Large-scale CuS nanotube arrays@graphdiyne for high-performance sodium ion battery

Copper sulfide (CuS) is emerged as a promising electrode material for Na-ion batteries due to its high theoretical specific capacity, environmental friendliness and abundant resource. However, the conversion type mechanism for storing the Na+ causes huge volume variations, irreversible phase changes and disintegration of the structure during charge and discharge processes. These intractable issues lead to the fast capacity degradation, and sluggish reaction kinetics, and performances are hard to fulfill the criteria in practical applications. Herein, the large-scale free-standing CuS nanotube arrays sandwiched by successive graphdiyne (GDY) nanofilm are readily prepared using a simple and efficient strategy. The in-situ protection of GDY nanofilm successfully enhances the structural stability and the network conductivity of the free-standing electrode. The as-obtained CuS electrode protected by GDY exhibits excellent electrochemical sodium storage capability, in the term of long-term reversibility (After 1000 cycles at 2 C, the capacity retention is 78.7%.) and rate performance.