Boosting Reversibility and Stability of Li Storage in SnO 2 -Mo Multilayers: Introduction of Interfacial Oxygen Redistribution.

Among the promising high-capacity anode materials, SnO 2 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, ≈60%), small reversible capacity, and poor cycling stability. Here, it is demonstrated that by carefully designing the interface structure of SnO 2 -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/SnO 2 /Mo electrode. Furthermore, high capacity retentions are also achieved in pouch-type Mo/SnO 2 /Mo||Li half cells and Mo/SnO 2 /Mo||LiFePO 4 full cells. The amorphous SnO 2 /Mo interfaces, which are induced by redistribution of oxygen between SnO 2 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 SnO 2 /Mo heterointerfaces boosts Li-ion transport kinetics by inducing a built-in electric field and improves the reaction reversibility of SnO 2 . 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.