Dual-modified surface encapsulation strategy for elevating rate performance and cycling stability of Ni-rich NCM811 cathode

LiNi0.8Co0.1Mn0.1O2 (NCM811) presents as a prevailing commercialized cathode material for lithium-ion batteries. Nevertheless, further restraint in the extensive application of NCM811 attributed to its intrinsic inferior ionic conductivity and sluggish diffusion kinetics necessitates ingenious strategies to alleviate the above deficiencies. Enlightened by experimental investigation coupled with theoretical calculation (density functional theory calculation), the Y3+-doped and LiYO2-coated (ionic conductor) interface is rationally created as an innovative surface engineering. The Y3+-doping contributes to reducing the diffusion barriers of Li+ (NCM with 0.78 eV, and NCM-Y with 0.62 eV), systemic energy (NCM with −1031.29 eV, and NCM-Y with −1041.32 eV), and lift Ni2+ irreversible migration energy barrier (NCM with 3.06 eV, and NCM-Y with 3.25 eV) so as to accelerate Li+ diffusion rate and effectively restrain the cationic mixing (NCM with 0.0202, and NCM-Y with 0.0198). Simultaneously, the ionic coating (LiYO2) can not only inhibit the occurrence of side reactions at the interface to improve the interfacial stability, but also as a fast ion-conductor to elevate the lithium-ion diffusion rate of the material. The pristine NCM represents a commonplace comprehensive electrochemical performance with unsatisfactory rate capacity (116.4 mAh·g−1 at 10 C), and poor long cycling stability (35.5 mAh·g−1 after 500 cycles at 5 C). Interestingly, the dual-modified NCM-Y exhibits distinguished electrochemical performance with fabulous rate capacity (144.5 mAh·g−1 even at 10 C), and preeminent long cycling stability (132.6 mAh·g−1 over 500 cycles at 5 C).