Lithium Deposition Research Articles

Covalent Organic Frameworks Interfacial Modification of Ceramic Electrolytes for Enhanced Electrochemical Performance

AbstractThe interface instability between inorganic ceramic electrolytes and lithium metal anodes seriously affects the cycling behavior of high‐performance lithium‐metal batteries. Herein, an in situ interfacial modification strategy is proposed to build the precise hybrid organic/inorganic lithium‐ion conducting layer where the Li1.3Al0.3Ti1.7(PO4)3 (LATP) particle surface is anchored by ion‐conducting covalent organic frameworks (COF) with affluent poly(ethylene glycol) (PEG) moieties. This interlayer features ion transport regulation to avoid high interfacial resistance and enhances interfacial stability by building a functional COF‐based shield against electrons. These as‐prepared particles are employed to fabricate flexible quasi‐solid electrolyte membranes interconnected by polytetrafluoroethylene binder based on the dry process. The obtained membranes perform two‐fold increase in ion conductivity at 30 °C of 2.55 × 10−3 S cm−1 and the prolonged lithium deposition up to 1000 h compared to the pristine, which are attributed to synergistic effects in the inorganic/organic phase. Moreover, an integrated cathode/electrolytes design is proposed and exhibits excellent cycling performance with capacity retention of 98.8% after 200 cycles at 1 C. The corresponding pouch cells can light up LED after bending and recovery. This research provides new insights into the great potential of fabricating soft ceramic‐based membranes in a low‐cost and green way for highly‐stable lithium‐metal batteries.

Boosting electrochemical performance by regulating rigid-flexible microphase separation of multiblock copolymers

The growth of lithium dendrites and associated safety issues hinder the further development of liquid lithium metal batteries. A novel rigid-flexible multiblock copolymer PBC-mb-PBS was successfully synthesized based on molecular design. Incorporating crystalline rigid phase polybutylene succinate (PBS) into PBC-mb-PBS significantly enhances its tensile strength and low-temperature toughness through physical crosslinking. The flexible polydibutyl 2-(2-cyanoethyl)malonate (PBC) phase with side-chain cyano groups facilitate ionic conduction, forming a LiN-rich stabilized interfacial layer, thereby improving oxidative stability and high-voltage cathode compatibility. A series of multiblock copolymers with varying segment lengths were synthesized to balance mechanical properties and ionic conductivity by adjusting microphase separation. The quasi-solid-state polymer electrolyte (QSPE), derived from PBC-mb-PBS with the molar block ratio of 0.42, exhibits optimal electrochemical performance with ionic conductivity of 6.20 × 10−5 S cm−1 at 30 °C and 4.22 × 10−4 S cm−1 at 60 °C. Due to its bicontinuous microphase structure, it also shows excellent mechanical strength and promotes uniform lithium deposition at high current densities. Li//LiFePO4 and Li//LiNi0.83Co0.05Mn0.12O2 cells demonstrate high capacity retention, confirming the potential of this polymer electrolyte in high-voltage applications. This design strategy offers insights for developing quasi-solid-state lithium metal batteries with superior overall performance.

From Bulk to Nanosheet: How Tellurene Can Influence the Performance of Li‐S Batteries on Both Electrodes

AbstractIn the face of growing environmental challenges and the need for alternative energy storage, lithium‐sulfur (Li‐S) batteries stand out for their high theoretical energy density and sulfur's eco‐friendliness. However, the practical application of Li‐S batteries faces significant obstacles, particularly at the cathode and anode. This study explores the transformative impact of 2D tellurene, focusing on how its dimensional variations influence Li‐S battery performance. At the cathode, tellurene not only improves the conductivity and sulfur utilization but also accelerates the conversion of lithium polysulfides (LiPSs). Its reduced size, compared to the bulk counterpart, offers numerous active sites for efficient Li‐ion migration and promotes LiPSs decomposition. At the anode, the protective polytellurosulfides are formed, thereby establishing a stable solid‐electrolyte interphase (SEI) and enhancing reversible lithium deposition. Diminishing the dimensions of tellurene improves its catalytic interface, leading to faster polysulfide conversion kinetics at the cathode and robust SEI formation at the anode. Li‐S batteries equipped with ultra‐thin tellurene‐modified separators demonstrate exceptional performance, exhibiting high areal capacity and significantly reduced capacity decay. Computational simulations further validate the advantages of optimizing tellurene dimensions, confirming its essential role in LiPSs decomposition and overall battery efficiency.

