CoSe₂-Decorated NbSe₂ Nanosheets Fabricated via Cation Exchange for Li Storage

Though 2D transition metal dichalcogenides have attracted a lot of attention in energy-storage applications, the applications of NbSe₂ for Li storage are still limited by the unsatisfactory theoretical capacity and uncontrollable synthetic approaches. Herein, a controllable oil-phase synthetic route for preparation of NbSe₂ nanoflowers consisted of nanosheets with a thickness of ∼10 nm is presented. Significantly, a part of NbSe₂ can be further replaced by orthorhombic CoSe₂ nanoparticles via a post cation exchange process, and the predominantly 2D nanosheet-like morphology can be well-maintained, resulting in the formation of CoSe₂-decorated NbSe₂ (denoted as CDN) nanosheets. More interestingly, the CDN nanosheets exhibit excellent lithium-ion battery performance. For example, it achieves a highly reversible capacity of 280 mAh g^-1 at 10 A g^-1 and long cyclic stability with specific capacity of 364.7 mAh g^-1 at 5 A g^-1 after 1500 cycles, which are significantly higher than those of reported pure NbSe₂.