Cobalt Doping Enables High-Performance MoSe2 and WSe2 Anodes for Lithium-Ion Batteries

Cobalt doping provides an effective strategy for tailoring the electronic structure and lithium-storage properties of transition metal dichalcogenides. In this work, Co-doped MoSe2 and WSe2 were synthesized through a scalable hydrothermal approach and systematically investigated as anode materials for lithium-ion batteries. Co incorporation enhances the electrochemical performance of both materials, with a substantially stronger improvement observed for WSe2, particularly under high-rate conditions. In contrast, Co-MoSe2 exhibits an unusual capacity evolution during prolonged cycling, characterized by an initial decrease followed by gradual capacity recovery. Density functional theory calculations show that Co incorporation induces metallization in both systems, whereas Li adsorption leads to different electronic responses: Co-MoSe2 undergoes a metal-to-semiconductor transition, while Co-WSe2 retains its metallic character. The preserved metallicity of Co-WSe2 provides a plausible microscopic explanation for its enhanced charge transport and superior rate performance, while the stronger electronic reconstruction in Co-MoSe2 may contribute to its initial capacity decay and subsequent electrochemical activation.