A Sodiophilic Interphase‐Mediated, Dendrite‐Free Anode with Ultrahigh Specific Capacity for Sodium‐Metal Batteries

Abstract

Despite efforts to stabilizesodium metal anodes and prevent dendrite formation, achieving long cycle life with high areal capacities remains difficult owing to ac ombination of complex failure modes that involve retardant uneven sodium nucleation and subsequent dendrite formation. Now,as odiophilic interphase based on oxygen-functionalized carbon nanotube networks is presented, which concurrently facilitates ahomogeneous sodium nucleation and adendrite-free,lateral growth behavior upon recurring sodium plating/stripping processes.T his sodiophilic interphase renders sodium anodes with an ultrahigh capacity of 1078 mAh g À1 (areal capacity of 10 mAh cm À2 ), approaching the theoretical capacity of 1166 mAh g À1 of pure sodium, as well as al ong cycle life up to 3000 cycles.I mplementation of this anode allows for the construction of as odium-air battery with largely enhanced cycling performance owing to the oxygen functionalizationmediated, dendrite-free sodium morphology.Metallic sodium (Na) has been considered as one of the most attractive anode materials for rechargeable high-energy batteries owing to its high theoretical capacity (1166 mAh g À1 ), low redox potential (À2.714 Vv s. standard hydrogen electrode), and much greater abundance over metallic lithium (Li). [1][2][3] Unfortunately,t he formation of Na dendrites caused by inhomogeneous deposition will decrease the utilization of reactive Na with poor cyclic stability,a nd more importantly,r esult in at hreat of internal short circuit towards thermal runaway and fire hazards (Figure 1a). Therefore,Nadendrites and their related issues have severely hindered the practical applications of sodium-metal batteries (SMBs), [4,5] fore xample,s odium-air batteries [2,6] and roomtemperature sodium-sulfur batteries. [7] To solve these problems,s ignificant progress has been achieved recently by applying various strategies,including an artificial solid-electrolyte interphase (SEI), [8,9] electrolyte additives, [10,11] solid-state electrolytes, [12,13] and nanostructured Na anodes. [14,15] Generally,t hese strategies mainly concentrate on the already formed Na plating morphology,t hat is, Na dendrites,y et few involve the initial Na deposition behavior, including the nucleation. However,t he final Na morphology significantly depends on the initial nucleating behavior, especially upon the realistic application requiring high areal capacity (for example,10mAh cm À2

Sodiophilically Graded Gold Coating on Carbon Skeletons for Highly Stable Sodium Metal Anodes

“…For example, carbon nanotubes have been functionalized with oxygen groups by microwave oxygen plasma. [ 38 ] This treatment lowered the overpotential of Na nucleation and mediated the subsequent Na growth without dendrite formation.…”

Dendrite‐free lithium and sodium metal anodes with deep plating/stripping properties for lithium and sodium batteries

“…The Pt–Cu foam, however, shows a relatively smooth surface only covered by a number of mossy Na (Figure 4E–H), indicating the uniform Na deposition on Pt–Cu/Cu foam. Element mapping analysis results show that on the Pt–Cu foam, the Na element presents a brighter intensity along the edge of Pt–Cu foam (Figure 4I–L), indicating that the deposited Na prefers to fill in the pores of foam for plating on the skeleton 22 . The 3D Pt–Cu foam can provide host for deposited Na, which prevents SEI from rupture and also relaxes the internal stress fluctuation.…”

“…The Na@Pt–Cu foam||Na@Pt–Cu foam symmetric cell can serve more than 300 h at the current density of 1 mA cm −2 with ultrahigh areal capacity of 20 mAh cm −2 . To the best of authors' knowledge, there are only very few reports on Na metal anodes that can cycle under such great areal capacities 22 . However, as there are no Pt atoms in the SEI, the SEI may maintain its long‐range crystallinity, which is not favorable for Na + at the electrode/electrolyte interface.…”

Definable Two-Dimensional Mesoporous Polydopamine-Graphene Heterostructure as Multi-Functional Ion Redistributor for Ultrastable Sodium Metal Anodes

“…19), suggestive of the stable SEI and superior reaction kinetic of Na metal anodes with mPG-12@PP separator. To the best of our knowledge, such a ultrahigh rate performance (25 mA cm − 2 , 25 mAh cm − 2 ) greatly surpassed to those of the state-of-the-art reported Na metal anodes stabilized by diversi ed strategies, such as 3D MXene-melamine foam (20 mA cm − 2 , 20 mAh cm − 2 ) 43 , Na-Hg alloy (8 mA cm − 2 , 8 mAh cm − 2 ) 51 , core-shell C@Sb nanoparticles (5 mA cm − 2 , 1 mAh cm − 2 ) 52 , Sb 2 MoO 6 microspheres (10 mA cm − 2 , 8 mAh cm − 2 ) 53 , oxygen-functionalized carbon nanotube (10 mA cm − 2 , 2 mAh cm − 2 ) 14 , reduced GO aerogel (5 mA cm − 2 , 5 mAh cm − 2 ) 54 , Sn 2+…”

“…Due to high theoretical capacity (1166 mAh g − 1 ), low redox potential (-2.714 V vs. standard hydrogen electrode), natural abundance and low price, metal sodium (Na) has been regarded as a highly competitive anode for next-generation rechargeable battery [5][6][7][8][9] . Unfortunately, its high reactive activity, large volume change, unstable solid electrolyte interface (SEI) and uncontrollable dendritic growth bring about low Coulombic e ciency, limited cyclability, and even safety risk for high-energy-density Na metal batteries, such as Na-S 10 and Na-O 2 batteries 11 , substantially inhibiting their actual applications 5,[12][13][14][15] . To overcome the issues, various strategies, including tailoring electrolyte formulation (e.g., highly concentrated electrolyte, uoroethylene carbonate additive) 16,17 , using solid-state electrolytes (gel polymer with boron nitride, Na 3 Zr 2 Si 2 PO 12 ) 18,19 , creating arti cial SEI (e.g., Al 2 O 3 , sodium benzenedithiolate, graphene) [20][21][22] , and designing nanostructured Na anodes (e.g., Na@O-functionalized carbon nanotube networks, Na@porous Al, Na@carbonized wood) 14,23,24 , have been developed to suppress the growth of Na dendrites and realize stable and safe Na metal anodes.…”