Passivation Layer Research Articles

Density functional theory study on vanadium selective leaching separation from iron in stone coal via Fe2O3 (001) surface passivation

When vanadium is extracted from stone coal, iron impurities readily precipitate and reduce the purity of the vanadium product. Thus, separating vanadium from iron impurities at source is essential. The mechanism of surface passivation of Fe2O3 (001) for the selective leaching separation of vanadium from iron in stone coal was established in the present work. Analysis of mineral phase transformation and microscopic morphology indicates that Fe2O3 in stone coal can undergo a reaction with HF and F-. Subsequently, the hematite surface was covered with FeF3 passivation layer, resulting in the inhibition of hematite dissolving reaction. The results of density functional theory (DFT) computations demonstrate that the HF and F- can reform the Fe2O3 (001) surface via sedimentary behavior at mineral interface, and the adsorption energy can be down to -99.93kJ/mol for the F- adsorption configuration. During sulfuric acid leaching with CaF2 as an aiding agent, the transfer of electrons from Fe atoms to F atoms can weaken the stable Fe-F bonds and decrease the reactive activation of Fe atoms in Fe2O3. This study demonstrates the separation of vanadium from iron by means of hematite passivation in the attendance of fluoride at the atomic level of analysis.

Directly Regenerating of Spent LiCoO2 with Gradient F-Doped Subsurface towards Ultra-Stable Storage Properties.

As great potential recycling strategy, the direct regeneration of spent LiCoO2 (LCO) is beneficial for lowering environmental pollutions and promoting global sustainability. However, owing to the using of binder and electrolyte, some fluorine impurities would be remained into spent materials. Considering the doping behaviors of F-elements, their suitable content introducing would facilitate the energy-storage abilities of regenerated LCO. Herein, through the tailored introduction of F-elements, spent LCO are successfully regenerated with physical-chemical evolutions. Benefitting from the existed oxygen vacancies, the diffusion energy-barrier of F-elements is reduced from 1.73 eV to 0.61 eV, facilitating the establishment of gradient F-doped subsurface, along with the formation of rigid CoO5F. Meanwhile, excess F-elements (1 wt %, as a threshold) lead to the formation of LiF passivation layer on the surface. Thus, the as-optimized sample displays a considerable capacity of 154.4 mAh g-1 even at 5.0 C, with retention rate (88.3 %) in 3.0-4.5 V. Supported by detailed electrochemical and kinetic analysis, the structural advantages are confirmed to boost the improved redox activity of Co-ions and the alleviating of irreversible oxygen-release. Give this, the work is anticipated to reveal the evolutions of regenerated LCO with the introduced F-elements, whilst providing the practical regeneration strategies toward excellent high-voltage properties.

Directly Regenerating of Spent LiCoO2 with Gradient F‐Doped Subsurface towards Ultra‐Stable Storage Properties

AbstractAs great potential recycling strategy, the direct regeneration of spent LiCoO2 (LCO) is beneficial for lowering environmental pollutions and promoting global sustainability. However, owing to the using of binder and electrolyte, some fluorine impurities would be remained into spent materials. Considering the doping behaviors of F‐elements, their suitable content introducing would facilitate the energy‐storage abilities of regenerated LCO. Herein, through the tailored introduction of F‐elements, spent LCO are successfully regenerated with physical‐chemical evolutions. Benefitting from the existed oxygen vacancies, the diffusion energy‐barrier of F‐elements is reduced from 1.73 eV to 0.61 eV, facilitating the establishment of gradient F‐doped subsurface, along with the formation of rigid CoO5F. Meanwhile, excess F‐elements (1 wt %, as a threshold) lead to the formation of LiF passivation layer on the surface. Thus, the as‐optimized sample displays a considerable capacity of 154.4 mAh g−1 even at 5.0 C, with retention rate (88.3 %) in 3.0–4.5 V. Supported by detailed electrochemical and kinetic analysis, the structural advantages are confirmed to boost the improved redox activity of Co‐ions and the alleviating of irreversible oxygen‐release. Give this, the work is anticipated to reveal the evolutions of regenerated LCO with the introduced F‐elements, whilst providing the practical regeneration strategies toward excellent high‐voltage properties.

