Stable prismatic layer structured cathode material via Cation mixing for sodium ion battery

Recently, P2-type (prismatic site) and O2 (octahedral site)/P2-type materials like Na0.66Fe0.33Mn0.5O2 exhibit favorable capacities more than its theoretical value (173 mAh g−1). However, their low operating potential window ≤ 3 V makes them not desirable for practical applications. Among the sodium (Na) cathodes, the P2-Na-Ni-Mn-O is a significant material because of its high theoretical capacity of ≤ 250 mAh g−1 even if it undergoes severe voltage decay with capacity fade due to stacking faults upon cycling above the cut-off voltage (≥ 4.2 V). En route to evade this problem, we substitute zinc (Zn) cation into the P2-Na-Ni-Mn-O system as structure stabilizer, and this material delivers high initial discharge capacity of 205 mAh g−1 while cycling in the range 1.5 to 4.5 V. The X-ray diffraction pattern, energy dispersive spectroscopy (EDS) with mapping, and XPS results show that Zn2+ befit in to the P2-layer structure of Na-Ni-Mn-O2 without changing its origin.