Journal
JOURNAL OF ENERGY CHEMISTRY
Volume 73, Issue -, Pages 114-125Publisher
ELSEVIER
DOI: 10.1016/j.jechem.2022.06.019
Keywords
Ni-rich layered oxide; Dual -modified; Electrochemical performance; Li1_xTMO2_y; Li2SO4
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The study enhances the high voltage cycle stability of nickel-rich layered cathode materials by designing a Li1_xTMO2_y/Li2SO4 hybrid layer, which suppresses the outward migration of oxygen anions through the construction of internal self-built electric fields and improves the bonding and charge transfer between the hybrid layer and the host material, resulting in excellent electrochemical performance of the modified materials.
The Nickel-rich layered cathode materials have been considered as promising cathode for lithium-ion batteries (LIBs), which due to it can achieve a high capacity of than 200 mAh g_1 under a high cutoff voltage of 4.5 V. However, the nickel-rich layered cathode materials show severely capacity fading at high voltage cycling, induced by the hybrid O anion and cation redox promote Oa_ (a< 2) migration in the crystal lattice under high charge voltage, lead to the instability of the oxygen skeleton and oxygen evolution, promote the phase transition and electrolyte decomposition. Here, Li1_xTMO2_y/Li2SO4 hybrid layer is designed by a simple pyrolysis method to enhance the high voltage cycle stability of NCM. In such constructed hybrid layer, the inner spinel structure of Li1_xTMO2_y layer is the electron-rich state, which could form an electron cloud coupling with the NCM with surface oxygen vacancies, while Li2SO4 is p-type semiconductors, thus constructing a heterojunction interface of Li1_xTMO2_y//Li2SO4 and Li1_xTMO2_y//NCM, thereby generating internal self-built electric fields to inhibit the outward migration of bulk oxygen anions. Moreover, the internal self-built electric fields could not only strengthen the bonding force between the Li1_xTMO2_y/Li2SO4 hybrid layer and host NCM material, but also boost the charge transfer. As consequence, the modified NCM materials show excellent electrochemical performance with capacity retention of 97.7% and 90.1% after 200 cycles at 4.3 V and 4.5 V, respectively. This work provides a new idea for the development of high energy density applications of Nickel-rich layered cathode materials.(c) 2022 Science Press and Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by ELSEVIER B.V. and Science Press All rights reserved.
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