Advancements and Challenges in Organic–Inorganic Composite Solid Electrolytes for All‑Solid‑State Lithium Batteries

To address the limitations of contemporary lithium-ion batteries,particularly their low energy density and safety concerns,all-solid-state lithium batteries equipped with solid-state electrolytes have been identified as an up-and-coming alternative.Among the various SEs,organic–inorganic composite solid electrolytes(OICSEs)that combine the advantages of both polymer and inorganic materials demonstrate promising potential for large-scale applications.However,OICSEs still face many challenges in practical applications,such as low ionic conductivity and poor interfacial stability,which severely limit their applications.This review provides a comprehensive overview of recent research advancements in OICSEs.Specifically,the influence of inorganic fillers on the main functional parameters of OICSEs,including ionic conductivity,Li+transfer number,mechanical strength,electrochemical stability,electronic conductivity,and thermal stability are systematically discussed.The lithium-ion conduction mechanism of OICSE is thoroughly analyzed and concluded from the microscopic perspective.Besides,the classic inorganic filler types,including both inert and active fillers,are categorized with special emphasis on the relationship between inorganic filler structure design and the electrochemical performance of OICSEs.Finally,the advanced characterization techniques relevant to OICSEs are summarized,and the challenges and perspectives on the future development of OICSEs are also highlighted for constructing superior ASSLBs.

Construction of a High‑Performance Composite Solid Electrolyte Through In‑Situ Polymerization within a Self‑Supported Porous Garnet Framework

Composite solid electrolytes(CSEs)have emerged as promising candidates for safe and high-energy–density solid-state lithium metal batteries(SSLMBs).However,concurrently achieving exceptional ionic conductivity and interface compatibility between the electrolyte and electrode presents a significant challenge in the development of high-performance CSEs for SSLMBs.To overcome these challenges,we present a method involving the in-situ polymerization of a monomer within a self-supported porous Li_(6.4)La_(3)Zr_(1.4)Ta_(0.6)O_(12)(LLZT)to produce the CSE.The synergy of the continuous conductive LLZT network,well-organized polymer,and their interface can enhance the ionic conductivity of the CSE at room temperature.Furthermore,the in-situ polymerization process can also con-struct the integration and compatibility of the solid electrolyte–solid electrode interface.The synthesized CSE exhibited a high ionic conductivity of 1.117 mS cm^(-1),a significant lithium transference number of 0.627,and exhibited electrochemical stability up to 5.06 V vs.Li/Li+at 30℃.Moreover,the Li|CSE|LiNi_(0.8)Co_(0.1)Mn_(0.1)O_(2) cell delivered a discharge capacity of 105.1 mAh g^(-1) after 400 cycles at 0.5 C and 30℃,corresponding to a capacity retention of 61%.This methodology could be extended to a variety of ceramic,polymer electrolytes,or battery systems,thereby offering a viable strategy to improve the electrochemical properties of CSEs for high-energy–density SSLMBs.

Rational Design of High-Performance PEO/Ceramic Composite Solid Electrolytes for Lithium Metal Batteries

Composite solid electrolytes(CSEs)with poly(ethylene oxide)(PEO)have become fairly prevalent for fabricating high-performance solid-state lithium metal batteries due to their high Li~+solvating capability,flexible processability and low cost.However,unsatisfactory room-temperature ionic conductivity,weak interfacial compatibility and uncontrollable Li dendrite growth seriously hinder their progress.Enormous efforts have been devoted to combining PEO with ceramics either as fillers or major matrix with the rational design of two-phase architecture,spatial distribution and content,which is anticipated to hold the key to increasing ionic conductivity and resolving interfacial compatibility within CSEs and between CSEs/electrodes.Unfortunately,a comprehensive review exclusively discussing the design,preparation and application of PEO/ceramic-based CSEs is largely lacking,in spite of tremendous reviews dealing with a broad spectrum of polymers and ceramics.Consequently,this review targets recent advances in PEO/ceramicbased CSEs,starting with a brief introduction,followed by their ionic conduction mechanism,preparation methods,and then an emphasis on resolving ionic conductivity and interfacial compatibility.Afterward,their applications in solid-state lithium metal batteries with transition metal oxides and sulfur cathodes are summarized.Finally,a summary and outlook on existing challenges and future research directions are proposed.

