High Initial Reversible Capacity and Long Life of Ternary SnO2?Co?carbon Nanocomposite Anodes for Lithium?Ion Batteries

The two major limitations in the application of SnO2for lithium?ion battery(LIB) anodes are the large volume variations of SnO2during repeated lithiation/delithiation processes and a large irreversible capacity loss during the first cycle, which can lead to a rapid capacity fade and unsatisfactory initial Coulombic e ciency(ICE). To overcome these limitations, we developed composites of ultrafine SnO2nanoparticles and in situ formed Co(CoSn) nanocrystals embedded in an N?doped carbon matrix using a Co?based metal–organic framework(ZIF?67). The formed Co additives and structural advantages of the carbon?confined SnO2/Co nanocomposite e ectively inhibited Sn coarsening in the lithiated SnO2and mitigated its structural degradation while facilitating fast electronic transport and facile ionic di usion. As a result, the electrodes demonstrated high ICE (82.2%), outstanding rate capability(～ 800 mAh g-1at a high current density of 5 A g-1), and long?term cycling stability(～ 760 mAh g-1after 400 cycles at a current density of 0.5 A g-1). This study will be helpful in developing high?performance Si(Sn)?based oxide, Sn/Sb?based sulfide, or selenide electrodes for LIBs. In addition, some metal organic frameworks similar to ZIF?67 can also be used as composite templates.