Composite Gel Polymer Electrolyte Research Articles

Flexible Aluminum-Air Battery Based on High-Performance Three-Dimensional Dual-Network PVA/KC/KOH Composite Gel Polymer Electrolyte.

With a large theoretical capacity and high energy density, aluminum-air batteries are a promising energy storage device. However, the rigid structure and liquid electrolyte of a traditional aluminum-air battery limit its application potential in the field of flexible electronics, and the irreversible corrosion of its anode greatly reduces the battery life. To solve the above problems, a PVA/KC/KOH (2 M) composite gel polymer electrolyte (GPE) with a three-dimensional dual-network structure consisting of polyvinyl alcohol (PVA), kappa-carrageenan (KC), and potassium hydroxide was prepared in this paper by a simple two-step method and applied in aluminum-air batteries. At room temperature, the ionic conductivity of the PVA/KC/KOH (2 M) composite GPE was found to be up to 6.50 × 10-3 S cm-1. By utilizing this composite GPE, a single flexible aluminum-air battery was assembled and achieved a maximum discharge voltage of 1.2 V at 5 mA cm-2, with discharge time exceeding 3 h. Moreover, the single flexible aluminum-air battery maintains good electrochemical performance under various deformation modes, and the output voltage of the battery remains at about 99% after 300 cycles. The construction of flexible aluminum-air batteries based on a three-dimensional dual-network PVA/KC/KOH composite GPE provides excellent safety and high-multiplication capabilities for aluminum-air batteries, making them potential candidates for various flexible device applications.

Multiscale Polyvinylidene Fluoride/Magnesium–Aluminum Layered Double Hydroxide Gel Electrolytes for Lithium Batteries

A multiscale of porous polyvinylidene fluoride–hexafluoropropylene copolymer/magnesium–aluminum layered double hydroxides (MgAl‐LDHs) composite gel polymer electrolyte is prepared by phase separation method. It is discovered that the ionic conductivity of the electrolyte reaches a maximum value of 1.36 × 10−3 S cm−1, the lithium ions’ mobility is 0.66, and the chemical performance is steady within the 4.85 V window along with the concentration of MgAl‐LDHs up to 0.4 wt% at room temperature. The density functional theory calculations show that the adsorption energy of Li+ with MgAl‐LDH is −3.59 eV and the diffusion potential barrier is 0.37 eV, which is favorable for the dissociation and transport of Li+. Moreover, the anode's initial discharge capacity at 0.1 C achieves 144 mAh g−1, keeping 84.7% of the theoretical capacity of 170 mAh g−1, and the capacity retention and the columbic efficiency maintain 92.4% and 95.7% after 100 cycles at 0.2 C, respectively, through assembling into a Li/PVP–MgAl/LiFePO4 battery.

Graphene Oxide Nanoribbon-Based Composite Gel Polymer Electrolytes: Enhancing Mechanical Strength and Ionic Conductivity for Long Cycling Lifetime of Flexible Zinc–Air Batteries

Graphene Oxide Nanoribbon-Based Composite Gel Polymer Electrolytes: Enhancing Mechanical Strength and Ionic Conductivity for Long Cycling Lifetime of Flexible Zinc–Air Batteries

The intermolecular interaction enables ordered ion transport in quasi-solid-state electrolyte for ultra-long life lithium-metal battery

Composite gel polymer electrolytes (CGPEs) have received wide attention due to their great potential to improve the safety and cycling stability of lithium (Li) metal batteries. However, the poor interface compatibility between the filler and polymer in CGPEs severely hinders lithium-ion (Li+) pathways and limits cell performance. Herein, we propose an Al(EtO)3 nanowires framework that can trigger poly (ethylene glycol) diglycidyl ether (PEGDE) to undergo ring opening polymerization, thus inducing polymer tight combination on the surface of Al(EtO)3 nanowires framework and dividing the polymer matrix into mesh units, contributing to ordered Li+ transport and dendrite-free deposition on the metallic anode. Such a CGPE with highly conductive and interface compatibility facilitates a high-performance quasi-solid-state Li||Li cell with an excellent long-term cycling stability for over 3000 h without a short circuit and registers a high capacity of 146.9 mAh g−1 after 46 cycles at a mass loading of 6 mg cm−2. Solid-state nuclear magnetic technology clearly clarifies the transport path of lithium ions in Al(EtO)3-based gel polymer electrolyte (AGPE). The results open up a new way to improve the electrochemical performances of composite electrolyte and promote its commercial application process.

