Constructing a Protective Pillaring Layer by Incorporating Gradient Mn4+ to Stabilize the Surface/Interfacial Structure of LiNi0.815Co0.15Al0.035O2 Cathode

Nickel-rich layered oxides are regarded as very promising materials as cathodes for lithium-ion batteries because of their environmental benignancy, low cost, and high energy density. However, insufficient cycle performance and poor thermotic characteristics induced by structural degradation at high potentials and elevated temperatures pose challenging hurdles for nickel-rich cathodes. Here, a protective pillaring layer, in which partial Ni 2+ ions occupy Li slabs induced by gradient Mn 4+, is integrated into the primary particle of LiNi 0.815 Co 0.15 Al 0.035 O 2 to stabilize the surface/interfacial structure. With the stable outer surface provided by the enriched Mn 4+ gradient concentration and the pillar effect of the NiO-like phase, Mn-incorporated quaternary cathodes show enhanced structural stability and improved Li + diffusion as well as lithium-storage properties. Compared with the severe capacity fade of a pure layered structure, the cathode with gradient Mn 4+ exhibits more stable cycling behavior with a capacity retention of 80.0% after 500 cycles at 5.0 C.