Lithium Dendrite Growth Research Articles

Effective Electrolyte Combination Composed of 1,1‐Diethoxyethane and Lithium Bis(fluorosulfonyl)imide for Dendrite‐suppressible Li Metal Anodes

AbstractAlthough Li metal is considered the most promising anode material owing to its high theoretical capacity, there are numerous restrictions on expanding its application because of undesired surface reactions occurring at the Li anode. To solve this, an effective electrolyte combination consisting of 1,1‐diethoxyethane (DEE) and lithium bis(fluorosulfonyl)imide (LiFSI) is used in this work, which can provide an organic/inorganic‐hybridized solid‐electrolyte interphase (SEI) at the Li anode. The DEE solvent affords flexible carbon‐abundant components, whereas LiFSI offers mechanically rigid lithium fluoride‐type components; these undergo electrochemical reduction to form SEI layers that are balanced in terms of organic and inorganic components. Systematic analysis results exhibit that when the SEI layer integrated with DEE and LiFSI is embedded in the lithium anode, electrolyte decomposition, and dendritic lithium growth are suppressed in Li/Li cells, thereby improving surface stability. Similarly, it provides stable cycle life characteristics even at 150 cycles in Li/S cells (72.0% vs 52.6%).

Electrochemical Impedance Spectroscopy Analysis of Dendrite Growth on the Lithium Metal Surface in Polysulfide-Insoluble Electrolytes

Abstract Lithium has been widely investigated owing to its high theoretical specific capacity and low electrochemical potential. This is required for high-energy-density lithium batteries such as lithium–sulfur (Li–S) batteries. Recently, Li–S batteries with polysulfide-insoluble electrolytes, such as sulfolane (SL) and triglyme (G3), have attracted research attention because they suppress the dissolution of lithium polysulfide intermediates. However, lithium dendrite growth on the Li metal anode during the charging–discharging process causes an internal short-circuit, which may lead to serious accidents. To realize a Li–S battery, a fail-safe system to prevent short-circuits is essential. In this study, we investigated the cycle degradation mechanism of a Li metal anode in SL and G3 electrolytes using electrochemical impedance spectroscopy. The changes in charge transfer resistance (Rct) and solid electrolyte interphase resistance (RSEI) of Li-Li symmetrical cells in SL and G3 electrolytes was measured under charge–discharge cycling in detail down to internal short-circuits. Consequently, in both the electrolyte systems, the RSEI and Rct behaviors were disparate during cycling, and a mechanism for the short-circuit process was proposed. In addition, before the short-circuit process occurred, the change in the trend of Rct from stable to increasing was indicative of an imminent short-circuit.

Tailoring the Lithium Deposition on Cu Substrate by a Functionalized‐Polysiloxane Layer

AbstractOwing to the high theoretical capacity of 3860 mAh g−1 and low redox potential, lithium metal is the best candidate for the development of next generation high‐energy density lithium‐ion batteries. However, notorious lithium dendrites growth and the poor compatibility of liquid electrolyte hinder the commercialization of lithium metal batteries. In this work, an anode‐less system was used to understand the change in lithium deposition on Cu current collector after the additional functionalized‐polysiloxane (PE) layer. The PE structure consists of lithiophobic and lithiophilic side chains which facilitate the uniform lithium deposition on Cu substrate. This evidence was collected by scanning electron microscopy (SEM) after the cycling test of half‐cell configuration and the lithium deposition with different current densities. The reversibility was improved by 5 % compared with the bare Cu. In addition, the potential polarization was lowered after the addition of PE layer on bare Cu. Thus, the higher cycle stability (40 %) and more stable coulombic efficiency are observed on the PE@Cu||NCM83 cell compared with the bare‐Cu||NCM83 during the cycle test.

