标题：Enhanced High-voltage Cycling Stability of Ni-rich Cathode Materials via Self-assembly of Mn-rich Shells
作者：Xinyu Dong, a, b, # Junyi Yao, a, b, # Wenchang Zhu, a, b Xue Huang, a, b Xiaoxiao Kuai, a, b Jing Tang, c, e, *Xiaolong Li, d Shuyan Dai, a, b Liwei Shen, a, b Ruizhi Yang, a, b Lijun Gao, a, b, *Jianqing Zhao a, b, *
a College of Energy, Soochow Institute for Energy and Materials InnovationS, Soochow University, Suzhou 215006, China.
b Key Laboratory of Advanced Carbon Materials and Wearable Energy Technologies of Jiangsu Province, Soochow University, Suzhou 215006, China.
c School of Chemistry and Molecular Engineering, Shanghai Key Laboratory of Green Chemistry and Chemical Processes, East China Normal University, Shanghai 20062, China
e School of Chemical Engineering and Australian Institute for Bioengineering and Nanotechnology (AIBN), The University of Queensland, Brisbane, Queensland 4072, Australia
摘要：Ni-rich layered LiNi1-x-yMnxCoyO2 (NMC, x+y<0.5) oxides have been demonstrated to bedominant cathode materials for high-energy lithium ion batteries. However, NMC cathode materials with high Ni contents usually show unsatisfied capacity decay and voltage fading cycled at high voltages, owing to aggravated side reactions and electrochemical irreversibility during prolonged lithiation/delithiation cycles. Here, we report the Mn-rich Li0.65Mn0.59Ni0.12Co0.13Oδ (marked as LMNCO) nanocomposite that is integrated of layered Li2MnO3 and spinel LiMn1.5Ni0.5O4-type phases as a desired shell for improving high-voltage cycling stability of the Ni-rich LiNi0.8Mn0.1Co0.1O2 (marked as NMC811) cathode material. The core-shell NMC811@x% LMNCO nanostructure has been fabricated in satisfied structural conformality by using an initial sonofragmentation, followed by the solvent evaporation-induced self-assembly (EISA) and post-annealing processes. The optimized NMC811@5% LMNCO cathode material can deliver an initial discharge capacity of150.0 mAh g-1 at 5C (1 C=200 mA g-1) in a voltage range of 2.7-4.6 V vs. Li+/Li with 83.4 % retention up to 500 cycles, significantly superior to 75.6 % of the bare NMC811 material. The Mn-rich shell also enables to effectively stabilize Ni-rich cathode materials for long-term cycles in such a high voltage range at 55 °C. In addition, this work offers a synthetic prototype for the conformal core-shell-structured fabrications, which could be adopted for the surface modification of various functional materials to achieve enhanced performancein device applications.