Composite Separator Research Articles

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

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

Multifunctional Composite Separator Based on NiS2/NiSe2 Homologous Heterostructure Polyhedron Promotes Polysulfide Conversion for High Performance Lithium-Sulfur Batteries.

The shuttle effect significantly hinders the industrialization of high-energy-density lithium-sulfur batteries. To address this issue, NiS2/NiSe2 homologous heterostructure polyhedron (HHP) composite separators were developed to immobilize polysulfides and promote their swift conversion. An in-situ visualization symmetrical cell was specifically designed to show the rapid polysulfide adsorption capability of NiS2/NiSe2 HHP, while the electrolyte-separator interfacial contact behavior was simulated to elucidate the mechanism of action of the composite separator in affecting the homogeneous nucleation of lithium metal surfaces. The electrochemical experimental result highlights the substantial enhancement in the reaction kinetics of polysulfides facilitated by NiS2/NiSe2 HHP, owing to its high Li+ diffusion coefficient and Li2S deposition capacity. The NiS2/NiSe2 HHP cells demonstrate high initial specific capacity (1224.1 mAh g-1) at 0.2 C and minimal decay rates (0.073%) at 2 C. The NiS2/NiSe2 HHP separator has high electrochemical catalytic activity with multiple adsorption sites, enabling the rapid polysulfide conversion and contributing to the preparation of high-performance lithium-sulfur batteries.

Preparation of Hierarchical Porous ZIF-67 and Its Application in Zinc Battery Separator

This study successfully prepared a hierarchically porous ZIF-67 (H-ZIF-67) by incorporating the polyvinylpyrrolidone (PVP) at room temperature. Compared to standard control ZIF-67 (C-ZIF-67) with a yield of 81% and a BET specific surface area of 1228 m2·g−1, the H-ZIF-67 not only exhibited improved crystallinity and pore structure but also achieved a yield of up to 93% and a BET specific surface area of 1457 m2·g−1. Due to its hierarchically porous structure, H-ZIF-67 demonstrated excellent adsorption capacity and efficiency for methylene orange (MO). Additionally, the composite separator created by combining H-ZIF-67 with nanocellulose (CNF) exhibited remarkable uniformity and dispersion in zinc batteries. In comparison to a conventional CNF separator, the porous structure and high specific surface area of H-ZIF-67 significantly enhanced its electrolyte wettability and Zn2+ transport rates. Its abundant Lewis acid sites effectively promoted the uniform deposition of Zn2+, thereby suppressing the formation of zinc dendrites and improving the cycling and safety performance of zinc-ion batteries. Experimental results indicate that the ion conductivity of the membrane was 4.31 mS·cm−1, the electrolyte absorption rate was 316%, and it could cycle stable for over 4000 h at a current density of 1 mA·cm−2 with a discharge capacity of 1 mAh·cm−2. This achievement will open up new avenues for the preparation and application of ZIF-67 composite separators in aqueous zinc-ion batteries.

Paper-Supported Sodium Alginate Composite Separator Prepared by Polymer-Assisted Phase Separation for Lithium Ion Batteries

Paper-Supported Sodium Alginate Composite Separator Prepared by Polymer-Assisted Phase Separation for Lithium Ion Batteries

Microporous Polyethylene and Cellulose Composite Separators for Reversible Lithium Electrode in Lithium Rechargeable Batteries

AbstractThe lithium metal anode is the best candidate for high energy density batteries because of its high specific capacity and low negative potential. Rechargeable lithium metal batteries (RLMB) have not yet been commercialized. The key factors that limit the practical use of RLMB are the formation and growth of lithium dendrites during the lithium deposition process and the reaction of the lithium anode with the organic solvent of the electrolyte, quantified by the Columbic efficiency (CE). To suppress the lithium dendrite formation and to improve CE, many approaches such as the formation of a protective layer on the lithium electrode and the use of additives to the electrolyte have been proposed. In this study, the effect of a thin cellulose film to improve CE of lithium deposition and stripping on the lithium electrode was examined. The cycle performance of a Li/Li symmetrical cell with a cellulose and polyethylene composite separator was examined for a carbonate electrolyte and an ether electrolyte. The improvements of CE were observed for both electrolytes with the cellulose film separator. The improvement could be explained by the good wettability of the cellulose film separator with the electrolyte.

