Dual-Functional Electrode Promoting Dendrite-Free and CO_(2) Utilization Enabled High-Reversible Symmetric Na-CO_(2) Batteries

Sodium-carbon dioxide(Na-CO_(2))batteries are regarded as promising energy storage technologies because of their impressive theoretical energy density and CO_(2)reutilization,but their practical applications are restricted by uncontrollable sodium dendrite growth and poor electrochemical kinetics of CO_(2)cathode.Constructing suitable multifunctional electrodes for dendritefree anodes and kinetics-enhanced CO_(2)cathodes is considered one of the most important ways to advance the practical application of Na-CO_(2)batteries.Herein,RuO2 nanoparticles encapsulated in carbon paper(RuCP)are rationally designed and employed as both Na anode host and CO_(2)cathode in Na-CO_(2)batteries.The outstanding sodiophilicity and high catalytic activity of RuCP electrodes can simultaneously contribute to homogenous Na+distribution and dendrite-free sodium structure at the anode,as well as strengthen discharge and charge kinetics at the cathode.The morphological evolution confirmed the uniform deposition of Na on RuCP anode with dense and flat interfaces,delivering enhanced Coulombic efficiency of 99.5%and cycling stability near 1500 cycles.Meanwhile,Na-CO_(2)batteries with RuCP cathode demonstrated excellent cycling stability(>350 cycles).Significantly,implementation of a dendrite-free RuCP@Na anode and catalytic-site-rich RuCP cathode allowed for the construction of a symmetric Na-CO_(2)battery with long-duration cyclability,offering inspiration for extensive practical uses of Na-CO_(2)batteries.

Self-assembled, highly-lithiophilic and well-aligned biomass engineered MXene paper enables dendrite-free lithium metal anode in carbonate-based electrolyte

Lithium metal anode is the ideal candidate for high-energy–density rechargeable batteries.However,uncontrolled dendrite growth hampers its commercialization.Herein,a dendrite-free composite Li metal anode is realized by a flexible,freestanding,well-aligned and highly-lithiophilic MXene paper designed by a facile electrostatic self-assembly of the exfoliated MXene nanosheets and natural polysaccharidechitosan (MX@CS).The MX@CS paper gets a well-aligned layered-3D structure with a micro-crumpled surface that can effectively decrease the local current density,guide even Li plating and suppress dendritic Li growth.More importantly,surface-adsorbed chitosan endows enhanced lithiophilicity for MXene substrate and thus reduces the Li nucleation overpotential,which is confirmed by the density functional theory calculations.Abundant lithiophilic groups on MX@CS surface provide highconcentration Li^(+)anchoring site promoting Li nucleation and laterally inducing uniform Li deposition,which effectively avoids the formation of dendritic Li.As a result,the MX@CS-Li anode with a dendrite-free Li morphology shows a significantly improved cycling life in commercial carbonatebased electrolyte.When coupled with LiNi_(0.8)Co_(0.1)Mn_(0.1)O_(2)cathode,the full cell exhibits a low capacity decay and steady ultrahigh Coulombic efficiency of 99.6%at a current density of 5C.These findings develop a new approach for designing high-performance metal-based rechargeable batteries.

Emerging Carbon Nanotube-Based Nanomaterials for Stable and Dendrite-Free Alkali Metal Anodes:Challenges,Strategies,and Perspectives

Alkali metals(Li,Na,and K)are promising candidates for high-performance rechargeable alkali metal battery anodes due to their high theoretical specific capacity and low electrochemical potential.However,the actual application of alkali metal anodes is impeded by the challenges of alkali metals,including their high chemical reactivity,uncontrolled dendrite growth,unstable solid electrolyte interphase,and infinite volume expansion during cycling processes.Introducing carbon nanotube-based nanomaterials in alkali metal anodesis an effective solution to these issues.These nanomaterials have attracted widespread attention owing to their unique properties,such as their high specific surface area,superior electronic conductivity,and excellent mechanical stability.Considering the rapidly growing research enthusiasm for this topic in the last several years,we review recent progress on the application of carbon nanotube-based nanomaterials in stable and dendrite-free alkali metal anodes.The merits and issues of alkali metal anodes,as well as their stabilizing strategies are summarized.Furthermore,the relationships among methods of synthesis,nano-or microstructures,and electrochemical properties of carbon nanotube-based alkali metal anodes are systematically discussed.In addition,advanced characterization technologies on the reaction mechanism of carbon nanotube-based nanomaterials in alkali metal anodes are also reviewed.Finally,the challenges and prospects for future study and applications of carbon nanotube-based AMAs in high-performance alkali metal batteries are discussed.

