Mitigating the Kinetic Hindrance of Single-Crystalline Ni-Rich Cathode via Surface Gradient Penetration of Tantalum.

Abstract

Single-crystalline Ni-rich cathodes are promising candidates for the next-generation high-energy Li-ion batteries. However, they still suffer from poor rate capability and low specific capacity due to the severe kinetic hindrance at the nondilute state during Li+ intercalation. Herein, combining experiments with density functional theory (DFT) calculations, we demonstrate that this obstacle can be tackled by regulating the oxidation state of nickel via injecting high-valence foreign Ta5+ . The as-obtained single-crystalline LiNi0.8 Co0.1 Mn0.1 O2 delivers a high specific capacity (211.2 mAh g-1 at 0.1 C), high initial Coulombic efficiency (93.8 %), excellent rate capability (157 mAh g-1 at 4 C), and good durability (90.4 % after 100 cycles under 0.5 C). This work provides a strategy to mitigate the Li+ kinetic hindrance of the appealing single-crystalline Ni-rich cathodes and will inspire peers to conduct an intensive study.