Thermodynamic and Kinetic Properties of the Lithium-Silver System.

A carbon-silver anode has recently been shown to suppress dendrite formation in all-solid-state lithium-ion batteries. The role that silver plays in enabling the reversible deposition and stripping of lithium remains unknown. Furthermore, very little is known about the thermodynamic and kinetic properties of Li x Ag1-x alloys. Here, we report on an in-depth first-principles study of phase stability and diffusion mechanisms in the Li-Ag alloy system. We identify two new intermetallic phases that are predicted to be stable in Li-rich Li x Ag1-x alloys with stoichiometries of Li3Ag and Li11Ag2. Our calculations show that the peculiar and highly anharmonic energy surface of pure Li along the Bain and Burgers paths persists upon the addition of Ag to BCC Li. This has important implications for room-temperature phase stability and mechanical properties. We have also performed a systematic study of diffusion mechanisms in the Li x Ag1-x alloy system as a function of alloy concentration x. Diffusion in alloys and intermetallics is mediated by vacancies. High vacancy formation energies are predicted in the Li x Ag1-x alloy, especially in Ag-rich FCC solid solutions. Complex diffusion mechanisms are identified in the B2 and γ-brass intermetallic phases that include two-atom hops and second-nearest neighbor hops. The migration barriers are found to decrease with increasing Li concentration, with predictions of exceptionally low migration barriers of 0.1 eV in the D03 Li3Ag phase.

Polymorph interface strategy presents avenues for kinetics-enhanced and dendrite-free lithium sulfur batteries

Shuttle effect and slow kinetic property are the challenges for the practical application of lithium-sulfur (Li-S) batteries. As an effective strategy, the polymorph effect is applied to rationally design multifunctional catalysts. Herein, the unique polymorph interface was constructed by different CoSe2 crystalline phases, and the systematic investigation on the sulfur cathodes and lithium anode is reported. Carbon nanofiber (CNF) derived from bacterial cellulose (BC) is used as a scaffold for disperse CoSe2 catalysts to construct electrically conductive highways. According to the experimental and calculation results, orthorhombic CoSe2 exhibits superior adsorption capacity and catalytic activity towards LiPSs, while cubic CoSe2 shows better electronic conductivity. Mixed phase CoSe2 not only balances the advantages of both, but also showcases impressive performance due to its unique polymorph interface structure. Besides, uniform lithium deposition can be also achieved. Consequently, the modified separators endow Li-S batteries with a high reversible discharge capacity (700 cycles at 1 C with only 0.063 % capacity decay per cycle) and excellent rate performance (702 mAh g−1 is maintained at 5 C). The pouch cell with separator modifications on both sides was assembled and exhibits a high discharge capacity. This work provides a polymorph interface strategy for the rational design of catalysts.

A bifunctional thiobenzamide additive for improvement of cathode kinetics and anode stability in lithium-sulfur batteries

Lithium-sulfur batteries (LSBs) are considered as the key candidates for the next generation of energy storage devices. However, the practical applications of LSBs are hindered by the slow conversion of sulfur species and the inhomogeneous Li+ precipitation /stripping of lithium anode. Here, we report a bifunctional thiobenzamide electrolyte additive, 4-(trifluoromethyl) thiobenzamide (TFBCA), which synergistically improves cathode redox kinetics and anode stability. Polysulfides (LiPSn) are in-situ transferred to more reactive polysulfide intermediates (T-Sn-T), which significantly improve the liquid–solid reduction process by promoting the deposition dimension of Li2S. A LiF/Li3N-rich solid electrolyte interphase is formed with TFBCA, the uniform lithium deposition is achieved and the growth of lithium dendrites is suppressed. Correspondingly, LSBs with TFBCA show a high capacity (888 mAh·g−1 at 5C) and cycling stability (0.055 % per cycle after 600 cycles at 2C). Even under high sulfur loading (7.1 mg·cm−2) and low E/S ratio of 7, the LSBs also exhibit an areal capacity of 7 mAh·cm−2 after 50 cycles, and an energy density of 314 Wh·kg−1 is achieved for the pouch cell. This work demonstrates an efficient additive strategy through molecular structure design to construct high-performance LSBs.

