Boosting high-rate Li-ion storage properties by La(III) ion doping in spinel (Co_0.2Cr_0.2Fe_0.2Mn_0.2Ni_0.2)₃O₄ high-entropy oxide anode

The present work aims to create lattice distortion and optimize the surface oxygen vacancy concentration in a model spinel (Co_0.2Cr_0.2Fe_0.2Mn_0.2Ni_0.2)₃O₄ high-entropy oxide (HEO) through heteroatom La³⁺ doping strategy. As demonstrated, La³⁺ with large radius can be doped successfully into the spinel lattice of (Co_0.2Cr_0.2Fe_0.2Mn_0.2Ni_0.2)₃O₄, 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_0.2Cr_0.2Fe_0.2Mn_0.2Ni_0.2)₃O₄ anode, the (La_0.01CoCrFeMnNi)_3/5.01O₄ with moderately doped anode presents excellent cycling performance (1228 mAh∙g^-1 after 400 cycles at 0.2 A∙g^-1), and yields an increase of 75% rate capability at 3 A∙g^-1 (420 mAh∙g^-1 at 3 A∙g^-1). The desirable kinetic transport of electron and diffusion of Li⁺ within moderately La³⁺-doped anode and the interface pseudocapacitive behavior synergistically satisfy the redox reaction at high rate, thus boosting the rate capability.