Boosting High-Rate Sodium Storage of CuS via a Hollow Spherical Nanostructure and Surface Pseudocapacitive Behavior

The fast capacity decay of existing anode materials at a high rate is a thorny problem that hinders the thriving development of sodium ion batteries (SIBs). Herein, we present a unique anode material constructed via cuprous sulfide hollow nanospheres (CuS HNs), which can achieve ultrafast sodiation-desodiation at high rate (20 A g(-1)) and stable cycling 2000 times without obvious capacity degradation (250.1 mAh g(-1), capacity retention of 93%). As far as we know, this excellent rate performance is superior to most of the other currently known metal oxides/sulfides anode materials for SIBs. It is believed that the contribution for high-rate sodium storage of CuS HNs mainly comes from the synergistic effect between hollow nanosphere structure and surface pseudocapacitive behavior. The open hollow nanostructure allows the pseudocapacitive storage simultaneously on the inner and outer surfaces of the nanospheres. Meanwhile, the pseudocapacitive behavior can relieve the large stress of nanospheres at high rate and retain the structural stability of electrode materials. The feature of ultralfast charging and discharging of CuS HNs without obvious capacity sacrifice would be expected to provide a strong boost for the large-scale application of SIBs.