Properties of hollow yolk-shell NiS2/FeS2@NC@NiFe LDH/FeO(OH) nanoflower microspheres as anode materials for lithium-ion batteries

As an anode material of lithium-ion batteries, transition metal sulfides have high theoretical capacity, and the structure design is an effective strategy to gain better electrochemical performance. Layered double hydroxides (LDHs) have significant preponderances in the field of energy storage on account of their exchangeable anions and biggish specific surface area. Nevertheless, its defects such as poor conductivity, easy agglomeration of nanosheets and biggish volume change during the cycle result in poor cycling durability and rate performance, which gravely constrain its further application. In this study, hollow yolk-shell NiS₂/FeS₂@NC@NiFe LDH/FeO(OH) nanoflower microspheres are prepared successfully by solvothermal and hydrothermal methods. Firstly, introducing N-doped carbon layer can availably heighten the electro-conductivity of the materials and stop the metallic particles from falling off to boost the structural stability. The design of hollow yolk-shell and nanoflower structure can effectively inhibit cubical expansion. In addition, the unique layered structure of the nanosheets can provide more active sites, shorten the ion transport path, and enhance the lithium storage performance. As a result, the NiS₂/FeS₂@NC@NiFe LDH/FeO(OH) electrode has splendid cycling performance (709.9 mAh g⁻¹ at 0.2 A g⁻¹ after 200 cycles). These prominent electrochemical properties demonstrate convincingly that the NiS₂/FeS₂@NC@NiFe LDH/FeO(OH) is a viable anode material.