Enhancing electrochemical performance of high-entropy Co/Ni-free P2/O3 hybrid-phase layered metal oxide cathode for sodium-ion batteries

Abstract

Sodium-ion batteries (SIBs) have currently garnered increasing attention due to their promising applications and potential advantages. Despite the cost and performance advantages, the Co/Ni-free Fe-Mn-based cathode materials tends to undergo a large phase transition in the sodium (de)intercalation layer, which will result in the material structure damage. In this work, high entropy P2/O3-Na0.75Cu0.1Fe0.2Mg0.2Mn0.4Ti0.1O2 (NCFMMT) materials were successfully prepared by employing NaTi2(PO4)3 (NTP) as the modification layer. It can be distinctly seen that the cyclic stability of NCFMMT@NTP has been significantly improved, and the first capacity at 0.2C reaches 165.32 mAh/g and the capacity can maintain 86.73 % after 100 cycles. Moreover, the voltage hysteresis after triggering anionic redox can be clearly ameliorated. Apparently, the high-entropy strategy not only can satisfactorily optimize the lattice structure and stability of the cathode material during sodium intercalation/de-intercalation process, but also can increase the ion mobilization rate and promote further electrochemical properties. Therefore, this study provides valuable exploration for the design and preparation of cobalt/nickel-free cathodes with excellent electrochemical performance.