Staged dendrite suppression for high safe and stable lithium-sulfur batteries

The unavoidable dendrite growth and shuttle effect have long been stranglehold challenges limiting the safety and practicality of lithium-sulfur batteries. Herein, we propose a dual-action strategy to address the lithium dendrite issue in stages by constructing a multifunctional surface-negatively-charged nanodiamond layer with high ductility and robust puncture resistance on polypropylene (PP) separator. The uniformly loaded compact negative layer can not only significantly enhance electron transmission efficiency and promote uniform lithium deposition, but also reduce the formation of dendrite during early deposition stage. Most importantly, under the strong puncture stress encountered during the deterioration of lithium dendrite growth under limiting current, the high ductility and robust puncture resistance (145.88 MPa) of as-obtained nanodiamond layer can effectively prevent short circuits caused by unavoidable lithium dendrite. The Li||Li symmetrical cells assembled with nanodiamond layer modified PP demonstrated a stable cycle of over 1000 h at 2 mA cm−2 with a polarization voltage of only 29.3 mV. Additionally, the negative charged layer serves as a physical barrier blocking lithium polysulfide ions, effectively mitigating capacity attenuation. The improved cells achieved a capacity decay of only 0.042% per cycle after 700 cycles at 3 C, demonstrating effective suppression of dendrite growth and capacity attenuation, showing promising prospect.

Metal-Free Polymer-Based Current Collector for High Energy Density Lithium-Metal Batteries.

The energy density of lithium-metal batteries (LMBs) relies substantially on the thickness of the lithium-metal anode. However, a bare, thin lithium foil electrode is vulnerable to fragmentation due to the inhomogeneity of the lithium stripping/plating process, disrupting the electron conduction pathway along the electrode. Accordingly, the current collector is an integral part to prevent the resulting loss of electronic conductivity. However, the common use of a heavy and lithiophobic Cu current collector results in a great anode mass increase and unsatisfactory lithium plating behavior, limiting both the achievable specific energy and the cycle life of LMBs. Herein, a metal-free polymer-based current collector is reported that allows for a substantial mass reduction, while simultaneously extending the cycle life of the lithium-metal anode. The specific mass of the ultra-light, 10µm thick polymer-based current collector is only 1.03mg cm-2, which is ≈11% of a 10 µm thick copper foil (8.96mg cm-2). As a result, LMB cells employing this novel current collector provide a specific energy of 448Wh kg-1, which is almost 18% higher than that of LMBs using the copper current collector (378Wh kg-1), and a greatly enhanced cycle life owing to a more homogeneous lithium deposition.

High‐Voltage Single‐Ion Covalent Organic Framework Electrolytes Enabled by Nitrile Migration Ladders for Lithium Metal Batteries

AbstractThe poor electrochemical stability window and low ionic conductivity in solid‐state electrolytes hinder the development of safe, high‐voltage, and energy‐dense lithium metal batteries. Herein, taking advantage of the unique electronic effect of nitrile groups, we designed a novel azanide‐based single‐ion covalent organic framework (CN−iCOF) structure that possesses effective Li+ transport and high‐voltage stability in lithium metal batteries. Density functional theory (DFT) calculations and molecular dynamics (MD) revealed that electron‐withdrawing nitrile groups not only resulted in an ultralow HOMO energy orbital but also enhanced Li+ dissociation through charge delocalization, leading to a high tLi+ of 0.93 and remarkable oxidative stability up to 5.6 V (vs. Li+/Li) simultaneously. Moreover, cyanation leveraging Strecker reaction transformed reversible imine‐linkage to a stable sp3‐carbon‐containing azanide anion, which facilitated contorted alignment of transport “ladders” along the one‐dimensional anionic channels and the ionic conductivity could reach 1.33×10−5 S cm−1 at ambient temperature without any additives. As a result, CN−iCOF allowed operation of solid‐state lithium metal batteries with high‐voltage cathodes such as LiNi0.8Mn0.1Co0.1O2 (NCM811), demonstrating stable lithium deposition up to 1,100 h and reversible battery cycling at ambient temperature up to 4.5 V, shedding light on the importance of discovering new functionality for forthcoming high‐performance batteries.

