Dendrite Suppression Research Articles

"Peapod-like" Fiber Network: A Universal Strategy for Composite Solid Electrolytes to Inhibit Lithium Dendrite Growth in Solid-State Lithium Metal Batteries.

Solid-state lithium metal batteries (SSLMBs) are a promising energy storage technology, but challenges persist including electrolyte thickness and lithium (Li) dendrite puncture. A novel three-dimensional "peapod-like" composite solid electrolyte (CSEs) with low thickness (26.8 μm), high mechanical strength, and dendrite inhibition was designed. Incorporating Li7La3Zr2O12 (LLZO) enhances both mechanical strength and ionic conductivity, stabilizing the CSE/Li interface and enabling Li symmetric batteries to stabilize for 3000 h. With structural advantages, the assembled LFP||Li and NCM811||Li cells exhibit excellent cycling performance. In addition, the constructed NCM811 pouch cell achieves a high gravimetric/volumetric energy density of 307.0 Wh kg-1/677.7 Wh L-1, which can light up LEDs under extreme conditions, demonstrating practicality and high safety. This work offers a generalized strategy for CSE design and insights into high-performance SSLMBs.

Self-assembled polysilane artificial solid electrolyte interphase layer towards highly reversible zinc electrochemistry

Commercial applications of aqueous Zn batteries primarily encounter challenges related to surface corrosion and dendrite formation. In this study, a hydrophobic polysilane layer functionalized with −CF3 groups (CF3-PSiOX) is tailored for Zn anode through a two-step process involving self-assembly and condensation. The CF3-PSiOX layer functions as a protective barrier, effectively isolating water and inhibiting corrosion. Moreover, the primary interactions between −CF3 and Zn2+ guides the diffusion and deposition processes of Zn2+ while optimizing the de-solvation process, ultimately resulting in dendrite inhibition. Hence, cells with CF3-PSiOX layer boasts a high Coulombic efficiency (∼99.8 % after 1500 cycles), a long lifespan (over 2400 h), and optimized capacity retention (73.3 % over 1000 cycles). The self-assembled polysilane layer with customizable groups offers a novel approach for tuning the interface properties of Zn anodes and establishes a general principle for interface adjustment applicable to alternative metallic electrodes.

Effects of solid electrolyte particle size and silver-carbon interlayer on lithium deposition in all-solid-state lithium-metal batteries

All-solid-state batteries with lithium-metal anodes are expected to exhibit high performance. For practical application, the growth of lithium dendrites must be suppressed. One method to suppress dendrite growth is to insert a carbon interlayer at the interface between the anode and solid electrolyte (SE). Dendrite growth is related to the anode interface properties and depends on the SE particle size used in the SE layer. Appropriate control of the SE particle size used at the anode interface can improve battery performance. In this study, the effects of SE particle size and carbon interlayer type on lithium-metal deposition morphology are investigated by X-ray CT measurement. The results show that dendrite growth is suppressed when the small-particle SE is used owing to the smaller pores between the SE layer and carbon interlayer. In addition, by controlling the SE particle size distribution using a double SE layer, both high ionic conductivity and dendrite suppression can be achieved. Furthermore, dendrite growth can be suppressed using a silver particle-added carbon interlayer, even with the large-particle SE where dendrites are prone to grow more easily.

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.

“Dragging” effect induced formation of AGGs-rich solvation structures in lithium metal batteries

The chemically homogeneous and mechanically robust solid electrolyte interphase (SEI) is a prerequisite for the realization of high-efficiency and long-life lithium metal batteries (LMBs). The performance of SEI is considerably influenced by the solvation structure of Li+ which can be precisely regulated by the interaction between electrolytes. In this study, new mechanism of the “dragging” effect on Li+ by diluents located outside the first solvation shell of Li+ was described by investigating diluent-Li+ interaction and diluent-anion interaction in a locally concentrated ionic liquid electrolyte (LCILE) based on lithium bis(fluorosulfonyl)imide (LiFSI), N-methyl-N-propylpyrrolidinium bis(fluorosulfonyl)imide (Pyr13FSI) and 1,1,2,2-tetrafluoroethyl 2,2,2-trifluoroethyl ether (TFETFE). A drag force on Li+ arising from the relatively powerful Li+-TFETFE interaction effectively contributes to the combination of Li+ with anion, creating a solvation structure rich in aggregate ion pairs (AGGs), which assists in the construction of high-quality SEI. With the exceptional lithium dendrite inhibition ability and Li+ transport characteristics of SEI, the lithium stripping/plating Coulombic efficiency is up to 99.2 % over 750 cycles at 1.0 mA cm−2 and Li/LFP cells achieves a remarkable capacity retention of 82.4 % for 100 cycles. This study presents a new viewpoint for diluents to modulate the solvation structure and provides a new strategy for the development of electrolytes suitable for next-generation high-performance LMBs.

