Interfacial friction enabling ≤ 20 μm thin free-standing lithium strips for lithium metal batteries

Silicified-montmorillonite assisted in-situ construction of LiF-rich phase for enhanced interfacial stability in solid-state lithium batteries

The interfacial failure of solid polymer electrolytes (SPEs) with Li anode, particularly those containing succinonitrile (SN) types, has significantly hindered the practical development of solid-state lithium-metal batteries. Herein, we introduce silicified montmorillonite (SiO2-MMT) into polyethylene oxide (PEO)/SN-based SPEs to facilitate the in-situ formation of a LiF-rich phase, thereby significantly enhancing the electrolyte/Li anode interface stability. Specifically, the SiO2-MMT strongly anchors the SN molecules, preventing their migration to the Li anode side. Meanwhile, the TFSI- reacts competitively with Li to generate a dense LiF phase, further blocking the SN chemical corrosion of Li metal. Furthermore, the SiO2-MMT greatly accelerates the Li+ transportability and enhances the thermal stability and mechanical strength of the composite electrolyte. Consequently, the composite electrolyte has a high ionic conductivity of 1.2 × 10-4 S cm-1 at 30 °C, which almost twice as higher as the counterpart. As for the solid-state battery, the LiFePO4||Li cell demonstrates remarkable cycling stability, achieving a high discharge capacity of 141.7 mA h g-1 with a remarkable capacity retention of 90.2 % after 350 cycles at 0.5C. Additionally, the high electrochemical window (4.6 V) ensures compatibility with high-voltage cathode materials. The NCM83||Li cell demonstrates a satisfactory initial discharge capacity and excellent capacity retention of 179.2 mA h g-1 and 81.8 % at 0.2 C after 100 cycles. This work offers a new insight for achieving a highly stable electrolyte/Li anode interface in SN-containing SPEs, facilitating the practical application of solid-state lithium metal batteries with enhanced safety and lifespan.

Fluorocarbon interlayer enhancing fast ion transport for low-temperature lithium metal batteries

Lithium metal batteries optimized for low-temperature conditions are essential for use in cold climate applications. Nevertheless, they are hindered by the markedly reduced kinetics of lithium-ion transport in the vicinity of the lithium metal anode under low-temperature conditions. In contrast to the commonly used electrolyte engineering approaches, this study introduces a design strategy of using a functional fluorocarbon interlayer to reconstruct the surface of the lithium foil (Li@GF), aiming to effectively enhance the electrochemical reaction kinetics of the lithium metal anode at low temperatures. Extensive experimental and theoretical investigations demonstrate that the fluorocarbon interlayer exhibits improved lithiophilicity and provides multiple ionic conductive pathways, thereby promoting uniform and rapid lithium ion transport at the interface. The Li(Ni0.8Co0.1Mn0.1)O2 (NCM811)||Li@GF full cells exhibit a commercial-grade capacity of 84.34 mAh g-1 and maintain an impressive capacity retention of 93.3 % after 300 cycles at -40 °C. The strategic design of a functional interphase aimed at improving ion transfer kinetics offers new perspectives for the advancement of lithium metal batteries characterized by high areal capacity and prolonged longevity under low-temperature conditions.

Construction of Organic-Inorganic Solid Electrolyte Interphase by Gas-Liquid Plasma for High Performance Lithium Metal Anodes