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

Although lithium(Li)and sodium(Na)metals can be selected as the promising anode materials for next‐generation rechargeable batteries of high energy density,their practical applications are greatly restricted by the uncontrollable dendrite growth.Herein,a platinum(Pt)–copper(Cu)alloycoated Cu foam(Pt–Cu foam)is prepared and then used as the substrate for Li and Na metal anodes.Owing to the ultrarough morphology with a threedimensional porous structure and the quite large surface area as well as lithiophilicity and sodiophilicity,both Li and Na dendrite growths are significantly suppressed on the substrate.Moreover,during Li plating,the lithiated Pt atoms can dissolve into Li phase,leaving a lot of microsized holes on the substrate.During Na plating,although the sodiated Pt atoms cannot dissolve into Na phase,the sodiation of Pt atoms elevates many microsized blocks above the current collector.Either the holes or the voids on the surface of Pt–Cu foam what can be extra place for deposited alkali metal,what effectively relaxes the internal stress caused by the volume exchange during Li and Na plating/stripping.Therefore,the symmetric batteries of Li@Pt–Cu foam and Na@Pt–Cu foam have both achieved long‐term cycling stability even at ultrahigh areal capacity at 20 mAh cm−2.

Stress relief and crystal face transition process contribute to the stability of zinc anodes

Zn electrodes are suffering the dendrite growth owing to the enrichment of local space charge, distinct exposed face and residual stress. In this work, we investigated the crystal face properties and stress state of Zn foil through static energy calculations, dynamic crystal growth analysis and finite element simulation of stress states. Then thermal driven is deployed to modify the exposure face and residual stress of Zn foil, aiming for a dendrite-free electrode. The calculation of surface energies and simulation of crystal growth models for different crystal faces indicate that the(0 0 1) face can maintain stability during deposition. Inspired by this mechanism, the(1 0 1) exposed commercial Zn foil is modified by thermal processing. Firstly, the exposure level of the(0 0 1) face increases, though only the peak corresponding to the(0 0 2) crystal face is observed, due to the extinction effect of the densely packed plane(0 0 1) face.Further, the surface morphology becomes smooth and the stress is released with the progresses time.These stress relief and crystal face transition process strengthen the uniformity of ion distribution, and increase the interface stability during the crystal growth, which reduce the defect sites in the deposition.As a result, the Zn electrode exhibits tiny voltage hysteresis and outstanding cycle stability, which reveals improved electrochemical performance. Additionally, Li and Na can also be improved in exposed crystal faces and release strain energy through similar methods to enhance cycling stability.

Asymmetric Zn-N_4 atomic sites embedded hollow fibers as stable Zn anode for high-performance Zn-ion hybrid capacitor

Zn based electrochemical energy storage systems(EES)have attracted tremendous interests owing to their low cost and high intrinsic safety.Nevertheless,the uncontrolled growth of Zn dendrites and the side reactions of Zn metal anodes(ZMAs)severely restrict their applications.To address these issues,we design the asymmetric Zn-N_(4) atomic sites embedded hollow fibers(AS-IHF)as the flexible host for stable ZMAs.Through introducing different nitrogen resources in the synthesis,two kinds of coordination,i,e.Zn-N(pyridinic)and Zn-N(pyrrolic),are introduced in the Zn-N_(4) atomic module synchronously.The asymmetric Zn-N_(4) module with regulated micro-environment facilitates the superior zincophilic features and promotes the Zn adsorption.Meanwhile,the highly porous structure of the hollow fiber effectively reduces local current density,homogenize Zn ion flux,and alleviate structure stress.All the advantages endow the high efficiency and good stability for Zn plating/stripping.Both theoretical and experimental results demonstrate the high reversibility,low nucleation overpotential,and dendritefree behavior of the AS-IHF@Zn anode,which afford the high stability in high-rate and long-term cycling.Moreover,the solid-state Zn-ion hybrid capacitor(ZIHC)based on AS-IHF@Zn anode shows the high flexibility,reliability,and superior long-term cycling capability in a wide-range of temperatures(-20-25℃).Therefore,the present work not only gives a new strategy for modulating local environments of single atomic sites,but also propels the development of flexible power sources for diverse electronics.

Designing Conformal Electrode-electrolyte Interface by Semi-solid NaK Anode for Sodium Metal Batteries

Solid-state Na metal batteries(SSNBs),known for its low cost,high safety,and high energy density,hold a significant position in the next generation of rechargeable batteries.However,the urgent challenge of poor interfacial contact in solid-state electrolytes has hindered the commercialization of SSNBs.Driven by the concept of intimate electrode-electrolyte interface design,this study employs a combination of NaK alloy and carbon nanotubes to prepare a semi-solid NaK(NKC)anode.Unlike traditional Na anodes,the paintable paste-like NKC anode exhibits superior adhesion and interface compatibility with both current collectors and gel electrolytes,significantly enhancing the intimate contact of electrode-electrolyte interface.Additionally,the filling of SiO_(2)nanoparticles improves the wettability of NaK alloy on gel polymer electrolytes,further achieving a conformal interface contact.Consequently,the overpotential of the NKC symmetric cell is markedly lower than that of the Na symmetric cell when subjected to a long cycle of 300 h.The full cell coupled with Na_(3)V_(3)(PO_(4))_(2)cathodes had an initial discharge capacity of 106.8 mAh·g^(-1)with a capacity retention of 89.61%after 300 cycles,and a high discharge capacity of 88.1 mAh·g^(-1)even at a high rate of 10 C.The outstanding electrochemical performance highlights the promising application potential of the NKC electrode.

