Boosting high-rate Li-ion storage properties by La(III) ion doping in spinel (Co <sub>0.2</sub>Cr <sub>0.2</sub>Fe <sub>0.2</sub>Mn <sub>0.2</sub>Ni <sub>0.2</sub>) <sub>3</sub>O <sub>4</sub> high-entropy oxide anode
Shi‐Jie Chen, Mengfan Bao, Yanggang Jia, Pengpeng Wang, Dan Wei, Yuhuan Guo, Jie Tan, Aiqin Mao
Abstract
The present work aims to create lattice distortion and optimize the surface oxygen vacancy concentration in a model spinel (Co<sub>0.2</sub>Cr<sub>0.2</sub>Fe<sub>0.2</sub>Mn<sub>0.2</sub>Ni<sub>0.2</sub>)<sub>3</sub>O<sub>4</sub> high-entropy oxide (HEO) through heteroatom La<sup>3+</sup> doping strategy. As demonstrated, La<sup>3+</sup> with large radius can be doped successfully into the spinel lattice of (Co<sub>0.2</sub>Cr<sub>0.2</sub>Fe<sub>0.2</sub>Mn<sub>0.2</sub>Ni<sub>0.2</sub>)<sub>3</sub>O<sub>4</sub>, thereby not only causes lattice distortion to increase oxygen vacancies, but also could refine the crystalline grain and improve the specific area. In comparison with (Co<sub>0.2</sub>Cr<sub>0.2</sub>Fe<sub>0.2</sub>Mn<sub>0.2</sub>Ni<sub>0.2</sub><strong>)</strong><sub>3</sub>O<sub>4</sub> anode, the (La<sub>0.01</sub>CoCrFeMnNi)<sub>3/5.01</sub>O<sub>4</sub> with moderately doped anode presents excellent cycling performance (1228 mAh∙g<sup>-1</sup> after 400 cycles at 0.2 A∙g<sup>-1</sup>), and yields an increase of 75% rate capability at 3 A∙g<sup>-1</sup> (420 mAh∙g<sup>-1</sup> at 3 A∙g<sup>-1</sup>). The desirable kinetic transport of electron and diffusion of Li<sup>+</sup> within moderately La<sup>3+</sup>-doped anode and the interface pseudocapacitive behavior synergistically satisfy the redox reaction at high rate, thus boosting the rate capability.