Uniform Lithium Research Articles

Curvature-induced strain to realize differential lithiophilicity for selective lithium deposition and stable lithium anode

Regulating the lithiophilicity of three-dimensional (3D) lithium hosts is crucial for improving lithium deposition and suppressing dendrite growth. However, previous research has mainly focused on varying lithiophilic components, and the impact of geometric structures induced strain remains poorly understood. Herein, we present a novel curvature-induced strain engineering approach to regulate lithiophilicity and deposition kinetics of lithium in lightweight 3D tubular carbon hosts. A hollow carbon fiber with bilateral growth of MnO2 nanosheet arrays both inside and outside the tubes (MnO2@HCFC) have been successfully synthesized. Theoretical calculations and experiments confirm that the MnO2 layers inside and outside the hollow carbon fiber tube undergo compressive and tensile strain, respectively. The curvatures induced strain modifies the O2p band center of the lithiophilic MnO2 layer, enabling the regulation of lithiophilicity and preferential and uniform lithium deposition within the carbon fiber tubes. The MnO2@HCFC framework exhibits excellent lithium affinity and uniform Li+ flux distribution, as evidenced by visualization techniques and COMSOL simulations, enabling dendrite-free lithium deposition. The Li-MnO2@HCFC||LiCoO2 full cell retains 85.7 % of its capacity after 400 cycles at 0.5 C with a high LiCoO2 loading of 10.3 mg cm-2. The optimized lithium anode pouch cell exhibits robust cycle stability under harsh conditions. This work offers new insight into the design of 3D lithium hosts to enhance the performance of lithium anodes through curvature-induced strain engineering.

Lewis-basic nitrogen-rich covalent organic frameworks enable flexible and stretchable solid-state electrolytes with stable lithium-metal batteries

Designing flexible and stretchable solid-state electrolytes (SSEs) holds promise but challenge in flexible all-solid-state lithium-metal batteries (LMBs) owing to their insufficient ion conductivity and mechanical strength. Herein, we develop nitrogen-rich covalent organic frameworks (NCOF) with abundant Lewis-basic N atoms as lithiophilic sites to incorporate Lewis-acidic Li+ into its inner order structure for fabricating flexible and stretchable PEO-LI+@NCOF SSEs with the crosslinking of polyethylene oxide (PEO). The SSE film displays high mechanical strain (2.2 MPa), Young's modulus (689 MPa), stretchability (1000 %), ion conductivity (2.4 × 10–4 S cm-1), good flame resistance, and wide electrochemical window (4.8 V). Owing to the rich Lewis-basic N atoms with strong Li+ adsorption energy, orderly nanochannels, and negative charge environment within NCOFs, the SSE film endows orderly and rapid ion migration, low Li-ion diffusion barrier, and significantly enhanced ion conductivity for uniform lithium plating/stripping and suppressing Li-dendrite growth. The crosslinking of Li+@NCOF with PEO greatly enhances the mechanical stretchability, flame resistance, and electrochemical window of PEO-based SSEs. Consequently, the Li/PEO-LI+@NCOF/Li symmetrical cell exhibits stable cycling without short-circuiting for 1200 h at 0.1 mA cm-2/0.1 mAh cm-2. The LiFePO4/PEO-LI+@NCOF/Li battery exhibits a 500-cycle long lifespan at 1 C (78 % capacity retention), and its pouch cell verifies promising applications in flexible all-solid-state LMBs. Therefore, introducting Lewis-basic N-rich COFs verifies an effective strategy to design a flexible and stretchable SSE film with high mechanical strength, superior ion conductivity and flame resistance.

