Long-Term Cycling Stability of 18650 Li-Ion Batteries Cells Using NMC811 Core@Shell Structure with Tetra-Materials

LiNi_0.8Mn_0.1Co_0.1O₂ (NMC811) material has been considered as a next-generation cathode of lithium-ion batteries, which can be used for many applications such as long-distance electric vehicles. Although NMC811 has high theoretical specific capacity and energy, its major drawbacks such as microcracks, cation mixing, too reactive surface reaction, result in poor long-term cycling and stability. In this work, the tetra-materials of garnet (Li₇La₃Zr₂O₁₂), reduced graphene oxide (rGO), carbon black (CB), and titanium dioxide (TiO₂) were coated on the surface of the NMC particle by a green and scalable mechano-fusion technique, forming the core@shell structure (namely NMC@4M) to protect the morphological instability and the electrolyte decomposition leading to long-term cycling stability. Also, the 4M shell elevates the Li-ion diffusion and ionic conductivity. Moreover, we have firstly reported the finely tuned step formation protocol of cylindrical cell type in lithium-ion battery (18650). As a result, the NMC@4T can deliver high-capacity retention over 85% after long cycling (400 cycles) at 1C.

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