Hierarchical assembly and superior sodium storage properties of a sea-sponge structured C/SnS@C nanocomposite

Abstract

The exploration of electrode materials with superior rate capability and cyclability has been a critical challenge for sodium-ion batteries (SIBs). Herein, a new sea-sponge structured C/SnS@C nanocomposite has been fabricated through the hierarchical assembly of SnS₂ nanoflakes on sea-sponge-like macrochannel-interconnected carbon spheres (S-MCSs) and subsequent carbon coating together with the phase transformation of SnS. A notably enhanced performance is achieved which is attributed to the formation of the sea-sponge-like rigid structure and layered SnS nanoflakes, which facilitate Na⁺ diffusion at a large current density based on the conductive S-MCS skeleton and carbon coating, thus significantly improving the kinetic process of Na⁺ insertion/extraction. When applied as an anode material for SIBs, the designed C/SnS@C composite exhibits superior cycling stability. It can endure a current density of 10 A g⁻¹ to complete the charge process in 22 s and deliver a capacity of 370 mA h g⁻¹ at 1 A g⁻¹ after five initial activation processes, with over 84% capacity retention from the 200^th to the 2000^th cycle, which is equivalent to 0.009% decay per cycle.