Electrochemical activation of oxygen atom of SnO2 to expedite efficient conversion reaction for alkaline-ion (Li+/Na+/K+) storages

SnO2-based anode materials have attracted much attention due to high capacity and relatively mild voltage platforms. However, limited by low initial Coulombic efficiency (ICE) and poor stability, its practical application is still challenging. Recently, it has been found that compositing carbon or metal particles with SnO2 is an effective strategy to achieve high alkaline-ion storages. Although this strategy may improve the kinetics and ICE of the electrochemical reaction, the specific mechanism has not been clearly elucidated. In this work, we found that the invalidation SnO2 may go through two steps: 1) the conversion process from SnO2 to Sn and Li2O; 2) the collapse of the electrode material resulted from huge volume changes during the alloyed Sn with alkaline ions. To address these issues, a unique robust Co-NC shell derived from ZIF-67 is introduced, in which the transited metallic Co nanoparticles could accelerate the decomposition of Sn−O and Li−O bonds, thus expedite the kinetics of conversion reaction. As a result, the SnO2@Co-NC electrode achieves a more complete and efficient transfer between SnO2 and Sn phases, possessing a potential to achieve high alkaline-ion (Li+/Na+/K+) storages.