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

Germanium sulfide (GeS2) 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 GeS2/C composites were synthesized via a facile solid-state method, and then the three-dimensional flexible electrode (3D-GeS2/C electrode) was prepared by freeze-drying and heat treatment after cross-linking the GeS2/C with carbon nanotube (CNT). The carbon layer of GeS2/C and the CNT network in 3D-GeS2/C electrode effectively restrain the volume expansion and enhance the electric conductivity, thus improving the cycling stability of GeS2. In consequence, the re-versible capacities of 3 3%-GeS2/C, 66 %-GeS2/C and 75 %-GeS2/C can remain at 159.6, 382.2 and 290.2 mAh g-1 at 200th cycle. More importantly, the 3D-GeS2/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 GeS2 and fabricating 3D flexible electrode.(c) 2022 Elsevier B.V. All rights reserved.