The construction of high-quality solid electrolyte interphase (SEI) on Li metal is one of the key strategies to improve the performance of Li metal anodes. Herein, we propose a novel gas-liquid hybrid source plasma technology to construct composite SEI consisting of organic lithium methyl carbonate (LMC) and inorganic lithium nitride (Li3N) and lithium oxide (Li2O) on the lithium metal. Supported by the theoretical calculation, the inorganic Li3N and Li2O phases possess low diffusion barrier potentials, favorable for fast Li+ transportation, and enhanced lithophilicity. Meanwhile, the organic LMC can effectively accommodate the volume expansion of lithium metal due to its high mechanical flexibility. Accordingly, the lithium metal anode modified by plasma-made SEI has a low overpotential of 11.4 mV at 1 mAh cm-2 for 950 h with an average Coulombic efficiency of 99.7%, superior to the unmodified Li metal anode. When coupled with LiNi0.8Co0.1Mn0.1O2 (NCM811) cathode, the assembled full cell is proven with a higher capacity retention of 87.77% after 100 cycles at 0.5 C, indicating its significantly enhanced cycling stability due to the synergistic effect between Li3N, Li2O, and LMC in the composite SEI. This research demonstrates that plasma is a unique method for constructing high-quality SEI to achieve enhanced lithium anodes for energy storage.

Topological Li-SbF3@Cu Alloying Anode for High-Energy-Density Li Metal Batteries

The ultrathin Lithium (Li) alloying anode (≤ 50 µm) plays a key role in advancing rechargeable Li metal batteries into practical use, especially because of the insurmountable difficulties in developing pure Li anode. Herein, a thickness-controllable (≈5.5-30 µm) and topological Li-SbF3@Cu anode with the embedded dual Li-based (Li3Sb and Li-Cu) alloys and outmost LiF-rich layer is prepared for high-energy-density Li metal batteries under high Li utilization. Upon cycling, the surface LiF-rich layer together with inner lithiophilic Li3Sb sites and ferroconcrete-like Li-Cu skeletons, synergistically regulates the Li deposition/dissolution behaviors and Li/electrolyte interface evolution. The assembled Li-SbF3@Cu symmetric cell can cycle stably over 1200 h at 1 mA cm-2/1 mAh cm-2, and realize an ultrahigh discharge/charge depth of 53.6% at 2 mA cm-2/3 mAh cm-2. Moreover, a full cell with a high-Li-capacity LiCoO2 cathode (3.8 mAh cm-2) delivers an energy density of 394.5 Wh kg-1 with impressive cycling reversibility at a low negative/positive electrode capacity (N/P) ratio of 1.5. All the findings provide a rewarding avenue toward the industrial application of high-Li-utilization alloying anodes for practical high-energy-density Li metal batteries.

Soluble Covalent Organic Frameworks as Efficient Lithiophilic Modulator for High-Performance Lithium Metal Batteries

Lithium metal batteries (LMBs) are regarded as the potential alternative of lithium-ion batteries due to their ultrahigh theoretical specific capacity (3860 mAh g-1). However, severe instability and safety problems caused by the dendrite growth and inevitable side reactions have hindered the commercialization of LMBs. To solve them, in this contribution, a design strategy of soluble lithiophilic covalent organic frameworks (COFs) is proposed. By introducing polyethylene glycol as the side chains, two COFs (CityU-28 and CityU-29) not only become soluble for the facile coating technique, but also can facilitate the lithium-ion migration in batteries. Furthermore, when coated on the lithium anode of LMB, both COFs can act as artificial solid electrolyte interphase to prevent dendrite growth thus enabling the long-term stability of the cells. Notably, the symmetric CityU-29@Li cell can work for more than 5000 h at a current density of 2 mA cm-2 and an areal capacity of 1 mAh cm-2. A remarkable capacity retention of 78.9 % after 1500 cycles and a Coulombic efficiency of about 99.9 % at 1.0 C can also be realized in CityU-29@Li||LiFePO4 full cell. This work could provide a universal design strategy for soluble COFs and enlighten their application in diverse scenarios, especially energy-related fields.

