Three-dimensional Ag/carbon nanotube-graphene foam for high performance dendrite free lithium/sodium metal 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 cy-cle 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 den-sity 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 mor-phology 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),respec-tively,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.

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

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(3 D) nanostructure composed of gold nanoparticles(Au NPs) supported on 3 D carbon nanotube-graphene foam(3 D CNT-GF)was designed and fabricated as the host of sodium metal anode.Na@3 D 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@3 D 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 3 D Au/CNT-GF is a promising sodium metal anode host.