Cu2S hollow spheres as an anode for high-rate sodium storage performance

Cu2S hollow spheres composed of nanoparticles are synthesized via a template-free hydrothermal process in the absence of additive. The obtained Cu2S hollow spheres not only provide a large surface for contacting between electrode and the electrolyte, but also keep sufficient space for the volume variation during the sodiation/desodiation process. Consequently, as an anode for sodium ion battery, the Cu2S hollow spheres deliver a large capacity of 369 mA h g(-1) after 100 cycles at 0.2 A g(-1) and demonstrated superior rate performance (331.7 mA h g(-1) at 0.5 A g(-1), 319 mA h g(-1) at 4 A g(-1)) and long-term cycling stability (343 mA h g(-1) at 2 A g(-1) after 1000 cycles).