MIL-125 (Ti) and porous dielectric polymer substrate introducing composite gel polymer electrolyte with enhanced mechanical property, thermal stability and electrochemical property

Lithium metal batteries have potentially high energy density, but severe uncontrolled lithium dendrites and unstable side reactions prevent large-scale applications. Serial three-dimensional porous poly (vinylidene fluoride) and copolymer membrane-based composite gel electrolytes are designed by introducing MIL-125 (Ti) and ethylene carbonate. Abundant lithium-ion transportation channels and homogeneous ion transport microregion are provided the new type porous fluoropolymer substrate. We also find that crystalline phase and dielectric properties of serial polymer membrane have significant impact on electrochemical performance for composite gel electrolytes. The mechanical and dielectric property of composite electrolyte enhanced by incorporating uniform and well distribution MIL-125 (Ti), which improve the electrolyte/electrode interface charge distribution and promote uniform lithium deposition, leading to lithium dendrite suppression. MIL-125 (Ti)/P(VDF-TrFE-CTFE) composite membrane shows the enhanced maximum strain of 181 %, thermal stability (188 °C) and corresponding composite gel electrolyte reflects higher ionic conductivity of 1.7 × 10–3 S cm-1 and wider electrochemical window at room temperature than PVDF and PVDF-HFP composite electrolytes. Expectedly, quasi-solid state lithium metal battery of MIL-125 (Ti)/P(VDF-TrFE-CTFE) composite gel electrolyte exhibits higher discharge capacity (152.8 mAh g-1) at 240th cycle and 1 C, longer cycling life and better rate performance under large current density than PVDF and PVDF-HFP composite electrolytes.

Boron-Doped Carbon Scaffold Hosts for Li Metal Batteries

Lithium metal anodes offer the promise of higher energy density batteries. However, the formation of lithium dendrites due to non-uniform plating and stripping of the lithium metal has proven to be a major hurdle for this technology, decreasing the lifetime of the device and causing safety hazards. Utilizing a carbon scaffold host for the lithium metal anode can limit dendrite formation by providing a more uniform electric field and numerous lithium nucleation sites to encourage uniform plating and stripping. In this poster, we present our work developing carbon scaffold hosts for lithium metal anodes. We synthesized scaffolds with various architectures and microstructures using different carbon materials. Our atomistic simulations demonstrated that the addition of boron to the carbon results in stronger binding of lithium to the carbon surface, further improving the lithiophilicity. Therefore, we also prepared boron-doped carbon scaffolds to test this experimentally. Boron was introduced using boric acid and incorporated into the carbon structure during carbonization under nitrogen, and these samples were characterized by XPS, SEM, and BET to try and correlate scaffold properties with performance. In addition, we are investigating other dopants (such as nitrogen), which have also been reported to increase the lithiophilicity of carbon materials. Utilizing these doped carbon scaffolds can help increase the lifetime of lithium metal batteries by improving the cycling uniformity.This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344

(Invited) Lithium Plating on Brittle Solid Electrolytes: Mechanics, Heterogeneities and Coatings

Solid-state batteries employing lithium metal as a negative electrode promise high energy and safety. Plating at the lithium metal/solid electrolyte interface is fundamentally complex compared to plating in a liquid electrolyte due to mechanical considerations as well as heterogeneities. Ideally, lithium metal should plate densely in a planner fashion, growing away from the solid electrolyte. In reality, however, lithium plating is heterogeneous and can be directed towards the solid electrolyte, ultimately leading to short-circuit and penetration through the solid electrolyte. In this talk, I will overview our recent efforts to understand and control chemo-mechanics in garnet solid electrolytes. Specifically, we employ local electrochemical probes to correlate current-voltage behavior to defect and mechanical forces, both locally and macroscopically. Building on these fundamental understanding, I will show how interfacial engineering through coatings enable more uniform lithium plating.