Anti-Corrosion Performance of Magnesium Potassium Phosphate Cement Coating on Steel Reinforcement: The Effect of Boric Acid

It has recently been found that magnesium potassium phosphate cement (MKPC) paste coating applied on the surface of steel reinforcement can effectively retard the onset of corrosion and suppress corrosion reactions. However, the fast-setting nature of MKPC—which is a merit in repair—can be problematic in a practical engineering process of coating the steel reinforcement with MKPC paste. To address this problem, boric acid (H3BO3) was added as a retarder in an MKPC formulation to prolong the setting time. This work investigated the impact of boric acid (at 5% by weight of MgO) on the anti-corrosion performance of MKPC paste coating through a series of electrochemical (EC) tests. The results showed that the anti-corrosion performance of MKPC paste coating for a mild steel bar could be interfered with by the presence of boric acid. In the same testing situation (immersed in 3.5 wt.% NaCl corrosion solution), the polarization resistance and corrosion current density of the group including boric acid were inferior and exceeded the corrosion thresholds prior to the control group without boric acid. Meanwhile, the time constant phase in the frequency range from 1 Hz to 10 kHz was rarely observed, implying that the presence of boric acid probably impaired the formation of the passivation layer. This decrease in anti-corrosion performance of MKPC paste coating could be related to the larger volume fraction of pores in the range from 0.1 to 10 µm that are formed during the initial stage of coating formation.

Investigation of Copper Addition on Corrosion Behavior of a Ferrous Based Shape Memory Alloy for Biomedical Implant Applications

Permanent biomedical implants pose several issues in long term scenarios like infections, inflammation, implant fracture, tissue damage, cancerous tumors formation, and skin allergies. Biodegradable biomedical implants are a new interest that function by degrading internally after achieving the implant goal. Shape memory alloys like Nitinol and Iron based shape memory alloys have applications in biomaterials due to the excellent property of super elasticity and shape memory effect respectively with the ease of small surgery requirement. To achieve biodegradability, the alloy composition is to be set while not compromising other properties such as biocompatibility, mechanical properties, shape memory properties, and magnetic properties. Slow corrosion rates of Fe-Mn alloys are reported and alloying addition, surface modifications, and novel manufacturing techniques are suggested to overcome this problem. In this study, the effect of addition of copper addition effect on the degradation behavior of Fe-30Mn-5Si is investigated. Austenite is the major phase present in both samples and small amounts of martensite are also present. For 10% copper, an additional copper rich phase is formed along the grain boundaries as it was beyond the solubility limit of iron matrix. The electrochemical corrosion test shows that 10% Cu addition resulted in 1.72 times higher corrosion rate than that of 5% Cu addition. As 5% Cu addition is within the solubility limit of iron matrix, and it forms a solid solution with iron that creates a passive layer during corrosion testing results in slower degradation.

Bio-inhibitive corrosion effect of carica papaya leaf extract on cold-rolled mild steel in 0.1 M HCl solution