Composite Separators with Very High Garnet Content for Solid‐State Batteries

AbstractLithium‐metal solid‐state batteries are attractive as next generation of Li‐ion batteries due to higher safety and potentially higher energy density. To improve processability, solid‐composite separators combine advantages of inorganic and polymer separators in hybrid structure. We report a systematic approach to fabricate composite separators with high content (90–95 wt %) of ceramic Li‐ion conducting Li6.45Al0.05La3Zr1.6Ta0.4O12 (LLZO) powder embedded in a polyethylene oxide (PEO)‐LiTFSI (20 : 1) matrix and understand factors affecting their properties and performance. Separators with good mechanical flexibility and excellent thermal stability were obtained, by optimizing materials and processing parameters. It was found that PEO molecular weight strongly influences the microstructure and electrochemical properties of the separators. In optimized separator with 90 wt % of LLZO and PEO with Mw 300,000 g/mol, a total ionic conductivity of 1.4×10−5 S/cm at 60 °C was achieved. The ceramic‐rich separator showed excellent long‐term cycling stability for more than 460 cycles (1000 h) at 0.1 mA/cm2 in Li/Li symmetrical cells and achieved a critical current density of 0.25 mA/cm2. The separators also enabled initial discharge capacities of more than 160 mAh/g in full cells with Li metal anode and composite solid‐state LiNi0.6Co0.2Mn0.2O2 cathode, although rapid capacity fade was observed after 10 cycles in fully solid‐state configuration.

Organic-Inorganic Dual-Network Composite Separators for Lithium Metal Batteries.

The suboptimal ionic conductivity of commercial polyolefin separators exacerbates uncontrolled lithium dendrite formation, deteriorating lithium metal battery performance and posing safety hazards. To address this challenge, a novel organic-inorganic composite separator designed is prepared to enhance ion transport and effectively suppress dendrite growth. This separator features a thermally stable, highly porous poly(m-phenylene isophthalamide) (PMIA) electrospun membrane, coated with ultralong hydroxyapatite (HAP) nanowires that promote "ion flow redistribution." The synergistic effects of the nitrogen atoms in PMIA and the hydroxyl groups in HAP hinder anion transport while facilitating efficient Li+ conduction. Meanwhile, the optimized unilateral pore structure ensures uniform ion transport. These results show that the 19µm-thick HAP/PMIA composite separator achieves remarkable ionic conductivity (0.68mS cm-1) and a high lithium-ion transference number (0.51). Lithium symmetric cells using HAP/PMIA separators exhibit a lifespan exceeding 1000h with low polarization, significantly outperforming commercial polypropylene separators. Furthermore, this separator enables LiFePO4||Li cells to achieve an enhanced retention of 97.3% after 200 cycles at 1C and demonstrates impressive rate capability with a discharge capacity of 72.7mAh g-1 at 15C.

Nanofibrous Covalent Organic Frameworks as the Cathode, Separator, and Anode for Batteries with High Energy Density and Ultrafast-Charging Performance.

To meet the demand for longer driving ranges and shorter charging times of power equipment in electric vehicles, engineering fast-charging batteries with exceptional capacity and extended lifespan is highly desired. In this work, we have developed a stable ultrafast-charging and high-energy-density all-nanofibrous covalent organic framework (COF) battery (ANCB) by designing a series of imine-based nanofibrous COFs for the cathode, separator, and anode by Schiff-base reactions. Hierarchical porous structures enabled by nanofibrous COFs were constructed for enhanced kinetics. Rational chemical structures have been designed for the cathode, separator, and anode materials, respectively. A nanofibrous COF (AA-COF) with bipolarization active sites and a wider layer spacing has been designed using a triphenylamine group for the cathode to achieve high voltage limits with fast mass transport. For the anode, a nanofibrous COF (TT-COF) with abundant polar groups, active sites, and homogenized Li+ flux based on imine, triazine, and benzene has been synthesized to ensure stable fast-charging performance. As for the separator, a COF-based electrospun polyacrylonitrile (PAN) composite nanofibrous separator (BB-COF/PAN) with hierarchical pores and high-temperature stability has been prepared to take up more electrolyte, promote mass transport, and enable as high-temperature operation as possible. The as-assembled ANCB delivers a high energy density of 517 Wh kg-1, a high power density of 9771 W kg-1 with only 56 s of ultrafast-charging time, and high-temperature operational potential, accompanied by a 0.56% capacity fading rate per cycle at 5 A g-1 and 100 °C. This ANCB features an ultralong lifespan and distinguished ultrafast-charging performance, making it a promising candidate for powering equipment in electric vehicles.

