Bacterial Cellulose/Zwitterionic Dual-network Porous Gel Polymer Electrolytes with High Ionic Conductivity

Bacterial cellulose(BC)was innovatively combined with zwitterionic copolymer acrylamide and sulfobetaine methacrylic acid ester[P(AM-co-SBMA)]to build a dual-network porous structure gel polymer electrolytes(GPEs)with high ionic conductivity.The dual network structure BC/P(AM-co-SBMA)gels were formed by a simple one-step polymerization method.The results show that ionic conductivity of BC/P(AM-co-SBMA)GPEs at the room temperature are 3.2×10^(-2) S/cm@1 M H_(2)SO_(4),4.5×10^(-2) S/cm@4 M KOH,and 3.6×10^(-2) S/cm@1 M NaCl,respectively.Using active carbon(AC)as the electrodes,BC/P(AM-co-SBMA)GPEs as both separator and electrolyte matrix,and 4 M KOH as the electrolyte,a symmetric solid supercapacitors(SSC)(AC-GPE-KOH)was assembled and testified.The specific capacitance of AC electrode is 173 F/g and remains 95.0%of the initial value after 5000 cycles and 86.2%after 10,000 cycles.

Bifunctional TiO_(2-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,Ti O_(2-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 Ti O_(2-x)NF accelerate the dissociation of Li PF_6,promote the rapid transfer of free Li^(+),and influence the formation of Li F-enriched solid electrolyte interphase.Consequently,the composite GPEs demonstrate enhanced ionic conductivity(1.90m S 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℃),and improved compatibility with lithium,resulting in superior cycling stability and rate performance in both Li||Li,Li||Li Fe PO_(4),and Li||Li Ni_(0.8)Co_(0.1)Mn_(0.1)O_(2)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.

Research Progress of Polymer Fire Extinguishing Gel and Its Application in Forest Fire Prevention

The paper summarizes the structure and water-absorbing mechanism,classification,and preparation method of polymer fire extinguishing gel,and prospects for its application in aerial firefighting,forest ground fire extinguishing,opening of firebreaks,and mitigating human casualties in forest fire extinguishing.

A gel polymer electrolyte with IL@UiO-66-NH_(2) as fillers for high-performance all-solid-state lithium metal batteries

All solid-state electrolytes have the advantages of good mechanical and thermal properties for safer energy storage,but their energy density has been limited by low ionic conductivity and large interfacial resistance caused by the poor Li~+transport kinetics due to the solid-solid contacts between the electrodes and the solid-state electrolytes.Herein,a novel gel polymer electrolyte(UPP-5)composed of ionic liquid incorporated metal-organic frameworks nanoparticles(IL@MOFs)is designed,it exhibits satisfying electrochemical performances,consisting of an excellent electrochemical stability window(5.5 V)and an improved Li^(+)transference number of 0.52.Moreover,the Li/UPP-5/LiFePO_(4) full cells present an ultra-stable cycling performance at 0.2C for over 100 cycles almost without any decay in capacities.This study might provide new insight to create an effective Li^(+)conductive network for the development of all-solid-state lithium-ion batteries.

A UV cross-linked gel polymer electrolyte enabling high-rate and high voltage window for quasi-solid-state supercapacitors

Serving as a promising alternative to liquid electrolyte in the application of portable and wearable devices,gel polymer electrolytes(GPEs)are expected to obtain more preferable properties rather than just be satisfied with the merits of high safety and deformability.Here,an easy-operated method is employed to fabricate cross-linked composite polymer membranes used for GPEs assisted by UV irradiation,in which N-doped carbon quantum dots(N-CQDs)and TiO2are introduced as photocatalysts and additives to improve the performances of GPEs.Specifically,N-CQDs participate as a cross-linker to construct the inner porous structure,and TiO2nanoparticles serve as a stabilizer to improve the electrochemical stability of GPEs under high voltage(3.5 V).The excellent thermal and mechanical stability of the membrane fabricated in this work guarantee the safety of the supercapacitors(SCs).This GPE based SC not only exhibits prominent rate performance(105%capacitance retention at the current density of 40A g^(-1))and cyclic stability(85%at 1 A g^(-1)under 3.5 V after 20,000 cycles),but also displays remarkable energy density(42.88 Wh kg^(-1))with high power density(19.3 k W kg^(-1)).Moreover,the superior rate and cycling performances of the as-prepared GPE based flexible SCs under flat and bending state confirm the feasibility of its application in flexible energy storage devices.

Progress in Gel Polymer Electrolytes for Sodium-Ion Batteries

Sodium-ion battery is a potential application system for large-scale energy storage due to the advantage of higher nature abundance and lower production cost of sodium-based materials.However,there exist inevitably the safety problems such as flammability due to the use of the same type of organic liquid electrolyte with lithium-ion battery.Gel polymer electrolytes are being considered as an effective solution to replace conventional organic liquid electrolytes for building safer sodium-ion batteries.In this review paper,the authors present a comprehensive overview of the research progress in electrochemical and physical properties of the gel polymer electrolyte-based sodium batteries.The gel polymer electrolytes based on different polymer hosts namely poly(ethylene oxide),poly(acrylonitrile),poly(methyl methacrylate),poly(vinylidene fluoride),poly(vinylidene fluoride-hexafluoro propylene),and other new polymer networks are summarized.The ionic conductivity,ion transference number,electrochemical window,thermal stability,mechanical property,and interfacial issue with electrodes of gel polymer electrolytes,and the corresponding influence factors are described in detail.Furthermore,the ion transport pathway and ion conduction mechanism are analyzed and discussed.In addition,the advanced gel polymer electrolyte systems including flame-retardant polymer electrolytes,composite gel polymer electrolytes,copolymerization,single-ion conducting polymer electrolytes,etc.with more superior and functional performance are classified and summarized.Finally,the application prospects,development opportunities,remaining challenges,and possible solutions are discussed.