A Ceramic/Lithiophilic Metal Dual Protective Layer for Stable Lithium Metal Anodes Fabricated via Transfer-Printing Methods

Lithium metal has attracted researcher’s attention because of its superior theoretical capacity (3860mAh g-1 or 2061 mAh cm-3), which is nearly 10 times higher than commercialized anode materials, for example, graphite (372 mAh g-1). However, lithium metal is not currently used in commercial lithium metal batteries due to safety and efficiency issues that arise during long-term battery operation. The high reactivity of lithium metal causes almost all available electrolytes to be spontaneously reduced on the Li surface to form a solid-electrolyte interface (SEI) layer. Unfortunately, this passivating SEI layer is typically too fragile to withstand significant mechanical deformation of the electrode during cycling, resulting in crack formation. These cracks expose fresh Li underneath, which locally enhances Li-ion flux and promotes morphological deformation of the lithium metal surface. This often leads to dendritic Li deposition that can cause internal short circuits and compromise battery safety. Additionally, repeated failures and repairs of SEIs result in the continued loss of both Li and electrolyte, leading to low coulombic efficiency (CE) and rapid capacity decrease.To mitigate these problems, researchers have attempted to suppress lithium dendrite growth by slurry coating on the lithium metal surface such as ceramic layer and lithiophilic metal. These materials and conventional lithium metal protection coating methods partially inhibit the growth of lithium dendrites; however, they come with several significant drawbacks. The ceramic layer possesses high mechanical properties that physically inhibit the growth of lithium dendrites. However, it exhibits poor interfacial characteristics with lithium metal, leading to increased resistance. This heightened resistance results in the formation of uneven lithium deposition layers at high current densities, causing cracks in the ceramic layer. Lithiophilic metals exhibit an advantage in reducing nucleation resistance through alloying reactions with lithium prior to nucleation, thereby facilitating uniform lithium ion deposition. However, their low mechanical properties limit their potential for enhancing electrochemical performance. Furthermore, the conventional coating method used for lithium metal protection involves the direct application of solvent-containing slurries onto the lithium metal surface using slurry coating techniques. Given the inherent reactivity of lithium metal, the presence of residual moisture and impurities within the solvent may induce sub-reactions, ultimately compromising the stability of lithium metal.In this study, we propose an approach to improve the cycling stability of lithium metal through Ceramic/lithiophilic metal dual protective layer fabricated via transfer-printing methods. The dual lithium metal protection layer, consisting of Ceramic/lithiophilic, involves coating a lithiophilic metal layer between the ceramic layer and the lithium metal. This method aims to maximize electrochemical performance improvement through a synergistic effect that utilizes the high mechanical properties of ceramics and solves the problem of interfacial resistance between the ceramic layer and lithium metal through the lithiophilic metal. Furthermore, we propose a coating process for lithium metal protection layers using a method based on transfer printing. This method involves applying pressure to the lithium metal surface through transfer printing of pre-finished composite protective layers on a film, rather than directly applying slurry onto the lithium metal surface. Transfer printing offers the advantage of maintaining the stability of lithium metal by avoiding direct application of slurry onto the lithium metal surface, thereby ensuring the integrity of the protection layer.

