Quasi-solid Gel Research Articles

Polymer-Ion Interaction Prompted Quasi-Solid Electrolyte for Room-Temperature High-Performance Lithium-Ion Batteries.

Lithium-ion batteries using quasi-solid gel electrolytes (QSEs) have gained increasing interest due to their enhanced safety features. However, their commercial viability is hindered by low ionic conductivity and poor solid-solid contact interfaces. In this study, a QSE synthesized by in situ polymerizing methyl methacrylate (MMA) in 1,2-dimethoxyethane (DME)-based electrolyte is introduced, which exhibits remarkable performance in high-loading graphite||LiNi0.8Co0.1Mn0.1O2 (NCM811) pouch cells. Owing to the unique solvent-lacking solvation structure, the graphite exfoliation caused by the well-known solvent co-intercalation is prohibited, and this unprecedented phenomenon is found to be universal for other graphite-unfriendly solvents. The high ionic conductivity and great interfacial contact provided by DME enable the quasi-solid graphite||NCM811 pouch cell to demonstrate superior C-rate capability even at a high cathode mass loading (17.5mgcm-2), surpassing liquid carbonate electrolyte cells. Meanwhile, the optimized QSE based on carbonates exhibits excellent cycle life (92.4% capacity retention after 1700 cycles at 0.5C/0.5C) and reliable safety under harsh conditions. It also outperforms liquid electrolytes in other high-energy-density batteries with larger volume change. These findings elucidate the polymer's pivotal role in QSEs, offering new insights for advancing quasi-solid-state battery commercialization.

In Situ Integration of a Flame Retardant Quasisolid Gel Polymer Electrolyte with a Si-Based Anode for High-Energy Li-Ion Batteries.

Silicon (Si) stands out as a promising high-capacity anode material for high-energy Li-ion batteries. However, a drastic volume change of Si during cycling leads to the electrode structure collapse and interfacial stability degradation. Herein, a multifunctional quasisolid gel polymer electrolyte (QSGPE) is designed, which is synthesized through the in situ polymerization of methylene bis(acrylamide) with silica-nanoresin composed of nanosilica and a trifunctional cross-linker in cells, leading to the creation of a "breathing" three-dimensional elastic Li-ion conducting framework that seamlessly integrates an electrode, a binder, and an electrolyte. The silicon particles within the anode are encapsulated by buffering the QSGPE after cross-linking polymerization, which synergistically interacts with the existing PAA binder to reinforce the electrode structure and stabilize the interface. In addition, the formation of the LiF- and Li3N-rich SEI layer further improves the interfacial property. The QSGPE demonstrates a wide electrochemical window until 5.5 V, good flame retardancy, high ionic conductivity (1.13 × 10-3 S cm-1), and a Li+ transference number of 0.649. The advanced QSGPE and cell design endow both nano- and submicrosized silicon (smSi) anodes with high initial Coulombic efficiencies over 88.0% and impressive cycling stability up to 600 cycles at 1 A g-1. Furthermore, the NCM811//Si cell achieves capacity retention of ca. 82% after 100 cycles at 0.5 A g-1. This work provides an effective strategy for extending the cycling life of the Si anode and constructing an integrated cell structure by in situ polymerization of the quasisolid gel polymer electrolyte.

A quasi-solid polymer electrolyte initiated by two-dimensional functional nanosheets for stable lithium metal batteries.

Lithium-metal batteries (LMBs) are expected to serve as next-generation energy storage systems due to their high theoretical energy density. However, their practical application is largely impeded due to the safety risks that arise from the uncontrollable Li dendrite growth and the high reactivity between high flammability liquid organic electrolytes and metallic lithium. Here, we report a highly safe quasi-solid gel polymer electrolyte (GPE) to achieve stable cycling of lithium metal with high coulombic efficiency, and it is prepared by in situ polymerization of 1,3-dioxolane (DOL) assisted by multi-functional H3Sb3P2O14 sheets. H3Sb3P2O14 acts as an initiator and a functional additive simultaneously that promotes the formation of a stable solid electrolyte interface (SEI) layer, thereby regulating the uniform deposition of Li and improving the Li plating/stripping efficiency. The obtained quasi-solid GPE exhibits high ionic conductivity and enhanced oxidative stability, favoring a stabilized electrode/electrolyte interface. Using the GPE, the electrochemical performance of the quasi-solid-state LMB with a LiFePO4 cathode and a lithium metal anode is significantly improved, delivering a discharge capacity of 125.7 mA h g-1 even after 1000 cycles. Therefore, the high reversibility and remarkable battery cyclability suggest that such a GPE is a promising choice of electrolyte for LMBs, while its facile preparation makes its large-scale application possible in the future.

