Rapid in situ growth of high-entropy oxide nanoparticles with reversible spinel structures for efficient Li storage†
a
Xun
Cao,
a
Mingzhen
Xiu,
d
Gang
Wu,
b
Shuo-Wang
Yang,
b
Zheng
Liu,
a
Kedar
Hippalgaonkar
*af
and
Yizhong
Huang
*a
Abstract
High-entropy oxides (HEOs) are considered promising electrode materials as they have great potential to provide much higher energy density and cyclability than their conventional electrode counterparts such as graphite. In the present work, nanostructured HEOs were fabricated on the surface of conductive carbon black using laser beam irradiation, which generally implements the rapid bottom-up carbothermal process. Furthermore, electrochemical performances of Co-free and Co-incorporated HEO nanoparticles in comparison with bulk-HEO counterparts were investigated. In particular, the Co-free (LiFeNiMnCuZn)3O4 nanoparticle electrode showed the best capability presenting both the highest cycling value of 866 mA h g−1 (100% capacity retention) after 800 cycles at 0.5 A g−1 and rate performances of 585 at 2.0 A g−1 and 436 mA h g−1 at 5.0 A g−1 without decay. The long cycling performance of Co-free HEOs could be derived from the reversible spinel structure, according to the in situ X-ray diffraction (XRD) results, as well as the strong thermal stability of high-entropy mixing phases, as indicated by a large positive decomposition enthalpy according to density functional theory (DFT) calculations. Additionally, the assembled full cell (LiFeNiMnCuZn)3O4‖LiNi0.6Co0.2Mn0.2O2 delivered a power density of 670 W h kg−1 with a high discharge voltage around 3.7 V based on the 0.1C discharge profile. As manifested by the DFT calculations, the low anode voltage of HEOs measured here is due to the electron-sufficient Zn, which favors the Ni2+/Ni3+ redox couple. This work is expected to provide a guideline for the development of advanced high-entropy nanostructured electrode materials for efficient batteries.
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