Three dimensional phase-field simulation for non-isothermal binary alloy solidification: Comparison with LKT theory

Using the advanced algorithm combining parallel computing,adaptive mesh re-griding and multigrid methods,quantitative 3D phase-field simulations of non-isothermal solidification of binary alloy were carried out.The 3D phase-field simulation results were compared with the analytical LKT(Lipton,Kurz and Trivedi)theory.For comparison,the simulation and analytical results for 2D cases were also given.The 3D phase-field simulation results support the transport portion of the LKT theory.However,the tip radius and tip velocity predicted by the simulations are not in good agreement with the LKT theory over the whole range of undercooling.The stability parameter calculated from phase-field simulations varies significantly with the Peclet number,indicating that the stability criterion,which assumes that the stability parameter is constant,is invalid.

Crystal Nucleation and Growth of Al-based Alloys Produced by Electrolysis

The nucleation and growth of grains in a series of Al-based alloys produced by electrolysis are observed under SEM. The atomic Ti/AI ratios of the nuclei and the distribution of Ti at certain points are analyzed by point EDS. The particles in different atomic Ti/AI ratios might act as the nuclei of α-Al. At the early stage of growth, the spherical Ti-enriched regions might form around these particles within very limited temperature ranges in which the reactions such as the peritectic reactions etc occur. At the latter stage of growth, the dendrites freely develop in the radial orientations, and the concentration of Ti decreases linearly along the dendrite arm and becomes negligible in the region near the periphery of the dendrite. It is believed that the nucleation is closely related with the number and dispersion of primary spherical areas in the melts, and the segregation of Ti leads to the free growth of dendrite, which is necessary for the formation of equiaxial grains.

Designer uniform Li plating/stripping through lithium–cobalt alloying hierarchical scaffolds for scalable high-performance lithium-metal anodes

Lithium metal anodes are of great interest for advanced high-energy density batteries such as lithiumair, lithium-sulfur and solid-state batteries, due to their low electrode potential and ultra-high theoretical capacity. There are, however, several challenges limiting their practical applications, which include low coulombic efficiency, the uncontrollable growth of dendrites and poor rate capability. Here, a rational design of 3D structured lithium metal anodes comprising of in-situ growth of cobalt-decorated nitrogen-doped carbon nanotubes on continuous carbon nanofibers is demonstrated via electrospinning.The porous and free-standing scaffold can enhance the tolerance to stresses resulting from the intrinsic volume change during Li plating/stripping, delivering a significant boost in both charge/discharge rates and stable cycling performance. A binary Co-Li alloying phase was generated at the initial discharge process, creating more active sites for the Li nucleation and uniform deposition. Characterization and density functional theory calculations show that the conductive and uniformly distributed cobalt-decorated carbon nanotubes with hierarchical structure can effectively reduce the local current density and more easily absorb Li atoms, leading to more uniform Li nucleation during plating. The current work presents an advance on scalable and cost-effective strategies for novel electrode materials with 3D hierarchical microstructures and mechanical flexibility for lithium metal anodes.

Host-guest supramolecular interaction behavior at the interface between anode and electrolyte for long life Zn anode

The hydrogen evolution reaction (HER) and dendrite growth associated with Zn anode have become the main bottlenecks for the further development of zinc ion batteries (ZIBs).In this work,the electrochemical activity of H_(3)O^(+) is inhibited by the supramolecular host–guest complex composed of H_(3)O^(+) as guest and 18-crown-6 as host.The even Zn plating is induced by the host–guest complex electrostatic shielding layer on Zn anode,as detected by in-situ optical microscopy.The lamellar Zn is plated which profits from the improved Zn plating behavior.Density functional theory (DFT) calculation presents the stable structure of complex.The less produced H_(2) content is monitored online by a mass spectrometer during Zn plating/stripping,which indicates HER can be hampered by the host–guest behavior.Thus,the ZIBs with long life and high Coulombic efficiency are achieved via introducing 18-crown-6.The proposed host–guest supramolecular interaction is expected to facilitate the furthermore development of Zn batteries.

