretical limit by more than one third. The authors demonstrate a new concept of cationic and anionic co-(de)intercalation in P3-Na0.5Ni0.25Mn0.75O2, a sodium ion cathode material with 134 mAh g−1 theoretical capacity based on complete Na extraction, but here shown to be capable of delivering 180 mAh g−1 reversible capacity (at 20 mA g−1) through the additional intercalation of anions from the electrolyte.