Plant extracts are prone to microbial growth that can lead to microbial-induced corrosion (MIC), a major setback for their performance and stability as corrosion inhibitors. Hence, this work aims to identify the microbes that may cause the ineffectiveness of carica papaya leaf extract (CPLE) as a bio-corrosion inhibitor of cold-rolled mild steel in 0.1 M HCl solution for 48 days at 28℃. Cold-rolled mild steel coupons were immersed in 100 ml of 0.1 M hydrochloric (HCl) acid solution containing 1 g, 2 g, 3 g, 4 g, and 5 g of carica papaya leaf extract (CPLE) for 48 days at 28℃. The gravimetric method was used to determine the coupons' corrosion rate (CR), surface coverage, and inhibition efficiency (IE%) of the CPLE. The functional groups in the CPLE were identified using Fourier Transform Infrared Spectroscopy (FTIR), and the surface appearance of the coupons after immersion was examined using an atomic force microscope (AFM). Gravimetric data showed the coupons dipped in a 0.1 M HCl solution containing 3 g/100 ml of the inhibitor exhibited the highest inhibition efficiency of 87.73%, surface coverage of 0.88, and lowest corrosion rate of 0.00255 mm/day or 0.93 mm/yr, after 48 days at 28℃. In FTIR, transmittance peaks occurred at 1558 cm−1 for amines (-NH) in alkaloid scissoring, 1452 cm−1 for aromatic -C = C in flavonoids, 2932 cm−1 for aliphatic methylene (-CH2) and aldehyde (RCOH) stretching, 1035 and 1077 cm−1 for aromatic-OR in tannin, and 3280 cm−1 for out-of-plane bending of hydroxyl (-OH) in phenolics. Vitamin C (522,940 μg/g), flavonoids (860 μg/g), saponins (637.9 μg/g), terpenoid (48.4 μg/g), phenol (120%μg/g), alkaloid (4.18 μg/g), tannin (59.84%), and glycosides (9.04%) make up the extract's average phytochemical content. AFM presents pits and ridges on the mild steel coupons immersed in 0.1 M HCl solution without the extract. Those immersed in the solutions with varying concentrations of the extract had a passive layer of the CPLE adhering to the surfaces of the coupons thereby preventing the coupon’s direct contact with the acid solution and weight loss. However, over time, microbial growth decreased the efficiency of CPLE due to metabolites. Microbial tests show creamy, irregular and raised bacterial total colony-forming units per gram (Tcfu/g) as 4.6 × 105 Tcfu/g and 1.9 × 107 Tcfu/g in 2 runs. Also, a mixture of white and fluffy appearance and spore formation of fungi population of 4.8 × 105 Tcfu/g and 3.2 × 107 Tcfu/g in 2 Runs made up of Penicillium spp, Coccidioides immitis, Aspergillus flavus, and Fusarium spp, with hyphae, were seen in the solutions containing CPLE.

Effect of passivation layers in bilayer with ZrO2 on Ge substrate for improved thermal stability

Effect of passivation layers in bilayer with ZrO2 on Ge substrate for improved thermal stability

Long-term performance and mechanism of in-situ biogenetic sulfidated zero-valent iron for enhanced nitrate reduction

The biogenetic sulfidation of zero-valent iron (BS-ZVI) by sulfate-reducing bacteria (SRB) has been demonstrated to enhance the reactivity of ZVI. However, long-term performance of BS-ZVI and related mechanism were still unknown. Therefore, columns containing sponge iron and SRB are built to prepare BS-ZVI in-situ and study its long-term performance. Over 80 % of NO3‾ was reduced to NH4+ by in-situ BS-ZVI within 140 days, which was higher than the sole ZVI treatment (40 %-60 %). The bonding of ZVI and FeSx was in-situ firstly and finally loaded on ZVI. The reduction of Fe(III) by S(−II) and SRB contributed to the formation of FeSx, which improved the electrons transfer. Moreover, BS-ZVI enhanced the enzymes activity of SRB, thus accelerating the metabolic transformation of lactic acid to acetic acid. The accumulation of acetic acid enhanced the removal efficiency of NO3‾ through the dissolution of passivation layer. Overall, this study demonstrated a reactivity enhancement of ZVI through biogenetic sulfidation, which provided a new alternative method for the remediation of groundwater.

Ultrathin Self-Assembled Monolayer for Effective Silicon Solar Cell Passivation.