Competitive ion-molecule-coordinated interactions for high-voltage and high-rate lithium batteries under ultra-wide temperature

The sluggish ion transport and deteriorating electrode-electrolyte interphase hinder the performance of lithium-ion batteries under wide temperature operation, thereby posing substantial challenges in improving both high-voltage and high-rate performance. Herein, the competitive ion-molecule-coordinated interactions (Li+-anion-solvent-diluent) achieve a balance that directs an anion-dominated and moderate diluent-interacting solvation structure, resulting in an excellent wide-temperature electrolyte with electrochemical stability up to 5.4 V and high Li-ion conductivity (1.034 mS/cm at -60 °C). The corresponding NCM811||Li cells exhibit capacity retention ratios of 90.74% after 200 cycles at -40 °C and 54.68% for 250 cycles at 70 °C. Additionally, the cell achieves stable cycling performance at a high rate of 10 C at 25 °C. Notably, the assembled NCM811||Graphite pouch battery (3 Ah) can be operated at -106 °C and possesses 2.6 Ah at -30 °C, with 90.28% capacity retention after 90 cycles and stable cycling performance at 50 °C. This work provides a new design principle for electrolyte, which may expedite the development of ultra-wide-temperature lithium-ion batteries.

Electrochemical Scanning Microwave Microscopy Reveals Ion Intercalation Dynamics and Maps Active Sites in 2D Catalyst

The accelerated demand for electrochemical energy storage urges the need for new, sustainable, and lightweight materials able to store high energy densities rapidly and efficiently. Development of these functional materials requires specialized techniques that can provide a close insight into the electrochemical properties at the nanoscale. For this reason, the electrochemical scanning microwave microscopy (EC-SMM) enabling local measurement of electrochemical properties with nanometer spatial resolution and sensitivity down to atto-Ampere electrochemical currents is introduced. Its power is demonstrated by studying NiCo-layered double hydroxide flakes, revealing active site locations and providing atomistic insights into the catalytic process. EC-SMM's spatial resolution of 16 ± 1 nm allows detailed analysis of edge effects in this 2D material, including localized electrochemical impedance spectroscopy and cyclic voltammetry. Coupled with advanced numerical modeling of diffusion and migration dynamics at the material interface, the findings elucidate the previously hypothesized processes responsible for localized enhancements in electrochemical activity, while pinpointing essential parameters for tuning the thermodynamics of ion intercalation and optimizing surface adsorption.

Flexible Organic-Polyphosphates Interfacial Layer for Stable Lithium Metal Anode

Lithium (Li) metal is regarded as a desired anode candidate for high-energy-density rechargeable battery systems in the future because of its high specific capacity and low redox potential. However, Li dendritic growth and volume expansion during cycling severely hinder its practical application. Herein, an artificial organophosphorus-inorganic Li hybrid flexbile solid electrolyte interphase (SEI) layer was designed by a prereaction between phytic acid (PA) and lithium hydroxide (LiOH) to generate metal chelates for quick Li+ conductivity. The organic-polyphosphate (PALi) layer not only can provide numerous channels for Li+ to migrate quickly but also can improve its lithiophilicity due to the uniform distribution of phosphorus (P) in the PALi layer; meanwhile, flexibility due to the existence of hydrogen bonds in the PALi layer effectively alleviates the effect of Li volume expansion on the SEI layer. Therefore, the PALi@Cu∥Li cells exhibit a high Coulombic efficiency of 98.85% over 500 cycles at a current density of 0.5 mA cm-2, and the PALi@Cu-Li∥Li symmetrical cells also can maintain good cycling stability with low voltage hysteresis of 20 mV for 2000 h at a current density of 1 mA cm-2. This organic-inorganic hybrid strategy provides a feasible way to fabricate a stable and efficient artificial SEI layer for the practical applications of Li metal batteries.

