Prelithiation enhanced initial Coulombic efficiency and cycling stability of spinel (FeCoCrNiMn)₃O₄ high entropy oxide anode

High entropy oxides (HEOs) are expected to be favorable contenders for next generation of lithium-ion battery (LIB) anode materials due to unique entropy stabilization effect and synergistic effect of multi-metal elements. However, HEOs still face issues of low initial coulomb efficiency (ICE, <90 %) and irreversible transformation of phase structures during the cycle, resulting in unsatisfactory cycling stability, which limit their commercialization applications. Herein, chemical prelithiation strategy is performed to form Li-rich surface modification layer (SML) on spinel (FeCoCrNiMn)₃O₄ HEOs. The prelithiated HEO (PreHEO-20) exhibits superior ICE (97.5 %) and cycling stability, delivering a reversible capacity of 495 mAh g⁻¹ after cycling at 2000 mA g⁻¹ for 4000 cycles. The good electrochemical performance can be attributed to the introduction of “extra Li” into the anode material by chemical prelithiation to offset lithium loss during cycling as well as the formation of dense LiF layer to effectively isolate the contact between the electrolyte and the active substance, thus guaranteeing the highly reversible spinel structure. In this situation, the (−)PreHEO-20||LiFePO₄(+) full cell presents an excellent reversible capacity of 121.8 mAh g⁻¹ after 100 cycles at 0.2C, revealing huge application potential of chemical prelithiated HEOs in LIB field.