Red blood cell-like hollow carbon sphere anchored ultrathin Na₂Ti₃O₇ nanosheets as long cycling and high rate-performance anodes for sodium-ion batteries

Sodium titanate (Na₂Ti₃O₇) has been proved to be a potential anode material for sodium-ion batteries. However, its poor rate capability and low electrical conductivity has seriously hindered its application. Therefore, a unique red blood cell-like hollow carbon sphere supported Na₂Ti₃O₇ sodium titanate nanosheet structure (Na₂Ti₃O₇@RHCS) was designed here, which can both improve the electrical conductivity and preserve the structural stability, thus obtaining high rate performance. In addition, the red blood cell-like spherical structure can greatly increase the compacted density via a dense packing mode just like red blood cells stacked together one by one. Meanwhile, the ultrathin nanosheet-like morphology of Na₂Ti₃O₇ could further increase the number of active reaction sites and reduce the diffusion path of sodium ions during the charge-discharge process. This well-designed material exhibits a good cycling performance: a reversible capacity of 110.46 mA h g^-1 at 5C and 45.71 mA h g^-1 at 50C.