Performance Of Li Metal Anode Research Articles

Impact of Li Ion Transport Properties on Reversibility of Li Metal Electrode in Glyme‐Based Electrolytes

AbstractThe demand for innovative batteries with high specific energy densities has increased. Li‐metal batteries employing Li‐metal anodes, regarded as the ultimate anodes with a high theoretical capacity, have been extensively studied over the past few decades. However, the poor reversibility and safety concerns regarding Li‐metal anodes remain unresolved. The importance of the electrode/electrolyte interface, especially the solid electrolyte interphase (SEI), for achieving reversibility of Li metal anodes has been extensively studied. Herein, we focused on the impact of the Li ion transport properties in oligoether (glyme)‐based electrolytes on the deposition/dissolution efficiency of Li metal anodes. Analysis of the low‐frequency impedance spectra of Li‐plated Cu/Li cells revealed that the diffusion resistance of Li ions (Rdiffusion) may be a dominant contributor to the internal resistance of the cells employing glyme‐based electrolytes. A higher Rdiffusion in poor‐mass‐transport electrolytes with a lower Li ion transference number resulted in larger polarization during Li deposition/dissolution, leading to more pronounced unfavorable side reactions and lower Coulombic efficiency. Rdiffusion rather than interfacial resistance affected the reversibility of the Li metal anode. Enhancing the Li ion mass transport ability of electrolytes is important for achieving highly reversible charge‐discharge performance of Li metal anodes at high current densities.

Cycling performance of Li metal anode in localized high concentration electrolyte and dynamic mechanism analysis

In this work, we investigated the apparent cycling performance of lithium metal at different chemical compositions and series current densities; examined the microscopic morphology and thickness variation of the deposition layer on the surface of lithium metal anode and the concentration-depth distribution of trace elements in the solid electrolyte interphase (SEI) film; and characterized the kinetic behavior and features of the elementary steps (mass transfer, charge transfer, electro-crystallization) at Li-electrolyte interface using microelectrode technology and various electrochemical test methods. The results show that the lithium metal anode has better cycling performance in high concentration and localized high concentration electrolyte. At the same time, the experimental results confirm that the formation of spherical crystal nucleus is favored only under certain chemical conditions and certain reaction rate; under these conditions, the induction period and the self-smoothing process of critical crystal nucleus can be found. It suggests that there are determined causal among the apparent performance of lithium metal anode, the kinetic parameters of the interfacial charge transfer step and the electro-crystallization step, and these correlations can be used as a reference for screening and evaluating electrolyte systems and battery operating conditions, providing a reliable kinetic basis for future work.

Protective layer for stable lithium-metal anodes at 60 mA·h/cm2 and 60 mA/cm2 with ion channel and inductive effect

Contradiction between ultrafast nucleation and deposition rates of lithium (Li) crystals at high rate and heterogeneity of Li+ flux resulting from concentration polarization has compromised the performance of Li metal anodes especially at high areal capacity and current density. Here, multifunctional protective layer consisting of MoO3 nanobelt films (MoO3-NF) is introduced on the surface of Li by a simple rolling method. The strong binding energy between Li and MoO3 guides the homogeneous nucleation and deposition of Li, while the nanobelt networks provide effective ion channels for uniform distribution of the Li+ flux. Because of the novel multifunctional protective layer, the MoO3-NF@Li anodes demonstrate a remarkable stability for 800 h with ultralow overpotential of 159 mV at extreme harsh conditions of 60 mA·h/cm2 and 60 mA/cm2. MoO3-NF@Li||LiNi0.6Co0.2Mn0.2O2 full-cells can run 100 cycles with a superior capacity retention of 84.2% under practical test conditions, demonstrating great potential for high output and energy-density metal batteries.