Fluorine-Rich Electrolyte Additive for Achieving Dendrite-Free Lithium Anodes at Low Temperatures.

The practical application of lithium metal anodes is significantly impeded by poor interfacial stability and uncontrolled dendrite growth. Herein, we introduce methyl trifluoroacetate (MTFA), a low-melting-point small molecule, as an electrolyte additive in an ether-based electrolyte. This additive facilitates the formation of an in situ composite solid electrolyte interphase (SEI) layer that is rich in LiF and features an ester-based flexible matrix. The resulting composite layer exhibits high ionic conductivity and mechanical stability, effectively regulating the lithium deposition behavior over a broad temperature range and inhibiting dendrite formation. Based on MTFA, the Li||Li symmetrical cell achieves a lifespan exceeding 5000 h at room temperature and 800 h at -20 °C, both with ultralow overpotential and exceptional cycling stability. In Li||LiFePO4 full cells with a high-area loading (10.52 mg cm-2) and an N/P ratio of 1.68, an average capacity decay of merely 0.096% per cycle is observed over 200 cycles. Even at -20 °C, the Li||LiFePO4 cell shows a CE of over 99% and maintains stable cycling performance. This work provides an innovative approach for optimizing lithium metal anode interfaces and enhancing low-temperature operation capabilities through the use of electrolyte additives.

Laser-Generated Au nanoparticles as lithophilic sites in self-supported film host for anode-free lithium metal battery

Anode-free lithium metal batteries (AFLMBs) are considered to have greater application potential than traditional LMBs because of their higher energy density and safety. Unfortunately, their poor cycling performances originated from the unsatisfactory reversibility of Li plating/stripping remains a big challenge. A rational designed host for lithium deposition is an effective solving strategy. Herein, pure Au nanoparticles (NPs) without any impurities are prepared by a liquid-phase laser irradiation technology to construct and develop a self-supported Au/reduced graphene oxide (Au/rGO) film as lithium deposition host for AFLMBs. The densely and uniformly distributed Au NPs provide abundant lithiophilic sites that significantly reduce the nucleation barrier of lithium. Attributed to the precise regulation of Au sites towards lithium nucleation/growth, dendrites-free anode and improved electrochemical performance are obtained by using the Au/rGO film host. It keeps stable for 30 min of lithiation at 6 mA cm−2 without dendrite formation. Additionally, the Li||Au/rGO half-cell shows an overpotential close to 0 mV and maintains a Coulombic efficiency exceeding 97 % after 500 cycles at 1 mA cm−2. Moreover, a symmetric Au/rGO-Li cell can operate for 700 h without short-circuit. When paired with LiFePO4 (LFP) to assemble a full battery, the Au/rGO-Li achieves 96 % capacity retention rate after 100 cycles. This work not only develops an efficient host for lithium, but also provides a unique strategy to the safety concerns associated with LMBs’ anodes.

Janus-structured graphene scaffold for bottom-up lithium deposition: A progressive gradient approach

Graphene-based materials have been explored as hosts for Li metal anodes, but their high interfacial activity and short diffusion distances frequently result in dendrite formation on the surface. Herein, we utilize the adjustable conductivity and Li affinity of graphene oxide (GO) to develop a Janus structure comprising a top GO layer and a bottom reduced graphene oxide (rGO) layer. The progressive conductivity and lithiophilicity gradient structure of GO/rGO enables a bottom-up Li deposition mode, rendering an average Coulombic efficiency of 99.1 % over 350 cycles at 1 mA cm−2 and 1 mAh cm−2. Full cells equipped with a LiFePO4 cathode maintain a capacity retention of 85 % after 350 cycles at 1 C. This innovative approach provides fresh insights into the development of graphene-based hosts, offering significant potential for future Li metal battery applications.

