Confining nano FeSb2S4 in carbon nanotube/oxide graphene 3D porous networks for high-capacity sodium ion battery anode

Abstract Sodium ion batteries (SIBs) are promising alternative for lithium ion batteries (LIBs) due to the abundant reserve of Na compared to Li. Although the three-dimensional (3D) thick electrodes for LIBs have been widely studied, corresponding researches are seldom reported for SIBs anode. Herein, a high theoretical capacity binary metal sulfide (FeSb2S4) on reduced oxide graphene (rGO) was used as active component to prepare the light-weight, current collector-free, 3D thick anode (FeSb2S4/CNTs/rGO/GO) for SIBs. The as-prepared 3D discs can keep its integral structure under the pressure from the battery assembly, as the interconnected macropores are formed during the freeze-drying process. The macropores can also act as the electrolyte channel to facilitate the mass transfer, thus enabling the low Na+ diffusion resistance when the thickness of the electrodes increased from 150 µm to 540 µm. Based on the capacity calculation of the active components (FeSb2S4/rGO), the as-prepared 3D discs with a thickness of 540 µm can achieve a mass capacity of 391.7 mAh g–1 under 0.1 A g–1, corresponding to 3.11 mAh cm–2 of area-capacity and 57.64 mAh cm–3 of volume-capacity, respectively.