High Rate Performance of Li Metal Anode in Na-Containing so2-Based Inorganic Electrolyte

Lithium metal anode is one of the best candidates for the next generation energy storage systems due to the lowest electrochemical potential (- 3.04 V vs. standard hydrogen electrode) and the highest theoretical capacity (3860 mAh g-1). However, lithium metal anode have critical problems including dendritic growth of Li deposits during cycling, poor stability of solid electrolyte interface (SEI) on lithium metal anode and severe chemical reaction between Li metal and the electrolyte. Recently, stable artificial interface layers on the Li metal anode have been proposed to solve these problems. In this work, surface modification of Li metal with a Na-containing SO2-based inorganic electrolyte was investigated as an effective way to prevent lithium dendritic growth during cell operation. The surface-modified lithium metal anode effectively prevented the dendritic deposits of Li deposits even at high current density (3 mA cm-2). More detailed reaction chemistry of Li metal with Na-containing inorganic electrolyte will be discussed in the presentation.

Converting LiNO3 additive to single nitrogenous component Li2N2O2 SEI layer on Li metal anode in carbonate-based electrolyte

With the increasing demand for high energy density energy storage device, Li metal has received intensive attention for its ultrahigh capacity and the lowest redox potential. LiNO3 is widely used as electrolyte additive for ether electrolyte, which can improve the cycle performance of Li metal anode. Compared to ethers, carbonates are more suitable for Li metal batteries with high voltage cathode because they have a wider electrochemical window. However, LiNO3 performs poor solubility in carbonate electrolyte, restricting its application in high voltage Li battery. Herein, we presented a facile method to introduce abundant LiNO3 additive to carbonate electrolyte system by introducing LiNO3-PAN es as the interlayer of the cell. LiNO3-PAN es is in sufficient contact with the electrolyte so that it can continuously releases LiNO3 to assist the formation of Li2N2O2-rich single nitrogenous component SEI layer on Li surface. With the help of LiNO3-PAN es, Li metal anode shows excellent cycle stability even at a high current density of 4 mA/cm2, so that the cycle performance of the full cells was significantly improved, whether in the anode-free Cu||LFP cell or the Li||NCM622 cell.

Liquid-source plasma technology for construction of dual bromine-fluorine-enriched interphases on lithium metal anodes with enhanced performance

The electrochemical performance of Li metal anode is closely bound up with the interphase between Li and lithium-loaded skeleton as well as solid electrolyte interphase (SEI) on Li surface. Herein, for the first time, we propose a novel liquid-source CHBr2F plasma technology to simultaneously construct dual bromine-fluorine-enriched interphases: NiBr2-NiF2 interphase on sponge Ni (SN) skeleton and LiBr-LiF-enriched SEI on Li anode, respectively. Based on density functional theory (DFT) calculations and COMSOL multiphysics simulation results, SN skeleton with NiBr2-NiF2 interphase can effectively decrease the local current density with good lithiophilicity. And the LiBr-LiF-enriched SEI on Li surface can function to block electron tunneling and hinder side electrochemical reduction of electrolyte components, thus suppressing the growth of dendrite and facilitating the homogeneous transportation of lithium ions. Consequently, the Li/SN electrodes with modified interphases show remarkable stability with a low overpotential of 22.6 mV over 1800 h at 1 mA cm–2/1 mAh cm–2 and an exceptional average Coulombic efficiency of 99.6%. When coupled with LiNi0.8Co0.1Mn0.1O2 (NCM811) cathode, the full cells deliver improved cycling stability with a capacity retention of 79.5% even after 350 cycles at 0.5 C. This study provides a facile and new plasma method for the construction of advanced Li anodes for energy storage.

Perspectives on the development of advanced lithium metal anode

The demand for high-energy Li batteries is rapidly increasing due to the growing market for electric vehicles and portable electronic devices. Lithium (Li) metal has been considered as an ideal anode for high-energy Li batteries because of its high theoretical capacity (3860 mAh g<sup>-1</sup>) and low redox potential (-3.04 V vs. SHE). However, the utilization of Li metal anode is still limited by fundamental problems associated with unavoidable dendritic growth and huge volume changes during cycling. To improve the electrochemical performance of Li metal anode, various strategies have been explored including electrolyte design, interfacial engineering, and structural modifications. One of the most promising approaches is to store Li metal in porous host materials, which can effectively suppress the formation of Li dendrite and volume expansion. Herein, we focus on recent progress in the development of advanced Li metal anodes and suggest research directions and design rules.

