Optimizing Electron Spin-Polarized States of MoSe 2 /Cr 2 Se 3 Heterojunction-Embedded Carbon Nanospheres for Superior Sodium/Potassium-Ion Battery Performances.

The principal challenges faced by sodium-ion batteries (SIBs) and potassium-ion batteries (KIBs) revolve around identifying suitable host materials capable of accommodating metal ions with larger dimensions and addressing the issue of sluggish chemical kinetics. Herein, a MoSe 2 /Cr 2 Se 3 heterojunction uniformly embedded is fabricated in nitrogen-doped hollow carbon nanospheres (MoSe 2 /Cr 2 Se 3 @N-HCSs) as an electrode material for SIBs and KIBs. Cr 2 Se 3 exhibits spontaneous antiparallel alignment of magnetic moments. Mo 2+ doping is employed to regulate the electron spin states of Cr 2 Se 3 . Moreover, the MoSe 2 and Cr 2 Se 3 heterojunctions induce a lattice mismatch at the heterostructure interface, resulting in spin-polarized states or localized magnetic moments at the interface, potentially contributing to spin-polarized surface capacitance. MoSe 2 /Cr 2 Se 3 @N-HCSs demonstrate a high capacity of 498 mAh g -1 at 0.1 A g -1 with good cycling stability (capacity of 405 mAh g -1 and a coulombic efficiency of 99.8% after 1000 cycles). Additionally, density functional theory (DFT) calculations simulate the accumulation of spin-polarized charges at the MoSe 2 /Cr 2 Se 3 @N-HCSs heterojunction interface, dependent on the surface electron density of the antiferromagnetic Cr 2 Se 3 and the surface spin polarization near the Fermi level. After regulating the electron spin states through Mo-doping, the band gap of the material decreases. These significant findings provide novel insights into the design and synthesis of electrode materials with exceptional performance characteristics for batteries.