Achieving highly stable Sn-based anode by a stiff encapsulation heterostructure

Rationally designed heterostructures provide attractive prospects for energy storage electrodes by combining different active materials with distinct electrochemical properties. Herein, through a phase separation strategy, a heterostructure of SnO2 encapsulated by amorphous Nb2O5 is spontaneously synthesized. Insertion-type anode Nb2O5 outer shell, playing as reaction containers and fast ionic pathways, physically inhibits the Sn atoms’ migration and enhances the reaction kinetics. Moreover, strong chemical interactions are found at the SnO2/Nb2O5 interfaces, which ensure the solid encapsulation of the SnO2 cores even after 500 cycles. When used for lithium-ion batteries, this heterostructured anode exhibits high cycling stability with a capacity of 626 mA h g−1 after 1000 cycles at 2 A g−1 (85% capacity retention) and good rate performance with the capacity of 340 mA h g−1 at 8 A g−1.