Three-dimensional Ag/carbon nanotube-graphene foam for high performance dendrite free lithium/sodium metal anodes

Abstract

• Porous 3D Ag/CNT-GF structure effectively alleviates the volume expansion of Li/Na. • Lithiophilic/sodiophilic Ag NPs directionally guide Li/Na deposition. • Dendrite free morphology is achieved in Li/Na@3D Ag/CNT-GF anodes. Although lithium metal and sodium metal are promised as ideal anodes for lithium ion batteries (LIBs) and sodium ion batteries (SIBs), they still suffer from inevitable dendrite growth. In light of this, silver nanoparticles (Ag NPs) are sputtered onto three-dimensional carbon nanotube decorated graphene foam (3D CNT-GF) to construct superior 3D Ag/CNT-GF composite matrix for lithium metal anodes (LMAs) and sodium metal anodes (SMAs). With this design, lithiophilic/sodiophilic Ag NPs could provide favorable sites to guide Li/Na metal nucleation and growth, thus leading to low nucleation overpotentials, high Coulombic efficiency and long cycle performance. Accordingly, 3D Ag/CNT-GF electrodes can stably cycle for 1000 and 750 cycles at 3 mA cm −2 with 1 mAh cm −2 for SMAs and LMAs, respectively. More attractively, it can also stably sustain 300 cycles (SMAs) and 500 cycles (LMAs) at a large current density of 5 mA cm −2 with 1 mAh cm −2 . The excellent electrochemical performance can be attributed to the lithiophilic/sodiophilic electrode surface, 3D porous electrode structure and the dendrite-free morphology as demonstrated by ex-situ scanning electron microscopy (SEM) and in-situ optical microscopy analyses. Furthermore, full cells based on Na@3D Ag/CNT-GF||Na 3 V 2 (PO 4 ) 3 @carbon (NVP@C) and Li@3D Ag/CNT-GF||LiFePO 4 (LFP) could deliver highly reversible capacities of 90.1 and 106.4 mAh g −1 respectively at 100 mA g −1 after 200 cycles for SIBs and LIBs, respectively. This work demonstrates a novel 3D Ag/CNT-GF matrix for boosting Li/Na deposition stability for their future applications. Porous 3D Ag/CNT-GF nanostructure was designed and further adopted as the stable host of lithium/sodium metal anodes. Lithiophilic/sodiophilic Ag NPs directionally guide Li/Na deposition with uniform current density distribution over the 3D Ag/CNT-GF current collector surface, enabling a dendrite free deposition morphology and long cycle stability.