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

Among the promising high-capacity anode materials, SnO 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 -Mo, a breakthrough comprehensive performance with ultrahigh average ICE of 92.6%, large capacity of 1067 mA h g , and 100% capacity retention after 700 cycles can be realized in a multilayer Mo/SnO /Mo electrode. Furthermore, high capacity retentions are also achieved in pouch-type Mo/SnO /Mo||Li half cells and Mo/SnO /Mo||LiFePO full cells. The amorphous SnO /Mo interfaces, which are induced by redistribution of oxygen between SnO 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 /Mo heterointerfaces boosts Li-ion transport kinetics by inducing a built-in electric field and improves the reaction reversibility of SnO . 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.