Solid-state Composite Electrolyte Research Articles

Hydrogen Bonding Induced Confinement Effect between Ultrafine Nanowires and Polymer Chains for Low-Energy-Barrier Ion Transport in Composite Electrolytes.

Achieving low-energy-barrier lithium ion transport is a fundamental issue for composite solid-state electrolytes (CSEs) in all-solid-state lithium metal batteries (ASSLMBs). In this work, a hydrogen bonding induced confinement strategy was proposed to construct confined template channels for low-energy-barrier lithium ion continuous transport. Specifically, the ultrafine boehmite nanowires (BNWs) with 3.7 nm diameter were synthesized and superiorly dispersed in a polymer matrix to form a flexible CSE. The ultrafine BNWs with large specific surface areas and abundant oxygen vacancies assist the dissociation of lithium salts and confine the conformation of polymer chain segments by hydrogen bonding between the BNWs and the polymer matrix, thus forming a polymer/ultrafine nanowire intertwined structure as template channels for dissociated lithium ions continuous transport. As a result, the as-prepared electrolytes displayed a satisfactory ionic conductivity of 0.714 mS cm-1 and low energy barrier (16.30 kJ mol-1), and the assembled ASSLMB delivered excellent specific capacity retention (92.8%) after 500 cycles. This work demonstrates a promising way to design CSEs with high ionic conductivity for high-performance ASSLMBs.

Protonated chitosan nanostructures for enhancing ionic conductivity of solid-state electrolytes

Solid polymer electrolytes (SPEs) have aroused widespread attention for their high flexibility and good interface contact with electrode. However, the low ionic conductivity severely hinders their application in energy storage devices. Herein, a novel protonated nanostructure was synthesized through the reaction between PEO and Chitosan (Chi) and applied as fillers to form PEO/Chi composite solid-state electrolytes (PCCSEs). The fillers, which achieve nanization by the reaction with PEO, plays an important role in promoting the property of transporting Li+, due to the protonated amino (–NH3+) improving the dissociation of LiTFSI and the nanoscale size with high dispersity. Various characterizations and density functional theory (DFT) calculations were applied to reveal the enhanced Li+ transport mechanism in PCCSE. Owing to the unique design, PCCSE exhibits excellent ionic conductivity at room temperature (1.02 × 10−4 S cm−1) and the Li||SSEs||Li symmetric cells and LFP||SSEs||Li batteries with PCCSE show great cycling stability. This strategy of taking full use of the cations in protonated Chi provides effective design guidance for promoting the Li+ transport in polymer-based electrolytes.

A Thin Composite Polymer Electrolyte Functionalized by a Novel Antihydrolysis Additive to Enable All-Solid-State Lithium Battery with Excellent Rate and Cycle Performance.

Composite solid-state electrolyte (CSE) incorporated with fluorine-containing functional additives usually endows the assembled cell with improved electrochemical performance by forming stable electrode/electrolyte interfaces. However, most of fluorine-containing additives are prone to hydrolysis, which is not suitable for the large-scale preparation of CSEs. In this work, an antihydrolysis and fluorine-containing additive of magnesium 2,3,4,5,6-pentafluorophenylacetate (MgPFPAA) is successfully synthesized and then used to regulate the properties of the electrode/electrolyte interfaces of the all-solid-state lithium batteries (ASSLBs). The antihydrolysis property of MgPFPAA facilitates the large-scale preparation of the ultrathin CSEs in atmospheric environment. Both theoretical calculations and experimental results indicate that MgPFPAA can effectively improve the composition and structure of the generated solid electrolyte interfacefilm by providing rich F sources and Mg2+ , thus leading to a stable CSE/Li interface. Furthermore, an ultrathin PEO/PVDF-based CSE (≈30 µm) functionalized by this novel MgPFPAA additive enables the assembled LiFePO4 -based ASSLB with greatly enhanced electrochemical performances, with high discharge specific capacity of 93.7 mAh g-1 at 10 C and a high capacity retention of 74.9% after 1500 cycles at 5.0 C. Also, this MgPFPAA functionalized CSE can be compatible with the high-areal-capacity LiFePO4 and the high-voltage LiNi0.8 Co0.1 Mn0.1 O2 cathodes.

