Li-substituted P2-Na0.66Li Mn0.5Ti0.5O2 as an advanced cathode material and new “bi-functional” electrode for symmetric sodium-ion batteries

In this study, we have introduced the layered materials P2-Na0.66LixMn0.5Ti0.5O2 as cathode materials for sodium ion batteries (SIBs), and then P2-Na0.66LixMn0.5Ti0.5O2 was employed as bi-functional electrode in SIBs. The structural stability and electrochemical properties of P2-Na0.66LixMn0.5Ti0.5O2 were promoted by inserting lithium. The Na0.66Li0.2Mn0.5Ti0.5O2 as a cathode material can exhibit a reversible discharge capacity of 128 mA h g−1 at 0.1C after 100 cycles, and even deliver 72 mA h g−1 at 5C. Interestingly, the P2-Na0.66Li0.2Mn0.5Ti0.5O2 is studied as a “bi-functional” active material for symmetric sodium-ion batteries. This novel symmetric full cell exhibits 65 mA h g−1 at a current density of 20 mA g−1.