Experimental correlation of anionic mass transport and lithium dendrite growth in solid-state polymer-based lithium metal batteries

Experimental correlation of anionic mass transport and lithium dendrite growth in solid-state polymer-based lithium metal batteries

Single ion conducting gel polymer electrolytes containing polybenzimidazole-based ionomers with abundant Li+ transport channels for dendrite-free lithium metal batteries

Single ion conducting polymer electrolytes (SIPEs) have attracted much attention due to their ability to effectively inhibit the growth of lithium dendrites, but still confront the problems of low ionic conductivity and poor mechanical properties. In this study, a new polybenzimidazole-based ionomer (M-OPBI) is synthesized by chemically modifying aromatic poly(2,2′-(p-oxydiphenylene)-5,5′-bibenzimidazole) (OPBI), and two series of novel SIPEs (i.e. M-OPBI/PEO and M-OPBI/PVDF) are achieved after blending with different polymer matrices (i.e. poly(ethylene oxide) (PEO) and poly(vinylidene fluoride) (PVDF)). Afterwards, some single ion conducting gel polymer electrolytes (SIGPEs) with abundant Li+ transport channels are fabricated by absorbing appropriate amount of plasticizers. The imidazole anions and sulfonylimide anions in the ionomer present low binding energies with Li+, which is beneficial for the dissociation and transport of Li+. Moreover, in view of the presence of rigid aromatic structure in the main chain of the ionomer and the interactions between the polymers, polybenzimidazole-based SIPEs all exhibit excellent thermal and mechanical properties. Most importantly, in comparison with PVDF matrix, PEO is approved to be more compatible with the ionomer and provide additional Li+ conduction sites, and this will enhance the interfacial compatibility and facilitate the construction of abundant Li+ transport channels in M-OPBI/PEO membranes. As a result, M-OPBI/PEO-0.4 membrane shows the lowest activation energy of 0.098 eV, the highest room-temperature ionic conductivity of 9.9 × 10-5 S cM-1, and a satisfactory lithium ion transference number of 0.88. Thanks to these merits, the symmetric Li||Li cell assembled with M-OPBI/PEO-0.4 membrane exhibits an excellent reversible lithium plating/stripping performance without short circuit over 2160 h. This study provides a new design strategy for the development of SIGPEs for application in dendrite-free lithium metal batteries.

Advanced Hierarchical Lithiophilic Scaffold Design to Facilitate Synchronous Deposition for Dendrite‐Free Lithium Metal Batteries

AbstractLocalized deposition behavior tends to induce the growth of lithium dendrite and hinder the the full utilization of lithium storage space, significantly impeding the practical application of 3D conductive hosts. Here, a novel synchronous deposition mode is proposed for the first time through hierarchical structure design of 3D Li host. The top‐down gradually enhanced lithiophilicity and conductivity of 3D scaffold provide sufficient driving force for Li+ to migrate downward, promoting synchronous Li deposition within the entire space of the host. Notably, the novel deposition mode has been theoretically and experimentally validated through finite element simulation and in situ optical microscopy, respectively. The meticulously designed strategy not only maximizes the utilization of the entire 3D scaffold space but also prevents the formation of Li dendrites under high current rate. Consequently, the symmetric Li//Li cell exhibits a long‐term cycling lifespan over 3700 h with a low overpotential of 15.6 mV, together with a Coulombic efficiency as high as 99.5% over 300 cycles at 3 mA cm−2. The full cell paired with LiFePO4 cathode demonstrates a cycling lifespan of 1000 cycles with a capacity retention rate of 91.6%. The proposed synchronous deposition strategy opens up a new paradigm for the design and construction of 3D hosts for dendrite‐free Li metal anode.