Large Scale Production of Lithium and Sodium Based NMC Oxide Cathodes

The ongoing embrace of innovative renewable energy conversion methods, couple with diverse and dynamic energy storage applications, necessitates the adoption of new adaptable process lines in industrial settings [1]. The adopting process line and methods are chosen based on various factors like overall cost, sustainable process, adaptable infrastructure, and pollution standards. Interestingly recent developments in lithium containing high energy dense battery for electric mobility solutions require varied industrial solutions in every other step for adopting the transition ahead. For example, high temperature treatment during large-scale production of lithium like volatile elements containing multi cation oxide battery materials suffer inconsistency in the nominal composition of its final product[2]. Currently, industries producing lithium-based battery materials use scalable techniques like sol-gel / coprecipitation based batch processing[3]. To offset lithium losses or incorporate lithium content, conventional approaches involve the use of complex precursors, excess lithium addition, and subsequent post-processing techniques. However, the conventional two-step process leads to uncontrollable lithium content during large scale production. Hence, in this study, we propose a new methodology based on thermal plasma spray pyrolysis and its optimization for large scale production of lithium and sodium based multi-cation oxide materials. Spray pyrolysis is a robust large scale production process utilized in multitude industries. Conventionally, spray pyrolysis-based techniques are used in industry to achieve relatively simple compound or two step procedures to achieve desired uniform, phase purity, and structures[4-7]. Herein, thermal plasma-based spray pyrolysis utilizes the plasma environment to pyrolyze the precursors of multiple cationic elements before depositing at a shorter distance. Optimization of spray pyrolysis parameters is made such that, lithium content is maintained and multi-cation oxide with phase purity, uniformity, and narrow size distribution is achieved. The advantage of the proposed method lies in adaptability of simpler precursors, cost, and time effectiveness. Thermal plasma-based spray pyrolysis mediated synthesis of uniform Lithium and Manganese rich NMC (Li-NMC) Li1.2MO2 (M = Ni (0.1), Mn (0.6), Co (0.1)) cathode material is attempted and achieved the reported rock salt pattern αNaFeO2 structure without cation mixing in the layered structure. X-ray diffraction results confirm that both Lithium NMC oxide and Sodium NMC oxides resulted in high phase purity. The layered nature of the samples identified from distinct hexagonal doublet (018) / (110) around 65º 2θ. Li-NMC resulted in a capacity of 160 mAh g-1. Optimized synthesis parameters of the thermal plasma spray pyrolysis method resulted in a production yield rate of 5 g min-1. Microscopic examination reveals cuboid shape of nanostructures with an average size of approximately 200 nm and narrow size distribution. Similarly, optimization of production scale parameters for Na-NMC oxide is being carried out.

Covalent Triazine Based Frameworks with Donor-Donor-π-Acceptor Structures for Dendrite-Free Lithium Metal Batteries.

The appearance of disordered lithium dendrites and fragile solid electrolyte interfaces (SEI) significantly hinder the serviceability of lithium metal batteries. Herein, guided by theoretical predictions, a multi-component covalent triazine framework with partially electronegative channels (4C-TA0.5TF0.5-CTF) is incorporated as a protective layer to modulate the interface stability of the lithium metal batteries. Notably, the 4C-TA0.5TF0.5-CTF with optimized electronic structure at the molecular level by fine-tuning the local acceptor-donor functionalities not only enhances the intermolecular interaction thereby providing larger dipole moment and improved crystallinity and mechanical stress, but also facilitates the beneficial effect of lithiophilic sites (C-F bonds, triazine cores, C=N linkages and aromatic rings) to further regulate the migration of Li+ and achieve a uniform lithium deposition behavior as determined by various in-depth in/ex situ characterizations. Due to the synergistic effect of multi-component organic functionalities, the 4C-TA0.5TF0.5-CTF modified full cells perform significantly better than the common two/three-component 2C-TA-CTF and 3C-TF-CTF electrodes, delivering an excellent capacity of 116.3 mAh g-1 (capacity retention ratio: 86.8 %) after 1000 cycles at 5 C and improved rate capability. This work lays a platform for the prospective molecular design of improved organic framework relative artificial SEI for highly stable lithium metal batteries.

Solid composite electrolyte with a Cs doped fluorapatite-interfacial layer enabling dendrite-free anodes for solid-state lithium batteries

