Electrolytes For Lithium Metal Batteries Research Articles

Thiol-ene crosslinked cellulose-based gel polymer electrolyte with good structural integrity for high cycling performance lithium-metal battery

Gel polymer electrolytes (GPEs) are considered to be one most promising alternative to liquid electrolytes due to their suitability for creating safe and durable solid-state lithium-metal batteries. However, the mechanical properties of GPEs usually deteriorate dramatically when polymer matrices are plasticized by a liquid electrolyte, which leads to significant loss of battery performance. Therefore, the long-term structural integrity and good mechanical strength are critical characteristics of GPEs designed for high-performance batteries. Here, an ecologically compatible cellulose-based GPE with a crosslinked structure is synthesized via a facile and effective thiol-ene click chemistry method. The prepared thiol-ene crosslinked GPE possesses enhanced mechanical strength (10.95 MPa) and rigid structure, which enabled us to fabricate LiFePO4|Li batteries with ultra-long cycling performance. The capacity retention of the crosslinked cellulose-based GPE can be up to 84% at 0.5 C, even after 350 cycles, which is considerably higher than that of non-crosslinked GPE for which rapid decline in capacity occurs after 200 cycles. In addition, a GPE preparation method described in this work compares favorably well with existing commercial electrolytes for lithium metal batteries.

Functional multilayer solid electrolyte films for lithium dendrite suppression

The improvement of the interface between a lithium metal and a solid electrolyte layer is very important for the application of a lithium anode coated by solid electrolytes in lithium metal batteries. In order to address the issues of interface performance and compatibility between solid electrolyte films prepared by magnetron sputtering and lithium metals and the suppression of lithium dendrite during the cycling, a three-layer interface solid electrolyte film based on carbon-doped lithium phosphate oxynitride (LiCPON) was employed for coating a lithium metal. The sandwich structure of LiCPON by introducing an ultra-thin lithium niobium oxynitride (LiNbON) layer prepared by sputtering LiNbO3 in nitrogen ambient can be confirmed by time-of-flight secondary ion mass spectrometry. Atomic force microscopy data indicated that the surface of the LiCPON thin film with the sandwich structure is flatter and smoother than that of the LiCPON thin film on the lithium metal. The interface impedance of the symmetric battery based on the sandwich structure of the LiCPON coating lithium metal was reduced from 512.2 to 65.4 Ω, and the symmetric battery stable cycles from 300 h with an overpotential of more than 200 mV to 400 h with low overpotential of about 77 mV. These results suggest that functional multilayer solid electrolyte films become an effective method for protecting lithium. The incorporation of ultra-thin LiNbON into the LiCPON thin film could significantly decrease interface impedance between the lithium metal and solid electrolyte layer.

The Anionic Chemistry in Regulating the Reductive Stability of Electrolytes for Lithium Metal Batteries.

Advanced electrolyte design is essential for building high-energy-density lithium (Li) batteries, and introducing anions into the Li+ solvation sheaths has been widely demonstrated as a promising strategy. However, a fundamental understanding of the critical role of anions in such electrolytes is very lacking. Herein, the anionic chemistry in regulating the electrolyte structure and stability is probed by combining computational and experimental approaches. Based on a comprehensive analysis of the lowest unoccupied molecular orbitals, the solvents and anions in Li+ solvation sheaths exhibit enhanced and decreased reductive stability compared with free counterparts, respectively, which agrees with both calculated and experimental results of reduction potentials. Accordingly, new strategies are proposed to build stable electrolytes based on the established anionic chemistry. This work unveils the mysterious anionic chemistry in regulating the structure-function relationship of electrolytes and contributes to a rational design of advanced electrolytes for practical Li metal batteries.

The Anionic Chemistry in Regulating the Reductive Stability of Electrolytes for Lithium Metal Batteries

AbstractAdvanced electrolyte design is essential for building high‐energy‐density lithium (Li) batteries, and introducing anions into the Li+ solvation sheaths has been widely demonstrated as a promising strategy. However, a fundamental understanding of the critical role of anions in such electrolytes is very lacking. Herein, the anionic chemistry in regulating the electrolyte structure and stability is probed by combining computational and experimental approaches. Based on a comprehensive analysis of the lowest unoccupied molecular orbitals, the solvents and anions in Li+ solvation sheaths exhibit enhanced and decreased reductive stability compared with free counterparts, respectively, which agrees with both calculated and experimental results of reduction potentials. Accordingly, new strategies are proposed to build stable electrolytes based on the established anionic chemistry. This work unveils the mysterious anionic chemistry in regulating the structure–function relationship of electrolytes and contributes to a rational design of advanced electrolytes for practical Li metal batteries.