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

AbstractThe 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.

Phosphorized 3D Current Collector for High-Energy Anode-Free Lithium Metal Batteries.

The anode-free lithium metal battery (AF-LMB) demonstrates the emerging battery chemistry, exhibiting higher energy density than the existing lithium-ion battery and conventional LMB empirically. A systematic step-by-step while bottom-up calculation system is first developed to quantitatively depict the energy gap from theory to practice. The attainable high energy of AF-LMB necessitates a homogeneous Li+ flux on the anode side to achieve an improved Li reversibility against inventory loss. On such basis, a lithiophilic Cu3P-decorated 3D copper foil to promote dendrite-free lithium deposition is further reported. The phosphorized surface of high affinity toward Li+ incorporating the nanostructure of abundant nucleation sites synergistically regulates the Li nucleation/growth behavior, extending the cycling lifespan of high-loading AF-LMBs. The processed foil featuring lightweight and ultrathin merits further increases the energy density, both gravimetrically and volumetrically. This study provides a novel scheme for simultaneously realizing the uniform deposition of lithium and increasing the energy density of future AF-LMBs.

3D structured lithiophilic current collector with lithiation nucleation overpotential near 0 V for dendrite-free lithium metal anode

The poor lithium affinity of most metal skeletons leads to uneven electric field distribution, resulting in the notorious Li dendrite growth. Herein, a 3D structured Cu mesh@Ag current collector is introduced using a simple chemical plating method to enable dendrite-free Li anode. The high electronic conductivity and matrix pore structure of Cu mesh can alleviate the local current density and provide buffer space for lithium deposition. The lithiophilic Ag can form infinite solid solution with Li while reducing the initial lithiation nucleation overpotential to about 0 V, achieving homogenous Li deposition. As a result, the symmetric cell can maintain a low polarization voltage (20 mV) after cycling at 0.5 mA cm-2 for 1300 h Full cells assembled with LiFePO4 cathode present a long-term cycling stability of 500 cycles at 1C with a capacity retention of 80.3%. This work provides a reliable approach to create stable Li-metal batteries.

Precise lithiophilicity regulation of atomically dispersed Znn-anchored C2N matrix for uniform lithium deposition

Precise lithiophilicity regulation of atomically dispersed Znn-anchored C2N matrix for uniform lithium deposition

In-situ formed Li2O and an artificial protective layer on copper current collectors to enhance the cycling stability of lithium metal anode batteries

In this study, we present a facile one-step method for the thermal treatment of commercial Cu foils, leading to the growth of Cu2O and CuO nanoparticles in an air atmosphere, resulting in the coating of an artificial protective layer on the copper foil surface. The as-prepared CuO/Cu2O nanoparticles exhibit a spherical morphology, providing ample active sites to improve uniform lithium plating and cyclic stability by building a highly stable In-situ Li2O-rich solid-electrolyte interphase (ISEI). The artificial solid-electrolyte interphase (ASEI) protective layer contains graphene oxide (GO) as a filler with PVDF-HFP and lithium Nafion polymers, enhances Li+ ion migration, which reduces volume expansion and stabilizes the interface, preventing unwanted side reactions between active lithium and electrolytes by facilitating controlled lithium deposition underneath. For integration into an anode-less full cell based on a 2032-type coin cell, alongside a lithium iron phosphate (LFP) cathode, the ISEI oxide layer was grown on a Cu foil electrode (denoted as Cu-30) via a thermal treatment at 320 °C in air for 30 min and coated ASEI (denoted as GO@Cu-30). This cell demonstrated remarkable electrochemical performance. After 250 cycles at 0.5C, it exhibited an outstanding capacity retention of 93.12 % with 99.92 % CE, significantly surpassing the performance of a bare Cu foil, which showed a capacity retention of only 9.54 % with CE of 98.77 %. This work highlights the potential of a simple thermally treated Cu foil as a current collector to overcome the Anode-less lithium metal battery (ALMB) challenges associated with high-energy-density demand.

