Reinforcing the Stability of Cobalt-free Lithium-rich Layered Oxides via Li-poor Ni-rich Surface Transformation

We report a lithium-rich layered oxide Li 1.2 Mn 0.6 Ni 0.2 O 2 (LMNO) with an electrochemically stable Li-poor nickel-rich surface by simple excessive calcination treatment, greatly suppressing the surface side reactions and Mn-ion dissolution.