A Versatile Metal-Organic-Framework Pillared Interlayer Design for High-Capacity and Long-Life Lithium-Sulfur Batteries.

Developing high-performance lithium-sulfur batteries is a promising way to attain higher energy density at lower cost beyond the state-of-the-art lithium-ion battery technology. However, the major issues blocking their practical application are the sluggish kinetics and parasitic shuttling reactions for sulfur and polysulfides. Here, pillaring multilayer graphene with the metal-organic framework (MOF) demonstrates the substantial impact of a versatile interlayer design in tackling those issues. Unlike regular composite separators reported so far, the participation of tri-metallic Ni-Co-Mn MOF (NCM-MOF) as pillars supports the construction of an ion-channel interconnected interlayer structure, unexpectedly balancing the interfacial concentration polarization, spatially confining the soluble polysulfides and vastly affording lithiophilic sites for highly efficient polysulfide sieving/conversion. As a demonstration, we show that the MOF-pillared interlayer structure enables outstanding capacity (1634 mAh g-1 at 0.1C) and longevity (average capacity decay of 0.034% per cycle in 2000 cycles) of lithium-sulfur batteries. Besides, the multilayer separator can be readily integrated into the high-nickel cathode (LiNi0.91Mn0.03Co0.06O2)-based lithium-ion batteries, which efficiently suppresses the undesired phase evolution upon cycling. These findings suggest the potential of "gap-filling" materials in fabricating multi-functional separators, bring forward the pillared interlayer structure for energy-storage applications.

A Versatile Metal‐Organic‐Framework Pillared Interlayer Design for High‐Capacity and Long‐Life Lithium‐Sulfur Batteries

Developing high‐performance lithium‐sulfur batteries is a promising way to attain higher energy density at lower cost beyond the state‐of‐the‐art lithium‐ion battery technology. However, the major issues blocking their practical application are the sluggish kinetics and parasitic shuttling reactions for sulfur and polysulfides. Here, pillaring multilayer graphene with the metal‐organic framework (MOF) demonstrates the substantial impact of a versatile interlayer design in tackling those issues. Unlike regular composite separators reported so far, the participation of tri‐metallic Ni‐Co‐Mn MOF (NCM‐MOF) as pillars supports the construction of an ion‐channel interconnected interlayer structure, unexpectedly balancing the interfacial concentration polarization, spatially confining the soluble polysulfides and vastly affording lithiophilic sites for highly efficient polysulfide sieving/conversion. As a demonstration, we show that the MOF‐pillared interlayer structure enables outstanding capacity (1634 mAh g‐1 at 0.1C) and longevity (average capacity decay of 0.034% per cycle in 2000 cycles) of lithium‐sulfur batteries. Besides, the multilayer separator can be readily integrated into the high‐nickel cathode (LiNi0.91Mn0.03Co0.06O2)‐based lithium‐ion batteries, which efficiently suppresses the undesired phase evolution upon cycling. These findings suggest the potential of “gap‐filling” materials in fabricating multi‐functional separators, bring forward the pillared interlayer structure for energy‐storage applications.

Low-cost and durable polyvinyl alcohol modified polyethylene separator for vanadium redox flow battery