Tuning the Unloading and Infiltrating Behaviors of Li-Ion by a Multiphases Gradient Interphase for High-Rate Lithium Metal Anodes

The random distribution of organic-phases (OPs) and inorganic-phases (IOPs) in native solid electrolyte interface (SEI) derived a sluggish Li-ion de-solvation and transmission, impairing the high-rate performance of lithium metal anodes (LMAs). Herein, a multiphases gradient distribution hybrid interface is constructed on metallic Li by surface chemical reconstruction. Theoretical simulations and experiments verify that the Li-ion unloading and infiltrating behaviors are tuned by functional complementary effects, enabling speedy kinetics. The upper OPs with polar functional group (─COO-) convert near-surface solvation structure, pushing Li-ion to unload the solvation cluster. Simultaneously, the bottom IOPs with plenty of crystal boundary accelerates Li-ion infiltration. Moreover, flexible OPs cooperate with rigid IOPs to buffer volume fluctuation and suppress dendritic Li growth. Consequently, the lifespan of the composited electrode is significantly prolonged over 520 h at 5 mA cm-2. The full cells also exhibit an exhilarated rate performance and capacity retention even under a low N/P ratio (≈2.5). This work offers a characteristic insight for the rational design of gradient hybrid interface on the practical LMAs.

Low-Solvent-Coordination Solvation Structure for Lithium-Metal Batteries via Electric Dipole-Dipole Interaction

Unveiling inherent interactions among solvents, Li+ ions, and anions are crucial in dictating solvation-desolvation kinetics at the electrode/electrolyte interface. Developing an electrolyte with a low ion-transport barrier and minimal solvent coordination in its interfacial solvation structure is essential for forming an anion-derived solid-electrolyte interface, a key component for high-performance Li-metal batteries. In this study, we harness electric dipole-dipole synergistic interactions to formulate an electrolyte with significantly reduced interfacial solvent coordination. Operando characterization and theoretical analysis reveal that 2-fluoropyridine (FPy) with high dipole preferentially adsorbs onto the Li metal surface. The adsorbed FPy molecule squeezes succinonitrile in the primary solvation sheath through steric hindrance, leading to the formation of an inorganic-rich interphase. Consequently, the introduction of FPy enhances the reversible capacity of the LiCoO2||Li cell, which maintains a capacity of 143 mAh g-1 after 500 cycles at a 1 C rate. Moreover, the cycle life of LiCoO2 batteries with a limited supply of lithium extends from 120 cycles to over 200 cycles. These findings offer a strategy that can be applied broadly to design interfacial solvation structures for various metal-ion/metal-based batteries.

Scalable Production of Thin and Durable Practical Li Metal Anode for High-Energy-Density Batteries

Utilization of thin Li metal is the ultimate pathway to achieving practical high-energy-density Li metal batteries (LMBs), but its practical implementation has been significantly impeded by formidable challenges of poor thinning processability, severe interphase instability and notorious dendritic Li growth. Here we report a practical thin (10-40 μm) Li/Mo/Li2Se with concurrently modulated interphase and mechanical properties, achieved via a scalable mechanical rolling process. The in situ generated Li2Se and Mo not only enhance the mechanical strength enabling the scalable fabrication of thin Li metal, but also promote homogeneous Li electrodeposition. Significantly, the Li/Mo/Li2Se demonstrates ultrahigh-rate performance (15 mA cm-2) and ultralong-lifespan cycling sustainability (2700 cycles) with exceptional anti-pulverization capability. The Li|LiFePO4 cells show substantially prolonged cyclability over 1200 cycles with an ultralow decay rate of ~0.01 % per cycle. Moreover, the Li|LiNi0.8Co0.1Mn0.1O2 pouch cells deliver enhanced cycling stability even under the extremely harsh conditions of low negative-to-positive-capacity (N/P) ratio of ~1.2 and lean electrolyte of ~0.95 g Ah-1, showing an exceptional energy density of 329.2 Wh kg-1. This work sheds light on facile pathway for scalable production of durable thin Li metal anode toward reliable practicability.