A PET-enhanced PEO-ionic liquid-based gel polymer electrolyte for solid state lithium metal batteries

Gel polymer electrolytes (GPEs) are attractive for their promising prospect in lithium metal batteries (LMBs) owing to their outstanding thermal stability and remarkable electrochemical performance. Nevertheless, the practical application of traditional GPEs is significantly impeded by their limited mechanical strength. In order to address this issue, this study introduces an ultrathin and mechanically-strong poly(ethylene terephthalate) (PET) nonwoven fabric (PET-NW) as a rigid support layer for the GPEs composed of poly (ethylene oxide) (PEO) and ionic liquid (IL) EMIM-TFSI. The resulting PEO-IL/PET-NW-based GPE (NW GPE) demonstrates an excellent lithium ionic conductivity of 4.21 × 10−4 S cm−1, a lithium ion transference number of 0.20, and an ultrahigh mechanical strength of 53.2 MPa. These characteristics collectively contribute to the suppression of lithium dendrites growth and improved electrochemical performance of Li|NW GPE|LiFePO4 full cells which exhibit enhanced rate capability and cycling stability in comparison with Li|GPE-I30|LiFePO4 full cells. The employment of PET-NW in the fabrication of GPEs can pave a viable way for significant advancements in high-performance solid state LMBs for various practical applications.

Highly crystalline nanorods pyrene-based covalent organic framework artificial solid electrolyte interface accelerated interface Li+ regulation on lithium anode

The detrimental effects of heterogeneous Li deposition and aeolotropic Li dendrite propagation critically hamper its serviceability of Li metal batteries. The exploitation of neutral multifunctional porous polymer artificial SEI is imperative to modulate interfacial ionic transfer behavior. Herein, we propose a strategy based on dual-functional nanorod-shaped covalent organic frameworks (COF) to accelerate Li+ diffusion and mitigate lithium dendrite growth by creating an artificial solid electrolyte interface (SEI) layer. As anticipated, the immobilized high-polarity –OH and −CN- groups, along with the porous channel facilitates, facilitate uniform Li+ flux distribution and rapid Li+ migration. Additionally, the highly conjugated nature of the pyrene moiety not only enhances the plane π-π stacking crystallinity of TFDH-COF, but contributes positively to Li+ and repelling TFSI−. The combination of comprehensive ex-situ/in-situ characterizations and DFT calculations have unraveled the underlying mechanisms on the reductive Li mitigation energy barrier and enhancive Li+ transfer ability. In contrast with bare Li, the resultant TFDH-COF@Li electrode demonstrates the elevated reversibility of Li+ utilization, slight polarization, dendrite-free interface and prolonged cyclic performance in Li|Cu, Li|Li, and Li-based full cells operated at rigorous current densities. Those unswerving evidences enlighten the feasibility of engineering the neutrality COF layer to get rid of adverse disordered Li proliferation.

Superionic conducting vacancy-rich β-Li3N electrolyte for stable cycling of all-solid-state lithium metal batteries.

The advancement of all-solid-state lithium metal batteries requires breakthroughs in solid-state electrolytes (SSEs) for the suppression of lithium dendrite growth at high current densities and high capacities (>3 mAh cm-2) and innovation of SSEs in terms of crystal structure, ionic conductivity and rigidness. Here we report a superionic conducting, highly lithium-compatible and air-stable vacancy-rich β-Li3N SSE. This vacancy-rich β-Li3N SSE shows a high ionic conductivity of 2.14 × 10-3 S cm-1 at 25 °C and surpasses almost all the reported nitride-based SSEs. A Li- and N-vacancy-mediated fast lithium-ion migration mechanism is unravelled regarding vacancy-triggered reduced activation energy and increased mobile lithium-ion population. All-solid-state lithium symmetric cells using vacancy-rich β-Li3N achieve breakthroughs in high critical current densities up to 45 mA cm-2 and high capacities up to 7.5 mAh cm-2, and ultra-stable lithium stripping and plating processes over 2,000 cycles. The high lithium compatibility mechanism of vacancy-rich β-Li3N is unveiled as intrinsic stability to lithium metal. In addition, β-Li3N possesses excellent air stability through the formation of protection surfaces. All-solid-state lithium metal batteries using the vacancy-rich β-Li3N as SSE interlayers and lithium cobalt oxide (LCO) and Ni-rich LiNi0.83Co0.11Mn0.06O2 (NCM83) cathodes exhibit excellent battery performance. Extremely stable cycling performance is demonstrated with high capacity retentions of 82.05% with 95.2 mAh g-1 over 5,000 cycles at 1.0 C for LCO and 92.5% with 153.6 mAh g-1 over 3,500 cycles at 1.0 C for NCM83. Utilizing the vacancy-rich β-Li3N SSE and NCM83 cathodes, the all-solid-state lithium metal batteries successfully accomplished mild rapid charge and discharge rates up to 5.0 C, retaining 60.47% of the capacity. Notably, these batteries exhibited a high areal capacity, registering approximately 5.0 mAh cm-2 for the compact pellet-type cells and around 2.2 mAh cm-2 for the all-solid-state lithium metal pouch cells.

