Sheet-to-layer structure of SnSe2/MXene composite materials for advanced sodium ion battery anodes

SnSe2 is regarded as an auspicious anode material for sodium-ion batteries owing to its high theoretical capacity and large interlayer spacing. However, the moderate conductivity, inevitable aggregation, and tremendous volumetric expansion (more than 300%) of SnSe2 still plague its large-scale use. Thus, a sheet-to-layer structure SnSe2/Ti3C2Tx (MXene) composite material has been synthesized in this work using an electrostatic assembling procedure. The SnSe2/Ti3C2Tx composite electrode delivered a superior sodium storage performance in a high specific capacity of 245 mA h g(-1) at 1 A g(-1) (5.4 times that of SnSe2 and 4.1 times that of Ti3C2Tx) with a capacity attenuation rate of only similar to 0.06% per cycle after 445 cycles. This electrode material not only combines the advantages (high theoretical capacity SnSe2 and high conductivity of Ti3C2Tx) of these two components, but also shows synergistic effects; these are: (i) the inserted SnSe2 nanosheets can inhibit the self-stacking problem of Ti3C2Tx and Ti3C2Tx and can prevent the aggregation of SnSe2 nanosheets and alleviate the volume expansion of SnSe2 nanosheets during cycling; (ii) the increased surface area with the mesoporous structure is favorable for sodium ion kinetics and simultaneously conducive to electrolyte penetration and rapid ion diffusion during cycling.

Automated summary

The SnSe2/Ti3C2Tx composite electrode, synthesized through an electrostatic assembling procedure, demonstrates superior sodium storage performance with high specific capacity and low capacity attenuation rate. The composite material overcomes the deficiencies of SnSe2 and Ti3C2Tx individually, showing synergistic effects.