Imide-pillared covalent organic framework protective films as stable zinc ion-conducting interphases for dendrite-free Zn metal anodes

The notorious growth of zinc dendrite and the water-induced corrosion of zinc metal anodes (ZMAs) restrict the practical development of aqueous zinc ion batteries (AZIBs). In this work, a zinc metallized, imide-pillared covalent organic framework (ZPC) protective film has been engineered as a stable Zn2+ ion-conducting interphase to modulate interfacial kinetics and suppress side reactions for ZMAs. Compared to bare Zn, ZPC@Zn exhibits a higher Zn2+ ionic conductivity, a larger Zn2+ transference number, a lower electronic conductivity, a smaller desolvation activation energy and correspondingly a significant suppression of corrosion, hydrogen evolution and Zn dendrites. Impressively, the ZPC@Zn||ZPC@Zn symmetric cell obtains a cycling lifespan over 3000 h under 5 mA cm−2 for 1 mA h cm−2. The ZPC@Zn||NH4V4O10 coin-type full battery delivers a specific capacity of 195.8 mA h g−1 with a retention rate of 78.5% at 2 A g−1 after 1100 cycles, and the ZPC@Zn||NH4V4O10 pouch full cell shows a retention of 70.1% in reversible capacity at 3 A g−1 after 1100 cycles. The present incorporation of imide-linked covalent organic frameworks in the surface modification of ZMAs will offer fresh perspectives in the search for ideal protective films for the practicality of AZIBs.

Reusable multifunctional interlayer for dendrite-free and ultrastable zinc anodes via regulating zinc-ion transport and inhibiting hydrogen evolution

The practical application of zinc anodes in aqueous zinc-ion batteries (ZIBs) is hindered due to uncontrollable dendritic Zn deposition and side reactions. Herein, a reusable interlayer constructed from Sn nanoparticles-modified polyhydroxy semi-carbonized bacterial cellulose (Sn@PHCBC) with three-dimensional interconnected network structure is proposed to achieve sustainable and smooth regulation of zinc anode. The suppression of dendrites is primarily attributed to the uniform Zn ions flux constructed by reversible Sn-Zn alloy nanoparticles channel, as well as the targeted transport and rapid desolvation of hydrated zinc ions through hydroxyl groups of PHCBC. Additionally, the abundant high overpotential Sn nanoparticles anchored in Sn@PHCBC interlayer effectively inhibit the hydrogen evolution reaction and minimize the formation of byproducts. As a result, the Zn||Zn symmetrical cell assembled with Sn@PHCBC interlayer demonstrates highly reversible electroplating/stripping behavior with an extended lifespan of 800 h at high current densities of 10 mA cm−2 and 10 mAh cm−2. Besides, after 1000 cycles of MnO2||Sn@PHCBC//Zn full cell, the Sn@PHCBC interlayer can still be reused with nearly 100 % coulombic efficiency after simple treatment. The rational design in this work provides a feasible solution for high-performance ZIBs and promote the development of advanced energy storage devices reutilization.

In situ coordinated ultrathin MOF-polymer electrolyte membrane with vertically aligned transfer channels for solid lithium metal batteries

Metal organic framework (MOF)-polymer composite solid electrolyte membrane with novel microstructure is expected to show attractive prospect for solid state lithium metal batteries. But the reported MOF were usually regarded as an entirety in composite solid electrolyte resulting in tradeoff between ionic conductivity and lithium dendrite inhibition ability. Herein, MOF-polymer composite membrane with vertically aligned channels and ultrathin MOF layer is proposed to decrease lithium ion transportation resistance obtained by simple phase inversion and in situ coordinated growth methods. The vertically aligned highways can decrease tortuous pathways and intensify ion conduction. The embedded ultrathin MOF layer on membrane surface leads to homogeneous plating/stripping of lithium. This novel structured MOF-polymer composite solid electrolyte exhibits improved ionic conductivity of 0.55 mS cm−1 at 22 ° C and lithium ion transference number of 0.87. Furthermore, the Li/Li symmetrical cell shows stable lithium plating/stripping performance for 1100 h at 0.1 mA cm−2 and 0.1 mA h cm−2. LiFePO4/MOF-polymer/Li coin battery demonstrates good rate capability and cycling performance with capacity retention of 82 % after 100 cycles at 0.2C and the pouch cell can light up the “DLUT” blue light lamp under folding and cutting states. This work encourages a new avenue to develop composite solid electrolytes with ion transportation highways and uniform distribution plane for solid lithium metal batteries.