Enabling high-performance all-solid-state lithium batteries with high ionic conductive sulfide-based composite solid electrolyte and ex-situ artificial SEI film

All-solid-state lithium batteries(ASSLBs) employing sulfide electrolyte and lithium(Li) anode have received increasing attention due to the intrinsic safety and high energy density.However,the thick electrolyte layer and lithium dendrites formed at the electrolyte/Li anode interface hinder the realization of high-performance ASSLBs.Herein,a novel membrane consisting of Li_(6)PS_(5) Cl(LPSCl),poly(ethylene oxide)(PEO) and Li-salt(LiTFSI) was prepared as sulfide-based composite solid electrolyte(LPSCl-PEO3-LiTFSI)(LPSCl:PEO=97:3 wt/wt;EO:Li=8:1 mol/mol),which delivers high ionic conductivity(1.1 × 10^(-3) S cm^(-1)) and wide electrochemical window(4.9 V vs.Li^(+)/Li) at 25 ℃.In addition,an ex-situ artificial solid electrolyte interphase(SEI) film enriched with LiF and Li3 N was designed as a protective layer on Li anode(Li(SEI)) to suppress the growth of lithium dendrites.Benefiting from the synergy of sulfide-based composite solid electrolyte and ex-situ artificial SEI,cells of S-CNTs/LPSCI-PEO3-LiTFSI/Li(SEI) and Al_(2)O_(3)@LiNi_(0.5)Co_(0.3)Mn_(0.2)O_(2)/LPSCl-PEO3-LiTFSI/Li(SEI) are assembled and both exhibit high initial discharge capacity of 1221.1 mAh g^(-1)(135.8 mAh g^(-1)) and enhanced cycling stability with 81.6% capacity retention over 200 cycles at 0.05 C(89.2% over 100 cycles at 0.1 C).This work provides a new insight into the synergy of composite solid electrolyte and artificial SEI for achieving high-performance ASSLBs.

A critical review on composite solid electrolytes for lithium batteries:Design strategies and interface engineering

The rapid development of new energy vehicles and 5G communication technologies has led to higher demands for the safety,energy density,and cycle performance of lithium-ion batteries as power sources.However,the currently used liquid carbonate compounds in commercial lithium-ion battery electrolytes pose potential safety hazards such as leakage,swelling,corrosion,and flammability.Solid electrolytes can be used to mitigate these risks and create a safer lithium battery.Furthermore,high-energy density can be achieved by using solid electrolytes along with high-voltage cathode and metal lithium anode.Two types of solid electrolytes are generally used:inorganic solid electrolytes and polymer solid electrolytes.Inorganic solid electrolytes have high ionic conductivity,electrochemical stability window,and mechanical strength,but suffer from large solid/solid contact resistance between the electrode and electrolyte.Polymer solid electrolytes have good flexibility,processability,and contact interface properties,but low room temperature ionic conductivity,necessitating operation at elevated temperatures.Composite solid electrolytes(CSEs) are a promising alternative because they offer light weight and flexibility,like polymers,as well as the strength and stability of inorganic electrolytes.This paper presents a comprehensive review of recent advances in CSEs to help researchers optimize CSE composition and interactions for practical applications.It covers the development history of solid-state electrolytes,CSE properties with respect to nanofillers,morphology,and polymer types,and also discusses the lithium-ion transport mechanism of the composite electrolyte,and the methods of engineering interfaces with the positive and negative electrodes.Overall,the paper aims to provide an outlook on the potential applications of CSEs in solid-state lithium batteries,and to inspire further research aimed at the development of more systematic optimization strategies for CSEs.