Composite electrolytes have garnered considerable attention owing to ease of processing, flexibility, and cost-effectiveness. Nevertheless, their practical applicability has been hindered by the insufficient ionic conductivity and the formation of dendrites duo to solid–solid interfacial interactions. In this work, an interfacial layer with Cs-doped fluorapatite (Ca5(PO4)3F, FA) as the filler was constructed to enhance the flame-retardant property of the composite electrolyte and inhibit dendrite growth during cycling process. The CSE with the Cs doped FA interfacial layer exhibits significant flame-retardant properties. Furthermore, the self-healing electrostatic shielding (SHES) mechanism of Cs+ effectively inhibits the growth of lithium dendrite and promotes uniform lithium deposition. The solid electrolyte integrated with the Cs doped FA interfacial layer exhibits a broad voltage window of 5.58 V vs. Li+/Li, high ionic conductivity of 5.43 × 10-4 S cm−1, and Li+ transference number of 0.716. Density functional theory (DFT) calculations reveal a competitive interaction between Cs+ and Li+ for TFSI- coordination, leading to reduced binding energy of LiTFSI and thus increasing the availability of free lithium ions, enhancing lithium ions mobility. Additionally, the symmetrical cell with the Cs doped FA interfacial layer demonstrates cyclic stability over 2000 h at 0.2 mA cm−2 due to the lower nucleation overpotential, demonstrating excellent lithium plating/stripping capabilities. The LFP||Li full cell shows a remarkable capacity retention of 99.54 % after 300 cycles at 0.5C, and 95.58 % with a higher Coulombic efficiency (CE) of 99 % after 600 cycles at 1C. In addition, the cell with this CSE and NCM811 cathode exhibits excellent capacity retention of 78 % after 150 cycles at 0.5C. This approach to designing interfacial layers offers new avenues for advancing solid-state lithium-metal batteries.

A facile superlithiophilic 3D host with a transition metal oxide heterostructure for ultrastable zero-volume-expansion lithium metal anodes

Lithium metal batteries (LMBs) are widely recognized as the candidate for next-generation energy devices due to their unprecedented capacity and low electrochemical potential. Nonetheless, their practical implementation has been hindered by the dendrite formation and unstable solid electrolyte interface (SEI). In this study, we introduce a novel approach involving the in-situ growth of a ZnO–CuO heterostructure within a crack shield construction on a three-dimensional (3D) copper foam host. Computational COMSOL simulations reveal remarkable improvements in homogenizing lithium ion flux subsequent to decoration. Through galvanostatic measurements, the Li@ZnO-CuO-CF electrode exhibits an exceptionally low 0.2 V hysteresis, no volume expansion and uniform lithium deposition in symmetry cells under a 50 mA cm−2 current density. Furthermore, the electrode retains 95.4 % initial capacity after 600 cycles at 0.5C and 85.5 % initial capacity after 220 cycles at 1 C when coupled with a LiFePO₄ (LFP) cathode. This work sheds light on the facile fabrication of practical Li metal anodes for high-energy-density LMBs.

Perfluorinated Amines: Accelerating Lithium Electrodeposition by Tailoring Interfacial Structure and Modulated Solvation for High-Performance Batteries.

Modulating interfacial electrochemistry represents a prevalent approach for mitigating lithium dendrite growth and enhancing battery performance. Nevertheless, while most additives exhibit inhibitory characteristics, the accelerating effects on interfacial electrochemistry have garnered limited attention. In this work, perfluoromorpholine (PFM) with facilitated kinetics is utilized to preferentially adsorb on the lithium metal interface. The PFM molecules disrupt the solvation structure of Li+ and enhance the migration of Li+. Combined with the benzotrifluoride, a synergistic acceleration-inhibition system is formed. The ab initio molecular dynamics (AIMD) and density functional theory (DFT) calculation of the loose outer solvation clusters and the key adsorption-deposition step supports the fast diffusion and stable interface electrochemistry with an accelerated filling mode with C─F and C─H groups. The approach induces the uniform lithium deposition. Excellent cycling performance is achieved in Li||Li symmetric cells, and even after 200 cycles in Li||NCM811 full cells, 80% of the capacity is retained. This work elucidates the accelerated electrochemical processes at the interface and expands the design strategies of acceleration fluorinated additives for lithium metal batteries.

Dual-Component Interlayer Enables Uniform Lithium Deposition and Dendrite Suppression for Solid-State Batteries.