Effect of support salts on apparent performance of Li metal anode in Ethylene carbonate/Ethyl methyl carbonate solvent and dynamic mechanism analysis

Lithium metal batteries (LMB) have received widespread attention due to their high energy density and potential commercial value. The relationship between the rate performance, cycling performance, microstructure of the deposition layer, and SEI of lithium anodes has not yet been elucidated. Here, we investigated the cycling performance and rate characteristics of metal lithium anodes in classic carbonate electrolytes containing different supporting salts. And the microstructure and chemical information of the lithium anode surface were analyzed. In addition, microelectrode technology was used to study the dynamic behavior and reaction of electroplating/stripping lithium process under different polarization conditions (current density), revealing the apparent performance, microscopic visual information, and dynamic causes and mechanisms of SEI. The results indicate that in carbonate electrolytes containing LiBOB and LiPF6, the cycling performance of lithium anodes, the microstructure of the deposition layer, and SEI can be significantly improved. Microelectrode research has revealed a close causal relationship between the stability and coordination of each basic step, including lithium ion mass transfer, interface charge transfer, and surface crystallization kinetics parameters, and the apparent performance of lithium anodes. This correlation can serve as a dynamic evaluation basis for future selection and optimization of operating and manufacturing conditions.

Ionic liquid as electrostatic shielding additive for dendrite-free lithium metal battery

Lithium (Li) metal anodes have attracted much attention as their high specific capacity and low electrochemical potential significantly boost the energy density of secondary batteries. Nonetheless, the uncontrolled growth of Li dendrites causing a poor cycle capability restricts the commercialization of Li metal batteries. Herein, an ionic liquid with a long aliphatic chain (N-methyl-N-decyl pyrrolidinium (Pyr1(10)+) bis(trifluoromethanesulphonyl)imide (TFSI−)) is introduced as a non-consuming electrostatic shielding additive into the ether-based electrolyte. The admirable compatibility of Pyr1(10)+ cation with Li metal is verified via electrochemical analysis, and the adsorption of Pyr1(10)+ on the Li-metal/electrolyte interface is confirmed by Surface-enhanced Raman spectroscopy technique. Through redistributing the Li ions on the surface of Li metal, the growth of Li dendrites is suppressed, so as to improve the cycling performance of Li metal anodes in symmetric cells, asymmetric cells and Li||LiFePO4 full cells with low N/P ratio (3:1). This study provides new insights into revealing the electrostatic shielding mechanism of regulating Li metal deposition and prolonging the long-term cycling.

Memory Effect of MgAl Layered Double Hydroxides Promotes LiNO3 Dissolution for Stable Lithium Metal Anode

AbstractLiNO3 is an effective additive for improving the performance of Li metal anodes. However, the practical application of LiNO3 is limited due to its poor solubility. Here, a novel electrolyte additive of MgAl layered double hydroxides (LDHs) with open interlayered anionic vacancies is proposed. The electropositive MgAl LDHs promote the spontaneous coordination of NO3− into anionic vacancies of LDH interlayers via memory effect, rehydrating to original NO3−‐MgAl LDHs structure and accelerating LiNO3 dissolution. The reconstructed NO3−‐MgAl LDHs play a crucial role as sustainable nitrate resources, preventing partial NO3− from participating in the Li+ solvent sheath to reduce the solvation binding energy. Moreover, MgAl LDHs absorb the anions due to electrostatic attraction, accounting for more dissociated Li+ and active Li+ migration in carbonate electrolytes. NO3− stored in MgAl LDHs is also preferentially reduced to form Li3N‐rich solid electrolyte interphase (SEI), decreasing the activation energy barrier for Li+ transport and striving to form a uniform Li deposition. The cells assembled with MgAl LDHs and LiNO3 additives deliver high Coulombic efficiency, excellent rate capability, and high capacity retention. This strategy provides new insights into LiNO3‐promotor design and excavates the potential of LDHs materials for Li metal batteries.

Spatially isolating Li+ reduction from Li deposition via a Li22Sn5 alloy protective layer for advanced Li metal anodes.

