CoSe ₂ -Decorated NbSe ₂ 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 NbSe ₂ 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 NbSe ₂ nanoflowers consisted of nanosheets with a thickness of ∼10 nm is presented. Significantly, a part of NbSe ₂ can be further replaced by orthorhombic CoSe ₂ nanoparticles via a post cation exchange process, and the predominantly 2D nanosheet-like morphology can be well-maintained, resulting in the formation of CoSe ₂ -decorated NbSe ₂ (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 NbSe ₂ .