β-Lithium thiophosphate (LPS) exhibits high Li+ conductivity and has been identified as a promising ceramic electrolyte for safe and high-energy-density all-solid-state batteries. Integrating LPS into solid-state lithium (Li) batteries would enable the use of a Li electrode with the highest deliverable capacity. However, LPS-based batteries operate at a limited current density before short-circuiting, posing a major challenge for the development of application-relevant batteries. In this work, we designed a dual-component interfacial protective layer called LiSn-LiN that forms in situ between the Li electrode and LPS electrolyte. The LiSn component, Li22Sn5, exhibits enhanced Li diffusivity compared with the metallic lithium and facilitates a more uniform lithium deposition across the electrode surface, thus eliminating Li dendrite formation. Meanwhile, the LiN component, Li3N, shows enhanced mechanical stiffness compared with LPS and functions to suppress dendrite penetration. This chemically robust LiSn-LiN interlayer provides a more than doubled deliverable critical current density compared to systems without interfacial protection. Through combined XPS and XAFS analyses, we determined the local structure and the formation kinetics of the key functional Li22Sn5 phase formed via the electrochemical reduction of a Sn3N4 precursor. This work demonstrates an example of the structural-specific design of a protective interlayer with a desired function - dendrite suppression. The structure of a functional protective layer for a given solid-state battery should be tailored based on the given battery configuration and its unique interfacial chemistry.

Lattice Strain and Charge Localization Dual Regulation of Phosphorus‐Doped CoSe2/MXene Catalysts Enable Kinetics‐Enhanced and Dendrite‐Free Lithium‐Sulfur Batteries

AbstractPhase engineering is considered an effective strategy to regulate the electrocatalytic activity of catalysts for Li–S batteries (LSBs). However, the underlying origin of phase‐dependent catalytic ability remains to be determined, which significantly impedes the design principles of high‐performance catalytic materials for LSBs. Herein, heteroatom‐doped engineering can trigger phase transformation from mixed‐phased cubic and orthorhombic cobalt diselenide into pure orthorhombic structure with a tensile strain and enhanced charge localization. The upshift of the d‐band center and enhanced Bader charge at Se sites synergistically strengthen the interaction with Li and S sites in polysulfide species, thus endowing the transformed P‐MoSe2/MXene with high catalytic activity and uniform lithium deposition for LSBs. Consequently, the P‐CoSe2/MXene Li–S batteries demonstrate a high‐rate capability of 603 mAh g−1 at 4C, and an excellent cyclability of 652 mAh g−1 at 1C over 500 cycles with a degradation rate of 0.076% per cycle. The work provides an in‐depth insight into the fundamental design principles of effective catalysts for LSBs.

Isomeric dichloropyrazine of dual-function additives: Synergistic enhancement of lithium anode protection and sulfur redox kinetics in lithium–sulfur batteries

Lithium-sulfur batteries (LSBs) currently face challenges such as low sulfur utilization, inadequate cycling stability, and unstable lithium anode interfaces. In this study, dichloropyrazines (DCPs) are introduced as dual-functional additives into electrolyte and 2,5-DCP exhibits the most promising performance enhancement. This superiority can be attributed to its strong redox activity, lower molecular orbital energy gap, and more negative relative binding energy compared to the other DCP isomers. Specifically, DCPs demonstrate their dual functionality by promoting the formation of a stable organic-inorganic hybrid solid electrolyte interface (SEI) rich in LiCl on lithium anodes. This ensures uniform lithium deposition and suppresses dendrite growth. At sulfur cathodes, density functional theory (DFT) calculations confirm that DCPs facilitate lithium polysulfides (LiPSs) conversion kinetics through Li–N bond formation. LSBs with 2,5-DCP exhibit excellent stability at a 1C rate and retain 86.6 % capacity after 800 cycles. This study demonstrates DCPs' potential as effective dual-functional electrolyte additives in designing high-performance LSBs.