In situ cross-linked plastic crystal electrolytes toward superior lithium metal batteries

The low ionic conductivity and unstable electrolyte/electrode interface of solid-state electrolytes are the key issues hindering the progress of solid-state lithium batteries. Herein, a cross-linked succinonitrile (SN)-based solid-state electrolyte was synthesized by in situ thermal polymerization using polyethylene glycol diacrylate, vinyl carbonate, and SN. Vinyl carbonate and polyethylene glycol diacrylate are cross-linked to form a polymer network structure, which can immobilize SN and lithium difluoro(oxalato)borate in the electrolyte, thereby preventing the side reactions of SN and lithium metal. The as-prepared quasi-solid gel electrolyte exhibits a wide electrochemical window (5.3 V vs. Li+/Li), a high ionic conductivity (0.3 mS/cm), a good lithium-ion transfer number (0.58) at room temperature, and good interfacial stability between the electrodes and electrolyte. Therefore, cross-linked SN-based polymer electrolyte not only enables reversible lithium anode stripping/plating and impedes side reactions on the anode side but also accommodates high voltage cathode materials. The LiCoO2/Li cell shows a high specific capacity of 140 mAh/g, with a capacity retention rate of 87.2% after 350 cycles and a stable coulombic efficiency of about 99.5% at an operating voltage of 2.75∼4.3 V. This work paves a new path for designing high-safety electrolytes and facilitating the practical application of high-voltage lithium metal batteries.

A roadmap for hydrogel-based quasi-solid electrolyte preparation for use in dye-sensitized solar cell

Although the use of quasi-solid electrolytes in dye-sensitized solar cells (DSSCs) is viewed as a solution to the stability problem of DSSCs, the network structure effect on the DSSCs’ performance has not been studied in detail. Structurally different hydrogels poly (2-methacryloyloxyethyl trimethylammonium chloride-co-acrylic acid) were prepared and used as quasi-solid gel electrolytes in DSSCs to investigate the network structure effect of hydrogels on DSSC performance. The hydrogel's network structure was changed using different amounts of cross-linkers during synthesis. Five quasi-solid electrolytes were prepared from the hydrogels. The increased cross-linking of quasi-solid electrolytes during synthesis raised conductivity from 0.102 to 0.144 S m−1. Despite expectations, it was observed that the energy conversion efficiency of DSSCs does not follow the rising trend in conductivity, as it rises from 6.57% to 6.62% and then decreases to 5.17%, with increased cross-linking. Moreover, cross-linking during hydrogel synthesis defines not only the electrical properties of quasi-solid electrolytes but also the swelling, wetting, and morphological properties of the structure. Therefore, this study aimed to investigate how and which parameters affect the energy conversion efficiency of DSSCs that are prepared with quasi-solid electrolytes.

All 3D Printing Shape‐Conformable Zinc Ion Hybrid Capacitors with Ultrahigh Areal Capacitance and Improved Cycle Life (Adv. Energy Mater. 27/2022)

Zinc-Ion Hybrid Capacitors In article number 2200341, Shuanghao Zheng, Zhong-Shuai Wu and co-workers demonstrate a new strategy for the fabrication of shape-conformable and all-3D-printed zinc-ion hybrid capacitors, including hierarchically porous micro-lattice cathodes, metal anode stabilizers, quasi-solid gel electrolytes and plastic packages. This strategy provides a general and innovative methodology for constructing custom-shape electrochemical energy storage devices with satisfactory electrochemical performance.