Ordered and Expanded Li Ion Channels for Dendrite‐Free and Fast Kinetics Lithium–Sulfur Battery

AbstractThe uncontrolled polysulfide shuttling and lithium dendrite growth greatly impede the practical implementation of Li–S batteries. These issues can be alleviated by constructing an artificial layer that immobilizes soluble polysulfides and regulates Li+ flux. Here, a layer‐expanded lithium montmorillonite is fabricated through molecular intercalation to serve as a dual regulator for Li–S batteries. The lithiophilic montmorillonite, with its ordered and expanded Li+ diffusion channels, exhibits a high transference number, and promotes homogeneous Li deposition. Additionally, its moderate adsorption of polysulfides, combined with favorable Li diffusion behavior, enhanced the redox kinetics of sulfur species. This unique structure enables a prolonged lifespan of 1000 cycles at 0.5C with a low capacity decay of 0.04% per cycle for practical Li–S batteries.

Cross-Linked Polyamide-Integrated Argyrodite Li6PS5Cl for All-Solid-State Lithium Metal Batterie.

Lithium dendrite growth has become a significant barrier to realizing high-performance all-solid-state lithium metal batteries. Herein, an effective approach is presented to address this challenge through interphase engineering by using a cross-linked polyamide (negative electrostatic potential) that is chemically anchored to the surface of Li6PS5Cl (positive electrostatic potential). This method improves contact between electrolyte particles and strategically modifies the local electronic structure at the grain boundary. This innovation effectively suppresses lithium dendrite formation and enhances the overall interface stability. As a result, the critical current density of the Li6PS5Cl sulfide electrolyte is dramatically boosted from 0.4 to 1.6mAcm-2, representing a remarkable fourfold improvement. Moreover, Li-Li symmetric batteries demonstrate exceptional stability, enduring over 10,000 h of consistent Li+ deposition/stripping at a high areal capacity of 3mAhcm-2. Impressively Li-LiNi0.89Mn0.055Co0.055O2 full cells exhibited outstanding cycle stability and rate performance, maintaining over 80% capacity retention after 750 cycles at a demanding 1C rate. Pouch cells produced using dry-process electrodes demonstrate strong potential for commercialization. The interphase engineering strategy offers a promising solution to the persistent challenge of dendrite growth, enabling the full realization of sulfide electrolytes' capabilities in next-generation battery technologies.

Anion-Tuned Fluorinated Solvation Sheath Enables Stable Lithium Metal Batteries.

Continuous side reactions between conventional carbonate-based electrolytes and electrodes lead to electrolyte consumption and the growth of lithium dendrites, which always lead to serious capacity fading or safety issues, hindering the development of lithium metal batteries. Here, a nonflammable all-fluorinated electrolyte with the anion-participating Li+ solvation sheath is developed and the corresponding electrochemical properties are studied. Combining theoretical calculations and X-ray photoelectron spectroscopy analysis, ethyl 2,2,2-trifluoroethyl carbonate (ETFEC) and methyl difluoroacetate (MDFA) as cosolvents in the all-fluorinated electrolyte, PF6- anions accumulate on the lithium metal anode and preferentially reduced to obtain a LiF-rich solid electrolyte layer, inducing uniform lithium metal deposition. Additionally, the anions located in the solvation structure improve the reduction stability of the solvent, which avoids the rapid decline in battery capacity caused by the continued decomposition of the solvent. Consequently, The Li||NCM811 battery achieved initial capacity retention of 71.48% after 430 cycles at a voltage of 4.3 V, and the capacity retention reached 64.52% after 225 cycles even at a high voltage of 4.5 V. This nonflammable electrolyte can alleviate the rapid decline in battery capacity caused by solvent decomposition.