Electrospun derived polymer-garnet composite quasi solid state electrolyte with low interface resistance for lithium metal batteries

Polymer garnet composite electrolyte is a promising stable electrolyte to replace the hazardous/unstable liquid electrolytes in lithium-ion batteries due to their synergistic advantage of solid organic polymer electrolytes and inorganic ceramic electrolytes. Herein, we report polymer blend-based garnet composite quasi solid state electrospun electrolytes for lithium metal batteries. To be specific, Ta doped lithium lanthanum zirconium oxide, Li6·4La3Ta0·6Zr1·4O12 (LLZTO) incorporated with poly (vinyldine fluoride-hexafluro propylene) (PVdF-HFP)/poly butyl methacrylate (PBMA) electrospun membrane as the composite electrolyte, named as Ta-ESM and similarly, LLZTO free electrolyte named as ESM. The inclusion of LLZTO into the polymer matrix enhances the room temperature ionic conductivity from 9.924 × 10−4 (ESM) to 4.858 × 10−3 S cm−1 (Ta-ESM) along with lithium-ion transference number (0.61). Furthermore, polymer garnet composite electrolytes (Ta-ESM) restraint the growth of lithium dendrites, confirmed by the time-dependent impedance method and galvanostatic cycling technique. We have demonstrated the charge-discharge behaviour of lithium-metal battery using LiFePO4 cathode and lithium metal anode using Ta-ESM electrolyte, delivering 178 mA h g−1 at 0.1C and cyclability of 100 cycles. The high electrolyte uptake (582%) and porosity (64.1%) in Ta-ESM help achieve fast ionic migration and thus attain stable cycling.

Incorporating 2D γ-Al2O3 nanosheets into the flexible PEO-based solid electrolyte for lithium metal batteries

Solid polymer electrolytes using polyethylene oxide (PEO) are promising for boosting the safety of lithium metal batteries (LMBs), but suffer from low ionic conductivity due to high crystallinity and poor segment motion of PEO. Adding plasticizers like succinonitrile (SN) is one of the solutions to improve the ionic conductivity of PEO, but it sacrifices the cycle performances of LMBs. In addition, the ability to conduct lithium ions of PEO-SN matrixes is yet to be improved. Herein, two-dimensional γ-Al2O3 nanosheets are first introduced into the PEO-SN matrix to facilitate the long-range migration of lithium ions and improve the electrochemical properties of PEO-SN matrix, realizing the new design of traditional materials. The mechanism between γ-Al2O3 nanosheets and the polymer matrix is discussed. The addition of γ-Al2O3 nanosheets improves the ionic conductivities and cycle performances of PEO-LiTFSI-SN (PLS) electrolytes. In specific, the ionic conductivity at 25 °C of the PEO-LiTFSI-SN-Al2O3 nanosheet (PLS-A) electrolyte is up to 2.02 × 10−4 S cm−1. Meanwhile, the electrochemical properties of Li/PLS-A/LiFePO4 are tested, with a low overpotential change of 0.06 V, coulombic efficiency above 99.6%, and capacity retention of 95% at 0.5C and 60 °C after 50 cycles. The solid electrolyte system provides a feasible strategy for the application of 2D nanofillers in PEO polymer electrolytes.

Nafion/ZrO2 hybrid membranes solvated by organic carbonates. Transport and mechanical properties

The use of cation-exchange membranes solvated by organic solvents as electrolytes for lithium metal batteries increases their safety. However, the mechanical properties of the solvated membranes are poor. In this work we have shown that incorporation of zirconium dioxide in Nafion-212 membrane significantly improves the mechanical properties of the membranes while slightly decreasing ionic conductivity. Incorporation of 6.0 wt% ZrO2 increases Young's modulus up to 66 ± 4 MPa and tensile strength up to 15 ± 3 MPa which is almost three times higher than similar parameters for unmodified membranes. In addition, incorporation of ZrO2 reduces the volumetric swelling of the membranes during solvation.