Laminar Composite Solid Electrolyte with Poly(Ethylene Oxide)-Threaded Metal-Organic Framework Nanosheets for High-Performance All-Solid-State Lithium Battery

Developing laminar composite solid electrolyte with ultrathin thickness and continuous conduction channels in vertical direction holds great promise for all-solid-state lithium batteries.Herein,a thin,laminar solid electrolyte is synthesized by filtrating–NH 2 functionalized metal-organic framework nanosheets and then being threaded with poly(ethylene oxide)chains induced by the hydrogen-bonding interaction from–NH_(2) groups.It is demonstrated that the threaded poly(ethylene oxide)chains lock the adjacent metal-organic framework nanosheets,giving highly enhanced structural stability(Young’s modulus,1.3 GPa)to 7.5-μm-thick laminar composite solid electrolyte.Importantly,these poly(ethylene oxide)chains with stretching structure serve as continuous conduction pathways along the chains in pores.It makes the non-conduction laminar metal-organic framework electrolyte highly conductive:3.97×10^(−5) S cm^(−1) at 25℃,which is even over 25 times higher than that of pure poly(ethylene oxide)electrolyte.The assembled lithium cell,thus,acquires superior cycling stability,initial discharge capacity(148 mAh g^(−1) at 0.5 C and 60℃),and retention(94% after 150 cycles).Besides,the pore size of nanosheet is tailored(24.5–40.9˚A)to evaluate the mechanisms of chain conformation and ion transport in confined space.It shows that the confined pore only with proper size could facilitate the stretching of poly(ethylene oxide)chains,and meanwhile inhibit their disorder degree.Specifically,the pore size of 33.8˚A shows optimized confinement effect with trans-poly(ethylene oxide)and cis-poly(ethylene oxide)conformation,which offers great significance in ion conduction.Our design of poly(ethylene oxide)-threaded architecture provides a platform and paves a way to the rational design of next-generation high-performance porous electrolytes.

Nuclear magnetic resonance studies of organic-inorganic composite solid electrolytes

Solid electrolytes have received widespread attention due to their higher safety than liquid electrolytes in the past decades.In particular,organic-inorganic composite solid electro-lytes(CSEs)in which inorganic fllers dispersed in polymer solid electrolytes are consid-ered to be one of the most promising candidate electrolytes for high-performance solid-state lithium batteries.Understanding the local environments and the conduction pathway/dynamics of Lit is essential for the design of high-performance CSEs.Nuclear magnetic resonance(NMR)is a non-invasive quantitative technique that has unique ca-pabilities in providing molecular structure information,morphological evolution,and measuring the movement of ions at different time scales.Therefore,for battery re-searchers,an accurate and comprehensive under standing of the basic principles and experimental design of solid-state NMR(SSNMR)is of great significance for investigating the abundant molecular structure and dynamics information in CSEs.The specific appli-cations of the SSNMR technique in CSEs are briefly introduced in this present review.

Evolution and function of residual solvent in polymer-Li_2B_(12)H_(12) composite solid electrolyte

Composite solid electrolytes(CSEs) containing polymer matrices and inorganic fillers hold promise for the next generation of solid-state batteries.However,the role of residual solvents in CSEs remains controversial.This study investigated the evolution and function of the residual solvent in a polymer-Li_2B_(12)H_(12) CSE.A partial reaction occurred between Li_2B_(12)H_(12) and solvent N,N-dimethylformamide(DMF),which produced dimethylaminomethanol(DMAM) in the CSE.Density functional theory calculations have revealed that DMA M forms stronger hydrogen bonds with polyvinylidene fluoride chains than DMF,which can have a plasticizing effect on the polymer matrix,leading to lower crystallinity and quicker segment motion.Therefore,this CSE exhibited improved Li-ion conducting properties,enabling the stable cycling of Li‖LiFePO_(4) solid-state batteries.This study provided insights into the role of residual solvents in CSEs.