Stabilizing Lithium Metal Anodes by Fiber Clustering

Lithium metal anodes generally suffer from uncontrolled dendrite growth and large volume change, while traditional skeletons such as Li13In3 and Li22Sn5 are too heavy and discontinuous to offer highly efficient structural supportability for composite Li anodes. In this work, lightweight and stable fiber-clustered skeletons, which are composed of LiB fibers and jointed Li22Si5 nanoparticles, can be obtained by smelting SiB6 powder and Li ingots. In addition to serving as both ionic and electronic conductors for composite Li anodes, the stable skeletons reduced volumetric fluctuation by offering uniform, heterogeneous, and continuous architectures while suppressing lithium dendrites with low nucleation overpotential and diffusion energy barrier. As a result, the Li-SiB6|Li-SiB6 symmetrical cells achieve an ultralong lifespan over 2000 h cycling at 1 mA cm-2 and 1 mA h cm-2. Eventually, the Li-SiB6|LiFePO4 full cells exhibit a long-term cyclability of 400 cycles with a high-capacity retention of 94.5% at 2 C, and the Li-SiB6|LiCoO2 pouch cells exhibit an impressive 85% capacity retention after 350 cycles. This work develops a new strategy to strengthen the stability of fibrous skeletons and minimize volume changes for dendrite-free Li metal anodes.

Interface engineering enabling thin lithium metal electrodes down to 0.78 μm for garnet-type solid-state batteries

Controllable engineering of thin lithium (Li) metal is essential for increasing the energy density of solid-state batteries and clarifying the interfacial evolution mechanisms of a lithium metal negative electrode. However, fabricating a thin lithium electrode faces significant challenges due to the fragility and high viscosity of Li metal. Herein, through facile treatment of Ta-doped Li7La3Zr2O12 (LLZTO) with trifluoromethanesulfonic acid, its surface Li2CO3 species is converted into a lithiophilic layer with LiCF3SO3 and LiF components. It enables the thickness control of Li metal negative electrodes, ranging from 0.78 μm to 30 μm. Quasi-solid-state lithium-metal battery with an optimized 7.54 μm-thick lithium metal negative electrode, a commercial LiNi0.83Co0.11Mn0.06O2 positive electrode, and a negative/positive electrode capacity ratio of 1.1 shows a 500 cycles lifespan with a final discharge specific capacity of 99 mAh g-1 at 2.35 mA cm-2 and 25 °C. Through multi-scale characterizations of the thin lithium negative electrode, we clarify the multi-dimensional compositional evolution and failure mechanisms of lithium-deficient and -rich regions (0.78 μm and 7.54 μm), on its surface, inside it, or at the Li/LLZTO interface.

Lithium metal based battery systems with ultra-high energy density beyond 500 W h kg-1

As industries and consumption patterns evolve, new electrical appliances are increasingly playing critical roles in national production, defense, and cognitive exploration. However, the slow development of energy storage devices with ultra-high energy density (beyond 500 W h kg-1) has impeded the promotion and widespread application of the next generation of intelligent, multi-scenario electrical equipment. Among the numerous ultra-high specific energy battery systems, lithium metal batteries (LMBs) hold significant potential for applications in advanced and sophisticated fields. This potential is primarily due to lithium metal's high specific capacity (3860 mA h g-1). However, LMBs face numerous challenges, including the growth of lithium dendrites, poor cycle stability, and safety concerns. In recent years, research on the mechanisms of Li metal-based battery systems, innovation in electrode materials, and optimization of device configurations have made significant progress. In this highlight, we provide a comprehensive overview of the storage mechanisms and the latest advancements in high-energy-density LMBs, represented by systems such as Li-Li1-xMO2, Li-S/Se, Li-gas (CO2/air/O2), Li-CFx, and all-solid-state LMBs. By integrating the current research findings, we highlight the opportunities and future research directions for high-energy-density LMBs, offering new guiding perspectives for their development under practical conditions.