Synergetic effects of silica-coated silver nanowires in composite single-ion conducting polymer electrolytes for lithium metal batteries

We report the gel-state single-ion conducting composite polymer membranes (CPMs) electrolytes, which are composed of poly(vinylidene fluoride-hexafluoropropylene) (PVDF-HFP), single-ion conducting polymer electrolyte (SIPE), silica-coated silver nanowires (AgNWs@SiO2), and liquid propylene carbonate (PC) as plasticizer without the addition of lithium salts. The electrospun SIPE/PVDF-HFP/AgNWs@SiO2 composites have abundant nanofibrous network, excellent thermal and mechanical performances. The introduction of PC leads to a relatively high ionic conductivity, a wide electrochemical stability window, and high lithium-ion transference number of the as-prepared CPMs. Moreover, the Li/CPMs/Li symmetric cells deliver an effective prevention of Li dendrite growth with a prolonged Li plating/stripping cycle of 600 h at 0.10 mA cm−2. Furthermore, the synergy between SIPE and AgNWs@SiO2 makes the assembled Li/CPMs/LiFePO4 cells (or Li/CPMs/LiNi0.8Co0.1Mn0.1O2 cells) good cyclic stability and rate discharge ability, which provides a promising prospect in designing the advanced lithium metal batteries.

Abundant Hydrogen Bonds Formed in a Urea-Based Gel Polymer Electrolyte Improve Interfacial Stability in Lithium Metal Batteries.

As an emerging and potential replacement system for liquid electrolytes, polymer electrolytes (PEs) exhibit unique capacity in suppressing metal dendrite formation and leakage risks. However, the most used polymer matrix, including polyether, polyester, and polysiloxane, still cannot meet the practical demands for metal electrode compatibility and long lifespan. In this study, gel polymer electrolytes consisting of a polyurea network with abundant hydrogen bonds and deep eutectic electrolyte (DEE) are designed and prepared in-situ. The hydrogen bonding between polyurea chains and polyurea-DEE provides good interfacial stability between PEs and lithium metal. As a result, the assembled Li/LiFePO4 cells based on this electrolyte deliver a long cycle life with 90 % retention after 500 cycles and 76.5 % retention after 1000 cycles at 1 C. In addition, the flexible design characteristics of polyurea structure permit easy operation for performance optimization by modulating the composition of hard and soft segments, and enhanced ionic conductivity and self-healing efficiency are obtained. This study provides a novel method for preparing advanced polymer electrolytes for lithium metal batteries.

A Competitive Solvation of Ternary Eutectic Electrolytes Tailoring the Electrode/Electrolyte Interphase for Lithium Metal Batteries.

The development of electrolytes with high safety, high ionic conductivity, and the ability to inhibit lithium dendrites growth is crucial for the fabrication of high-energy-density lithium metal batteries. In this study, a ternary eutectic electrolyte is designed with LiTFSI (TFSI = bis(trifluoromethanesulfonyl)imide), butyrolactam (BL), and succinonitrile (SN). This electrolyte exhibits a high ion conductivity, nonflammability, and a wide electrochemical window. The competitive solvation effect among SN, BL, and Li+ reduces the viscosity and improves the stability of the eutectic electrolyte. The preferential coordination of BL toward Li+ facilitates the formation of stable solid electrolyte interphase films, leading to homogeneous and dendrite-free Li plating. As expected, the LiFePO4/Li cell with this ternary eutectic electrolyte delivers a high capacity retention of 90% after 500 cycles at 2 C and an average Coulombic efficiency of 99.8%. Moreover, Ni-rich LiNi0.8Co0.1Al0.1O2/Li and LiNi0.8Co0.1Mn0.1O2/Li cells based on the modified ternary eutectic electrolyte achieve an outstanding cycling performance. This study provides insights for understanding and designing better electrolytes for lithium metal batteries and analogous sodium/potassium metal batteries.

Engineered interfaces between perovskite La2/3xLi3xTiO3 electrolyte and Li metal for solid-state batteries.

