N-rich carbon coated CoSnO3 derived from in situ construction of a Co–MOF with enhanced sodium storage performance

In this study, N-rich carbon coated interconnected CoSnO3 nanoboxes (CoSnO3–NCs) with controllable amounts of N-rich carbon ranging from 7.5% to 24.6% were firstly prepared by the carbonization of CoSnO3–MOFs. Impressively, the preparation of CoSnO3–MOFs has been realized for the first time by directly utilizing CoSnO3 as the precursor under solvent-free conditions, bridging between the cobalt(II) ion in the skeleton of CoSnO3 and the 2-methylimidazole. Interestingly, the growth of these CoSnO3–MOFs can be manipulated by changing the amount of 2-methylimidazole used, resulting in a tunable N-rich carbon content. Furthermore, the electrochemical storage behavior of these materials for SIBs was initially explored. Compared with the pure CoSnO3, the as-resulted CoSnO3–NC materials showed largely enhanced sodium storage performance with a reversible capacity of 493.9 mA h g−1 at a current density of 0.1 A g−1 after 100 cycles. Moreover, the as-prepared materials showed an excellent high rate storage performance with a remarkable capacity of 273.8 mA h g−1 at 1 A g−1 after 1000 cycles. This work provides a new approach for constructing Co–MOFs as well as providing an efficient N-rich carbon-coating route, which may be expanded to other Co-based oxides and can greatly expand the development of new species of Co-based MOFs.