All 3D Printing Shape‐Conformable Zinc Ion Hybrid Capacitors with Ultrahigh Areal Capacitance and Improved Cycle Life

AbstractAqueous zinc ion hybrid capacitors (ZIHCs) with notable advantages like cost‐effectiveness and safety are promising new‐generation electrochemical energy storage devices (EESDs). However, unsatisfactory areal capacitance, zinc dendrites, and rigid form factor of typical aqueous ZIHCs impede their further practical applications. Herein, a protocol is developed for 3D‐printing shape‐conformable ZIHCs, including hierarchically porous microlattice cathode, metal anode stabilizer, quasisolid gel electrolyte, and plastic packages, through direct ink writing and fused deposition modeling methods. Among these components, microlattice cathodes with a high mass loading density of 22.8 mg cm−2 effectively improve the areal capacitance of ZIHCs, and the metal anode stabilizer sufficiently inhibits dendritic growth to prolong the cycle life of ZIHCs. As a result, the obtained all 3D‐printed ZIHCs deliver a high areal capacitance of 4259 mF cm−2 as well as a considerable energy density of 1514 μWh cm−2, surpassing most reported ZIHCs. The 3D‐printed metal anode stabilizer endows ZIHCs with better cycling stability with almost no capacitance loss after 10 000 cycles. Impressively, the ZIHCs can easily be manufactured into shape‐conformable devices encapsulated by 3D‐printed polylactic acid package, demonstrating their viability. Therefore, this all 3D‐printing strategy provides a general and innovative methodology for constructing customized EESDs.

Self-assembly of two-dimensional supramolecular as flame-retardant electrode for lithium-ion battery

Owing to natural abundance, economic efficiency, and easy design of the molecular structure, organic polymer materials have caught much attention in the fields of electronics, separation, catalysis, and etc. However, low fire safety is the main obstacle for their applications. Herein, a novel phosphorus-rich and nitrogen-rich organic polymer material (MAPA) is prepared for the first time by supramolecular self-assembly with natural phytic acid as phosphorus precursor and melamine as nitrogen precursor. When MAPA is used as an anode for lithium-ion batteries (LIBs), it shows excellent specific capacity and stability. Specifically, at a current density of 0.1 A g−1 an initial capacity of 570 mA h g−1 and 397 mA h g−1 after 600 cycles are achieved, which is attributed to the abundant functional groups such as phosphate and π bonds of MAPA. Furthermore, the flame-retardant properties of MAPA are evaluated in two kinds of commonly used electrolytes, the ethylene carbonate and dimethyl carbonate (1: 1 vol, ECDC) for LIBs and the quasi-solid gel electrolyte of solid supercapacitor (polyvinyl alcohol, PVA). Both the ECDC/MAPA obtained through ultrasound sonication technology and the PVA/MAPA obtained through electrospinning technology exhibit excellent flame-retardant property. Notably, the peak heat release rate (pHRR) and total heat release (THR) values of ECDC/10% MAPA reduce to 31.2% and 44.8% of those for pure ECDC, respectively. And the pHRR and THR values of MAPA/15% PVA reduce to 57.4% and 75.6%, respectivly, and the char residues increases to 21% from 6%.

Polyvinyl Alcohol-Based Gel Electrolytes with High Water Content for Flexible Zinc-Air Batteries with High Rate Capability

Due to the fast development of consumer electronics and wearable devices, demand for safe and light batteries is soaring. Flexible zinc-air batteries using quasi-solid gel electrolytes are considered a potential candidate because of their high energy density, long-term durability and safety. In this work, spinel NiCo2O4 is employed as the bifunctional catalyst for fabricating flexible zinc-air batteries. Electrochemical measurements in both the three-electrode and full-cell configurations indicate a good bifunctionality for both the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). The flexible zinc-air batteries are assembled using a gel electrolyte consisting of polyvinyl alcohol (PVA) and 6 M KOH. A simple method for preparing the gel electrolyte is reported to maintain a high water content within the gel, which is the key factor facilitating the high discharge rate of flexible zinc-air batteries. The optimal flexible battery can be discharged at a large current density of 50 mA cm−2 for 5 min and reaches a capacity of 37 mAh cm−2 and a maximum power density of 64 mW cm−2. The origin of the decayed charge/discharge behavior and cell failure is investigated by the three-electrode chronopotentiometry and post-mortem X-ray diffraction (XRD) analysis. ZnO precipitation is considered the main reason for the decay of both zinc and air electrodes. The good flexibility during cycling is also demonstrated by a continuous bending test, revealing its potential for practical applications.