Constructing 3D porous network channel on PP-based separator to achieve homogeneous deposition of lithium ions for lithium metal battery

Lithium metal anode is broadly regarded as one of the most promising anode materials for batteries due to its extremely high specific capacity, very low redox potential, and mass density. Nevertheless, non-uniform deposition of lithium ions hinder the practical application of lithium metal batteries (LMBs). Herein, it was essential to design a separator with high electrolyte affinity to inhibit the non-uniform deposition of lithium ions. In this work, the wettability and electrolyte uptake of the polypropylene (PP) separator were remarkably improved by introducing reduced graphene oxide (rGO) and polyvinylidene fluoride (PVDF) to the surface of the separator through one-sided coating. The composite separator resulted in lithium ion with high conductivity (1.35 × 10–3 S cm-1) and transfer number (0.63). After assembling the rGO/PVDF@PP separator into the LiFePO4||Li battery and conducting the test, it was found that the specific discharge capacity could still reach 136 mAh g-1 after 100 cycles at 1C. Furthermore, After 1000 h of cycling in the assembled Li‖Li symmetric battery, there is no obvious generation of lithium dendrites on the surface of the lithium metal, indicating the successful suppression of lithium dendrites by the composite separator. This study offers a promising pathway for producing large quantities of new composite separators with high levels of safety.

PVDF–HFP@Nafion-based quasisolid polymer electrolyte for high migration number in working rechargeable Na–O2 batteries

Rechargeable sodium-oxygen (Na-O2) battery is deemed as a promising high-energy storage device due to the abundant sodium resources and high theoretical energy density (1,108 Wh kg-1). A series of quasisolid electrolytes are constantly being designed to restrain the dendrites growth, the volatile and leaking risks of liquid electrolytes due to the open system of Na-O2 batteries. However, the ticklish problem about low operating current density for quasisolid electrolytes still hasn't been conquered. Herein, we report a rechargeable Na-O2 battery with polyvinylidene fluoride-hexafluoropropylene recombination Nafion (PVDF-HFP@Nafion) based quasisolid polymer electrolyte (QPE) and MXene-based Na anode with gradient sodiophilic structure (M-GSS/Na). QPE displays good flame resistance, locking liquid and hydrophobic properties. The introduction of Nafion can lead to a high Na+ migration number (tNa+ = 0.68) by blocking the motion of anion and promote the formation of NaF-rich solid electrolyte interphase, resulting in excellent cycling stability at relatively high current density under quasisolid environment. In the meantime, the M-GSS/Na anode exhibits excellent dendrite inhibition ability and cycling stability. Therefore, with the synergistic effect of QPE and M-GSS/Na, constructed Na-O2 batteries run more stably and exhibit a low potential gap (0.166 V) after an initial 80 cycles at 1,000 mA g-1 and 1,000 mAh g-1. This work provides the reference basis for building quasisolid state Na-O2 batteries with long-term cycling stability.

Design a polymer-based composite electrolyte with high ionic conductivity for high-performance lithium-metal batteries

Constructing a stable and robust solid polymer electrolyte (SPE) is crucial for achieving dendrite-free lithium-metal anodes and high-performance lithium batteries. However, realizing the integrity of solid electrolytes with high ion conductivity during long-life cycling under high current density remains a significant challenge. In this study, we propose a multifunctional SPE with a polyvinylidene fluoride (PVDF)/co-polyphenol coordination polymer (EACo2) hybrid composite to improve the durability of Li metal anode during repeat plating/stripping cycles by using a facile solution-casting method. The PVDF as a substrate with high mechanical strength and improved lithiophilicity exhibits high ionic conduction and excellent dendrite inhibition ability; meanwhile, the EACo2 fillers with a high density of Lewis-acidic sites contribute to the dissociation of lithium salts and decrystallization of the PVDF, resulting in a high Li-ion transference number and ion conductivity (2.66 × 10−3 S cm−1 at 30 ℃). The symmetrical cells with PVDF/EACo2 SPE can stabilize cycling over 1200 hours at a deposition capacity of 0.1 mAh cm−2. Moreover, the assembled full cells Li|LiFePO4 demonstrate long-term stability (1000 cycles at 1 C) with impressive capacity retention of 75 %, offering a promising approach towards high-performance lithium metal batteries.