Controlling the Potential of Affordable Quasi‐Solid Composite Gel Polymer Electrolytes for High‐Voltage Lithium‐Ion Batteries

AbstractThis study focuses on the development of a composite gel polymer electrolyte membrane (CGPEM) as a solution to address safety concerns arising from the reactivity of lithium metal and the formation of dendrites. The CGPEM integrates a solid polymer matrix, solid‐electrolyte LSiPS (Li10SiP2S12), with a plasticizer that countering the performance decline caused by sulfide solid electrolyte (SSE) interactions with the cathode. Poly ethylene oxide (PEO) emerges as a promising polymer matrix due to its flexibility, cost‐effectiveness, eco‐friendliness, solvability for Li‐salt, mechanical processing adaptability, adhesive strength, and ionic conductivity. Conductivity and processability of CGPEM were optimized through meticulous adjustment of liquid plasticizer concentration. The CGPEM′s chemical and electrochemical stability were systematically investigated using in‐situ electrochemical impedance spectroscopy (EIS) and distribution of relaxation times (DRTs). A lithium metal battery is constructed against a high voltage cathode and newly developed CGPEM. Impressively, the cell exhibited outstanding performance, maintaining a discharge capacity of around 146.22 mAh/g after 200 cycles, retaining 86.38 % of its initial capacity. The formation of a LiF‐rich interface layer near the lithium surface, a vital element in curbing CGPE degradation and dendritic growth, resulted in enhanced overall cell performance.

A composite gel polymer electrolyte by incorporating modified POSS endowing inorganic-rich SEI formation and stable cycle life for lithium metal batteries

Low density and high theoretical capacity lithium metal anode is an ideal material to replace graphite anode. However, key issues such as the instability of the solid electrolyte intermediate phase (SEI), the degradation of the liquid electrolyte, and the growth of dendrites still hinder its practical application. Here, a composite gel polymer electrolyte with a well Li+ solvated structure was prepared by incorporating PEG-modified POSS. The introduction of modified POSS not only enhanced the structural strength of GPE, but also induced the formation of Li+ solvated sheath structures that dominated by SSIPs/CIPs and AGGs. The well solvated structure of Li+ is beneficial for the generation of stable LiF-rich SEIs to resist the lithium dendrites, improving the anti-oxidation ability of GPE and the cycling performance of the LMBs. Benefiting from the uniform and stable SEIs, the capacity retention rate of the composite GPE-based LiFePO4 full cell can be high up to 95.7 % after 300 cycles at 0.2C and 87.9 % after 400 cycles at 0.5C. This work provides valuable ideas for the study of organic–inorganic composite gel electrolytes.

A composite gel polymer electrolyte for sodium metal battery at a wide temperature range

AbstractSodium‐metal batteries (SMBs) are considered a promising alternative to lithium‐metal batteries due to their high‐energy density, low cost, and good low‐temperature performance. However, the serious side reactions and dendrites growth during the process of sodium ions deposition/stripping are the bottleneck that inhibits the further capitalization of SMBs, especially at low temperatures. Herein, a porous framework of 50 μm thickness composite gel‐polymer‐electrolyte (GPE) supported by polyvinylidene difluoride nanowires membrane and Na3Zr2Si2PO12 ceramic particles is proposed to tackle the issues. This GPE not only has high ionic conductivity but also can promote the uniform transportation of sodium ions to form a stable and dense metal‐GPE interfacial layer, which can effectively inhibit the side reactions and dendrites growth in a wide temperature range. The assembled Na//GPE//Na3V2(PO4)3 full battery provides a specific capacity of 100 mAh g−1 at 10 C for more than 3000 cycles calendar life at room temperature. Moreover, the full battery based on this GPE has an extraordinary performance at low temperatures, reaching a specific capacity of 93 and 61 mAh g−1 at 0.5 and 1 C at −20°C, respectively. This work provides a reliable solution for low‐temperature applications of high‐energy density and long‐cycle life SMBs.