A quasi-solid composite separator with high ductility for safe and high-performance lithium-ion batteries

The safety of lithium ion batteries is correlated closely to the mechanical property and thermal stability of separators. The polymer/ceramic particle composite separators are widely investigated for quasi-solid gel separators of lithium ion batteries, but the nonuniform dispersion of ceramic particles limits their performance. In this study, ball-milled Al-doped Li6.75La3Zr1.75Ta0.25O12 suspension is incorporated into poly (vinylidene fluoride-co-hexafluoropropylene) gel to prepare a highly uniform quasi-solid composite separator. The results show that adding only 4.29 wt% Li6.75La3Zr1.75Ta0.25O12 into PVDF-HFP increases ductility by three times and the mechanical strength by 38% as compared with pure PVDF-HFP separator. Batteries with the composite separator show significantly improved cyclic stability and rate performance at both room temperature and temperatures up to 80 °C. In particular, the composite separator promotes homogenous Li+ flux through the separator and suppresses Li dendrite growth in Li-metal based batteries.

A promising hybrid graphite counter electrode doped with fumed silica nano-spacers for efficient quasi-solid state dye sensitized solar cells

Preparation of low-cost electrocatalytic counter electrode (CE) at low temperature is desired in the fabrication of photo-electrochemical quasi-solid state dye-sensitized solar cell (Qs-DSSC). We present facile doping of fumed silica (SiO2) as mesoporous nano-spacers in cationically functionalized graphite network and its synthesis into an electrically conductive hybrid paste for Qs-DSSC CEs. Polyethylene oxide (3%) based electrolyte solution is used as a quasi-solid gel electrolyte. With an optimized quantity of fumed silica nano-spacers (10%), an increase of 53.6% is achieved in power conversion efficiency (PCE) compared to bare cationised graphite coated CE. Our suggested Si@G 10% CE demonstrates commendable power conversion efficiency of 6.42% compared to 7.32% with expensive platinum (Pt) based Qs-DSSC. It exhibits a low charge transfer resistance (RCT) of 0.61 Ω cm2, owing to the improved interconnection, formation of the porous structure, and enhanced mobility of electrolyte ions. The cyclic voltammetry (CV) shows excellent electro-catalytic activity towards the I−/I3− redox couple and it is stable up to 50 cycles at a scan rate of 10 mV s−1. The facile synthesis route, excellent electro-catalytic activity, appreciable stability, and considerable photovoltaic performance makes Si@G 10% based CE a promising candidate for Qs-DSSC fabrication.

A flexible lithium-ion battery with quasi-solid gel electrolyte for storing pulsed energy generated by triboelectric nanogenerator

Sustainable operation of flexible and wearable electronic devices is possible with energy harvested from environment, but such power could be in the form of pulses with varying amplitude and frequency. In this work, we prepared quasi-solid lithium-ion batteries (LIBs) for storing the energy generated by a triboelectric nanogenerator (TENG). The lithium-ion batteries composed of a gel electrolyte, LiFePO4 cathode and metallic lithium anode can deliver a capacity of ~ 140mAhg−1 at 0.2 C rate and ~ 120mAhg−1 at 1 C rate. A flexible pouch cell was further fabricated with this quasi-solid electrolyte, which shows good flexibility, high mechanical strength and excellent safety against the nail puncture. The flexible LIB was used to store the pulse form energy harvested by a TENG to provide more stable power output sustainably. The quasi-solid LIB can be charged by TENG directly for three times with a capacity loss of 17%. Importantly, a power management unit (PMU) was designed to make the output of TENG to be more suitable for charging the flexible LIBs. Our results show that this PMU is beneficial for decreasing the output voltage of TENGs, thus improving the cyclability of the cell, which may be utilized in various systems consisting of different batteries and TENGs.