Formatted PVDF in lamellar composite solid electrolyte for solidstate lithium metal battery

Solid polymer electrolytes(SPEs)hold great application potential for solid-state lithium metal battery because of the excellent interfacial contact and processibility,but being hampered by the poor room-temperature conductivity(~10^(−7)S·cm^(−1))and low lithium-ion transference number(tLi+).Here,a lamellar composite solid electrolyte(Vr-NH_(2)@polyvinylidene fluoride(PVDF)LCSE)withβ-conformation PVDF is fabricated by confining PVDF in the interlayer channel of-NH_(2)modified vermiculite lamellar framework.We demonstrate that the conformation of PVDF can be manipulated by the nanoconfinement effect and the interaction from channel wall.The presence of-NH_(2)groups could induce the formation ofβ-conformation PVDF through electrostatic interaction,which serves as continuous and rapid lithium-ion transfer pathway.As a result,a high room-temperature ionic conductivity of 1.77×10^(−4)S·cm^(−1)is achieved,1-2 orders of magnitude higher than most SPEs.Furthermore,Vr-NH_(2)@PVDF LCSE shows a high tLi+of 0.68 because of the high dielectric constant,~3 times of that of PVDF SPE,and surpassing most of reported SPEs.The LiNi_(0.8)Co_(0.1)Mn_(0.1)O_(2)||Li cell assembled by Vr-NH_(2)@PVDF LCSE obtains a discharge specific capacity of 137.1 mAh·g^(−1)after 150 cycles with a capacity retention rate of 93%at 1 C and 25℃.This study may pave a new avenue for high-performance SPEs.

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

Solid-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,theirwide 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.

Lithiated Nafion-garnet ceramic composite electrolyte membrane for solid-state lithium metal battery

Single-ion conducting solid polymer electrolytes are expected to play a vital role in the realization of solid-state Li metal batteries.In this work,a lithiated Nafion(Li-Nafion)-garnet ceramic Li6.25La3 Zr2 Al0.25O12(LLZAO)composite solid electrolyte(CSE)membrane with 30μm thickness was prepared for the first time.By employing X-ray photoelectron spectroscopy and transmission electron microscope,the interaction between LLZAO and Li-Nafion was investigated.It is found that the LLZAO interacts with the Li-Nafion to form a space charge layer at the interface between LLZAO and Li-Nafion.The space charge layer reduces the migration barrier of Li-ions and improves the ionic conductivity of the CSE membrane.The CSE membrane containing 10 wt%LLZAO exhibits the highest ionic conductivity of2.26×10-4 S cm-1 at 30℃among the pristine Li-Nafion membrane,the membrane containing 5 wt%,20 wt%,and 30 wt%LLZAO,respectively.It also exhibits a high Li-ion transference number of 0.92,and a broader electrochemical window of 0-+4.8 V vs.Li+/Li than that of 0-+4.0 V vs.Li+/Li for the pristine Li-Nafion membrane.It is observed that the CSE membrane not only inhibits the growth of Li dendrites but also keeps excellent electrochemical stability with the Li electrode.Benefitting from the above merits,the solid-state LiFePO4/Li cell fabricated with the CSE membrane was practically charged and discharged at 30℃.The cell exhibits an initial reversible discharge specific capacity of 160 mAh g-1 with 97%capacity retention after 100 cycles at 0.2 C,and maintains discharge specific capacity of 126 mAh g-1 after500 cycles at 1 C.The CSE membrane prepared with Li-Nafion and LLZAO is proved to be a promising solid electrolyte for advanced solid-state Li metal batteries.

High-conductivity free-standing Li_(6)PS_(5)Cl/poly(vinylidene difluoride)composite solid electrolyte membranes for lithium-ion batteries

Bulk-type all-solid-state batteries(ASSBs)using sulfide solid electrolyte are considered as a promising alternative to commercial lithium-ion batteries owing to their high energy density and safety.However,cell energy density is often comparatively low due to use of a thick solid electrolyte separator and a lithium alloy as anode.For achieving high-performance ASSBs,creating a thin free-standing electrolyte with high-conductivity and good cycling stability against lithium anode is essential.In this work,we present Li_(6)PS_(5)Cl/poly(vinylidene difluoride)(LPSCl/PVDF)composite electrolytes prepared by a slurry method.The influence of the PVDF content on the microstructure,morphology,ionic conductivity and activation energy of the LPSCl/PVDF electrolytes is systematically investigated.Free-standing LPSCl/PVDF membranes with a thickness of 100-120 mm and a high ionic conductivity of about 1·10^(-3) S cm^(-1) at 25℃ are obtained.After adding PVDF to the LPSCl electrolyte,the cycling stability of the LPSCl electrolyte against lithium metal improves significantly.Therefore,LPSCl/PVDF composite electrolytes are promising candidates to be used in ASSBs.