Passivation technology is crucial for reducing interface defects and impacting the performance of crystalline silicon (c-Si) solar cells. Concurrently, maintaining a thin passivation layer is essential for ensuring efficient carrier transport. With an ultrathin passivated contact structure, both Silicon Heterojunction (SHJ) cells and Tunnel Oxide Passivated Contact (TOPCon) solar cells achieve an efficiency surpassing 26%. To reduce production costs and simplify solar cell manufacturing processes, the rapid development of organic material passivation technology has emerged. However, its widespread industrial production is hindered by environmental safety concerns, such as strong acid corrosion and biological and ecological safety issues. Here, we discovered a low-cost self-assembled monolayer (SAM) hole-selective transport material known as 2PACz ([2-(9H-carbazol-9-yl) ethyl] phosphonic acid) with phosphate groups to form c-Si solar cells for the first time. The ultrathin film of 2PACz with phosphate groups can establish strong and stable P-O-Si bonds on the silicon surface. Meanwhile, like 2PACz, a uniform ultrathin film with a carbazole function group can offer electron-localizing and thus hole-selective properties, which provides ideas for studying dopant-free silicon solar cells. As a result of such interfacial passivation engineering, it plays an important role in repairing porous structures, such as pyramid-textured silicon surfaces, and cutting losses during the commercialization of c-Si solar cells. Crucially, this advancement offers insights for the development of new high-efficiency ultrathin film passivation methods in the postsilicon era.

Photodiodes Made of Cascade Perovskite Single Crystals with Passivation Layers for High-Energy-Resolution γ-ray Spectroscopy.

Lead halide perovskite single crystals (LHPSC) are promising for room-temperature γ-ray spectroscopy in radiation detection. While MA(CH3NH3)-based LHPSCs are the most straightforward and cost-effective to synthesize from solution, their performance in γ-ray spectroscopy is hindered by significant noise and ion migration at high bias, which degrades their energy resolution (ER). The work introduced an n-type/intrinsic/n-type photodiode incorporating passivation layers of MA-based LHPSCs, grown through solution-process epitaxial growth. This single-polarity device demonstrated an outstanding ER of 3.6% for 662 keV γ-ray photons. Overall, this work provides useful information for developing room-temperature γ-ray detectors based on solution-processed lead halide perovskites.

Stability of thermal convection in two superimposed miscible viscous fluids under gravitational modulation

Abstract The thermal stability of a system of two superimposed miscible viscous fluid layers, under gravitational modulation, is investigated using linear stability analysis. It is well known in the literature that in the absence of gravitational modulation, there exist two convection regimes depending on the buoyancy number: the single-cell regime, where convection is oscillating and occupies the entire volume of the two fluid layers, and the stratified regime where stationary convection occurs in each fluid layer. Using Chebyshev's spectral collocation method and Floquet's theory, the numerical results show that under gravitational modulation, single-cell convection oscillates at half the frequency of the external oscillation (subharmonic threshold), while the stratified regime oscillates at a frequency equal to that of the forcing (harmonic threshold). The critical buoyancy number corresponding to the transition between the two convection regimes depends, in addition to the viscosity ratio and the depth of the two layers, on certain dimensionless frequencies permeating this transition and also on the amplitude of oscillation via the Froude number. In the plane of the critical Rayleigh number versus dimensionless modulation frequency, the branch associated with stratified convection does not depend on the buoyancy number for equal viscosities whereas this is the case for the whole-convection regime. For different viscosities, both convection regimes depend on the buoyancy number. At last, in the stratified regime (harmonic threshold), the critical value of the viscosity contrast, corresponding to the passage from an active layer to a passive layer and vice versa, increases with the modulation frequency.