Fluorine-Doped Li7La3Zr2O12 Fiber-Based Composite Electrolyte for Solid-State Lithium Batteries with Enhanced Electrochemical Performance.

Garnet-based electrolytes with high ionic conductivity and excellent stability against lithium metal anodes are promising for commercial applications in solid-state lithium batteries (SSLBs). However, the further development of SSLBs is inhibited by issues such as low ionic conductivity and uncontrolled lithium dendrite growth. Herein, we report the synthesis of fluorine-doped Li7La3Zr2O12 (LLZO-F0.2) fibers by electrospinning and the subsequent calcination at high temperatures. The solid composite electrolyte with LLZO-F0.2 exhibits an ionic conductivity of 5.37 × 10-4 S cm-1 and a high lithium-ion transference number of 0.61 at room temperature. Meanwhile, it exhibits lower resistance and more uniform lithium metal stripping and deposition in symmetric cells. The full cell with LiFePO4 cathode exhibits excellent rate capability and cycling stability for 800 cycles at 0.5 C with a discharge specific capacity retention of 97.7%. This fluorine-doped fibrous garnet-type electrolyte provides a viable option for preparing high-performance SSLBs.

Electrolyte Engineering via Fluorinated Siloxane Solvent for Achieving High-Performance Lithium-Metal Batteries.

Advanced solvent is of important significance to develop an excellent electrolyte that simultaneously maintains a high ionic conductivity, wide electrochemical window, and good compatibility with electrodes for high-performance lithium-metal batteries (LMBs). To realize a stable electrode/electrolyte interface and a uniform lithium (Li) deposition process, an optimal fluorinated siloxane (3,3,3-trifluoropropyltrimethoxysilane, TFTMS) is proposed as a cosolvent with 1,2-dimethoxyethane (DME) and highly antioxidative fluoroethylene carbonate (FEC) to formulate a Li-metal compatibility electrolyte. The TFTMS-based electrolyte presents high oxidization stability, high Li+ conductivity, and high Li+ transfer number, contributing to the accelerated reaction kinetics, homogeneous Li deposition behavior, and stable interfacial chemistry. Therefore, high Li stripping/plating reversibility (∼99%) and stable cycling (1400 h) are achieved in the TFTMS-based electrolyte, giving rise to the excellent electrochemical performance of practical Li-metal full cells. Moreover, an industrial 4 Ah NCM811|Gr pouch cell with the TFTMS-based electrolyte is demonstrated to display similar cycling performance with the commercial carbonate electrolyte in 120 cycles at 1 C. This work offers an approach toward high-performance LMBs through rational electrolyte design with fluorinated siloxane solvent.

A Facile Chemical Reduction Approach of Li–Sn Modified Li Anode for Dendrite Suppression

Lithium dendrites are among the most significant threats associated with the practical application of lithium metal anode in lithium batteries. Lithium dendrites are caused by the slow Li‐ion diffusivity in the bulk lithium, which results in a non‐uniform electric field‐cum‐uneven Li plating/stripping at the electrode/electrolyte interface over prolonged cycling. Herein, a facile chemical reduction method is utilized to construct a Li‐ion diffusive Li–Sn protective layer on the electrolyte‐exposed surface of lithium metal to overcome the aforementioned challenge. A systematic study on the SnCl4 precursor concentration variation demonstrated that 25 mM SnCl4 concentration is the most effective and displays a cumulative areal capacity beyond 700 mAh cm−2 at 1 mA cm−2 for 1 h. Moreover, it exhibits superior cumulative capacities than bare Li metal at higher current densities of 2 and 3 mA cm−2. In situ optical microscopy reveals more uniform lithium deposition on the Li–Sn‐modified electrode, while mossy and dendritic lithium growth is observed on the bare lithium electrode. Full cells fabricated with Li–Sn modified anode and NMC532 cathode exhibited 83% capacity retention after 150 cycles, outperforming bare Li‐containing cells, which shows a catastrophic decay post 100 cycles, illustrating the propensity for safer Li metal batteries with Li–Sn modified anode.