Synergistic coupling among Mg_(2)B_(2)O_(5),polycarbonate and N,Ndimethylformamide enhances the electrochemical performance of PVDF-HFP-based solid electrolyte

Polymer solid electrolytes(SPEs)based on the[solvate-Li+]complex structure have promising prospects in lithium metal batteries(LMBs)due to their unique ion transport mechanism.However,the solvation structure may compromise the mechanical performance and safety,hindering practical application of SPEs.In this work,a composite solid electrolyte(CSE)is designed through the organic-inorganic syner-gistic interaction among N,N-dimethylformamide(DMF),polycarbonate(PC),and Mg_(2)B_(2)O_(5) in poly(vinylidene fluoride-co-hexafluoropropylene)(PVDF-HFP).Flame-retardant Mg_(2)B_(2)O_(5) nanowires provide non-flammability to the prepared CSEs,and the addition of PC improves the dispersion of Mg_(2)B_(2)O_(5) nanowires.Simultaneously,the organic-inorganic synergistic action of PC plasticizer and Mg_(2)B_(2)O_(5) nanowires pro-motes the dissociation degree of LiTFSI and reduces the crystallinity of PVDF-HFP,enabling rapid Li ion transport.Additionally,Raman spectroscopy and DFT calculations confirm the coordination between Mg atoms in Mg_(2)B_(2)O_(5) and N atoms in DMF,which exhibits Lewis base-like behavior attacking adjacent C-F and C-H bonds in PVDF-HFP while inducing dehydrofluorination of PVDF-HFP.Based on the syner-gistic coupling of Mg_(2)B_(2)O_(5),PC,and DMF in the PVDF-HFP matrix,the prepared CSE exhibits superior ion conductivity(9.78×10^(-4) s cm^(-1)).The assembled Li symmetric cells cycle stably for 3900 h at a current density of 0.1 mA cm^(-2) without short circuit.The LFP||Li cells assembled with PDL-Mg_(2)B_(2)O_(5)/PC CSEs show excellent rate capability and cycling performance,with a capacity retention of 83.3%after 1000 cycles at 0.5 C.This work provides a novel approach for the practical application of organic-inorganic Synergistic CSEs in LMBs.

Flexible,solid-state,fiber-network-reinforced composite solid electrolyte for long lifespan solid lithium-sulfurized polyacrylonitrile battery

Solid lithium-sulfur batteries(SLSBs)show potential for practical application due to their possibility for high energy density.However,SLSBs still face tough challenges such as the large interface impedance and lithium dendrite formation.Herein,a highperformance SLSB is demonstrated by using a fiber network reinforced Li_(6.75)La_(3)Zr_(1.75)Ta_(0.25)O_(12)(LLZTO)based composite solid electrolyte(CSE)in combination with sulfurized polyacrylonitrile(SPAN)cathode.The CSE consisting of an electrospun polyimide(PI)film,LLZTO ionically conducting filler and polyacrylonitrile(PAN)matrix,which is named as PI-PAN/LLZTO CSE,possesses high room-temperature ionic conductivity(2.75×10^(-4)S/cm),high Li^(+)migration number(tLi+)of 0.67 and good interfacial wettability.SPAN is utilized due to its unique electrochemical properties:reasonable electronic conductivity and no polysulfides shuttle effect.The CSE enables a highly stable Li plating/stripping cycle for over 600 h and good rate performance.Moreover,the assembled SLSB exhibits good cycle performance of accomplishing 120 cycles at 0.2 C with the capacity retention of 474 mAh/g,good rate properties and excellent long-term cycling stability with a high capacity retention of 86.49%from 15^(th)to 1,000^(th)cycles at 1.0 C.This work rationalizes our design concept and may guide the future development of SLSBs.

