Boosting Reversibility and Stability of Li Storage in SnO2-Mo Multilayers: Introduction of Interfacial Oxygen Redistribution

Among the promising high-capacity anode materials, SnO2 represents a classic and important candidate that involves both conversion and alloying reactions toward Li storage. However, the inferior reversibility of conversion reactions usually results in low initial Coulombic efficiency (ICE, approximate to 60%), small reversible capacity, and poor cycling stability. Here, it is demonstrated that by carefully designing the interface structure of SnO2-Mo, a breakthrough comprehensive performance with ultrahigh average ICE of 92.6%, large capacity of 1067 mA h g(-1), and 100% capacity retention after 700 cycles can be realized in a multilayer Mo/SnO2/Mo electrode. Furthermore, high capacity retentions are also achieved in pouch-type Mo/SnO2/Mo||Li half cells and Mo/SnO2/Mo||LiFePO4 full cells. The amorphous SnO2/Mo interfaces, which are induced by redistribution of oxygen between SnO2 and Mo, can precisely adjust the reversible capacity and cycling stability of the multilayers, while the stable capacities are parabolic with the interfacial density. Theoretical calculations and in/ex situ investigation reveal that oxygen redistribution in SnO2/Mo heterointerfaces boosts Li-ion transport kinetics by inducing a built-in electric field and improves the reaction reversibility of SnO2. This work provides a new understanding of interface-performance relationship of metal-oxide hybrid electrodes and pivotal guidance for creating high-performance Li-ion batteries.

Automated summary

This study demonstrates the breakthrough comprehensive performance of SnO2-Mo multilayers by carefully designing the interface structure, achieving high initial Coulombic efficiency, large capacity, and excellent cycling stability. The amorphous SnO2/Mo interfaces induced by oxygen redistribution can precisely adjust the reversible capacity and cycling stability, with stable capacities being parabolic with the interfacial density. This work provides new understandings of the interface-performance relationship of metal-oxide hybrid electrodes and offers important guidance for creating high-performance Li-ion batteries.