MOF derived double-carbon layers boosted the lithium/sodium storage performance of SnO₂nanoparticles

Tin oxide (SnO₂) was considered as a promising alternative to commonly used graphite anode in energy storage devices thanks to its superior specific capacity. However, its electrochemical property was severely limited due to the inherent poor conductivity and drastic volume variation during the charging/discharging process. To overcome this disadvantage, we grew Sn-MOF directly on graphene oxide (GO) layers to synthesize a double carbon conductive network-encapsulated SnO₂nanoparticles (SnO₂/C/rGO) via a facile solvothermal method. During the process, Sn-MOF skeleton transformed into porous carbon shells, in which nanosized SnO₂particles (~8nm) were embedded, while GO template was reduced to highly conductive rGO layer tightly wrapping the SnO₂/C particles. This double-carbon structure endowed SnO₂/C/rGO anode with enhanced specific capacity and rate property both in lithium ion batteries (LIB) and sodium ion batteries (SIB). The SnO₂/C/rGO anode showed a highly reversible specific capacity of 1038.3 mAh g^-1at 100 mA g^-1, and maintained a stable capacity of 720.2 mAh g^-1(70.1%) under 500 mA g^-1after 150 cycles in LIBs. Similarly, highly reversible capacity of 350.7 mAh g^-1(81.1%) under 100 mA g^-1after 150 cycles was also achieved in SIBs. This work provided a promising strategy in improving the electrochemical properties of SnO₂nanoparticles (NPs), as well as other potential anode materials suffering from huge volume change and poor conductivity.