Gel Electrolytes with Polyamidopyridine Dendron Modified Talc for Dye-Sensitized Solar Cells.

Organic-inorganic hybrid layered materials are proposed as additives in a quasi-solid gel electrolyte for dye-sensitized solar cells. Talcs could provide a low-cost and environmentally friendly, as well as abundant, option as gelators. Here, talcs were prepared by functionalizing an organotalc with three polyamidopyridine dendron generations, PAMPy-talc-Gn (n = 1, 2 and 3). PAMPy dendrons grow parallel to the lamellae plane and form an organized structure by intermolecular interactions. In addition, polyiodide-dendron charge-transfer complexes were prepared onto the organotalc by adsorption of iodine. In this work, the effect of the dendron generation of PAMPy-talc and the influence of polyiodide intercalation on solar cell performance and stability were investigated. The best results were reached with the use of lowest-generation PAMPy-talc (η = 4.5 ± 0.3%, VOC = 710 ± 19 mV, Jsc = 10.4 ± 0.9 mA cm-2, and FF = 61 ± 2%): 15% higher efficiency compared to similar liquid devices. While some previously studied talcs illustrate very strong absorption of the iodide from the electrolyte, in the case of PAMPy-talc such interfering effects were absent: In a 1000 h light soaking test, the PAMPy-talc cells both with and without polyiodide intercalation demonstrated stable performances. Furthermore, the color analysis of the electrolyte indicated that the color of the electrolyte remained stable after an initial period of stabilization, which is a good indication of the compound being stable and not absorbing charge carriers from the electrolyte. The performance and stability results indicate that PAMPy-talc has potential as a gelling method for electrolytes for dye solar cells.

Ternary natural deep eutectic solvent (NADES) infused phthaloyl starch as cost efficient quasi-solid gel polymer electrolyte

A first-of-its-kind, eco-friendly quasi-solid bioelectrolyte derived from potato starch was prepared. Starch was chemically modified via phthaloylation to synthesize amorphous, hydrophobic starch derivative and the attachment of the phthaloyl group was confirmed via FTIR which showed phthalate ester peak at 1715cm−1; and 1H NMR peaks between 7.30–7.90ppm attributed to the aromatic protons of the phthaloyl group. The resulting starch derivative was then infused with ternary natural deep eutectic solvent (NADES) made from different molar ratios of choline chloride, urea and glycerol. Electrochemical Impedance Spectroscopy (EIS) revealed that the highest ionic conductivity was obtained by the system consisting of NADES with choline chloride:urea:glycerol in molar ratios of 4:6:2, with a magnitude of 2.86mScm−1, hence validating the prospects of the materials to be further experimented as an alternative electrolyte in various electrochemical devices.

An imidazolium iodide–containing hyperbranched polymer ionic liquid that improves the performance of dye-sensitized solar cells

In this study, we synthesized an imidazolium iodide–containing hyperbranched polymer ionic liquid (HPIL) for use as the gel electrolyte of dye-sensitized solar cells (DSSCs). We incorporated HPIL at various contents (4, 8, and 15 wt%) in a solvent-free ionic liquid (1-propyl-2,3-dimethylimidazolium iodide and 1-ethyl-3-methylimidazolium tetrafluoroborate)–based quasi-solid gel electrolyte (IL-A) and a solvent (3-methoxypropionitrile)-based fluid gel electrolyte (IL-B). After fabricating N719 dye–based DSSCs incorporating the HPIL/IL-A and HPIL/IL-B gel electrolytes, we recorded the electrochemical impedance spectra and measured the photovoltaic (PV) performance of these devices. In the dark, the DSSCs incorporating HPIL exhibited higher charge recombination resistances at the interface between TiO2/dye and the electrolyte. This high recombination resistance suppressed the dark current and improved the PV performance of the devices incorporating HPIL. The DSSCs fabricated from the HPIL/IL-B gel electrolyte displayed higher photo-conversion efficiency, while those fabricated from the HPIL/IL-A gel electrolyte provided superior operational stability. Under AM 1.5 illumination (100 mW cm−2), we measured a photo-conversion efficiency of 7.18 %, a short-circuit current density of 16.09 mA cm−2, an open-circuit voltage of 0.69 V, and a fill factor of 0.65 for the DSSC incorporating the gel electrolyte HPIL/IL-B (4:96, w/w). The DSSC incorporating the gel electrolyte HPIL/IL-A (15:85, w/w) exhibited good operational stability, retaining approximately 93 % of its original efficiency after 500 h.