Elucidating the effect of strain path-dependent crystallographic texture evolution on the electrochemical behavior of nanostructured AA2024 aluminum alloy

This research provides insight into the effect of strain path-dependent texture evolution on the electrochemical behavior of nanostructured AA2024 aluminum alloy in a phosphate buffer solution (pH = 8.3). To achieve this, AA2024 alloy sheets were processed using two methods: accumulative roll bonding (ARB) and cross accumulative roll bonding (CARB), i.e., rotating the sheets 90° around the normal direction (ND) axis between each cycle. The ARB-processed AA2024 alloy exhibited a pancake-shaped structure and included texture components of Copper {112}<111>, Brass {011}<211>, P {110}<221>, and S {123}<634>. Meanwhile, the CARB-processed AA2024 alloy had extremely fine and equiaxed nano-grains (< 100 nm) and texture components of S {123}<634>, Brass {011}<211>, Goss {011}<100>, Rotated Cube {001}<110>, and P {110}<221> after eight cycles. Electrochemical studies demonstrated an increase in corrosion current density due to high imposed strains in the ARB route, which in effect made the conditions of passive layer formation more difficult and lowered the corrosion resistance. Additionally, achieving a more uniform distribution of extremely fine grains and {011} orientation textures such as Brass {011}<211>, Goss {011}<100>, and P {110}<221> texture components in the CARB route, provided ideal conditions for forming oxide passive films with superior protection properties compared to ARB. These unique findings can contribute to the broader application of crystallographic-orientation-dependent electrochemical behavior of alloys in the field of corrosion management.

Exploring the mechanism of stress-induced passive layer degradation in additively manufactured Ni-Fe-Cr-based alloy 718

This study explores the formation and degradation mechanisms of the passive layer on laser powder bed fusion (L-PBF) processed Ni-Fe-Cr-based alloy 718 using high-resolution submicron analysis and microcapillary electrochemical techniques. The findings provide new insights into passive layer breakdown under tensile loading, revealing the influence of microstructural characteristics, dislocation distribution, and mechanical stresses. Tensile loading caused oxide layer cracking near cell boundaries with higher dislocation density. Detachment of the oxide layer from the matrix created voids, allowing aggressive ions to penetrate, promoting crevice corrosion. Cell boundaries remained mostly intact, as metallic particles within the surface oxide layer.

Coulomb drag induced non-local resistance in double graphene layers.

We study the effect of Coulomb drag between graphene layers in presence of viscosity term. To do this, we use the simple model of Stokes equations for drift velocities in active and passive layers, known as Pogrebinskii's approach. The solution to these equations allows us to find the potential distribution, and thus the non-local drag resistance of passive layer. It is shown that in viscous regime the non-local resistance may take negative values, in contrast, the ohmic regime results in positive non-local resistance for all drag strengths. Additionally, we discuss the influence of magnetic field on the non-local drag magnetoresistance.

Enhancing anti-adhesion properties by designing microstructure - the microscopy and spectroscopy study of the intercellular bacterial response.

This study is the first one that investigates in detail the bacterial intercellular response to the high density of crystallographic defects including vacancies created in Cu by high pressure torsion. To this aim, samples were deformed by high pressure torsion and afterward, their antibacterial properties against Staphylococcus aureus were analyzed in adhesion tests. As a reference an annealed sample was applied. To avoid the influence of surface roughness, specially elaborated conditions for surface preparation were employed, which do not introduce defects and assure comparable surface roughness. The analysis of the chemical composition and thickness of passive layers by X-ray photoelectron spectroscopy showed that they were comparable for nanostructured and micrograined samples, consisting of Cu2O and CuO, and a thickness of 6nm. The interface bacterium-substrate was prepared by a focused ion beam and further analyzed by scanning transmission electron microscopy and energy dispersive spectroscopy. High pressure torsion processed Cu shows enhanced anti-adhesion properties while in contact with S. aureus than micrograined Cu. There is a linear correlation between luminous intensity and grain size-0.5. The bacterial intercellular defence mechanism includes the creation of Cu2O nanoparticles and the increased concentration of sulphur-rich compounds near these nanoparticles.