Porous separators are considered a viable alternative to the high cost Nafion membrane for vanadium redox flow battery (VRFB) commercialization. However, the porous separators suffer from high vanadium ion crossover due to the presence of large micron size pores, which leads to decay in capacity of the VRFB system. To tackle the same, a composite separator is synthesized wherein a cross-linked polyvinyl alcohol (PVA) layer is coated on to the porous polyethylene silica separator (PE separator) to mitigate the vanadium ion crossover rate and employed in the VRFB application. Scanning electron microscopy (SEM) analysis confirmed the successful coating of the PVA film on to the PE separator. Synthesized PE-PVA separator showed a significant decrease in the vanadium ion crossover by 31.44 times compared to the pristine PE separator. Consequently, the self-discharge time increases by 8 and 1.66 times compared to the pristine PE separator and the Nafion117 membrane, respectively. VRFB cell equipped with the synthesized separator showed better capacity retention with a capacity fade rate of 0.2 % Ah·cycle−1 than the Nafion117 membrane (0.5 % Ah·cycle−1). In-situ and ex-situ oxidative stability of the separator is explored in detail and a degradation mechanism of the cross-linked PVA membrane is proposed accordingly. The synthesized single side coated PE-PVA´ separator exhibits higher coulombic efficiency of 99 % and comparable energy efficiency of 71 % at a current density of 120 mA·cm−2 and demonstrated excellent lifetime durability tested up to 1600 charge-discharge cycles at 80 mA·cm−2.

A bacterial cellulose composite separator with high thermal stability and flame retardancy for high-performance lithium ion batteries

Separators play a crucial role in enhancing the safety of lithium-ion batteries (LIBs); however, commercial polyolefin separators exhibit poor thermal stability and are flammable. This study investigates the use of green, environmentally friendly, and renewable bacterial cellulose as a substrate for developing a composite separator (BHM/5). The BHM/5 separator, comprising bacterial cellulose, an inorganic mineral nano-hydroxyapatite (HAP) and flame-retardant melamine polyphosphate (MPP), is fabricated via freeze drying and high-temperature pressing. The developed composite separator demonstrates superior thermal stability and excellent flame retardancy compared with commercial polyolefin separators while maintaining structural integrity at 200℃ and exhibiting self-extinguishing properties after ignition. Furthermore, the BHM/5 separator exhibits a high porosity of 74 % and a substantial electrolyte uptake of 459 %, achieving an ion conductivity of 1.44 mS/cm. As a result, the cell of the LiFePO4-Li system assembled demonstrates an initial discharge capacity of 131.35 mAh·g−1 at a current density of 1C and a capacity retention of 95.4 % after 150 cycles.

Thermally-stable and flame-retardant metal-organic framework-based separator for high-performance lithium-ion batteries

Safety hazards hinder the development of lithium-ion batteries (LIBs), in which the failure of separator is a key point. However, commercial polyolefin separators display poor thermal stability and flame-retardant property. Aramid nanofiber (ANF) is a promising material for safer separators in batteries due to its excellent thermal stability and remarkable flame retardancy, but the pure ANF separator often shows low ionic conductivity because of the tightly packed fibers. Metal-organic framework (MOF) is a promising candidate for increasing the porosity and ionic conductivity of ANF separator due to its ultrahigh porosity and ultrahigh specific area. Herein, a thermally-stable and high-performance composite separator is fabricated by combining MOF pore-forming agent and ANF network skeleton. The MOF/ANF1composite separator with 10 wt% ANF shows excellent thermal-stability (melting-point above 300 °C and decomposition temperature above 500 °C) and remarkable flame-retardant property. And it exhibits high ionic-conductivity of 1.01 mS·cm−1, contributed to the superior long-term cycling performance of the coin cell with the capacity of 147.3 mAh·g−1 after 200 cycles at 1 C, almost 25.4 % higher than that of the coin cell with PP separator for LIBs. The strategy of this research provides new ideas for the design of high-safety LIBs.

The long-lasting maintenance of the pore structure achieves the stability of lithium metal batteries

The separator is considered critical to the safety and performance of lithium metal batteries (LMBs), however, the separator structure fails under high temperature conditions due to damage resulting in decreased mechanical strength, which causes short-circuiting of the battery. This paper describes a novel process to prepare stable and uniform dispersions of aramid nanofibers (ANFs) by bottom-up low-temperature polymerization, and then crosslink the ANFs with N2 plasma-treated polypropylene (PP) separator through capping isocyanate crosslinkers. The composite separator not only has excellent mechanical properties with hardness and modulus of elasticity up to 0.35 and 2.26 GPa, which is three times higher than the PP separator, but also has high-temperature thermal stability, the size maintenance rate reaches 99.8 % at 200 °C. Meanwhile, real-time monitoring of the pore size at different temperatures by synchrotron radiation small-angle X-ray scattering (SR-SAXS) showed that the pore radius of gyration was kept at 8.81 nm and the size change rate was only 22.8 % at 200 °C, which demonstrated that the composite separator had an outstanding ability to maintain the pore structure to ensure the stability of the ionic transport channel. Therefore, the crosslinked composite separator has greater potential for improving the performance and safety of LMBs in extreme high-temperature environments.