Design of an LiF-rich interface layer using high-concentration fluoroethylene carbonate and lithium bis(fluorosulfonyl)imide (LiFSI) to stabilize Li metal batteries.

The development of high-energy-density Li metal batteries is limited by the uncontrollable growth of Li dendrites and an unstable Li/electrolyte interface during long-term Li plating/stripping. In this work, using high-concentration fluoroethylene carbonate (FEC) electrolyte, an LiF-rich interface layer was generated on the Li metal surface. This LiF-rich interface layer could effectively inactivate the high reactivity of the Li metal surface and suppress lithium dendrite growth, forming a uniform and dense structure at the Li/electrolyte interface to stabilize Li metal batteries. Owing to the enhanced interface stability offered by the high-concentration FEC electrolyte with LiFSI additive, the Li‖LiFePO4 cell presented high capacity retention (89.1%) after 200 cycles at 1C (165 mA g-1) and retained over 133.7 mA h g-1 at 10C rate, whereas only 115.0 mA h g-1 was achieved in the traditional carbonate ester electrolyte. The results show an obvious improvement in the cycle performance and rate capability of Li metal batteries containing a high-concentration FEC electrolyte with LiFSI as an additive.

Metal‐Organic Framework‐Derived Elastic Solid Polymer Electrolytes Enabled by Covalent Crosslinking for High‐Performance Lithium Metal Batteries

AbstractThe key issue in utilizing solid polymer electrolytes for high‐energy‐density lithium metal batteries is to balance the conflicting demands of superior processability, adequate ionic conductivity, and mechanical stability. Inspired by molecular structure design, a metal‐organic framework‐derived polyether poly(urethane urea) solid polymer electrolyte (denoted as ePU@H SPE) has been synthesized via a facile polycondensation method involving covalent crosslinking. The reduced crystallinity and numerous polar groups in ePU@H SPEs enhance Li salt dissociation and create efficient Li+ ion diffusion channels, yielding remarkable ionic conductivity (1.48 × 10−4 S cm−1). The polymer backbones, incorporating covalent bonds and dynamic hydrogen bonds, provide superb mechanical strength (5.12 GPa), high toughness (1240%), and excellent resilience, which suppress lithium dendrite growth and buffer electrode volume fluctuations during cycling. Leveraging these attributes, the well‐designed ePU@H SPE enables ultra‐high durability in lithium plating/stripping over 2300 h. Moreover, the integrated LFP|ePU@H|Li batteries, generating delicate electrode/electrolyte interfacial contact, deliver an exceptionally long lifespan (86% retention over 500 cycles at 1 C). Moreover, the LFP|ePU@H|Li pouch cell operates reliably even under severe deformation and external damage. Impressively, the stable cycling performance of full batteries incorporating high‐voltage LCO and high‐capacity S cathodes further verifies the significant potential of advanced ePU@H SPEs for practical applications.

Bridging links between solid electrolytes and electrodes: Boosting the electrochemical performance of flame-retardant solid electrolytes with vapor-deposited carbon and gold-sputtered nanolayers

