Ultrasmall SnO2 nanocrystals embedded in porous carbon as potassium ion battery anodes with long-term cycling performance†
Alloy-based anodes have been perceived as promising candidates for potassium ion batteries with regard to their remarkable electrochemical performance. Although tin dioxide (SnO2) has been widely studied as a high performance alloy-based anode in lithium ion batteries, there are few works on the use of SnO2 as an anode in potassium ion batteries. Here, we successfully synthesized ultrasmall SnO2 nanocrystals with a homogeneous size of 2–6 nm embedded in porous carbon using a facile hydrothermal method. The composite exhibits excellent electrochemical performance, which can be attributed to the well-defined porous carbon matrix and the well-restrained nano-scale SnO2 nanocrystals. At a low current density of 100 mA g−1, the composite material delivers a reversible capacity of 300 mA h g−1 after 100 cycles. Notably, the anode maintains a high reversible capacity of 108.3 mA h g−1 (based on the total mass of the composite) even after 10 000 cycles at a current density of 1 A g−1.