Ultrafine SnO nanoparticles anchored on N, P-doped porous carbon as anodes for high performance lithium-ion and sodium-ion batteries.

An ultrafine tin dioxide/N, P-doped porous carbon (SnO/NPPC) nanocomposite is prepared through in-situ growth of tin dioxide (SnO) nanoparticles in N, P-doped porous carbon (NPPC). Owing to the in-situ growth method, the size of SnO nanoparticles in SnO/NPPC is quite small and uniform (generally less than 5.0 nm). NPPC provides a support and a conductive carbon skeleton for the SnO nanoparticles. The small SnO nanoparticles are less likely to aggregate during the discharge-charge process due to the presence of Sn-O-C bonding and nanoconfinement effect of SnO nanoparticles in carbon matrix. The N and P doping can provide abundant defects to facilitate the penetration of Li or Na into the interior of the electrode. In addition, the presence of Sn-N bonding can further improve the electrochemical properties of the electrodes. Thus, as an anode material for lithium-ion batteries, SnO/NPPC possesses an enhanced rate performance, an excellent cycling stability, and a high initial Coulombic efficiency. The structure of the ultrafine SnO nanoparticles is well maintained in cycled SnO/NPPC. Meanwhile, SnO/NPPC also possesses good electrochemical performance as an anode for sodium-ion batteries. The good electrochemical properties for SnO/NPPC materials can be ascribed to the synergetic effect between small SnO nanoparticles and NPPC.