Synergetic effect of lattice distortion and oxygen vacancies on high-rate lithium-ion storage in high-entropy perovskite oxides

High-entropy oxides (HEOs) have gained great attention as an emerging kind of high-performance anode materials for lithium-ion batteries (LIBs) due to the entropy stabilization and multi-principal synergistic effect. Herein, the porous perovskite-type RE(Co_0.2Cr_0.2Fe_0.2Mn_0.2Ni_0.2)O₃ (RE (= La, Sm, and Gd) is the abbreviation of rare earth) HEOs were successfully synthesized by a solution combustion synthesis (SCS) method. Owing to the synergistic effect of lattice distortion and oxygen vacancies (O_V), the Gd(Co_0.2Cr_0.2Fe_0.2Mn_0.2Ni_0.2)O₃ electrode exhibits superior high-rate lithium-ion storage performance and excellent cycling stability. A reversible capacity of 403 mAh·g^–1 at a current rate of 0.2 A·g^–1 after 500 cycles and a superior high-rate capacity of 394 mAh·g⁻¹ even at 1.0 A·g^–1 after 500 cycles are achieved. Meanwhile, the Gd(Co_0.2Cr_0.2Fe_0.2Mn_0.2Ni_0.2)O₃ electrode also exhibits a pronounced pseudo-capacitive behavior, contributing to an additional capacity. By adjusting and balancing the lattice distortion and oxygen vacancies of the electrode materials, the lithium-ion storage performance can be further regulated.