A Li alloy based artificial coating layer can improve the cyclic performance of Li metal anodes. However, the protective mechanism is not well clarified due to multiple components of the artificial layer and complicated interface in liquid electrolytes. Herein, a single-component Li22Sn5 alloy layer buffered Li anode is paired with a solid-state polymer electrolyte, where a metallic Sn film is sputtered onto the Li anode and the subsequent alloying reaction leads to the formation of a Li22Sn5 phase. During the striping/plating process, the thickness and composition of the Li-Sn alloy passivation layer remain unchanged. Meanwhile, Li+ ions are reduced on the top surface of the Li22Sn5 layer, then the reduced Li atoms immediately pass through the alloy layer, and finally dense Li deposition occurs beneath the protective layer, realizing spatial isolation of the electrochemical reduction of Li+ from Li nucleation/growth. This unique protection mechanism can principally avoid the formation of Li dendrites and efficiently mitigate irreversible reactions between the Li anode and the polymer electrolyte. The synergistic effects lead to a clean and flat surface of the protected Li electrode, enabling a prolonged cycle lifetime over 1300 h at 25 °C at 0.1 mA cm-2 and 0.1 mA h cm-2 in a configuration of symmetrical cells.

Three-dimensional MOF-derived host with surface-preferred and spatial-selective effect for dendrite-free lithium metal battery

The large-scale applications of lithium metal batteries (LMBs) are still impeded by the unsatisfactory electrochemical performance of Li metal anode associated with the infinite volumetric change and the uncontrollable Li dendrite growth. Herein, free-standing and robust nitrogen-doped 3D porous carbon nanofibers networks embedded with Zn-carbon hybrid nanocages are obtained as stable hosts for guiding uniform Li nucleation and accommodating volume expansion. Benefiting from the reduced local current density and abundant lithiophilic sites with low nucleation barriers, the as-prepared NCNFs-Zn-CCs electrode can achieve a low overpotential of 20 mV at 3 mA cm−2 and a stable Li plating/stripping process for 3200 h were achieved in symmetric cells. This work opens a new avenue to explore and broaden the applications of lithiophilic carbon materials in next-generation lithium metal batteries with excellent cycling stability and rate performance.

Advanced Composite Lithium Metal Anodes with 3D Frameworks: Preloading Strategies, Interfacial Optimization, and Perspectives.

Lithium (Li) metal is regarded as the most promising anode candidate for next-generation rechargeable storage systems due to its impeccable capacity and the lowest electrochemical potential. Nevertheless, the irregular dendritic Li, unstable interface, and infinite volume change, which are the intrinsic drawbacks rooted in Li metal, give a seriously negative effect on the practical commercialization for Li metal batteries. Among the numerous optimization strategies, designing a 3D framework with high specific surface area and sufficient space is a convincing way out to ameliorate the above issues. Due to the Li-free property of the 3D framework, a Li preloading process is necessary before the 3D framework that matches with the electrolyte and cathode. How to achieve homogeneous integration with Li and 3D framework is essential to determine the electrochemical performance of Li metal anode. Herein, this review overviews the recent general fabrication methods of 3D framework-based composite Li metal anode, including electrodeposition, molten Li infusion, and pressure-derived fabrication, with the focus on the underlying mechanism, design criteria, and interfacial optimization. These results can give specific perspectives for future Li metal batteries with thin thickness, low N/P ratio, lean electrolyte, and high energy density (>350Wh Kg-1 ).

(Digital Presentation) Higher Surface Area Lithium Anode for Mediated Lithium-Sulfur Flow Batteries