Scalable,thin asymmetric composite solid electrolyte for high-performance all-solid-state lithium metal batteries

All-solid-state Li metal batteries(ASSLMBs)have been considered the most promising candidates for next-generation energy storage devices owing to their high-energy density and safety.However,some obstacles such as thick solid electrolyte(SSEs)and unstable interface between the solid-state electrolytes(SSEs)and the electrodes have restricted the practical application of ASSLBs.Here,the scalable polyimide(PI)film reinforced asymmetric ultrathin(~20μm)composite solid electrolyte(AU-CSE)with a ceramic-rich layer and polymer-rich layer is fabricated by a both-side casting method and rolling process.The ceramic-rich layer not only acts as a“securer”to inhibit the lithium dendrite growth but also redistributes Li-ions uniform deposition,while the polymer-rich layer improves the compatibility with cathode materials.As a result,the obtained AU-CSE demonstrates an ionic conductivity of 1.44×10^(−4)S cm^(−1)at 35°C.The PI-reinforced AU-CSE enables Li/Li symmetric cell stable cycling over 1200 h at_(0.2)mA cm^(−2)and_(0.2)mAh cm^(−2).Li/LiNi_(0.6)Co_(0.2)Mn_(0.2)O2 and Li/LiFePO4 ASSLMBs achieve superior performances at 35°C.This study provides a new way of solving the interface problems between SSEs and electrodes and developing high-energy-density ASSLMBs for practical applications.

Challenges and Development of Composite Solid Electrolytes for All-solid-state Lithium Batteries

All-solid-state lithium batteries are considered to be a new battery system with great development potential and application prospects due to the advantages of high energy density and high security.As a key component of all-solid-state lithium batteries,the development of solid-state electrolytes has received extensive attention in recent years,but most solid electrolytes still exhibit problems,such as low ion conductivity and poor interface compatibility.The design of composite solid-state electrolyte materials with both excellent electrochemical and mechanical properties is an effective way to develop all-solid-state lithium batteries.This review introduces different types of pure component solid electrolytes and analyzes their respective advantages and characteristics firstly.Furthermore,the research progress of composite electrolytes in preparation method,ionic conduction,suppression of lithium dendrites,and the improvement of electrochemical performances are reviewed from the perspective of composite electrolyte structure design,which is to meet different performance requirements.And the future development direction and trend of composite electrolytes are prospected.

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

Solid-state electrolytes(SSEs)can address the safety issue of organic electrolyte in rechargeable lithium batteries.Unfortunately,neither polymer nor ceramic SSEs used alone can meet the demand although great progress has been made in the past few years.Composite solid electrolytes(CSEs)composed of flexible polymers and brittle but more conducting ceramics can take advantage of the individual system for solid-state lithium metal batteries(SSLMBs).CSEs can be largely divided into two categories by the mass fraction of the components:“polymer rich”(PR)and“ceramic rich”(CR)systems with different internal structures and electrochemical properties.This review provides a comprehensive and in-depth understanding of recent advances and limitations of both PR and CR electrolytes,with a special focus on the ion conduction path based on polymer-ceramic interaction mechanisms and structural designs of ceramic fillers/frameworks.In addition,it highlights the PR and CR which bring the leverage between the electrochemical property and the mechanical property.Moreover,it further prospects the possible route for future development of CSEs according to their rational design,which is expected to accelerate the practical application of SSLMBs.

Status and prospect of garnet/polymer solid composite electrolytes for all-solid-state lithium batteries