AgF-PEO composite interfacial layer for electrolyte-free LAGP-based lithium metal batteries

NASICON-type LAGP solid state electrolyte has become one of the most promising solid-state electrolytes due to its superior performance such as favorable room-temperature ionic conductivity, high stability in air, wide electrochemically stable window, and low cost. The key constraint to the development of LAGP electrolyte is the LAGP/Li interface problem. In this paper, a composite interfacial layer (AgF@Li-PEO@LAGP) is introduced between LAGP electrolyte and electrode material. The LiF and Ag nanoparticles are generated on the Li surface by utilizing the substitution reaction to uniform lithium flux and prevent the side reaction, while the flexible PEO polymer buffer layer on the LAGP will improve the interface wettability. The Li/LAGP/Li symmetric cell modified with composite interfacial layer can maintain a low polarization voltage of 0.11 V at 0.1 mA cm−2 for stable cycling for more than 1200 h. The full cell also shows excellent cycling stability with the capacity retention of 93.6 % after 100 cycles. The composite interface layer can realize the elimination of liquid electrolyte and greatly reduce interface resistance. This broadens the road for the realization of all-solid-state batteries.

Two-dimensional MXene/MOFs heterojunction nanosheets as confinement hosts for dendrite-free lithium metal anodes

Although metallic lithium is regarded as the most potential anode candidate for next-generation batteries, its applications are greatly restricted by the uncontrollable growth of lithium dendrites and unstable anode/electrolyte interface. Herein, MXene/MOFs heterojunction nanosheets are developed through a convenient self-assembly process by harnessing the chemical interactions between MXene and Ni-MOFs monolayers. In this heterojunction, not only the MXene interlayer induces uniform lithium nucleation, but also MOFs monolayers act as stable interfaces to promote Li ion transport and homogenize the subsequent lithium deposition. Moreover, the MXene/MOFs substrate mitigates the volume change of lithium anodes. Consequently, 2D MXene/MOFs heterojunction nanosheets as confinement hosts effectively suppress lithium dendrites and exhibit enhanced electrochemical performances including a coulombic efficiency of 99 % over 300 cycles at 0.5 mA cm−2 and 1 mAh cm−2, and a long cycling life up to 500 h at 1 mA cm−2 and 1 mAh cm−2. The MXene/MOFs-Li||LiFePO4 cells exhibit a stable cycling performance with a capacity retention of 91 % after 600 cycles.

High-Performance Dendrite-Free Lithium Metal Anode Based on Metal-Organic Framework Glass.

The performance of lithium metal batteries is severely hampered by uncontrollable dendrite growth and volume change within the anode. This work addresses these obstacles by introducing a novel strategy: applying an isotropic and internal grain-boundary-free layer, specifically, a metal-organic framework (MOF) glass layer with nano-porosity onto the electrochemically plated lithium metal anode. Both ab initio and classical molecular dynamics simulations indicate that the MOF glass layer makes the lithium transport smooth and uniform via its internal monolithic and interfacial advantages. This MOF glass layer with the fast and more uniform lithium diffusion in the monolithic interior and its interface enables dendrite-free lithium plating and stripping through surface confinement effect and interfacial effect. When employed in symmetric batteries, the achieved Li metal anode can operate over 300h at 1mAcm-2. The full batteries matched with LiFePO4 exhibit high capacity (148mAhg-1), excellent rate performance (61mAhg-1 at 5C), and outstanding cycling stability (with capacity retention of ≈90% after 1000 cycles). The full batteries matched with high-voltage LiCoO2 also show superior performances. Therefore, the strategy of utilizing a MOF glass layer enables the development of high-performance lithium metal anodes.