Carbon confined GeS2 particles and its three-dimensional flexible electrode toward sodium ion battery anode

Germanium sulfide (GeS 2 ) is promising anode material for sodium ion batteries (SIBs) because of its high theoretical capacity, but it usually shows poor long-term cycling performance owing to the large volume change during sodiation/desodiation. In this work, the GeS 2 /C composites were synthesized via a facile solid-state method, and then the three-dimensional flexible electrode (3D-GeS 2 /C electrode) was prepared by freeze-drying and heat treatment after cross-linking the GeS 2 /C with carbon nanotube (CNT). The carbon layer of GeS 2 /C and the CNT network in 3D-GeS 2 /C electrode effectively restrain the volume expansion and enhance the electric conductivity , thus improving the cycling stability of GeS 2 . In consequence, the reversible capacities of 3 3%-GeS 2 /C, 66 %-GeS 2 /C and 75 %-GeS 2 /C can remain at 159.6, 382.2 and 290.2 mAh g −1 at 200th cycle. More importantly, the 3D-GeS 2 /C electrode exhibit a capacity of 266.5 mAh g −1 and the corresponding specific surface capacities of 3.30 mAh cm −2 after 500 cycles. These results probably provide an inspiration for elevating the performance of GeS 2 and fabricating 3D flexible electrode.