High-efficiency Lithium Metal Stabilization and Polysulfide Suppression in Li-S Battery Enabled by Weakly Solvating Solvent.

Lithium-sulfur batteries (LSBs) are considered a highly promising next-generation energy storage technology due to their exceptional energy density and cost-effectiveness. However, the practical use of current LSBs is hindered primarily by issues related to the "shuttle effect" of lithium polysulfide (LiPS) intermediates and the growth of lithium dendrites. In strongly solvating electrolytes, the solvent-derived solid electrolyte interphase (SEI) lacks mechanical strength due to organic components, leading to ineffective lithium dendrite suppression and severe LiPS dissolution and shuttling. In contrast, the weakly solvating electrolyte (WSE) can create an anion-derived SEI layer which can enhance compatibility with lithium metal anode, and restricting LiPS solubility. Herein, a WSE consisting of 0.4м LiTFSI in the mixture of 1,4-dioxane (DX):dimethoxymethane (DMM) is designed to overcome the issues associated with LSB. Surface analyses confirmed the formation of a beneficial SEI layer rich in LiF, enabling homogeneous lithium deposition with an average Coulombic efficiency CE exceeding 99% over 100 cycles. Implementing the low-concentration WSE in Li||SPAN cells yielded an impressive initial specific capacity of 671mAhg-1. This research highlights the advantages of WSE and offers the pathway for cost-effective electrolyte development, enabling the realization of high-performance LSBs.

Bimetallic MOFs-Derived NiFe2O4/Fe2O3 Enabled Dendrite-free Lithium Metal Anodes with Ultra-High Area Capacity Based on An Intermittent Lithium Deposition Model.

In practical operating conditions, the lithium deposition behavior is often influenced by multiple coupled factors and there is also a lack of comprehensive and long-term validation for dendrite suppression strategies. Our group previously proposed an intermittent lithiophilic model for high-performance three-dimensional (3D) composite lithium metal anode (LMA), however, the electrodeposition behavior was not discussed. To verify this model, this paper presents a modified 3D carbon cloth (CC) backbone by incorporating NiFe2O4/Fe2O3 (NFFO) nanoparticles derived from bimetallic NiFe-MOFs. Enhanced Li adsorption capacity and lithiophilic modulation were achieved by bimetallic MOFs-derivatives which prompted faster and more homogeneous Li deposition. The intermittent model was further verified in conjunction with the density functional theory (DFT) calculations and electrodeposition behaviors. As a result, the obtained Li-CC@NFFO||Li-CC@NFFO symmetric batteries exhibit prolonged lifespan and low hysteresis voltage even under ultra-high current and capacity conditions (5 mA cm-2, 10 mAh cm-2), what's more, the full battery coupled with a high mass loading (9 mg cm-2) of LiFePO4 cathode can be cycled at a high rate of 5 C, the capacity retention is up to 95.2 % before 700 cycles. This work is of great significance to understand the evolution of lithium dendrites on the 3D intermittent lithiophilic frameworks.

Superhalide-Anion-Motivator Reforming-Enabled Bipolar Manipulation toward Longevous Energy-Type Zn||Chalcogen Batteries.

Neutrophilic superhalide-anion-triggered chalcogen conversion-based Zn batteries, despite latent high-energy merit, usually suffer from a short lifespan caused by dendrite growth and shuttle effect. Here, a superhalide-anion-motivator reforming strategy is initiated to simultaneously manipulate the anode interface and Se conversion intermediates, realizing a bipolar regulation toward longevous energy-type Zn batteries. With ZnF2 chaotropic additives, the original large-radii superhalide zincate anion species in ionic liquid (IL) electrolytes are split into small F-containing species, boosting the formation of robust solid electrolyte interphases (SEI) for Zn dendrite inhibition. Simultaneously, ion radius reduced multiple F-containing Se conversion intermediates form, enhancing the interion interaction of charged products to suppress the shuttle effect. Consequently, Zn||Se batteries deliver a ca. 20-fold prolonged lifespan (2000 cycles) at 1 A g-1 and high energy/power density of 416.7 Wh kgSe-1/1.89 kW kgSe-1, outperforming those in F-free counterparts. Pouch cells with distinct plateaus and durable cyclability further substantiate the practicality of this design.