Investigation on the properties of PVDF matrix composite porous gel polymer electrolyte doped with lithium silicon gel

Gel polymer electrolytes are safer because they do not contain liquid phase components. On this basis, the introduction of inorganic fillers effectively overcame the problem of low ionic conductivity of polymer electrolyte at room temperature, and the constructed composite polymer electrolyte (CPEs) combined the advantages of inorganic fillers and polymer segments. In this paper, lithium silicon gel SiO2(Li+) was prepared by in-situ polymerization and sol-gel method, and doped in PVDF composite porous gel polymer electrolyte film prepared by immersion precipitation method. The electrochemical properties and surface topography of lithium iron phosphate were investigated by mounting a bonded lithium iron phosphate quasisolid lithium-ion battery. The experimental results show that the solid electrolyte film modified by SiO2(Li+) has good electrochemical and a certain reference value.

Tailoring composite gel polymer electrolytes with regularly arranged pores and silica particles for sodium metal batteries via breath-figure self-assembly

This study presents a novel method for fabricating composite gel polymer electrolytes through breath-figure self-assembly for Na metal batteries.

Ceramic Composite Gel Polymer Electrolyte for Aqueous Zinc-Ion Battery

As the most extreme application of electrical energy storage devices, lithium-ion batteries (LIBs) not only have the high energy density, but also show long charge/discharge life cycles. Nevertheless, some inherent issues hinder its widespread application, such as the safety problems, lithium metal extrusion, dendrite growth, and the high cost, together with the limited resources of lithium metal. As one of the next-generation batteries, zinc-ion battery (ZIB) is a promising candidate to solve the above problems, due to their high theoretical capacity, low cost, high abundance, low potential, high energy density, and intrinsic safety. Three-types electrolytes, liquid-state, solid-state, and gel-state, are included in ZIBs. The aqueous ZIBs with liquid-state electrolytes are usually considered as ultra-intrinsic batteries. However, various side reactions of dendrite growth, oxygen evolution reaction, hydrogen evolution reaction, and metal Zn corrosion deteriorate the electrochemical reaction of ZIB.Herein, ceramic composite gel polymer electrolytes preparing by electrospinning process were applied to improve the electrochemical properties of ZIB. The gel polymer electrolytes containing amounts of aqueous liquid electrolytes have the activity of water, which can extend the electrochemical stability window and provide good flexibility and H+ insertion/extraction during charge/discharge process for high capacity and good cyclic stability.

An Ultrahigh Modulus Gel Electrolytes Reforming the Growing Pattern of Li Dendrites for Interfacially Stable Lithium-Metal Batteries.

Gel polymer electrolytes (GPEs) have aroused intensive attention for their moderate comprehensive performances in lithium-metal batteries (LMBs). However, GPEs with low elastic moduli of MPa magnitude cannot mechanically regulate the Li deposition, leading to recalcitrant lithium dendrites. Herein, a porous Li7 La3 Zr2 O12 (LLZO) framework (PLF) is employed as an integrated solid filler to address the intrinsic drawback of GPEs. With the incorporation of PLF, the composite GPE exhibits an ultrahigh elastic modulus of GPa magnitude, confronting Li dendrites at a mechanical level and realizing steady polarization at high current densities in Li||Li cells. Benefiting from the compatible interface with anodes, the LFP|PLF@GPE|Li cells deliver excellent rate capability and cycling performance at room temperature. Theoretical models extracted from the topology of solid fillers reveal that the PLF with unique 3D structures can effectively reinforce the gel phase of GPEs at the nanoscale via providing sufficient mechanical support from the load-sensitive direction. Numerical models are further developed to reproduce the multiphysical procedure of dendrite propagation and give insights into predicting the failure modes of LMBs. This work quantitatively clarifies the relationship between the topology of solid fillers and the interface stability of GPEs, providing guidelines for designing mechanically reliable GPEs for LMBs.