Long-term corrosion protection of reinforcing bars via a self-responsive coating incorporating ZrP functional fillers

The conventional coating of reinforcing bars exhibits inadequate anti-corrosion efficacy stemming from a non-specific, blind protection mechanism, poses a threat to the durability of concrete. We devised a novel self-responsive functional filler, L-arginine (LA) intercalated zirconium phosphate (LCZrP), synthesized via an intercalation reaction. This innovative filler was seamlessly integrated into an epoxy (EP) resin matrix, yielding a smart anticorrosive coating that harmoniously combines active and passive corrosion protection strategies. The integration of LCZrP within the coating matrix serves a trifecta of purposes: it extends the corrosion propagation path, effectively disperses nanofiller agglomeration, and enhances interfacial adhesion with the epoxy coating. Critically, the controlled release of corrosion inhibitors from the interlayer further fortifies the coating's resistance to corrosion, imparting a multi-layered protective shield. After enduring a 60-day immersion in a simulated concrete pore solution, the LCZrP/EP coating demonstrated exceptional durability, maintaining a low-frequency impedance modulus value consistently within the range of 4.27×1010 to 5.12×1010 Ω·cm2, marking a remarkable 34-fold enhancement over the performance of the epoxy coating alone. This breakthrough underscores the LCZrP/EP coating's potential as a groundbreaking solution for reinforcing bar protection in concrete, harnessing the complementary strengths of epoxy resin's physical barrier, the impermeability of two-dimensional lamellar structures, and the proactive release of corrosion inhibitors to forge a robust, multi-faceted passivation layer.

Self-Repairable Carbon Fiber-Reinforced Epoxy Vitrimer Actuator with Multistimulus Responses and Programmable Morphing.

Smart shape-changing structures in aerospace applications are vulnerable to damage in harsh environments. Balancing high mechanical performance with self-repair capabilities poses a challenge due to inherent trade-offs between strength and flexibility. To address this challenge, an asymmetric bilayer-structured actuator was fabricated using commercially available continuous carbon fiber tows (CFs) as the passive layer and a dynamic cross-linked epoxy vitrimer as the active layer. The construction of the vitrimer-CF actuator involves a simple and scalable hot-pressing process, resulting in a tensile strength of 234 MPa and an interfacial bonding strength of 405 N·m-1. This actuator exhibits remarkable deformation capability (210°/7 s) and an efficient self-repair ability under various stimuli, including thermal (60-160 °C), light (0.4-1.0 W·cm-2), electric (2-4 V), and solvent (acetone). By adjustment of the orientation angle of CFs, complex left-handed and right-handed curling structures can be achieved. Leveraging the insights from photothermal/electrothermal actuation mechanisms, a quadruped crawling robot is developed capable of crawling 4 cm with a single light illumination. The actuator can lift objects 45 times its weight when subjected to light stimuli. Additionally, a flap actuator is constructed to achieve an angle change of 63° within 10 s under an electric stimulus, enabling remote control over the aircraft flight angle. These results demonstrate the potential of the vitrimer-CF actuator for advanced applications in intelligent aerospace structures.

Tribological and corrosion performance of duplex electrodeposited Ni-P/Ni-W-P coatings

The present research investigates the properties of duplex electrodeposited Ni-P/Ni-W-P coatings consisting of Ni-P and Ni-W-P as inner layers alternately. This study aims to examine how various heat treatment conditions affect the mechanical, tribological, and electrochemical properties of the coatings.The results show that the heat treatment temperature and duration have a profound influence on the coating’s microstructure, which significantly affects its overall performance. Optimal microhardness and lower wear rates are observed at 400 °C temperature for 1 h duration. However, at 800 °C for 4 h, duplex electrodeposited coatings display cracks and increased oxide layers, negatively impacting mechanical, tribological, and corrosion properties. The Ni-W-P outer layer coating exhibited higher hardness and a lower wear rate compared to the Ni-P outer layer coatings. However, the assessment of corrosion behavior shows that Ni-P offers increased corrosion resistance, largely due to its ability to form a passive layer, which is further enhanced after heat treatment. When compared to their individual single-layer coatings, the present duplex coatings demonstrate superior overall performance.