Self-extinguishing polyimide sandwiched separators for high-safety and fast-charging lithium metal batteries

Developing fast-charging lithium metal battery (LMB) with high specific capacity arouses enormous attentions. Unfortunately, during the operation of fast-charging LMB, substantial amount of Joule heat generated within battery often induces inhomogeneous heat accumulation that concomitantly deteriorates the lithium dendrite growth issues, resulting in rapid capacity fading and potentially fatal thermal runaway. It is critically essential to develop advanced separator that possesses high ionic conductivity, effective dendrite inhibition and self-extinguishing property for fast-charging LMB with high-safety. Here, we report a facile approach to fabricate polyimide composite separator (denoted as PIFAP), where the polyimide fiber (PIF) membrane is sandwiched by aerogel layers of polyimide/ammonium polyphosphate composite. Notably, compared with PIF, the PIFAP features significant enhancement in flame retardance, electrolyte affinity, electrolyte adsorption and ionic conductivity. Moreover, beneficiating from the aerogel layers with uniform nanopores of ∼100 nm, the optimized PIFAP separator can enable homogeneous lithium deposition, achieving a dendrite-free lithium deposition on the surface of anode for over 1600 h, superior to the PIF and Celgard separators. The resulting “LiFePO4/PIFAP/Li” cell can exhibit a remarkably high cycling stability with 99.1 % of capacity retention after long-term cycling at a current density of 10 C.

20 nm-ultra-thin fluorosiloxane interphase layer enables dendrite-free, fast-charging, and flexible aqueous zinc metal batteries

Dendrite growth of zinc (Zn) anode at high current density severely affects the fast-charging performance of aqueous zinc metal batteries (AZMBs). While interfacial modification strategies can optimize Zn performance, challenges such as complicated preparation processes, excessive layer thicknesses, and high voltage hysteresis should be addressed. Herein, we utilize a cost-effective liquid fluorosiloxane, (3,3,3-trifluoropropyl)trimethoxysilane, for scalable modification of Zn foil via drop-casting at room temperature, resulting in an ultra-thin interphase layer of only 20 nm. The Si-O-Zn bonds formed between fluorosiloxane and Zn ensure interfacial stability, and the Si-O-Si bonds between fluorosiloxane molecules help to homogenize the electric field distribution. Additionally, the abundant highly electronegative fluorine atoms on the anode surface act as zincophilic sites, promoting the uniform deposition of Zn2+. Thus, the modified Zn foil (SiFO-Zn) exhibits excellent dendrite suppression, reduced voltage hysteresis, and prolonged cycle life at ultra-high current density (40 mA/cm2), achieving a cumulative areal capacity of 12.9 Ah/cm2. Further, the full cell assembled with 10 μm-thick SiFO-Zn anode and MnO2 cathode achieves 2600 cycles at 5 A/g with minimal capacity degradation, and a large-size (22.5 cm−2) pouch cell powers the light-emitting diode even after reverse bending, demonstrating the potential of AZMBs for fast-charging flexible devices.

High-performance lithium batteries achieved by electrospun MXene-Enhanced cation-selective membranes

Conventional separators applied in lithium batteries face limitations like low porosity, poor electrolyte wettability, lower cation selectivity, and thermal instability, which impact battery performance and safety characteristics. Besides the challenge in separator design, transition metal ion migration from positive electrodes during cycling greatly accelerates capacity fading because of unrestricted diffusion of transition metal cation across the separator. This study explores an innovative strategy for the separator design by incorporating MXene (spraying MXene solution on both sides of the separator), a two-dimensional material, into electrospun Polyacrylonitrile/Polyetherimide membranes with the function of cation selection. Li+ can be accelerated, and its transference number increases along with the anion limitation in the MXene layer. Ni, Co, and Mn ion dissolution from the positive electrode is inhibited due to the cation selectivity of the MXene layer. Leveraging electrospinning advantages, the resultant membranes exhibit high porosity, excellent liquid absorption, mechanical strength, and superior thermal properties. Benefiting from MXene's layered structure and excellent adsorption ability, the membrane significantly inhibits the dissolution of transition metal ions while enabling smooth lithium deposition due to its cation selectivity. Eventually, the Li||NMC811 batteries deliver outstanding cyclic performance (91.3 % capacity retention after 200 cycles) and robust lithium dendrite suppression (800 h of stable cycling). Moreover, the MXene-modified membrane demonstrates exceptional electrolyte wettability, significantly improving ionic transference number (0.67) and conductivity (1.6 mS/cm). Modification of membrane surfaces with MXene offers insights into addressing transition metal ion migration from the positive electrode material perspective, providing a promising avenue for high-performance LIBs.