A high-safety lithium-ion battery electrospun separator with Si3N4-assisted sulfonated poly(ether ether ketone) for regulating lithium flux

The uncontrolled lithium (Li) dendrite growth significantly impacts the safety performance of polymer separators. To mitigate this growth, this study introduces Si3N4 into sulfonated poly(ether Ether Ketone) (SPEEK) and prepares Si3N4/SPEEK composite separators via electrospinning. At the interface between the Si3N4/SPEEK separator and the Li anode, the Si nanowires that form impede Li dendrite growth, thereby enhancing the electrochemical performance of lithium-ion batteries (LIBs). The Li deposition test of the 10 % Si3N4/SPEEK separator can operate for 1000 h without short-circuiting. Additionally, the LiFePO4||Li cell with the 10 % Si3N4/SPEEK separator shows improved initial discharge capacity (157.8 mAh g−1 at 1C) and superior rate performance (125 mAh g−1 at 10C). Moreover, the nano-scale Si3N4 endows the separator with robust thermal and mechanical properties. The FLIR observations reveal that the 10 % Si3N4/SPEEK separator maintains uniform thermal distribution and structural integrity even at 300 °C, ensuring safe battery operation at high temperatures. The additional load of the 10 % Si3N4/SPEEK separator can reach 10.2 mN, which enhances the puncture resistance of the separator. This work provides a solid approach for the application of SPEEK as a high-safety and high-rate LIB separator.

Effect of porous irregular ZrO2 nanoparticles on the performance of alkaline water electrolysis composite separator membranes under complex conditions

Developing composite separator membranes with low area resistance, high bubble point pressure, and long-term safety and stability is crucial for alkaline water electrolysis for hydrogen production as a key component of electrolyzer systems. In this study, PPS mesh fabric reinforced PSF@ZrO2 composite separator membranes were successfully prepared using the immersion-drawing phase inversion method, with PSF as the alkali-resistant polymer matrix and porous irregular ZrO2 nanoparticles as the hydrophilic additive. The experimental results showed that replacing commercial ZrO2 with porous irregular ZrO2 nanoparticles at an 85 wt% ZrO2 nanoparticle loading improved both bubble point pressure and current transmission efficiency, attributed to the change in the morphological structure of the ZrO2 nanoparticles. The P-Z85 composite separator membrane exhibited highly promising characteristics, with a high bubble point pressure of 3.76 bar and a low area resistance of 0.20 Ω cm2. Stability tests conducted in 30 wt% KOH electrolyte at 80 °C and a current density of 0.65 A cm−2 demonstrated excellent continuous electrolysis stability for the P-Z85 composite separator membrane. These results indicate that the PSF@ZrO2/PPS composite separator membrane prepared in this study exhibits excellent performance in 30 wt% KOH electrolyte, significantly extending its service life.

Robust Composite Separator Randomly Interwoven by PI and Pre-oxidized PAN Nanofibers for High Performance Lithium-ion Batteries

Robust Composite Separator Randomly Interwoven by PI and Pre-oxidized PAN Nanofibers for High Performance Lithium-ion Batteries

Surface functionalization of cellulose derived from hemp by tetraethyl orthosilicate (TEOS) and poly vinylidene fluoride (PVDF)-based composite separator membrane for lithium-ion batteries (LIBs)

Separators play a crucial role in enhancing the electrochemical performance of lithium-ion batteries (LIBs). However, achieving separators with exceptional electrochemical performance and high stability remains a significant challenge. In this study, we meticulously designed composite membranes based on polyvinylidene fluoride (PVDF) with varying contents of microcrystalline cellulose/tetraethyl orthosilicate (MCC/TEOS). The increase in hydrophilicity of PVDF by adding MCC-TEOS weight contents endowed the 3 wt% MCC/TEOS-based PVDF separator membrane with superior electrolyte absorption and reduced resistance, resulting in an impressive ionic conductivity of 0.514 mS/cm higher than the pristine PVDF membrane (0.253 mS/cm). Furthermore, the LIB cell utilizing the 3 wt % MCC/TEOS-based PVDF separator membrane consistently demonstrated stable charge/discharge profiles at a rate of 0.2C, achieving a specific capacity of 98 mAh/g, compared to only 43 mAh/g for the pristine PVDF membrane. These findings underscore the significant potential of MCC/TEOS as a biofiller for bio-membranes, making it an optimal choice for applications in LIBs.