Enhanced Oxidation Resistance and Interface Stability of Atomic-Layer-Deposited MoNx Electrodes via TiN Passivation for DRAM Cell Capacitor Applications.

The continuous miniaturization of dynamic random-access memory (DRAM) capacitors has amplified the demand for electrode materials featuring specific characteristics, such as low resistivity, high work function, chemical stability, excellent interface quality with high-k dielectrics, and superior mechanical properties. In this study, molybdenum nitride (MoNx) films were deposited using a plasma-enhanced atomic layer deposition (PEALD) employing bis(isopropylcyclopentadienyl)molybdenum(IV) dihydride and NH3 plasma for DRAM capacitor electrode applications. Depending on the deposition temperatures of the PEALD MoNx films ranging from 200 to 400 °C, the Mo/N ratio and crystal structure varied, transitioning from the cubic NaCl-B1-type MoN phase with Mo/N ratio of 1.4 to the cubic γ-Mo2N phase with Mo/N ratio of 1.9. Notably, MoNx films grown at 400 °C exhibited low resistivity (435 μΩ·cm), a high work function (5.28 eV), and superior mechanical hardness (11.3 GPa) compared to ALD TiN films. Despite these excellent properties, the PEALD MoNx electrode demonstrated insufficient chemical stability, particularly in terms of oxidation resistance and interface quality with ALD HfxZr1-xO2 (HZO) films. This resulted in poor morphology and the formation of significant oxygen-deficient HZO layers (such as HfO2-x), leading to considerable degradation in the electrical performance of metal-insulator-metal (MIM) capacitors. To mitigate this issue, a thin (2.5-14 nm) ALD TiN layer was introduced as a passivation layer between the MoNx bottom electrode and HZO dielectric. The TiN-passivated MoNx (TiN/MoNx) electrode showed substantially enhanced oxidation resistance and reduced interfacial reactions with the HZO dielectric. Consequently, MIM capacitors with TiN/MoNx bottom electrodes demonstrated outstanding electrical performance, including excellent dielectric properties, low leakage current density, and high mechanical strength. Hence, this study proposes a promising candidates for storage nodes in the next-generation DRAM capacitors.

In situ Triggered Rich‐LiF/Mg Multifunctional Passivation Layer for Modifying the Anode Interface of All‐Solid‐State Lithium Metal Batteries

AbstractLithium (Li) is a promising anode material for all‐solid‐state Li metal batteries (ASSLMBs) due to its high energy density. However, the interface incompatibility of Li/solid electrolyte and uneven Li deposition induces the penetration of Li dendrites. Herein, a multifunctional rich‐LiF/Mg artificial solid electrolyte interphase (SEI) layer is constructed from a MgF2‐PVDF‐HFP film to passivate the Li anode and achieve effective inhibition of Li dendrites. Notably, the triggered LixMg alloys rivet the Li6PS5Cl (LPSCl) electrolyte and Li anode together well, producing satisfactory interface contact and reducing overpotential. The mechanism of LiF and LixMg alloys to enhance the stability of the Li/LPSCl interface is further elucidated by density functional theory (DFT). Moreover, the synergistic interaction of LiF with high interfacial energy and LixMg alloys with low diffusion barrier promotes uniform deposition of Li during plating/stripping and structural stability. Therefore, the modified Li‐symmetric cell exhibits ultra‐high critical current density (2.0 mA cm−2) and considerable cyclic stability (more than 1000 h at 0.5 mA cm−2). Remarkably, NCM//LPSCl//3% MgF2‐PVDF‐HFP@Li ASSLMBs exhibit considerable long‐term cycle stability (86.9% capacity retention after 100 cycles at 0.2 C). This work highlights the critical role of the intermediate passivating layer in mitigating side reactions and preventing Li penetration.