Chemical surface tuning of zinc metal anode toward stable,dendrite-less aqueous zinc-ion batteries

The commercialization of Zn batteries is confronted with urgent challenges in the metal anode,such as dendrite formation,capacity loss,and cracking or dissolution.Here,surface interfacial engineering of the Zn anode is introduced for achieving safety and dendritic-free cycling for high-performance aqueous Zn batteries through a simple but highly effective chemical etching-substitution method.The chemical modification induces a rough peak-valley surface with a thin fluorine-rich interfacial layer on the Zn anode surface,which regulates the growth orientation via guiding uniform Zn plating/stripping,significantly enhances accessibility to aqueous electrolytes and improves wettability by reducing surface energy.As a result,such a synergetic surface effect enables uniform Zn plating/stripping with low polarization of 29 m V at a current density of 0.5 m A cm^(-2) with stable cyclic performance up to 1000 h.Further,a full cell composed of a fluorine-substituted Zn anode coupled with aβ-MnO_(2)or Ba-V_(6)O_(13)cathode demonstrates improved capacity retention to 1000 cycles compared to the pristine-Zn cells.The proposed valley deposition model provides the practical direction of surface-modified interfacial chemistries for improving the electrochemical properties of multivalent metal anodes via surface tuning.

Designing sodium alloys for dendrite‐free sodium‐metal batteries

Sodium metal,with a high theoretical specific capacity(~1165 mA h g^(−1))and a low redox potential(−2.71 V vs.SHE)as well as low cost,becomes an attractive option for high‐energy‐density sodium secondary batteries.However,the practical application of sodium metal anodes is hindered by dendrite growth,which results in low energy efficiency,poor lifetime and serious safety issues.To address this challenge,researchers propose various strategies,including the formation of sodium alloys(Na‐M alloys,M=Sn,Sb,Bi,In,etc.)through alloying reaction.The alloying effect has a positive impact in terms of reducing the local current density,mitigating the volume expansion,and inhibiting the dendrite growth.It is thus an effective solution for constructing high‐performance sodium secondary batteries.This review systematically de-scribes the mechanism of dendrite growth and the alloying process of Na‐M alloys,summarizes recent research progress and strategies for applying Na‐M alloys to create dendrite‐free sodium secondary batteries,as well as pre-sents prospects for the development of Na‐M alloys and offers clear sugges-tions for future research.This review aims to inspire further efforts to build dendrite‐free,high‐performance sodium secondary batteries and broaden a new aspect for the next‐generation battery systems.

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.

Highly reversible Zn anode enabled by anticatalytic carbon layer with suppressed hydrogen evolution

Aqueous zinc-ion batteries(AZIBs)have emerged as a promising high-efficiency energy storage system due to the high energy density,low-cost and environmental friendliness.However,the practical application of AZIBs is severely restricted by the challenges faced by the Zn anode,which include uncontrollable dendrite growth,corrosion and hydrogen evolution reaction.Herein,a simple and convenient physical vapor deposition(PVD)method is reported for fabricating uniform graphite as a protection layer on the surface of Zn anode.The high conductivity graphite layer on Zn anode(denoted as Zn@C)not only benefits the uniform distribution of the electric field,but also provides numerous Zn nucleation sites to regulate and navigate Zn-ion stripping/plating behaviors.Additionally,the graphite layer with a poor catalytic activity endows the Zn@C anode with a highly suppressed hydrogen evolution.Consequently,a hydrogen and dendrite free anode is achieved with artificial anticatalytic carbon layer on Zn anode,exhibiting a high reversibility and excellent cycling stability over 2600 h at the current density of 5 mA·cm^(-2)with a capacity of 2.5 mAh·cm^(-2)and longtime cycling stability for assembled full cells.This work strategically designs the properties of the artificial interface layer to effectively address various challenges simultaneously,which presents insights for the future development of high-performance rechargeable AZIBs.

Ultralong-life lithium metal batteries enabled by decorating robust hybrid interphases on 3D layered framworks

Stable solid-electrolyte interphase(SEI)is crucial for advanced development of lithium metal batteries.However,the continuous collapse and reconstruction of SEI will deplete fresh Li and electrolytes upon cycling,leading to irreversible capacity loss.Herein,we addressed this issue by pre-formation of artificial robust hybrid interphase on a 3D layered graphene/lithium metal framework,in which is constructed by LiF associated with Li2TiF 6generated by the in-situ reaction between the surfacial lithium and titanium fluoride contained electrolytes.The as-obtained interphase can maintain the structure integrality and avoid continuous consumption of the fresh Li and electrolytes.As a consequence,the Li symmetric cells achieve high-efficiency Li deposition and stable cycling over 3600 h.When paired with LiFePO_(4)cathodes,the coin cells exhibit long lifespan(>800 cycles)with almost 88.3%retention of the initial capacity.