A Quasi-Solid State DSSC with 10.1% Efficiency through Molecular Design of the Charge-Separation and -Transport.

Organic-based solar cells potentially offer a photovoltaic module with low production costs and low hazard risk of the components. We report organic dye-sensitized solar cells, fabricated with molecular designed indoline dyes in conjunction with highly reactive but robust nitroxide radical molecules as redox mediator in a quasi-solid gel form of the electrolyte. The cells achieve conversion efficiencies of 10.1% at 1 sun, and maintain the output performance even under interior lighting. The indoline dyes, customized by introducing long alkyl chains, specifically interact with the radical mediator to suppress a charge-recombination process at the dye interface. The radical mediator also facilitates the charge-transport with remarkably high electron self-exchange rate even in the quasi-solid state electrolyte to lead to a high fill factor.

Crystallization and assembling of FAU nanozeolites on porous ceramic supports for zeolite membrane synthesis

In this study, a novel route for preparing nanocrystalline porous FAU layers s stably supported on porous α-Al2O3 tubular substrates is reported. A highly reactive sodium hydroxide rich hydrogel was used to promote the nucleation process on the support surface. After 24 h of treatment at near ambient condition, a heavily nucleated quasi-solid gel layer containing nanozeolite precursor species was first formed on the support surface. This matrix was used as starting material for the synthesis of nanozeolite-based membranes. The support coated with the extensively nucleated gel phase was isolated and cured at higher temperature in different conditions. A rapid and diffuse crystallization was observed by treating the gel matrix with a synthesis solution of lower alkalinity, leading to the formation of a dense nanocrystalline FAU layer firmly adhered to the substrate surface. The FAU layers (Si/Al ratio of ca. 2) have a thickness of ca. 2 μm and are constituted by closely packed, well intergrown nanocrystals (crystallite dimension of ca. 20–30 nm). The results of this study indicate that supersaturation as well as the elevate amount of sodium ions synergistically contribute to induce the assembling of soluble aluminosilicate species on the support surface and to effectively promote the heterogeneous nucleation process.

Exceptionally stable and hierarchically porous self-standing zeolite monolith based on a solution-mediated and solid-state transformation synergistic mechanism

Although many strategies exist for fabricating hierarchical zeolite monolith, it is still challenging to synthesize pure hierarchical zeolite monolith with intracrystalline meso-/macropores and stability suitable for industrial application in a general and efficient process. Here we describe a simple quasi-solid gel crystallization route to prepare hierarchical self-standing ZSM-5 zeolite monolith via the use of Na+ and OH− as counterions to modify the breaking and remaking of T–O–T (T = Si or Al) bonds. X-ray diffraction (XRD), scanning electron microcopy (SEM), transmission electron microscopy (TEM), laser scan confocal microscopy (LSCM), N2 adsorption–desorption, mercury porosimetry, solid-state nuclear magnetic resonance (NMR), and compression mechanical testing were applied to elucidate the structure and mechanical stability of the obtained monolith. The self-standing monolith is composed of self-interconnected meso-/macroporous MFI crystals with tunable intracrystalline meso-/macropores and possesses an unusually mechanical stability with a crushing strength of 5.01 MPa. Combined with controllable structure of the defect-free membrane layer on the monolith top, the self-standing zeolite monolith should widen their potential applications.

An efficient quasi solid state dye sensitized solar cell based on polyethylene glycol/graphene nanosheet gel electrolytes

A poly(ethylene glycol)/graphene nanosheet quasi solid gel electrolyte was synthesized using an in situ polymerization technique for dye-sensitized solar cells (DSSCs).

Highly efficient photochemical upconversion in a quasi-solid organogel

Photochemical upconversion in a quasi-solid gel proceeds with an identical efficiency to an otherwise identical liquid composition.