Perovskite La2/3xLi3xTiO3 (LLTO) materials are promising solid-state electrolytes for lithium metal batteries (LMBs) due to their intrinsic fire-resistance, high bulk ionic conductivity, and wide electrochemical window. However, their commercialization is hampered by high interfacial resistance, dendrite formation, and instability against Li metal. To address these challenges, we first prepared highly dense LLTO pellets with enhanced microstructure and high bulk ionic conductivity of S cm−1 at room temperature. Then, the LLTO pellets were coated with three polymer-based interfacial layers, including pure (polyethylene oxide) (PEO), dry polymer electrolyte of PEO-LITFSI (lithium bis (trifluoromethanesulfonyl) imide) (PL), and gel PEO-LiTFSI-SN (succinonitrile) (PLS). It is found that each layer has impacted the interface differently; the soft PLS gel layer significantly reduced the total resistance of LLTO to a low value of 84.88 Ω cm−2. Interestingly, PLS layer has shown excellent ionic conductivity but performs inferior in symmetric Li cells. On the other hand, the PL layer significantly reduces lithium nucleation overpotential and shows a stable voltage profile after 20 cycles without any sign of Li dendrite formation. This work demonstrates that LLTO electrolytes with denser microstructure could reduce the interfacial resistance and when combined with polymeric interfaces show improved chemical stability against Li metal.

Ion conduction path in composite solid electrolytes for lithium metal batteries: from polymer rich to ceramic rich

Ion conduction path in composite solid electrolytes for lithium metal batteries: from polymer rich to ceramic rich

Multiple ionic conduction highways and good interfacial stability of ionic liquid-encapsulated cross-linked polymer electrolytes for lithium metal batteries

PEO-based electrolytes are promising for solid-state lithium metal batteries, but their low ionic conductivity and unstable interfacial compatibility with electrodes are the bottlenecks restricting their further applications. Herein, a unique ionic liquid (Pyr14TFSI)-encapsulated cross-linked polymer electrolyte with abundant ether–oxygen repeat units (C-SPE-IL) is proposed and prepared through an in-situ thermal polymerization process. The Pyr14+ cations of ionic liquid present a stronger affinity towards ether–oxygen groups by means of tight coordinated interactions, which promotes ionic liquid encapsulated uniformly in the polymer matrix to release more mobile Li ions into ionic liquid and create multiple ionic conduction highways in both ionic liquid and polymer matrix. The C-SPE-IL shows a much higher ionic conductivity of 3.98 × 10−4 S/cm at 30 °C. Moreover, tight interfaces with LiF– and Li3N– rich components between C-SPE-IL and Li anode are constructed to ensure effective suppression of lithium dendrites during cycling. The LiFePO4/Li batteries using C-SPE-IL present stable cycling performances at both 35 °C and 60 °C. This work provides a facile and accessible approach to design novel SPE with both ionic conduction highways and good interfacial stability for high-performance solid-state lithium metal batteries.

High-Performance Liquid Electrolytes for Lithium Metal Batteries Discovered By Machine Learning and High-Throughput Experimentation

High-performance liquid electrolytes for lithium metal batteries were discovered via a closed-loop machine learning and high-throughput robotic experimentation workflow. The novel workflow iterates: (1) machine-learning property prediction of a given electrolyte formulation based on a training dataset; (2) machine-learning electrolyte search for optimal candidates; (3) robotic high-throughput sample preparation and testing; and (4) training dataset updates based on new results. As a result, for the electrolytes, the lithium coulombic efficiency at 3 mA/cm2 was increased to 98.2% from the baseline of 76.2%. The full cell capacity was 98.6% at cycle 373 with one improved electrolyte. In comparison, a baseline electrolyte showed a cycle life of 96 cycles. In addition, for machine learning, the electrolyte prediction showed promising prediction accuracy vs. lab-verified data.The advancement of electric drive vehicle batteries is crucial for improving transportation energy efficiency. Batteries using high-capacity lithium (Li) metal anode hold promise due to their high energy densities to extend the driving range and lower costs. Li metal batteries (LMBs) are a technological pathway to below $100/kWh, but with high risk. Currently, an advanced electrolyte is urgently needed to stabilize lithium metal anode for longer battery life.Liquid electrolyte formulation development that discovers effective electrolyte components (including solvents, Li salts, and additives) and optimizes their contents in the electrolyte is a promising approach. The combination of machine learning and robotic high-throughput experimentation shows promise as an effective and efficient development methodology, to tackle the electrolyte formulation search space >1020 formulation candidates too large for researchers to manually study in a timely fashion. Natural language processing was developed to capture latent knowledge from materials science literature without human labelling and demonstrated the capability to recommend materials several years before their discovery. An early prediction model and a Bayesian optimization algorithm were developed to perform closed-loop optimization of fast-charging protocols for LIBs. Using machine learning coupled to a robotic test-stand, hundreds of sequential experiments were performed on aqueous electrolytes containing 6 lithium and sodium salts for conductivities, pHs, and electrochemical responses on platinum, with non-intuitive discoveries.In this work, by using a novel closed-loop machine learning and high-throughput robotic experimentation workflow, liquid electrolytes for lithium metal batteries were optimized. The primary Li CE was improved to 99.7% from the baseline performance of 76.7%. The optimized electrolyte showed high ionic conductivity and oxidation voltage as well. Coin cell validation showed that the cell capacity retention was 98.6% at cycle 373, with the coulombic efficiency of around 100%. Furthermore, 200 mAh NCA pouch cell with the optimized electrolyte showed improved cycle life and thermal stability. Regarding the machine learning algorithm, the correlation between the actual values and the predicted values for the unseen data achieved a high value of 0.986, and the r2 value was 0.79.This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Energy Efficiency and Renewable Energy under Award Number DE-SC0020872. This research used resources of the Molecular Foundry at Lawrence Berkeley Nation Lab, which is a DOE Office of Science User Facility.

