Three-dimensional Au/carbon nanotube-graphene foam hybrid nanostructure for dendrite free sodium metal anode with long cycle stability

Abstract

• Sodiophilic Au NPs guide the sodium metal uniformly deposited onto the surface of Au/CNT-GF without dendrite formation. • The regulated uniform Na metal deposition mechanism is investigated by the in-situ optical microscopy, ex-situ SEM and simulation analysis. • It exhibits a low nucleation overpotential and stable cycle performance for 2600 h at 1 mA cm −2 with 1 mAh cm −2 . Moreover, it can cycle for more than 300 h at 5 mA cm −2 with 1 mAh cm −2 . • Furthermore, a full cell with Na@3D Au/CNT-GF as the anode is fabricated and delivers a capacity of 84.6 mAh g −1 at 100 mA g −1 after 200 cycles. Sodium metal anode has been attracting widely research attention due to its large capacity and low electrode potential as the anode of sodium-ion batteries. However, the uncontrollable growth of Na dendrite is one of the critical issues for its real applications. Herein, a three-dimensional (3D) nanostructure composed of gold nanoparticles (Au NPs) supported on 3D carbon nanotube-graphene foam (3D CNT-GF) was designed and fabricated as the host of sodium metal anode. Na@3D Au/CNT-GF anode can deliver a Coulombic efficiency of 99.14% and stably cycle for 2600 h at 1 mA cm −2 with 1 mAh cm −2 . It can cycle for 300 h at 5 mA cm −2 with 1 mAh cm −2 . Detailed results indicate that its excellent electrochemical performance can be attributed to the unique macroporous structure and sodiophilic surface formed by Au NPs guiding the uniform sodium metal deposition enabled a dendrite-free morphology investigated by the ex-situ SEM and in-situ optical microscopy. At last, a full cell was assembled with Na@3D Au/CNT-GF as the anode and Na 3 V 2 (PO 4 ) 3 @C as the cathode. It can deliver a capacity of 84.6 mAh g −1 at 100 mA g −1 after 200 cycles. Our results demonstrate that 3D Au/CNT-GF is a promising sodium metal anode host.