There is a need for safe, reliable, high capacity storage for long duration energy storage. The low cost and high capacity of sulfur make Li-S batteries ideal for this purpose. However, sulfur has poor electrical conductivity and Li-S batteries are prone to polysulfide shuttling that decreases the battery life. Additionally, lithium metal cannot be cycled at high rates or dendritic growth is produced. We have previously addressed the issues with the S by combining aspects of a static Li-S battery with aspects of a redox targeting system and flow battery. With this system we demonstrated that fundamental Li-S chemistry and novel SEI engineering strategies can be adapted to the hybrid redox flow battery architecture, obviating the need for ion-selective membranes or flowing carbon additives, and offering a potential pathway for inexpensive, scalable, safe MWh scale Li-S energy storage.However, with a planar Li anode the current density was limited to 0.5 mA cm-2, severely limiting the flow battery power output. In this study we present recent progress developing higher surface area anodes to enhance the rate performance of Li metal anodes in flow batteries. The high effective surface area of these structures decreases the local current density while maintaining a high device-level current and thus charge rate. The low local current density and seeded nucleation points on the scaffold promote uniform Li deposition during charging. Candidate electrode materials are evaluated in a mediated Li-S flow battery and cycling rate and capacity retention are compared against a traditional planar Li anode.Sandia National Laboratories is a multi-mission laboratory managed and operated by National Technology and Engineering Solutions of Sandia, LLC., a wholly owned subsidiary of Honeywell International, Inc., for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-NA0003525.

Li Metal Anode Stabilized By Artificial Solid Interphase with Polymers of Intrinsic Microporosity

Lithium metal has drawn attention as one of the most promising anode materials because of its highest specific capacity and lowest working potential. However, poor capacity retention and dendrite formation during cycling mainly caused by high chemical reactivity of Li metal with the electrolyte still remain challenges for practical battery application. In this presentation, we demonstrate that polymers of intrinsic microporosity(PIM-1) is highly effective in stabilizing the interface between Li metal anode and the electrolyte as an artificial solid interphase using various analytical techniques and electrochemical characterization techniques. We found a desolvation effect of electrolyte by PIM-1 coating through size-sieving, thereby forming the uniform and stable lithium deposition during cycling. Highly stable artificial solid interphase with polymers of intrinsic microporosity improved the interfacial stability and electrochemical performance of Li metal anode. The electrochemical performance and morphological change of lithium metal anode will be discussed in more detail in the presentation.

Molecular Layer Deposition for Stable Lithium Metal Anode: From Composition Design to Mechanism Study

Energy storage systems with higher gravimetric energy density is highly desirable to fulfil the increasing requirement for various applications. One of the most promising direction is the development of next-generation batteries. Lithium (Li) metal is considered as the ‘Holy Grail’ for the anode materials owing to its ultrahigh capacity and low electrochemical potential [1]. Nevertheless, the application of Li metal as anode material has long been hindered due to some great challenges, such as poor cycling stability and short life span. The serious side reaction between metallic Li and organic electrolyte results in the formation of solid electrolyte interphase (SEI). On one hand, the SEI serves as a passivation layer on the surface which partially prevents further side reaction. On the other hands, the undesired dendrite growth cannot be prevented by SEI due to its heterogeneous and unstable properties [2]. Modification on the interphase to tune and stabilize its property has been considered as an approach to improve the cycling performance of Li metal anode. Recent studies on stabilizing SEI for Li metal anode can be divided into two categories, in-situ and ex-situ approach. In-situ approach refers to the design of electrolyte using electrolyte additives or adjusting the concentration of Li salt. Ex-situ approach refers to the construction of surface coating, including metal oxides, phosphates, and polymers on Li prior to electrochemical cycling [3]. An ideal SEI requires high ionic conductivity, good mechanical property, thin thickness, and high chemical stability. Nevertheless, it is still challenging to fulfil all the requirements of an ideal SEI for long-life and stable Li metal anode.Recent studies have demonstrated the application of Atomic layer deposition (ALD) and Molecular layer deposition (MLD) on the interphase modification of batteries. As a coating technique, ALD is can be applied to deposit inorganic materials such as various metal oxides. It shows unique advantages such as low depositing temperature, uniform film morphology and precise control over thickness in nanoscale [4-6]. As a derivative technique to ALD, MLD is widely used to fabricated inorganic-organic hybrid or pure polymer coatings. MLD still possesses the advantages of ALD and provides additional advantages such as tuneable mechanical property and adjustable coating composition. Our group previously reported ALD metal oxide and MLD metalcone as artificial SEI for metallic Li anodes [7-8].In this report, we demonstrate a type of MLD Polyurea (PU) coatings for metallic Li to modify the SEI layer [9-10]. The cycling life and stability has been improved upon the application of MLD PU. The surface chemistry of PU on Li is characterized by TOF-SIMS and XPS to investigate the evolution of SEI and the role of polymer coating. The results showed that MLD coating can effectively suppress the dendrite growth and remain stable under repeated Li plating/stripping. Furthermore, the nitrogen-containing polar groups in PU can effectively regulate the Li-ion flux and lead to a uniform Li deposition. In our following study, aluminium crosslinkers have been introduced into PU to achieve a hybrid nanoscale polymeric protective film with tuneable composition and improved stiffness. Owing to the improvement in the mechanical property, the protected Li can deliver much stable performance for more than 350 h with a higher cycling capacity of 2 mAh cm−2 without a notable increase in overpotential. Moreover, a stable charge/discharge cycling in Li–O2 batteries with the protected Li can be maintained for more than 600 h. Our study on MLD protected Li provides guidance on the rational design of electrode interfaces and opens new opportunities for the fabrication of next‐generation energy storage systems.[1] D. Lin, Y. Cui, et al, Nature Nanotechnology, 2017, 12, 194-206[2] X. Cheng, Q. Zhang, et al, Chemical Reviews, 2017, 117, 10403-10473[3] X. Cheng, Q. Zhang, et al, Adv. Sci., 2016, 3, 1500213[4] Y. Zhao, X. Sun, ACS Energy Lett. 2018, 3, 4, 899–914[5] Y. Zhao, X. Sun, et al, Joule, 2018, 2, 12, 2358-2604[6] Y. Zhao, X. Sun, et al, Chem. Soc. Rev., 2021, 50, 3889-3956[7] Y. Zhao, X. Sun, et al, Small Methods, 2018, 2, 1700417[8] K. R. Adair, X. Sun et al, Angew. Chem. Int. Ed., 2019, 58, 15797.[9] Y. Sun, X. Sun, et al, Adv. Mater., 2019, 31, 1806541[10] Y. Sun, X. Sun, et al, Adv. Energy Mater., 2020, 10, 2001139.