Solvent-free green synthesis of nonflammable and self-healing polymer film electrolytes for lithium metal batteries

Fire-resistant and self-healing flexible electrolytes are a promising alternative to address thermal runaway in lithium batteries. However, self-healing electrolytes for lithium batteries are not widely used due to their low ionic conductivity, limited self-healing ability, and potential combustion risk. Ionic liquid-based polymer electrolytes are a simple and effective approach to obtaining polymer solid electrolytes with high ionic conductivity, fast self-healing and flame retardant properties. In this work, methyl methacrylate (MMA) and 1-Allyl-3-methylimidazolium Bis(trifluoromethanesulfonyl)imide (AMIMTFSI) are used as the membrane-forming backbone and also possess ion transport channels. 1-ethyl-3 methylimidazolium bis[(trifluoromethyl)sulfonyl]imide (EMIMTFSI) is added to the membrane to further enhance the ionic conductivity. Due to the existence of ionic liquid units and free ionic liquids in the prepared electrolytes, the fast interaction of ionic bonds confers a faster self-healing ability to the films, and the flame retardancy of the ionic liquids is fully maintained after polymerization. The prepared electrolytes show good flame retardance properties, excellent mechanical properties (tensile rate is ∼ 400%), high thermal decomposition temperature (>260 °C), and can effectively enhance the reliability of lithium metal batteries. When ionic liquids filler mass fraction is 40%, the polymer electrolytes have an ionic conductivity of 1.9 × 10-4 S cm−1, a decomposition voltage of 4.6 V (vs. Li/Li+), and can achieve an initial discharge capacity of 134.9 mAh g−1 with a capacity retention of 96.4% after 90 cycles at 0.1C for LiFePO4/Li half-cell at 25 °C.

Pseudo-concentrated electrolytes for lithium metal batteries

Lithium metal batteries suffer from short lifespans and low Coulombic efficiency (CE) due to the high reactivity of Li and the poor stability of the solid electrolyte interphase (SEI). Herein, we propose the concept of a pseudo-concentrated electrolyte (PCE) induced by an electron-deficient additive (4-pyridylboronic acid; 4-PBA) to form a robust, LiF-rich SEI, thus addressing the above issues. Molecular dynamics simulations confirm that 4-PBA can increase the coordination number of PF6- anions in the Li+ solvation sheath to achieve pseudo-concentrated LiPF6 in the electrolyte. Moreover, the 4-PBA can scavenge harmful PF5 decomposed from LiPF6 to stabilize the LiF-rich SEI. The resulting robust LiF-rich SEI promotes Li growth along the SEI/Li interface and represses the growth of Li dendrites. Thus, excellent performance is achieved, with a high CE of 97.1% for a Li||Cu cell at 1.0 ​mA ​cm−2, and over 950 cycles at 0.5 ​mA ​cm−2 for Li||Li symmetric cells with 1.0 ​wt% 4-PBA electrolyte. Meanwhile, the resulting stable boron-containing cathode electrolyte interphase enables Li||LiNi0·6Co0·2Mn0·2O2 (NCM622) cells to achieve excellent stability, with a capacity retention of 86.9% after 200 cycles.