Bifunctional TiO2−x nanofibers enhanced gel polymer electrolyte for high performance lithium metal batteries

Exploration of advanced gel polymer electrolytes (GPEs) represents a viable strategy for mitigating dendritic lithium (Li) growth, which is crucial in ensuring the safe operation of high energy density Li metal batteries (LMBs). Despite this, the application of GPEs is still hindered by inadequate ionic conductivity, low Li+ transference number, and subpar physicochemical properties. Herein, TiO2−x nanofibers (NF) with oxygen vacancy defects were synthesized by a one-step process as inorganic fillers to enhance the thermal/mechanical/ionic-transportation performances of composite GPEs. Various characterizations and theoretical calculations reveal that the oxygen vacancies on the surface of TiO2−x NF accelerate the dissociation of LiPF6, promote the rapid transfer of free Li+, and influence the formation of LiF-enriched solid electrolyte interphase. Consequently, the composite GPEs demonstrate enhanced ionic conductivity (1.90 mS cm−1 at room temperature), higher lithium-ion transference number (0.70), wider electrochemical stability window (5.50 V), superior mechanical strength, excellent thermal stability (210 °C), and improved compatibility with lithium, resulting in superior cycling stability and rate performance in both Li||Li, Li||LiFePO4, and Li||LiNi0.8Co0.1Mn0.1O2 cells. Overall, the synergistic influence of nanofiber morphology and enriched oxygen vacancy structure of fillers on electrochemical properties of composite GPEs is comprehensively investigated, thus, it is anticipated to shed new light on designing high-performance GPEs LMBs.

3D hierarchical fireproof gel polymer electrolyte towards high-performance and comprehensive safety lithium-ion batteries

Gel polymer electrolyte (GPE) stands as an extensively investigated solid-state electrolytes for next-generation lithium-ion batteries (LIBs). Nonetheless, their inherent flammability necessitates the addition of flame retardants, which adversely impact LIBs’ electrochemical performance. Herein, we propose a groundbreaking conceive of a fireproof cross-linking composite GPE that united phosphene and a P-N synergistic flame retardant (DPM), equipping a dual-enhanced conduction effect on Li+ ions and a cooperative P-N flame-retardant effect. By strategically manipulating the polymer segments hierarchy and incorporating efficient function groups from DPM, freely Li+ mobility has been propelled, thereby delivering satisfactory ionic conductivity (1.263 mS cm−1, 20 ℃), elevated oxidative stability (5.42 V vs. Li+/Li) and improved Li+ transference number (0.53). The composite GPE-based batteries (LFP||Li, NCM523||Li and LFP||Graphite) indicate acceptable specific capacities at 1 C, together with good reversible capacity retention rate and stable coulombic efficiency after 200 cycles. Noticeably, the pouch cells (LFP||Graphite) assembled with composite GPE demonstrate superior safety robustness and fire-resistance under mechanical mishandling and ignition situations. Finally, the elucidation of Li+ ions interaction mechanism with polymer matrix is unraveled through molecular orbital energy levels and density function theory (DFT) calculation. This study offers valuable insights for harnessing novel electrolyte materials in high-safety LIBs.

Lithiated Phosphoryl Cellulose Nanocrystals Enhance Cycling Stability and Safety of Quasi-Solid-State Lithium Metal Batteries.

Cycling stability and safety are two of the main challenges facing lithium metal batteries with metallic lithium as anodes. Quasi-solid-state lithium metal batteries based on gel polymer electrolytes are one of the important development directions for lithium metal batteries addressing those challenges. Herein, we prepare lithiated phosphoryl cellulose nanocrystals (PCNC-Li) as a modification material for poly(vinylidene fluoride) (PVDF) gel polymer electrolyte to improve cycling stability and safety of quasi-solid-state lithium metal batteries. The synthesized PCNC-Li tends to form a uniform network structure on the surface of the PVDF membrane, in which the phosphoryl groups grafted regularly on celluloses can regulate the transport of lithium ions. As a result, a more uniform ion flux and more stable lithium anode interface support an obviously improved cycling stability for lithium metal batteries. Moreover, the introduction of the PCNC-Li coating layer makes the modified PVDF membranes have a better thermal stability and an enhanced mechanical strength, which is beneficial for improvement of safety of lithium metal batteries. This work provides a new alternative to fabricating a better composite gel polymer electrolyte for lithium metal batteries.