Solid electrolytes provide significant advantages such as high safety, minimal leakage, elevated energy density, and flexibility. However, challenges like sluggish ion transport (both in bulk and at interfaces), lithium dendrite formation, and suboptimal interface compatibility persist. This study delineates a strategy for enhancing composite solid electrolytes (CSE) through the sputtering and evaporation of an Au-C nanolayer, thereby augmenting interface contact and facilitating ion transport. The modified nanointerface layer ensures swift and homogeneous heat transfer at the interface, promoting uniform lithium-ion deposition and stripping and restrain lithium dendrite growth. The dual-network structure gel, synthesized by blending carrageenan and polyethylene oxide, imparts exceptional flexibility and thermal stability to the CSE. The obtained polymer solid electrolyte exhibits high ionic conductivity (2.48 × 10-4 S cm−1), an ion transference number of 0.76, and puncture strength of 6 MPa. It also demonstrates excellent thermal stability, withstanding 100 °C for 24 h and resisting ignition for 120 s when exposed to an open flame. Surface modifications Au-C nanolayers decrease interfacial resistance by 200 % and enhance thermal conductivity by 20 %. Non-destructive X-CT analysis and COMSOL-Multiphysics thermal simulations were utilized to investigate the function of modified nanolayers and composite structure. This innovative surface nanolayers modification, combined with advanced testing and analysis, promising strategies for the scalable application of solid electrolytes.

Dual driven asymmetric electrolyte with gradient distributed UPy-CNTs for high-performance lithium metal batteries

Asymmetric electrolytes with both anode and cathode compatibility are promising candidates for high-energy–density batteries and high-safety lithium metal batteries (LMBs). However, the asymmetric electrolyte is still hindered by the complex multi-layer coating process, resulting in multiple internal interfaces of the electrolyte and poor battery performance. Herein, a one-step constructed asymmetric electrolyte with gradient distributions of 2‐ureido‐4[1H]-pyrimidinone functionalized carbon nanotubes (UPy-CNTs) is prepared via the dual driving forces of solvent evaporation and fluoropolymer migration. On the one hand, during the solvent evaporation process, based on the competitive effect between evaporation of solvent and diffusion of dispersions, the gradient distribution of asymmetric electrolyte can be constructed by enhancing evaporation and inhibiting uniform diffusion. On the other hand, due to the abundant hydrogen bonds between UPy and F, the gradient distribution of UPy-CNTs can be further promoted when the fluoropolymer spontaneously migrates to the surface. The gradient distribution of UPy-CNTs not only greatly increases Young’s modulus of the asymmetric electrolyte on the Li metal side, but also can adjust the Li+ solvation structure to form a LiF-rich solid electrolyte interface (SEI), thereby inhibiting the generation and growth of lithium dendrites. Because of the ingenious structure of the asymmetric electrolyte, the ionic conductivity is 0.226 mS cm−1 and the Li+ transferences number is 0.79. Prominently, Li||Li symmetric batteries can stably cycle for 2500 h at 0.1 mA cm−2 and 0.1 mAh cm−2. In addition, Li||LFP batteries can maintain a high specific capacity of 146 mAh g−1 after 200 cycles at 0.5C.

Diffusion Behavior and Kinetics for the Vapor Phase Infiltration of Trimethylaluminum in Poly(ethylene oxide): An In Situ Quartz Crystal Microgravimetry Study.

Vapor phase infiltration (VPI) facilitates the incorporation of inorganic components into organic polymers, emerging as an effective technique for fabricating organic-inorganic hybrid materials. However, the complexity of diffusion behavior during the VPI process presents challenges in studying diffusion kinetics, particularly for highly reactive precursor-polymer systems such as trimethylaluminum (TMA) and poly(ethylene oxide) (PEO). In this study, we investigate the VPI process of TMA in PEO using in situ quartz crystal microgravimetry (QCM), which enables measurement of diffusion behavior and kinetics with high precision due to its high temporal resolution. Our results indicate that the VPI process consists of two main regions: a rapid diffusion process, corresponding to the initial penetration of the precursor into the film, followed by a slower relaxation process, attributed to the ongoing chemical reaction. The equivalent diffusion coefficient (De) was estimated to be on the order of 10-9 cm2/s and decreased with increasing aluminum content. Using energy application as a proof-of-concept, when optimized, VPI-modified PEO films were successfully utilized as solid polymer electrolytes (SPEs) for lithium metal batteries (LMBs), showcasing superior performance in mitigating lithium dendrite growth. This study offers valuable insights into the VPI process for PEO-TMA systems and provides guidance for optimizing VPI conditions to enhance the performance of advanced materials.