Homogeneously Planar-Exposure LiB Fiber Skeleton Toward Long-Lifespan Practical Li Metal Pouch Cells

LiB alloy is promising lithium (Li) metal anode material because the continuous internal LiB fiber skeleton can effectively suppress Li dendrites and structural pulverization. However, the unvalued surface states limit the practical application of LiB alloy anodes. Herein, the study examined the influence of the different exposure manners of the internal LiB fiber skeleton owing to the various surface states of the LiB alloy anode on electrochemical performance and targetedly proposed a scalable friction coating strategy to construct a lithiated fumed silica (LFS) functional layer with abundant electrochemically active sites on the surface of the LiB alloy anode. The LFS significantly suppresses the inhomogeneous interfacial electrochemical behavior of the LiB alloy anode and enables the exposure of the internal LiB fiber skeleton in a homogeneously planar manner (LFS-LiB). Thus, a 0.5 Ah LFS-LiB||LiCoO2 (LCO) pouch cell exhibits a discharge capacity retention rate of 80% after 388 cycles. Moreover, a 6.15 Ah LFS-LiB||S pouch cell with 409.3 Wh kg-1 exhibits a discharge capacity retention rate of 80% after 30 cycles. In conclusion, the study findings provide a new research perspective for Li alloy anodes.

Adjusting Ion Diffusion Kinetics of Li Deposition Enabled by an Elastic Porous Melamine Sponge Host for Stable Lithium Metal Anodes

Lithium (Li) dendritic growth and huge volume expansion seriously hamper Li-metal anode development. Herein, we design a lightweight 3D Li-ion-affinity host enabled by silver (Ag) nanoparticles fully decorating a porous melamine sponge (Ag@PMS) for dendrite-free and high-areal-capacity Li anodes. The compact Ag nanoparticles provide abundant preferred nucleation sites and give the host strong conductivity. Moreover, the high specific surface area and polar groups of the elastic, porous melamine sponge enhance the Li-ion diffusion kinetics, prompting homogeneity of Li deposition and stripping. As expected, the integrated 3D Ag@PMS-Li anode delivered a remarkable electrochemical performance, with a Coulombic efficiency (CE) of 97.14% after 450 cycles at 1 mA cm-2. The symmetric cell showed an ultralong lifespan of 3400 h at 1 mA cm-2 for 1 mAh cm-2. This study provides a facile and cost-effective strategy to design an advanced 3D framework for the preparation of a stable dendrite-free Li metal anode.

A bifunctional surfactant-like electrolyte additive for a stable lithium metal anode

Nonafluorobutanesulfonyl fluoride (NtF) was developed as a bifunctional additive for enhancing the stability of the lithium metal anode. NtF can yield Nt+ and LiF. The presence of lithiophobic and lithiophilic groups in Nt+ facilitates the uniform deposition of Li+, while LiF contributes to forming a stable solid electrolyte interphase.

Ultralong Cycling and Safe Lithium-Sulfur Pouch Cells for Sustainable Energy Storage

While layered metal oxides remain the dominant cathode materials for the state-of-the-art lithium-ion batteries, conversion-type cathodes such as sulfur present unique opportunities in developing cheaper, safer, and more energy-dense next-generation battery technologies. There has been remarkable progress in advancing the laboratory scale lithium-sulfur (Li-S) coin cells to a high level of performance. However, the relevant strategies cannot be readily translated to practical cell formats such as pouch cells and even battery pack. Here these key technical challenges are addressed by molecular engineering of the Li metal for hydrophobicization, fluorination and thus favorable anode chemistry. The introduced tris(2,4-di-tert-butylphenyl) phosphite (TBP) and tetrabutylammonium fluoride (TBA+F-) as well as cellulose membrane by rolling enables the formation of a functional thin layer that eliminates the vulnerability of Li metal towards the already demanding environment required (1.55% relative humidity) for cell production and gives rise to LiF-rich solid electrolyte interphase (SEI) to suppress dendrite growth. As a result, Li-S pouch cells assembled at a pilot production line survive 400 full charge/discharge cycles with an average Coulombic efficiency of 99.55% and impressive rate performance of 1.5 C. A cell-level energy density of 417 Wh kg-1 and power density of 2766 W kg-1 are also delivered via multilayer Li-S pouch cell. The Li-S battery pack can even power an unmanned aerial vehicle of 3 kg for a fairly long flight time. This work represents a big step forward acceleration in Li-S battery marketization for future energy storage featuring improved safety, sustainability, higher energy density as well as reduced cost.