Interfacial Design Strategy for Polymeric Lithium Metal Batteries with Superfast Charge‐Transfer Kinetics

AbstractInterfacial instability including the high charge‐transfer resistance and the uncontrolled lithium dendrite growth have severely restricted the safety, fast‐charging, and high‐power capabilities of solid‐state polymeric lithium metal batteries (PLMBs). Here, the study demonstrates the ionic nanoclusters self‐assembled between the lithium ions and a rigid‐rod sulfonated aromatic polyamide Poly 2,2′‐disulfonyl‐4,4′‐benzidine terephthalamide (PBDT) can facilitate uniform lithium deposition; meanwhile, realizing 102–103 times lower interfacial charge‐transfer resistance than PEO‐based electrolytes and excellent lithium dendrite suppression at the interfaces. The cells assembled with this solid‐state polymer electrolyte at room temperature show a record high critical current density (6 mA cm−2/3 mAh cm−2), 80% capacity retention at 10 000 cycles (5 C) with the LiFePO4 cathode. With the temperature increased to 80 °C, the cells enable almost 100% of the theoretical capacity at 3 C and high specific power density (20 kW kg−1). According to the Cryo‐TEM imaging and computational simulation results, it is concluded that these nanoscale self‐assembled ionic nanoclusters play a critical role in realizing the superfast charge‐transfer kinetics by balancing the pre‐exponential factor and activation energy at the lithium‐polymer space‐charge interfaces. This interfacial design strategy based on thermodynamically favored ion‐association and self‐assembly between the metal ions and the polyanions guarantees superior charge‐transfer kinetics in PLMBs.

5.1µm Ion-Regulated Rigid Quasi-Solid Electrolyte Constructed by Bridging Fast Li-Ion Transfer Channels for Lithium Metal Batteries.

An ultra-thin quasi-solid electrolyte (QSE) with dendrite-inhibiting properties is a requirement for achieving high energy density quasi-solid lithium metal batteries (LMBs). Here, a 5.1µm rigid QSE layer is directly designed on the cathode, in which Kevlar (poly(p-phenylene terephthalate)) nanofibers (KANFs) with negatively charged groups bridging metal-organic framework (MOF) particles are served as a rigid skeleton, and non-flammable deep eutectic solvent is selected to be encapsulated into the MOF channels, combined with in situ polymerization to complete safe electrolyte system with high rigidness and stability. The QSE withconstructed topological network demonstrates high rigidity (5.4GPa), high ionic conductivity (0.73 mS cm-1 at room temperature), good ion-regulated properties, and improved structural stability, contributing to homogenized Li-ion flux, excellent dendrite suppression, and prolonged cyclic performance for LMB. Additionally, ion regulation influences the Li deposition behavior, exhibiting a uniform morphology on the Li-metal surface after cycling. According to density-functional theory, KANFs bridging MOFs as hosts play a vital function in the free-state and fast diffusion dynamics of Li-ions. This work provides an effective strategy for constructing ultrathin robust electrolytes with a novel ionic conduction mode.

Grain refinement and Laves phase dispersion by high-intensity ultrasonic vibration in laser cladding of Inconel 718

Laser cladding is a promising surface modification and repair technology for fabricating Inconel 718 parts. However, laser cladding may produce coarse grains and brittle Laves phase, leading to a significant decrease in performance. The application of high-intensity ultrasonic vibration in laser cladding is able to refine grain and reduce Laves phase. This study investigates the distribution characteristics and the evolution mechanism of the grains and Laves phase in laser cladding with high-intensity ultrasonic vibration. The effects of high-intensity ultrasonic vibration on alteration of grain characteristics and the reduction of Laves phase were analyzed and discussed through ultrasonic vibration-assisted laser cladding experiments. Results indicate that high-intensity ultrasonic vibration promoted a columnar-to-equiaxed transition, and reduced the grain size from 75.6 μm to 48.8 μm. Furthermore, the Laves phase had a decrease of 47.1% in the volume fraction, and transformed from a long-striped shape into a fine granular shape, leading to a more homogeneous distribution of elements in Laves phase. The change in the grains and the Laves phase is attributed to dendrite fragmentation and inhibition of element segregation by nonlinear effects of ultrasound including cavitation and acoustic streaming. The findings of this study confirm the significant benefits of applying high-intensity ultrasonic vibration in laser cladding and provide insight into the underlying evolution mechanisms of high-intensity ultrasonic vibration for grains and Laves phase.