Calcium Alginate Fibers/Boron Nitride Composite Lithium-Ion Battery Separators with Excellent Thermal Stability and Cycling Performance.

As one of the most critical components in lithium-ion batteries (LIBs), commercial polyolefin separators suffer from drawbacks such as poor thermal stability and the inability to inhibit the growth of dendrites, which seriously threaten the safety of LIBs. In this study, we prepared calcium alginate fiber/boron nitride-compliant separators (CA@BN) through paper-making technology and the surface coating method using calcium alginate fiber and boron nitride. The CA@BN had favorable electrolyte wettability, flame retardancy, and thermal dimensional stability of the biomass fiber separator. Meanwhile, the boron nitride coating provided excellent thermal conductivity and mechanical strength for the composite separator, which inhibited the growth of lithium dendrites and enabled lithium-ion symmetric batteries to achieve more than 1000 stable and long cycles at a current density of 0.5 mA cm-2. The interwoven fiber mesh formed by the boron nitride coating and the calcium alginate provided multiple pathways for ion migration, which enhanced the storage capacity of the electrolyte, improved the interfacial compatibility between the separator and the electrode, widened the window of electrochemical stability, and enhanced ionic migration. This eco-friendly bio-based separator paves a new insight for the design of heat-resistance separators as well as the safe running of LIBs.

Covalently Anchoring an Ultrathin Conformal SiOx Coating on Polyolefin Separator for Enhanced Lithium Metal Battery Performance

AbstractSurface modification of separators with inorganic oxide ceramics such as SiOx, Al2O3, and TiO2 has emerged as a promising strategy to suppress lithium dendrite growth in lithium metal batteries, thereby enhancing safety and extending battery life. However, the binder‐dependent nature of these modifications often leads to increased separator thickness and a heightened risk of detachment during lithium plating, ultimately compromising both battery performance and energy density. In this study, a conformal, ultrathin (≈20 nm) SiOx coating with strong covalent bonding is grown on a porous separator through a liquid polymer‐derived method. Compared to the pristine polyethylene (PE) separators, this SiOx‐co‐PE separator exhibits significantly improved electrolyte wettability, mechanical strength, and thermal stability without any increase in thickness, leading to vastly enhanced cycling stability and dendrite resistance in cells with Li metal anodes. In a practical demonstration, a 402.9 Wh·kg−1 Li‐S pouch cell, with a high sulfur loading of 9 mg cm−2 and a low E/S ratio of 3.3 µL mg−1, is assembled with the SiOx‐co‐PE separator, achieving stable cycling over 70 cycles at 25 °C.

Perfluoropolyether-terminated Single-ion Polymer for Enhancing Performance of PEO-based Solid Polymer Electrolyte.

Solid-state electrolytes are receiving increasing attention in lithium metal batteries due to the advantage of high energy density. Poly(ethylene oxide) (PEO) electrolyte possesses good compatibility with lithium salts. However, PEO suffers from a low lithium-ion transference number and poor high-voltage resistance, which significantly hinder its application in lithium metal batteries. Herein, a perfluoropolyether-terminated single-ion polymer (PFPE-polymer) is designed and synthesized in this contribution. By incorporating the PFPE-polymer and lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) into PEO via casting, the polymer electrolyte (PFPE-SE) is successfully prepared. Compared to PEO-based electrolytes, PFPE-SE forms a solid electrolyte interface (SEI) layer and inhibits the growth of lithium dendrites on the anode. At 70°C, the lithium-ion transference number and the electrochemical window reach 0.72 and 4.7V, respectively. When tested at a discharge rate of 0.5 C, the Li|PFPE-SE|LFP cell exhibits a specific capacity of 156.0 mAh g-1, with a capacity retention of 74.3% after 230 cycles, superiority the performance of the electrolyte prepared by mixing PEO with LiTFSI. This work presents a promising polymer electrolyte strategy for achieving high-performance lithium metal batteries, leveraging the in situ construction of the SEI layer and the utilization of a single-ion polymer.