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.