Towards high-performance cathode materials for lithium-ion batteries: Al2O3-coated LiNi0.8Co0.15Zn0.05O2
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Zn-doped LiNi0.8Co0.2O2 exhibits impressive electrochemical performance but suffers limited cycling stability due to the relative large size of irregular and bare particle which is prepared by conventional solid-state method usually requiring high calcination temperature and prolonged calcination time. Here, submicron LiNi0.8Co0.15Zn0.05O2 as cathode material for lithium-ion batteries is synthesized by a facile sol-gel method, which followed by coating Al2O3 layer of about 15 nm to enhance its electrochemistry performance. The as-prepared Al2O3-coated LiNi0.8Co0.15Zn0.05O2 cathode delivers a highly reversible capacity of 182 mA h g−1 and 94% capacity retention after 100 cycles at a current rate of 0.5 C, which is much superior to that of bare LiNi0.8Co0.15Zn0.05O2 cathode. The enhanced electrochemistry performance can be attributed to the Al2O3-coated protective layer, which prevents the direct contact between the LiNi0.8Co0.15Zn0.05O2 and electrolyte. The escalating trend of Li-ion diffusion coefficient estimated form electrochemical impedance spectroscopic (EIS) also indicate the enhanced structural stability of Al2O3-coated LiNi0.8Co0.15Zn0.05O2, which rationally illuminates the protection mechanism of the Al2O3-coated layer.
KeywordsLiNi0.8Co0.15Zn0.05O2 Al2O3 Cathode Lithium-ion batteries Electrochemical impedance spectroscopic
We thank Analytical and Testing Center of Huazhong University of Science and Technology and the Center of Micro-Fabrication and Characterization (CMFC) of WNLO for use of their facilities.
This work was supported by the NSFC (51673077, 21474034, 51603078), National Basic Research Program of China (Grant no. 2015CB755602 and 2013CB922104) and the Fundamental Research Funds for the Central Universities (HUST: 2016YXMS029).
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