A new type of LATP doped PVDF-HFP based electrolyte membrane with flame retardancy and long cycle stability for solid state batteries

Lithium ion batteries are a widely used high-density energy storage device due to their low self-discharge rate and lack of memory effect. However, their use in liquid electrolyte systems poses a significant safety risk due to issues such as lithium dendrite growth and toxic electrolytes that are also prone to leakage. Therefore, the development of gel polymer electrolytes (GPE) with high ionic conductivity and elevated lithium ion migration numbers is crucial to addressing these concerns. This work focuses on the preparation of flexible microporous composite gel polymer electrolytes (L-GPE) based on Polyvinylidene fluoride-Hexafluoropropylene (PVDF-HFP) and Li1.3Al0.3Ti1.7P3O12 (LATP) as a filler and on testing its performance as an electrolyte in applications of lithium ion battery. The L-GPE demonstrated an ionic conductivity of 8.13 × 10−4 S·cm−1 at 40 °C, with a lithium ion mobility number of 0.58, indicating high ionic mobility. Notably, in all-solid-state lithium ion battery applications, the L-GPE demonstrated excellent long-cycle stability, with a capacity retention of 90.3 % after 1000 cycles at 0.5C. These results demonstrate that the interaction force between LATP and anions enhances lithium ion mobility in composite gel polymer electrolytes, which is favorable for the regulation of lithium ion deposition and the control of lithium dendrite growth. Besides, the performance of this L-GPE membrane is significantly improved due to its suitable porosity, gratifying mechanical properties, and excellent flame retardancy. In summary, this strategy provides a valuable contribution to the development of safe and long-lasting energy storage systems by presenting a novel L-GPE membrane with enhanced mechanical, high ionic conductivity, excellent flame retardant property and thermal stability.

PMMA-Based Composite Gel Polymer Electrolyte with Plastic Crystal Adopted for High-Performance Solid ECDs.

A PMMA-based gel polymer electrolyte (GPE) modified by a plastic crystal succinonitrile (SN) was synthesized using a facile solvent-casting method. The effects of SN additives upon lithium-ion dissociation and ionic conductivity were investigated primarily using Fourier transform infrared spectroscopy and electrochemical impedance spectroscopy, accompanied by other structural characterization methods. The results show that SN is distributed uniformly in the PMMA matrix with a high content and produces vast dipoles that benefit the dissociation of lithium salt. Hence, the SN-modified GPE (SN-GPE) achieves an excellent ionic conductivity of 2.02 mS·cm-1 and good mechanical properties. The quasi-solid-state ECD fabricated using the SN-GPE exhibits stable cyclability and excellent electrochromic performance, in which the bleaching/coloration response time is 10 s/30 s. These results add significant insight into understanding the inter- and intra-molecular interaction in SN-GPEs and provide a type of practicable high-performance GPE material for solid electrochromic devices.

Glass Fiber Reinforced Epoxy-Amine Thermosets and Solvate IL: Towards New Composite Polymer Electrolytes for Lithium Battery Applications.

To effectively use (Li) lithium metal anodes, it is becoming increasingly necessary to create membranes with high lithium conductivity, electrochemical and thermal stabilities, as well as adequate mechanical properties. Composite gel polymer electrolytes (CGPE) have emerged as a promising strategy, offering improved ionic conductivity and structural performance compared to polymer electrolytes. In this study, a simple and scalable approach was developed to fabricate a crosslinked polyethylene oxide (PEO)-based membrane, comprising two different glass fiber reinforcements, in terms of morphology and thickness. The incorporation of a solvated ionic liquid into the developed membrane enhances the ionic conductivity and reduces flammability in the resulting CGPE. Galvanostatic cycling experiments demonstrate favorable performance of the composite membrane in symmetric Li cells. Furthermore, the CGPE demonstrated electrochemical stability, enabling the cell to cycle continuously for more than 700 h at a temperature of 40 °C without short circuits. When applied in a half-cell configuration with lithium iron phosphate (LFP) cathodes, the composite membrane enabled cycling at different current densities, achieving a discharge capacity of 144 mAh·g-1. Overall, the findings obtained in this work highlight the potential of crosslinked PEO-based composite membranes for high-performance Li metal anodes, with enhanced near room temperature conductivity, electrochemical stability, and cycling capability.