Enhancing aqueous zinc-ion energy storage performance with ion-mediating carbon quantum dots-modified separators regulating zinc deposition behavior

Aqueous zinc-ion batteries (AZIBs) hold promising applications owing to their safety, cost-effectiveness, and competitive capacity. However, issues such as zinc dendritic formation and side reactions severely impede their practical viability. Utilizing carbon quantum dots (CQDs) to modify cheap, tenacious, and highly hydrophilic filter paper (FP) as separator effectively improves the electrochemical performance of zinc ion energy storage systems. The structured arrangement of CQDs redistributes zinc ion transport and induces uniform zinc icon deposition, thereby improving zinc ion reaction kinetics. Moreover, the rich functional groups on the surface of CQDs readily form hydrogen bonds with active H2O, further inhibiting corrosion reactions. With the assistance of CQDs, the FP-CQDs separator maintains high ionic conductivity and a high zinc-ion transference number, ensuring dendrite-free and corrosion-resistant operation with high coulombic efficiency and a prolonged lifespan of 1200 h at 1 mA cm−2. Zn//AC hybrid capacitors incorporating FP-CQDs separator demonstrate superior capacity retention compared to those using FP separator alone, with a high capacity retention after 600 cycles at 1 A/g, while Zn//V2O5 full batteries also exhibit excellent cycling stability. Given these findings, this study presents a new composite separator for advanced aqueous zinc-ion energy storage systems.

High-Viscosity Phase Inversion Separators for Freestanding and Direct-on-Electrode Manufacturing in Lithium-Ion Batteries.

Separators play a critical role in lithium-ion batteries (LIBs) by facilitating lithium-ion (Li-ion) transport while enabling safe battery operation. However, commercial separators made from polypropylene (PP) or polyethylene (PE) impose a discrete processing step in current LIB manufacturing as they cannot be manufactured with the same slot-die coating process used to fabricate the electrodes. Moreover, commercial separators cannot accommodate newer manufacturing processes used to produce leading-edge microbatteries and flexible batteries with customized form factors. As a path toward rethinking LIB fabrication, we have developed a high-viscosity polymer composite separator slurry that enables the fabrication of both freestanding and direct-on-electrode films. A streamlined phase inversion process is used to impart porosity in cast separator films upon drying. To understand the impacts of material composition and rheology on phase inversion processing and separator performance, we investigated four different separator formulations. We used either diethylene glycol (DEG) or triethyl phosphate (TEP) as a nonsolvent, and either silica (SiO2) or alumina (Al2O3) as an inorganic additive in a polyvinylidene fluoride-co-hexafluoropropylene (PVDF-HFP) matrix. Through a down-selection process, we developed a TEP-SiO2 separator formulation that matched or outperformed a commercial Celgard 2325 (PP/PE/PP) separator and a Beyond Battery ceramic-coated PE (CC/PE/CC) separator under rate and cycle life tests in LiFePO4|Li4Ti5O12 (LFP|LTO) and LiNi0.5Mn0.3Co0.2O2|graphite (NMC-532|graphite) coin cells at C/10-1C rates. Our TEP-SiO2 slurry had a viscosity of 298 Pa s at a 1 s-1 shear rate and shear-thinning behavior. When deposited directly onto an LTO anode and cycled against an LFP cathode, the direct-on-electrode TEP-SiO2 separator increased the specific capacity by 58% and 304% at 2C rates relative to the PP/PE/PP and CC/PE/CC separators, respectively. Additionally, the freestanding TEP-SiO2 separator maintained dimensional stability when heated to 200 °C for 1 h and demonstrated a higher elastic modulus and hardness than the PP/PE/PP and CC/PE/CC separators when measured with nanoindentation.