A gradient “Ceramic-in-Ionogel” electrolyte with tidal ion flow for ultra-stable lithium metal batteries

Composite solid-state electrolytes are considered as key components for safe and high-energy-density lithium metal batteries, given their superior mechanical properties and ion conductive kinetics. However, it still remains a challenge to simultaneously guarantee high ionic conductivity and excellent interfacial compatibility. Herein, a gradient “Ceramic-in-Ionogel” electrolyte with tidal ion flow is proposed for decoupling ionic conductivity and interfacial property. It is composed of poly(vinylidene fluoride-co-hexafluoropropylene) (P(VDF-HFP))/EMIMTFSI/Al2O3 (30 wt. %) layer (Ionogel-dual30) toward cathode and P(VDF-HFP)/EMIMTFSI/Al2O3 (50 wt. %) layer (Ionogel-dual50) to Li-metal anode. Ionogel-dual50 can provide a relatively large number of Al2O3 particles for the formation of AlF3 and Li3AlF6 after being offered electrons at lithium-metal anode and carbon-fluorine bond cleavage in TFSI-, resulting in rapid Li+ transfer and insulated electron transport at interface. Both simulation and experimental characterization suggest that the tidal-flow-like ion transport pathway can offer [Li+-NMP]-P(VDF-HFP) dominant pathway in Ionogel-dual30 and [Li(TFSI)x]+-Al2O3 interface dominant pathway in Ionogel-dual50, achieving a high ionic conductivity of 0.25 mS cm−1. Benefiting from these unique merits, the cycling performance of symmetric Li batteries was greatly improved with a lifetime of over 1000 h at 0.1 mA h cm−2. The effect of this gradient ionogel electrolyte could be well demonstrated in various full cells, evidenced by substantially enhanced cyclability under large current density (2 C), wide voltage range (3–4.5 V) and extreme conditions. This novel “Ceramic-in-Ionogel” electrolyte with tidal ion flow will accelerate the commercialization of high-energy-density lithium metal batteries.

A porous garnet Li7La3Zr2O12 scaffold with interfacial modification for enhancing ionic conductivity in PEO-based composite electrolyte

The composite combined Li7La3Zr2O12 (LLZO) and PEO is viewed as a promising solid-state electrolyte for lithium-ion batteries due to its chemical stability, wide electrochemical window, mechanical flexibility and easy fabrication procedure. However, the primary challenges of low ionic conductivity and poor interfacial compatibility remain unresolved. Herein, a co-modified composite solid-state electrolyte based on the porous Al-doped LLZO (Al-LLZO) garnet scaffold cooperated with Ca-coordinated Dynasylan IMEO (Triethoxy-3-(2-imidazolin-1-yl) propylsilane, named DI) and PEO (denoted as CSE-DI-Ca) is reported. Benefiting from the fast lithium ion conduction in porous Al-LLZO network and interfacial strengthening modification between ceramics and polymer, CSE-DI-Ca exhibits a high ionic conductivity of 6.38✕10−4 S cm−1 at room temperature. The unique ceramic structure of CSE-DI-Ca also leads to an enlarged electrochemical window of 6 V vs. Li+/Li, good thermal stability under 360 °C, and an improved mechanical strength of 8.91 MPa to block lithium dendrites. Furthermore, as an evidence of the compatibility with high-voltage battery, the LiNi0.6Co0.2Mn0.2O2(NCM622)|CSE-DI-Ca|Li coin cell delivers an initial discharge capacity of 130.2 mAh g−1 at 0.1 C at room temperature and maintains a capacity of 127.3 mAh g−1 after 120 cycles. All these superior properties indicate that the as-prepared composite holds great promise as an effective solid-state electrolyte to be used in next-generation lithium-ion batteries.

Building the homogeneous ionic interfaces and channels for high compatible composite PVDF/SiO2 solid electrolyte by grafting sulfonate betaine

Poor solid–solid interfacial compatibility has been a troubling challenge to the development of solid-state lithium metal batteries. For this purpose, inspired by mussel mimetic chemistry, the homogeneous ionic interfaces and channels between PVDF matrix and SiO2 nanospheres were built by grafting sulfonate betaine (SB) on their surfaces via Schiff base reaction and ring opening reaction. Furthermore, the influence of SB-SiO2 content on the structure, mechanical properties, thermal stability and electrochemical performances of the composite solid-state electrolyte was also studied. Desirably, Li+ transference number and ionic conductivity of 8%SB-SiO2/SB-PVDF/LiTFSI electrolyte membrane were as high as 0.50 and 5.5 × 10−5 S/cm, respectively, much higher than those of the counterparts in literatures. Uniform dispersion of SB-SiO2 nanospheres in 8%SB-SiO2/SB-PVDF/LiTFSI electrolyte membrane built the homogeneous continuous ion channels, while the homogeneous structure of SB-PVDF and PVDF binder in the electrode also facilitated the interface compatibility of the membrane/electrode, and thus the synergistic effect improved the Li+ transference number. The reversible specific capacity of LiFePO4//8%SB-SiO2/SB-PVDF/LiTFSI//Li battery was 129.7 mAh/g at 1.0 C for 200 cycles, higher than those of other two electrolyte membranes, meanwhile, high-voltage LCO//8%SB-SiO2/SB-PVDF/LiTFSI//Li battery also exhibited good Li-storage performance, indicating high feasibility of 8%SB-SiO2/SB-PVDF/LiTFSI electrolyte membrane in solid-state lithium metal batteries.

