Fig. 4
From: Environmentally stable interface of layered oxide cathodes for sodium-ion batteries
Diminished performance mechanism of the NM samples and protective mechanism of the NMTN samples. a Structural degradation of the NM samples subjected to attack from air (red dotted left arrow) and electrolyte (blue dotted right arrow). b 3D structural model of the NMTN samples composed of a Ti-rich spinel-like interface (green shell) and Mn-rich layered bulk (brown core). The layered bulk (brown core) is composed of P2 (left) and O′3 (right) phases. The Ti-rich spinel-like interface not only protects the bulk NMTN samples against atmospheric and electrochemical corrosion but also enhances the electrochemical properties via facile electron and ion transport