An ultralight, pulverization-free integrated anode toward lithium-less lithium metal batteries

The high-capacity advantage of lithium metal anode was compromised by common use of copper as the collector. Furthermore, lithium pulverization associated with "dead" Li accumulation and electrode cracking deteriorates the long-term cyclability of lithium metal batteries, especially under realistic test conditions. Here, we report an ultralight, integrated anode of polyimide-Ag/Li with dual anti-pulverization functionality. The silver layer was initially chemically bonded to the polyimide surface and then spontaneously diffused in Li solid solution and self-evolved into a fully lithiophilic Li-Ag phase, mitigating dendrites growth or dead Li. Further, the strong van der Waals interaction between the bottommost Li-Ag and polyimide affords electrode structural integrity and electrical continuity, thus circumventing electrode pulverization. Compared to the cutting-edge anode-free cells, the batteries pairing LiNi0.8Mn0.1Co0.1O2 with polyimide-Ag/Li afford a nearly 10% increase in specific energy, with safer characteristics and better cycling stability under realistic conditions of 1× excess Li and high areal-loading cathode (4 milliampere hour per square centimeter).

Artificial LiF-Rich Interface Enabled by In situ Electrochemical Fluorination for Stable Lithium-Metal Batteries

Lithium (Li)-metal batteries are promising next-generation energy storage systems. One drawback of uncontrollable electrolyte degradation is the ability to form a fragile and nonuniform solid electrolyte interface (SEI). In this study, we propose the use of a fluorinated carbon nanotube (CNT) macrofilm (CMF) on Li metal as a hybrid anode, which can regulate the redox state at the anode/electrolyte interface. Due to the favorable reaction energy between the plated Li and fluorinated CNTs, the metal can be fluorinated directly to a LiF-rich SEI during the charging process, leading to a high Young's modulus (~2.0 GPa) and fast ionic transfer (~2.59×10-7  S cm-1 ). The obtained SEI can guide the homogeneous plating/stripping of Li during electrochemical processes while suppressing dendrite growth. In particular, the hybrid of endowed full cells with substantially enhanced cyclability allows for high capacity retention (~99.3 %) and remarkable rate capacity. This work can extend fluorination technology into a platform to control artificial SEI formation in Li-metal batteries, increasing the stability and long-term performance of the resulting material.

Stabilizing Lithium Metal Batteries by Synergistic Effect of High Ionic Transfer Separator and Lithium-Boron Composite Material Anode

The development of lithium (Li) metal batteries (LMBs) has been limited by problems, such as severe dendrite growth, drastic interfacial reactions, and large volume change. Herein, an LMB (8AP@LiB) combining agraphene oxide-poly(ethylene oxide) (PEO) functionalized polypropylene separator (8AP) with a lithium-boron (LiB) anode is designed to overcome these problems. Raman results demonstrate that the PEO chain on 8AP can influence the Li+ solvation structure in the electrolyte, resulting in Li+ homogeneous diffusion and Li+ deposition barrier reduction. 8AP exhibits good ionic conductivity (4.9 × 10-4 S cm-1), a high Li+ migration number (0.88), and a significant electrolyte uptake (293%). The 3D LiB skeleton can significantly reduce the anode volume changes and local current density during the charging/discharging process. Therefore, 8AP@LiB effectively regulates the Li+ flux and promotes the uniform Li deposition without dendrites. The Li||Li symmetrical cells of 8AP@LiB exhibit a high electrochemical stability of up to 1000 h at 1 mA cm-2 and 5 mAh cm-2. Importantly, the Li||LiFePO4 full cells of 8AP@LiB achieve an impressive 2000 cycles at 2C, while maintaining a high-capacity retention of 86%. The synergistic effect of the functionalized separator and LiB anode might provide a direction for the development of high-performance LMBs.