Hybrid Poly(Ethylene Oxide)-Based composite polymer electrolyte for high-performance all-solid-state lithium batteries

Composite solid-state electrolytes (CSSEs) using solid-state lithium metal batteries (SSLMBs) are widely used as one among the primary technological paths aimed towards chemically necessary safety with acceptable energy density. Nevertheless, the unchecked growth of lithium dendrites and the sluggish transport of lithium ions impede the development of SSLMBs based on CSSEs. Herein, the simultaneous introduction of multilayer g-C3N4 and exceptionally thermally stable boron nitride (BN) into the PVDF/PEO system is presented. Benefitting from the unique trait and synergistic effect of g-C3N4 and BN in the synthesized CSSEs (g-C3N4/BN/PVDF/PEO-LiTFSI), the prepared CSSEs yield excellent Li+ transfer number (0.75), surprising thermal stability (shrinkage of only 14.13% after heated at 130 °C for 4 h), and high electrochemical stability window over 4.73 V vs. Li/Li+, which are much higher than those reported in the current literature PEO-based CSSEs. Moreover, the Li||CSSEs||LiFePO4 cell applying the CSSEs attained outstanding cycling stability (capacity retention rate of 85% after 350 cycles) and excellent rate performance (58.6 mAh g−1 at 5C). This study offers a simple, promising application, robust, and scalable manufacturing strategy to develop a dual role for stable and safe polymer-based all-solid-state lithium batteries.

LiCoO2 sintering aid towards cathode-interface-enhanced garnet electrolytes

Garnet-type Li7La3Zr2O12 (LLZO) has high ionic conductivity and good compatibility with lithium metal. High-temperature processing has been proven an effective method to decrease the interface resistance of cathode|LLZO. However, its application is still hindered by the interlayer co-diffusion with the cathode and high sintering temperature (>1200 °C). In this work, a new garnet-type composite solid-state electrolyte (SSE) Li6.54La2.96Ba0.04Zr1.5Nb0.5O12-LiCoO2 (LLBZNO-LCO) is firstly proposed to improve the chemical stability and electrochemical properties of garnet with high-temperature processing. Small doses of LCO (3%) can significantly decrease the LCO|SSE interface resistance from 121.2 to 10.1 Ω cm2, while the sintering temperature of garnet-type LLBZNO decreases from 1230 to 1000 °C. The all-solid-state battery based on the sintered LLBZNO-LCO SSE exhibits excellent cycling stability. Our approach achieves an enhanced LCO|SSE interface and an improved sintering activity of garnet SSE, which provides a new strategy for optimizing the comprehensive performance of garnet SSE.

Building cross-phase ion transport channels between ceramic and polymer for highly conductive composite solid-state electrolyte

Building cross-phase ion transport channels between ceramic and polymer for highly conductive composite solid-state electrolyte

Constructing a PVDF-based composite solid-state electrolyte with high ionic conductivity Li6.5La3Zr1.5Ta0.1Nb0.4O12 for lithium metal battery

Constructing a PVDF-based composite solid-state electrolyte with high ionic conductivity Li6.5La3Zr1.5Ta0.1Nb0.4O12 for lithium metal battery

Ultrathin and Robust Composite Electrolyte for Stable Solid-State Lithium Metal Batteries