Sulfonic Acid-Functionalized Graphdiyne for Effective Li-S Battery Separators.

Lithium-sulfur (Li-S) batteries enable a promising high-energy-storage system while facing practical challenges regarding lithium dendrites and lithium polysulfides (LiPSs) shuttling. Herein, a fascinating SO3H-functionalized graphdiyne (SOGDY) was developed by grafting SO3H onto GDY to modify the separator in Li-S batteries. It realizes structure-retained material transformation, that is, SOGDY retains the crystalline all-carbon network and uniform subnanopores from the initial GDY. The abundant SO3H and uniform pores create a rapid Li+ transport relay station, benefit rapid Li+ transport and even lithium deposition, and prevent lithium dendrite growth. The spatial obstruction and strong polar adsorption sites from SO3H effectively inhibit LiPS shuttling. Additionally, SOGDY establishes a fast electron-transfer pathway to facilitate the LiPS conversion. The SOGDY/PP separator exhibited steady cycling at 1 mA cm-2 over 3500 h in the Li∥Li symmetric battery and achieved outstanding low-temperature and high-rate performance in the Li-S battery with a high initial specific capacity of 804.5 mA h g-1 and a final capacity of 504.9 mA h g-1 after 500 cycles at 3 C and -10 °C. This work demonstrates that introducing a stable all-carbon network and uniform functionalized nanopores is an effective strategy to modify the Li-S battery separator.

Mechanochemistry induced mixed ionic/electronic conductive interphase enabling dendrite-free lithium metal anodes

High-energy-density lithium metal batteries have shown promising applications in drones and electrical vehicles. However, the growth of lithium dendrites and the formation of unstable solid electrolyte interphase (SEI) become the main factors restricting their development. In this study, dendrite-free lithium metal anodes (ZB@Li) were developed with ionic/electronic conductive interface layers by a solvent-free mechanochemical method. By rubbing zinc borate (ZB) powder on lithium foil, a mixed interface layer is formed with the generation of lithium borate phase and the Li–Zn alloy phase. The lithium borate phase provides a low diffusion energy barrier and high ionic conductivity for sufficient potential gradient to induce rapid deposition of ions on the interface layer. The Li–Zn alloy phase owns the lithiophilic characteristic and a high electronic conductivity. The combination of the two phases provides mixed ions/electrons paths with enhanced transport kinetics and realize uniform and planar deposition of lithium. As a result, the ZB@Li symmetrical cell exhibits a prolonged cycling performance of over 4,200 h and the ZB@Li||LFP (LFP= lithium iron phosphate [LiFePO4]) full cell shows a long cycle life for more than 500 cycles at 2 C with a high capacity retention rate of 84.6% at a high loading mass of 10 mg/cm2.

Construction of flexible asymmetric composite polymer electrolytes for high-voltage lithium metal batteries with superior performance

The primary obstacle hindering the application of composite solid electrolytes lies in the varying demands posed by the Li metal anode and the cathode, which needs to be capable of suppressing dendrite growth and resisting high voltage simultaneously. In this work, a new asymmetric composite solid-state electrolyte prepared via electrospinning and in-situ polymerization is proposed to address these shortcomings. In this bilayer architecture, polyacrylonitrile (PAN) layer of high-voltage tolerance, polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP) layer of robust mechanical strength and good compatibility towards Li-anode are constructed, and metal-organic-frameworks (MOFs) are pre-embedded within both layers. The unique design provides a wide electrochemical stability window meanwhile ensures uniform lithium deposition. Remarkably, it exhibits a superior lithium utilization of 41 mAh cm−2 using a lean polymer electrolyte precursor and a high critical current density of 2.2 mA cm−2 with a thickness of 40 μm. Beneficial from the formation of a self-adjustable gradient solid electrolyte interphase in the Li/PVDF-HFP interface, the asymmetric electrolyte endows Li||Li and Li||NCM811 cells with excellent cycling stability. Moreover, the solid-state pouch cell exhibits reliable operation under extreme conditions. This work provides inspiration for the design and fabrication of composite solid electrolytes for next-generation high-voltage Li metal batteries.