Stable quasi-solid-state lithium-organic battery based on composite gel polymer electrolyte and compatible organic cathode material

High-performance organic small-molecule electrode materials are troubled with their high solubility in liquid electrolytes. The construction of quasi-solid-state lithium organic batteries (LOBs) using gel polymer electrolytes with high mechanical properties, compromised ionic conductivity, high safety, and eco-friendly is an effective way to inhibit the dissolution of active materials. Herein, two hexaazatriphenylene (HATN)-based organic cathode materials (HATNA-6OCH3 and HATNA-6OH) are synthesized and then matched with polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP)-based gel polymer electrolytes to construct quasi-solid-state LOBs. Thanks to the enhanced interfacial compatibility between organic cathode material and gel polymer electrolyte, HATNA-6OH with compatible hydroxyl group shows the enhanced electrochemical properties compared with HATNA-6OCH3. Further, the electrochemical performance is improved when HATNA-6OH is combined with a gel polymer electrolyte modified with a succinonitrile (SN) plasticizer (GPE-0.4SN), including a high specific capacity of 153.3 mAh g−1 at 50 mA g−1 and a good reversible capacity of 88 mAh g−1 after 100 cycles at 200 mA g−1. In addition, the good electrochemical properties and lithium-ion storage mechanism of HATNA-6OH have been elucidated using density functional theory (DFT) and spectral characterizations.

Preparation of Antioxidative MXene by Deep Eutectic Solvent-Assisted Electrochemical Ultrasonic Composite Exfoliation and Its Application in Flexible Solid-State Supercapacitors

In this work, we achieved a novel preparation of Ti3C2 MXene (MXene–DES) with few layers and a high degree of hydroxylation by a deep eutectic solvent (DES)-assisted electrochemical ultrasonic composite exfoliation method which is easy to scale up. The electrochemical process used a mixture of low-cost DES (choline chloride–urea) and water as the electrolyte, in which DES acts as a triple role of intercalation, interlayer expansion, and anti-oxidation. DES attached to the surface and interlayer of layered Ti3C2 formed an antioxidative protective cover, resulting in the layered Ti3C2 being grafted with hydroxyl functional groups instead of forming TiO2 in water during the entire exfoliation process. The prepared MXene–DES exhibits fewer layers, larger interlayer spacing, higher degree of hydroxylation, and stronger oxidation resistance than the MXene prepared by traditional ultrasound in a nitrogen atmosphere (MXene–N2). The symmetric flexible solid-state supercapacitor based on an activated carbon electrode and the composite gel polymer electrolyte composed of MXene–DES, DES, and polyvinyl alcohol exhibits good mechanical properties, a wide voltage window of 2.3 V, and a high specific capacitance of 133.7 F·g–1 (0.1 A·g–1). Our strategy paved a simple, low-cost, and relatively environmentally friendly way to the scalable preparation and application of antioxidative high-quality MXene.

Inorganic Filler Enhanced Formation of Stable Inorganic‐Rich Solid Electrolyte Interphase for High Performance Lithium Metal Batteries

AbstractLithium metal (LM) is a promising anode material for next generation lithium ion based electrochemical energy storage devices. Critical issues of unstable solid electrolyte interphases (SEIs) and dendrite growth however still impede its practical applications. Herein, a composite gel polymer electrolyte (GPE), formed through in situ polymerization of pentaerythritol tetraacrylate with fumed silica fillers, is developed to achieve high performance lithium metal batteries (LMBs). As evidenced theoretically and experimentally, the presence of SiO2not only accelerates Li+transport but also regulates Li+solvation sheath structures, thus facilitating fast kinetics and formation of stable LiF‐rich interphase and achieving uniform Li depositions to suppress Li dendrite growth. The composite GPE‐based Li||Cu half‐cells and Li||Li symmetrical cells display high Coulombic efficiency (CE) of 90.3% after 450 cycles and maintain stability over 960 h at 3 mA cm−2and 3 mAh cm−2, respectively. In addition, Li||LiFePO4full‐cells with a LM anode of limited Li supply of 4 mAh cm−2achieve capacity retention of 68.5% after 700 cycles at 0.5 C (1 C = 170 mA g−1). Especially, when further applied in anode‐free LMBs, the carbon cloth||LiFePO4full‐cell exhibits excellent cycling stability with an average CE of 99.94% and capacity retention of 90.3% at the 160th cycle at 0.5 C.