Solid-state polymer electrolytes (SPEs) are considered as one of the most promising candidates for the next-generation lithium metal batteries (LMBs). However, the large thickness and severe interfacial side reactions with electrodes seriously restrict the application of SPEs. Herein, we developed an ultrathin and robust poly(vinylidene fluoride) (PVDF)-based composite polymer electrolyte (PPSE) by introducing polyethylene (PE) separators and SiO2 nanoparticles with rich silicon hydroxyl (Si-OH) groups (nano-SiO2). The thickness of the PPSE is only 20 μm but possesses a quite high mechanical strength of 64 MPa. The introduction of nano-SiO2 fillers can tightly anchor the essential N,N-dimethylformamide (DMF) to reinforce the ion-transport ability of PVDF and suppress the side reactions of DMF with Li metal, which can significantly enhance the electrochemical stability of the PPSE. Meanwhile, the Si-OH groups on the surface of nano-SiO2 as a Lewis acid promote the dissociation of the lithium bis(fluorosulfonyl)imide (LiFSI) and immobilize the FSI- anions, achieving a high lithium transference number (0.59) and an ideal ionic conductivity (4.81 × 10-4 S cm-1) for the PPSE. The assembled Li/PPSE/Li battery can stably cycle for a record of 11,000 h, and the LiNi0.8Co0.1Mn0.1O2/PPSE/Li battery presents an initial specific capacity of 173.3 mA h g-1 at 0.5 C, which can stably cycle 300 times. This work provides a new strategy for designing composite solid-state electrolytes with high mechanical strength and ionic conductivity by modulating their framework.

A promising composite solid electrolyte of garnet-type LLZTO and succinonitrile in thermal polyurethane matrix for all-solid-state lithium-ion batteries

For solid-state electrolyte in lithium-ion batteries, high crystal boundary impedance leads to tough electrolyte-electrode interfacial issues. Here, we introduce garnet Li6.4La3Zr1.4Ta0.6O12 (LLZTO) nanoparticles and succinonitrile (SN) into thermal polyurethane (TPU) to fabricate a composite solid-state electrolyte (TPU/LLZTO/SN), achieving high ionic conductivity of 6.452 × 10−4 S cm−1. The TPU polymer with specific soft and hard segments allows lithium ions fast transport and holds good mechanical strength as the electrolyte matrix. The ionic conductor LLZTO further improves the ionic conductivity and mechanical property of the composite electrolyte membrane. Additional SN supplies the electrolyte’ wide electrochemical stabilization window, and enhances the metallic lithium compatibility of the TPU matrix. As a result, the as prepared TPU/LLZTO/SN electrolyte presents high lithium ions transference number of 0.64, and also good mechanical property.

A dielectric electrolyte composite with high lithium-ion conductivity for high-voltage solid-state lithium metal batteries.

The ionic conductivity of composite solid-state electrolytes does not meet the application requirements of solid-state lithium (Li) metal batteries owing to the harsh space charge layer of different phases and low concentration of movable Li+. Herein, we propose a robust strategy for creating high-throughput Li+ transport pathways by coupling the ceramic dielectric and electrolyte to overcome the low ionic conductivity challenge of composite solid-state electrolytes. A highly conductive and dielectric composite solid-state electrolyte is constructed by compositing the poly(vinylidene difluoride) matrix and the BaTiO3-Li0.33La0.56TiO3-x nanowires with a side-by-side heterojunction structure (PVBL). The polarized dielectric BaTiO3 greatly promotes the dissociation of Li salt to produce more movable Li+, which locally and spontaneously transfers across the interface to coupled Li0.33La0.56TiO3-x for highly efficient transport. The BaTiO3-Li0.33La0.56TiO3-x effectively restrains the formation of the space charge layer with poly(vinylidene difluoride). These coupling effects contribute to a quite high ionic conductivity (8.2 × 10-4 S cm-1) and lithium transference number (0.57) of the PVBL at 25 °C. The PVBL also homogenizes the interfacial electric field with electrodes. The LiNi0.8Co0.1Mn0.1O2/PVBL/Li solid-state batteries stably cycle 1,500 times at a current density of 180 mA g-1, and pouch batteries also exhibit an excellent electrochemical and safety performance.

Thin, Flexible, and High-Performance Solid-State Polymer Electrolyte Membranes for Li–O2 Batteries

A solid-state lithium–oxygen battery (SSLOB) has become more attractive as a next-generation energy storage device, with the expectation of long-term safe and wide applications with superior energy density. However, the development of a thin and flexible solid-state electrolyte having good interfacial and chemical stability toward lithium metal and/or oxygen has been a big challenge. Accordingly, a solid-state composite electrolyte membrane has been prepared by impregnating polyethylene glycol (PEG) and succinonitrile plastic crystals (SNPCs) along with lithium bromide redox mediator into a porous polytetrafluoroethylene (PTFE) substrate for application in a SSLOB. The prepared thin electrolyte membrane (23 μm) displays a high ionic conductivity of 1.03 mS cm–1, a tensile strength of 46.5 MPa, and elongation at a break of 100% with excellent flexibility. It also exhibits a wide electrochemical stability window (∼4.9 V) and low interfacial resistance of 80 Ω cm2. The SSLOB cell assembled with the synthesized XPEG/SNPC@PTFE electrolyte membrane shows excellent electrochemical stability during 277 cycles, maintaining a 1000 mAh g–1 discharge capacity. The low terminal voltage difference between the charge and discharge processes of these polymer electrolyte membranes (∼0.65 V) compared to those of liquid or other polymer electrolytes (∼1.4 V) is also an advantageous characteristic for their application in high-performance SSLOBs.