Dendrite-Free Li Metal Anodes and the Formation of Plating Textures with a High Transference Number Modified Separator.

The application of Li metal anodes is currently hindered by the uncontrolled growth of Li dendrites. Herein, the effects of a modified separator with a high Li+ transference number (t+ ) on the structure and electrochemical performance of Li metal anodes are reported. Stable and dendrite-free plating/stripping cycles are achieved under current densities up to 5mA cm-2 and areal capacities up to 20 mAh cm-2 . The uniformly grown Li grains under the high t+ environment also exhibit well-defined textures (preferred orientations). At a low plating capacity, epitaxial growth takes place on the {100} textures already existing in the rolled Li foils and the uniform Li+ flux strengthens this preferred orientation. Increasing the plating capacity to 20mAh cm-2 , the later-grown textures change to {110} due to the reduced space charges and alleviated transport limits of Li+ under the high t+ environment, which favor the exposure of the close-packed {110} planes. Compression-induced <111>fiber textures are also resolved and the content increases with the plating capacity. Identification of the textures is meaningful for the exploration of advanced epitaxial substrates beyond Cu foils for high-energy-density Li metal batteries. LiS pouch cells are finally evaluated for the potential application of the modified separator.

Synergistic Effect of a Dual-Salt Liquid Electrolyte with a LiNO3 Functional Additive toward Stabilizing Thin-Film Li Metal Electrodes for Li Secondary Batteries.