Solid polymer electrolytes(SPEs), such as polyethylene oxide(PEO), are characteristic of good flexibility and excellent processability, but they suffer from low ionic conductivity and small Li+transference number at ambient temperature. Inorganic solid electrolytes(ISEs), garnet-type Li7La3Zr2O12 and its derivatives(LLZO-based) in particular, possess high ionic conductivity at room temperature, wide electrochemical stability window, large Li+transference number as well as good stability against Li metal anode.Nevertheless, lithium dendrites growth, interfacial contact issue and brittle nature of LLZO-based ceramic electrolytes prevent their practical applications. In response to these shortcomings, LLZO-based/polymer solid composite electrolytes(SCEs), taking complementary advantages of two kinds of electrolytes, and thus simultaneously improving the electrode wettability, ionic conductivity and mechanical strength, have been made to develop high-performance SCEs in recent years. Herein, the intrinsic properties and research progress of LLZO-based/polymer SCEs, including LLZO-based/PEO SCEs(LLZO-based/PEO SCEs with uniform dispersion of LLZO-based fillers and LLZO-based/PEO layered SCEs) and LLZO-based/novel polymers SCEs, are summarized. Besides, comprehensive updates on their applications in solid-state batteries are also presented. Finally, challenges and perspectives of LLZO-based/polymer SCEs for advanced allsolid-state lithium batteries(ASSLBs) are suggested. This review paper aims to provide systematic research progress of LLZO-based/polymer SCEs, to allow for more efficient and target-oriented research on improving LLZO-based/polymer SCEs.

Anion-immobilized solid composite electrolytes based on metal-organic frameworks and superacid ZrO_(2) fillers for high-performance all solid-state lithium metal batteries

Anion-immobilized solid composite electrolytes(SCEs)are important to restrain the propagation of lithium dendrites for all solid-state lithium metal batteries(ASSLMBs).Herein,a novel SCEs based on metal-organic frameworks(MOFs,UiO-66-NH_(2))and superacid ZrO_(2)(S-ZrO_(2))fillers are proposed,and the samples were characterized by X-ray diffraction(XRD),scanning electron microscope(SEM),energy dispersive X-ray spectroscopy(EDS),thermo-gravimetric analyzer(TGA)and some other electrochemical measurements.The-NH_(2) groups of UiO-66-NH_(2) combines with F atoms of poly(vinylidene fluoride-co-hexafluoropropylene)(PVDF-HFP)chains by hydrogen bonds,leading to a high electrochemical stability window of 5 V.Owing to the incorporation of UiO-66-NH_(2) and S-ZrO_(2) in PVDF-HFP polymer,the open metal sites of MOFs and acid surfaces of S-ZrO_(2) can immobilize anions by strong Lewis acid-base interaction,which enhances the effect of immobilization anions,achieving a high Li-ion transference number(t_(+))of 0.72,and acquiring a high ionic conductivity of 1.05×10^(-4) S·cm^(-1) at 60℃.The symmetrical Li/Li cells with the anion-immobilized SCEs may steadily operate for over 600 h at 0.05 mA·cm^(-2) without the shortcircuit occurring.Besides,the solid composite Li/LiFePO_(4)(LFP)cell with the anion-immobilized SCEs shows a superior discharge specific capacity of 158 mAh·g^(-1) at 0.2 C.The results illustrate that the anion-immobilized SCEs are one of the most promising choices to optimize the performances of ASSLMBs.

The critical role of inorganic nanofillers in solid polymer composite electrolyte for Li+transportation

Compared with commercial lithium batteries with liquid electrolytes,all-solidstate lithium batteries(ASSLBs)possess the advantages of higher safety,better electrochemical stability,higher energy density,and longer cycle life;therefore,ASSLBs have been identified as promising candidates for next-generation safe and stable high-energy-storage devices.The design and fabrication of solid-state electrolytes(SSEs)are vital for the future commercialization of ASSLBs.Among various SSEs,solid polymer composite electrolytes(SPCEs)consisting of inorganic nanofillers and polymer matrix have shown great application prospects in the practice of ASSLBs.The incorporation of inorganic nanofillers into the polymer matrix has been considered as a crucial method to achieve high ionic conductivity for SPCE.In this review,the mechanisms of Li+transport variation caused by incorporating inorganic nanofillers into the polymer matrix are discussed in detail.On the basis of the recent progress,the respective contributions of polymer chains,passive ceramic nanofillers,and active ceramic nanofillers in affecting the Li+transport process of SPCE are reviewed systematically.The inherent relationship between the morphological characteristics of inorganic nanofillers and the ionic conductivity of the resultant SPCE is discussed.Finally,the challenges and future perspectives for developing high-performance SPCE are put forward.This review aims to provide possible strategies for the further improvement of ionic conductivity in inorganic nanoscale filler-reinforced SPCE and highlight their inspiration for future research directions.