Cold sintering-enabled interface engineering of composites for solid-state batteries

The cold sintering process (CSP) is a low-temperature consolidation method used to fabricate materials and their composites by applying transient solvents and external pressure. In this mechano-chemical process, the local dissolution, solvent evaporation, and supersaturation of the solute lead to “solution-precipitation” for consolidating various materials to nearly full densification, mimicking the natural pressure solution creep. Because of the low processing temperature (<300°C), it can bridge the temperature gap between ceramics, metals, and polymers for co-sintering composites. Therefore, CSP provides a promising strategy of interface engineering to readily integrate high-processing temperature ceramic materials (e.g., active electrode materials, ceramic solid-state electrolytes) as “grains” and low-melting-point additives (e.g., polymer binders, lithium salts, or solid-state polymer electrolytes) as “grain boundaries.” In this minireview, the mechanisms of geomimetics CSP and energy dissipations are discussed and compared to other sintering technologies. Specifically, the sintering dynamics and various sintering aids/conditions methods are reviewed to assist the low energy consumption processes. We also discuss the CSP-enabled consolidation and interface engineering for composite electrodes, composite solid-state electrolytes, and multi-component laminated structure battery devices for high-performance solid-state batteries. We then conclude the present review with a perspective on future opportunities and challenges.

Gel Polymer-Based Composite Solid-State Electrolyte for Long-Cycle-Life Rechargeable Zinc–Air Batteries

Developing high-performance, safe, and flexible solid-state electrolytes (SSEs) for rechargeable solid-state zinc–air batteries (ZABs) is becoming increasingly crucial but remains fraught with tremendous challenges. Herein, a novel multinetwork cross-linked composite gel electrolyte (PVAA-Cellulose) was constructed by introducing poly(acrylic acid) (PAA) and ultrafine cellulose to the poly(vinyl alcohol) (PVA) gel electrolyte. By virtue of the extensive porous network and hydrogen bonding, the PVAA-Cellulose SSEs achieve optimal water retention, thermal stability, and high ionic conductivity of 123 mS cm–1 compared with PVAA (mixture of PVA and PAA). The investigation of the effects of different SSEs on zinc anodes after ZAB cycling reveals that PVAA-Cellulose SSE can effectively inhibit dendrite growth and oxidation byproduct generation on zinc anodes, which contributes to the long-term cycling stability of ZABs. As a result, solid-state ZABs assembled with PVAA-Cellulose SSEs possess a high power density of 74 mW cm–2, a specific capacity of 724 mAh gZn–1, and a long cycle stability of 54 h as well as the outstanding flexibility exhibited by the flexible ZAB devices.

Halide/sulfide composite solid-state electrolyte for Li-anode based all-solid-state batteries

Li2ZrCl6 (LZC) solid-state electrolytes (SSEs) have been recognized as a candidate halide SSEs for all-solid-state Li batteries (ASSLBs) with high energy density and safety due to its great compatibility with 4 V-class cathodes and low bill-of-material (BOM) cost. However, despite the benefits, the poor chemical/electrochemical stability of LZC against Li metal causes the deterioration of Li/LZC interface, which has a detrimental inhibition on Li+ transport in ASSLBs. Herein, we report a composite SSE combining by LZC and argyrodite buffer layer (Li6PS5Cl, LPSC) that prevent the unfavorable interaction between LZC and Li metal. The Li/LPSC-LZC-LPSC/Li symmetric cell stably cycles for over 1000 h at 0.3 mA/cm2 (0.15 mAh/cm2) and has a high critical current density (CCD) value of 2.1 mA/cm2 at 25 °C. Under high temperature (60 °C) which promotes the reaction between Li and LZC, symmetric cell fabricated with composite SSE also display stable cycling performance over 1200 h at 0.3 mAh/cm2. Especially, the Li/NCM ASSLBs fabricated with composite SSE exhibit a high initial coulombic efficiency, as well as superior cycling and rate performance. This simple and efficient strategy will be instrumental in the development of halide-based high-performance ASSLBs.