Li metal thickness has been considered a key factor in determining the electrochemical performance of Li metal anodes. The use of thin Li metal anodes is a prerequisite for increasing the energy density of Li secondary batteries intended for emerging large-scale electrical applications, such as electric vehicles and energy storage systems. To utilize thin (20 μm thick) Li metal anodes in Li metal secondary batteries, we investigated the synergistic effect of a functional additive (Li nitrate, LiNO3) and a dual-salt electrolyte (DSE) system composed of Li bis(fluorosulfonyl)imide (LiTFSI) and Li bis(oxalate)borate (LiBOB). By controlling the amount of LiNO3 in DSE, we found that DSE containing 0.05 M LiNO3 (DSE-0.05 M LiNO3) significantly improved the electrochemical performance of Li metal anodes. DSE-0.05 M LiNO3 increased the cycling performance by 146.3% [under the conditions of a 1C rate (2.0 mA cm-2), DSE alone maintained 80% of the initial discharge capacity up to the 205th cycle, whereas DSE-0.05 M LiNO3 maintained 80% up to the 300th cycle] and increased the rate capability by 128.2% compared with DSE alone [the rate capability of DSE-0.05 M LiNO3 = 50.4 mAh g-1, and DSE = 39.3 mAh g-1 under 7C rate conditions (14.0 mA cm-2)]. After analyzing the Li metal surface using scanning electron microscopy and X-ray photoelectron spectroscopy, we were able to infer that the stabilized solid electrolyte interphase layer formed by the combination of LiNO3 and the dual salt resulted in a uniform Li deposition during repeated Li plating/stripping processes.

Atomic layer deposition assisted superassembly of ultrathin ZnO layer decorated hierarchical Cu foam for stable lithium metal anode

Lithium metal (Li) is regarded as the “holy grail” in the anode material of next-generation high-energy-density batteries. However, the Li dendrites and “dead Li” produced during cycling limit its commercialization process. A properly designed three-dimensional (3D) skeleton plays an important role in determining the performance of Li metal anodes (LMA). Herein, we develop a super-assembled surface-modified lipophilic thin ZnO layer by atomic layer deposition (ALD) and multi-level Cu nanofibers (MCN) on a Cu foam (ZnO-MCNCF) as an advanced Li metal anode host. During the Li plating process, lipophilic ZnO layer can induce uniform nucleation of Li. Meanwhile, the unique hierarchical structure provides a larger specific surface area to distribute the surface charge uniformly, adjust the current density, and ensure more uniform Li deposition. Consequently, the as-designed ZnO-MCNCF host enables dendrite-free deposition of Li, high coulombic efficiency, and remarkable cycling stability at various current densities. Compared with CF and MCNCF host, ZnO-MCNCF has significantly improved Li plating/stripping behavior, with high coulombic efficiency (CE) and excellent Li dendrite growth inhibition ability. The Li@ZnO-MCNCF electrode can be operated for 1400 h at a current density of 10 mA cm−2 and large area specific capacity of 10 mAh cm−2 with an ultra-low overpotential (57.1 mV) without significant fluctuations. The LiFePO4-Li (LFP-Li) and LiCoO2-Li (LCO-Li) full cells also exhibit superior cycling and rate performance.

Lithiophilic Vertical Cactus‐Like Framework Derived from Cu/Zn‐Based Coordination Polymer through In Situ Chemical Etching for Stable Lithium Metal Batteries

AbstractDetrimental dendritic lithium (Li) growth, infinite volume expansion of Li deposition and inevitable excess electrolyte consumption have always impeded the successful application of Li metal anodes. Herein, a unique lithiophilic vertical cactus‐like framework (LVCF) derived from a Zn/Cu‐based coordination polymer through in situ chemical etching of Cu foam is proposed to enhance the safety and electrochemical performance of Li metal anodes. An ingenious strategy of releasing Cu ions from Cu foam in the presence of organic ligands is implemented successfully to achieve the coordination polymer precursor, resulting in the coexistence of massive lithiophilic nitrogen‐containing functional groups, ZnO quantum dots and in situ grown carbon nanotubes (CNTs) in the LVCF, which is beneficial to avoiding the generation of harmful Li dendrites. Benefiting from the positive effects of the improved lithiophilicity, decreased local current density and relieved volume expansion, LVCF delivers an ultrastable Coulombic efficiency of 98.6% for 600 cycles at 1 mA cm–2 and an improved cycling lifespan of 1800 h for symmetric cells. Full cells comprising LVCF@Li anodes and LiFePO4 cathodes can deliver an ultrahigh capacity of 101.8 mAh g–1 (capacity retention ratio: 77.9%) after 900 cycles at 1 C and excellent rate performance.