Dual In Situ Polymerization Strategy Endowing Rapid Ion Transfer Capability of Polymer Electrolyte toward Ni‐Rich‐Based Lithium Metal Batteries

Poly(vinylidenefluoride-co-hexafluoropropylene) (PVDF-HFP) is one of the most promising candidate electrolyte matrices for high energy batteries. However, the spherical skeleton structure obtained through the conventional method fails to build continuous Li ion transmission channels due to the slow volatilization of high boiling solvent, leading to inferior cycling performance, especially in a Ni-rich system. Herein, a novel strategy is presented to enrich the Li ion transfer paths and improve the Li ion migration kinetics. The tactic is to prepare cross-linked segments through the PVDF-HFP matrix by adopting free radical polymerization and Li salt induced ring-opening polymerization. Most significantly, the visualization of the structure of as-prepared electrolyte is innovatively realized with the combination of polarization microscopy, transmission electron microscopy, scanning electron microscope-energy dispersive spectroscopy, PVDF-HFP, and cross-linked network form interconnected microstructures. Therefore, poly(glycidyl methacrylate and acrylonitrile)@poly(vinylidene fluoride-hexafluoropropylene) electrolyte presents a high ionic conductivity (1.04mScm-1 at 30°C) and a stable voltage profile for a Li/Li cell after 1200h. After assembly with a LiNi0.8 Co0.15 Al0.05 O2 cathode, a high discharge specific capacity of 190.3mAhg-1 is delivered, and the capacity retention reaches 88.2% after 100 cycles. This work provides a promising method for designing high-performance polymer electrolytes for lithium metal batteries.

In-situ construction of dual lithium-ion migration channels in polymer electrolytes for lithium metal batteries

Solid polymer electrolytes (SPEs) are expected to play an important role in high-energy lithium metal batteries (LMBs). Unfortunately, SPEs suffer from inadequate room-temperature ionic conductivity and sluggish interfacial charge transport, which severely limit their widespread applications in LMBs. Herein, we in-situ construct dual lithium-ion migration channels based SPEs by combining ring-opening polymerization of 1,3-dioxolane and solid-state organic ionic plastic crystals. “Coordination-dissociation” with the oxygen atoms in polymer chain segments and fast ion migration inside the organic ionic plastic crystal are two migration modes formed in-situ to synergistically enhance the ionic conductivity and interfacial charge transfer of SPEs. As a result, the in-situ formed poly(1,3-dioxolane)-based solid electrolytes (PDEs) not only afford an integrated battery structure with stabilized electrodes/electrolyte interface but also achieve outstanding oxidation stability, uniform lithium deposition (greater than1200 h under 0.5 mAh cm−2 in symmetric Li cells). Based on PDEs, the Li-LiFePO4 batteries demonstrate excellent cycle stability (almost no capacity decay after 500 cycles under 2C at 25 °C) and a wide operating temperature (-15 ∼ 45 °C). Also, applications of PDEs in Li-LiNi0.6Mn0.2Co0.2O2 batteries further demonstrate the compatibility of PDE with high voltage battery systems. Our study provides a facile and practical approach for creating solid electrolytes that meet both the ionic conductivity and interfacial charge transport requirements for practical solid-state batteries.

Protection of Cobalt-Free LiNiO2 from Degradation with Localized Saturated Electrolytes in Lithium-Metal Batteries

Protection of Cobalt-Free LiNiO₂ from Degradation with Localized Saturated Electrolytes in Lithium-Metal Batteries

Interface science in polymer‐based composite solid electrolytes in lithium metal batteries

AbstractSolid‐state lithium metal batteries (SSLMBs) have attracted considerable attention as one of the most promising energy storage systems owing to their high safety and energy density. Solid electrolytes, particularly polymer‐based composite solid electrolytes (CSEs), are considered promising electrolyte candidates for SSLMBs. However, their wide application is inhibited by various electrochemical issues, such as low ionic conductivity, the growth of lithium dendrites, and poor cycling stability, which are related to interface issues within SSLMBs. In this review, the parameters related to various interfaces in the CSE of SSLMBs, including the interfaces between the polymer matrix and inorganic fillers, between the CSEs and the cathode, and between the CSEs and the lithium metal anode, are examined. Relevant issues and corresponding remediation strategies are proposed. Finally, future perspectives based on interfacial engineering and the characterization of polymer/inorganic filler interactions are proposed for building high‐performance CSEs for use in SSLMBs.