12 µm‐Thick Sintered Garnet Ceramic Skeleton Enabling High‐Energy‐Density Solid‐State Lithium Metal Batteries

AbstractUltrathin composite solid‐state electrolytes (CSSEs) demonstrate great promise in high‐energy‐density solid‐state batteries due to their ultrathin thickness and good adaptability to lithium metal anodes. However, uncontrolled dendrite growth and performance deterioration caused by the aggregation of inorganic powder restrict the practical application of ultrathin CSSEs. Herein, a flexible, self‐supporting Li6.5La3Zr1.5Ta0.5O12 (LLZO) ceramic skeleton is prepared by the tape‐casting method. Subsequently, a 12 µm‐thick CSSE with a 3D interconnection structure is achieved through in situ UV curing of ethoxylated trimethylolpropane triacrylate (ETPTA) in a ceramic skeleton (CS‐CSSE). This design includes a sintered LLZO ceramic, which can avoid the uneven distribution of the inorganic phase and regulate ion migration. Meanwhile, the cross‐linked ETPTA polymer electrolyte contributes to lower interfacial impedance. In addition, the continuous two‐phase interface can also provide a fast transmission channel for Li+. As a result, CS‐CSSE demonstrates superior Li+ transference number (0.83) and ionic conductivity (1.19 × 10‐3 S cm‐1) at 25 °C. As‐prepared Li|LiNi0.83Co0.12Mn0.05O2 batteries exhibit high discharge specific capacities of 185.4 mAh g‐1 at 0.1 C and average coulombic efficiency greater than 99%. The pouch cells exhibit high energy densities of 376 Wh Kg‐1 and 1186 Wh L‐1. This work provides new insights into the application of ceramics to high‐energy‐density solid‐state batteries.

Prospects of Sulfide-Based Solid-State Electrolytes Modified by Organic Thin Films

Lithium-ion batteries are key to tackling today’s energy crisis. In recent years, compared with the research on other components of lithium-ion batteries, the research on solid-state electrolytes is particularly hot. Among various solid-state electrolyte modification measures, we found that the material design of organic/inorganic composite flexible solid-state electrolytes can achieve the best all-solid-state battery cycling performance. Based on the study of sulfide-based organic/inorganic composite solid-state electrolytes, this article firstly introduces the classification of inorganic solid electrolytes and the advantages and disadvantages of each type of materials. At the same time, the research progress of various oxide solid electrolyte materials and sulfide solid electrolyte materials in recent years is introduced as well as the advantages of organic/inorganic composite solid-state electrolyte materials. Then the influencing factors that affect the performance of solid-state electrolytes, such as material lattice, lattice defects, electrolyte interface problems, and electrolyte microcracks, are introduced. Finally, the superiority of the industrial electrochemical performance of the organic/inorganic composite solid electrolyte material and its future prospects are introduced.

Al and Ta co-doped LLZO as active filler with enhanced Li+ conductivity for PVDF-HFP composite solid-state electrolyte

Battery safety calls for solid state batteries and how to prepare solid electrolytes with excellent performance are of significant importance. In this study, hybrid solid electrolytes combined with organic PVDF-HFP and inorganic active fillers are studied. The modified active fillers of Li7−x−3y Al y La3Zr2–x Ta x O12 are obtained by co-element doping with Al and Ta when LLZO is synthesized by calcination. And an high room temperature ionic conductivity of 5.357 × 10−4 S cm−1 is exhibited by ATLLZO ceramic sheet. The composite solid electrolyte PVDF-HFP/LiTFSI/ATLLZO (PHL-ATLLZO) is prepared by solution casting method, and its electrochemical properties are investigated. The results show that when the contents of lithium salt LiTFSI and active filler ATLLZO are controlled at 40 wt% and 10%, respectively, the ionic conductivity of the resulting composite solid electrolyte is as high as 2.686 × 10−4 S cm−1 at room temperature, and a wide electrochemical window of 4.75 V is exhibited. The LiFePO4/PHL-ATLLZO/Li all-solid-state battery assembled based on the composite solid-state electrolyte exhibits excellent cycling stability at room temperature. The cell assembled by casting the composite solid-state electrolyte on the cathode surface shows a discharge specific capacity of 134.3 mAh g−1 and 96.2% capacity retention after 100 cycles at 0.2 C. The prepared composite solid-state electrolyte demonstrates excellent electrochemical performance.