Leak-off behavior and water shut-off performance of a polymer/chromium(Cr^(3+)) gel in fractured media

During gel treatments for fractures, the leak-off behavior of gelant has a great effect on the water shut-off performance of gel. Experiments were carried out using a polymer/chromium(Cr^(3+)) gel system to explore the leak-off behavior and the water shut-off performance of gel in fractured media. Results of the gelant leak-off study show that the gelant leak-off from fracture into matrix contributes to the formation of the gelant leak-off layer during the gelant injection. Moreover, because of the gradual formation of the gelant leak-off layer along fracture, the initial leak-off ratio of gelant is relatively high, but it declines and finally levels off with the increase of the injection volume. The polymer concentration of gelant has a great effect on the chromium output in fluids produced from fractures. With the increase of the polymer concentration, the chromium concentration first decreases and then increases, and the leak-off depth of gelant into matrix is gradually reduced. Results of the water shut-off study present that the decrease of the chromium concentration inside the fracture greatly reduces the water shut-off performance after the gel formation. Therefore, because of the relatively high degree of chromium leak-off, enough injection volume of gelant is essential to ensure the sufficient chromium concentration inside the fracture and to further achieve a favorable water shut-off performance. On the premise of gel strength assurance inside the fracture, the water shut-off performance of gel gradually declines with the extension of the distance from the fracture inlet, and different leak-off degrees of gelant along the fracture are responsible for this phenomenon. Therefore, a proper degree of gelant leak-off contributes to enhancing the water shut-off performance of gel for fractures.

Recent advances in gel polymer electrolyte for high-performance lithium batteries

Lithium batteries (LBs) have become increasingly important energy storage systems in our daily life. However, their practical applications are still severely plagued by the safety issues from liquid electrolyte, especially when the batteries are exposed to mechanical, thermal, or electrical abuse conditions. Gel polymer electrolytes (GPEs) are being considered as an effective solution to replace currently available organic liquid electrolyte for building safer LBs. This review provides recent advancements in GPEs applied for high-performance LBs. On the one hand, from the environmental and economic point of view, the skeletons of GPEs changed from traditional polymer to renewable and degradable polymer. On the other hand, in addition to being as a component with good electrochemical and physical characterizations, the GPEs also need to provide some functions for addressing the concerns of lithium (Li) dendrites, unstable cathode electrolyte interface, dissolution and migration of transition metal ions,"shuttle effect" of polysulfides, and so on. Finally, to synchronously meet the challenges from the advanced cathode and Li metal anode, the bio-based GPEs with multi-functionality are proposed to develop high-energy/powerdensity batteries in the future.

High-performance PVDF-HFP based gel polymer electrolyte with a safe solvent in Li metal polymer battery

Poly(vinylidenefluoride-co-hexafluoropropylene)(PVDF-HFP)based gel polymer electrolytes are widely studied owing to their electrochemical stability and high dielectric constant.However,most gel polymer electrolytes show unsatisfied safety and interface compatibility due to excessive absorption of volatile and flammable liquid solvents.Herein,by using a safe solvent(N-methyl-2-pyrrolidone)with higher boiling(203℃)and flash points(95℃),we initiatively fabricate a flexible PVDF-HFP based gel polymer electrolyte.The obtained gel polymer electrolyte demonstrates a high ionic conductivity of 7.24×10^−4 S cm−1,an electrochemical window of 5.2 V,and a high lithium transference number of 0.57.As a result,the synthesized polymer electrolyte exhibits a capacity retention of 70%after 500 cycles at 0.5 C,and a discharge capacity of 86 mAh g−1 even at a high current rate of 10 C for LiFePO4 based Li metal batteries.Moreover,a stable Li plating/stripping for more than 500 h is achieved under 0.1 mAh at both room temperature and 70℃.Our results indicate that the PVDF-HFP polymer electrolyte is promising for manufacturing safe and high-performance Li metal polymer batteries.

Research progress on gel polymer electrolytes for lithium-sulfur batteries

Lithium-sulfur(Li-S)batteries have become a promising candidate for advanced energy storage system owing to low cost and high theoretical specific energy.In the last decade,in pursuit of Li-S batteries with enhanced safety and energy density,the investigation on the electrolytes has leaped form liquid organic electrolytes to solid polymer ones.However,such solid-state Li-S battery system is greatly limited by unfavorable ionic conductivity,poor interfacial contact and narrow electrochemical windows on account of the absence of any liquid components.To address these issues,gel polymer electrolytes(GPEs),the incorporation of liquid electrolytes into solid polymer matrixes,have been newly developed.Although the excellent ionic transport and low interfacial resistance provided by GPEs have prompted numerous researchers to make certain progress on high-performance Li-S coins,a comprehensive review on GPEs for Li-S batteries remains vacant.Herein,this review focuses on recent development and progress on GPEs in view of their physical and chemical properties for the applications in Li-S batteries.Studies on the components including solid hosts,liquid solutions and fillers of GPEs are systematically summarized with particular emphasis on the relationship between components and performance.Finally,current challenges and directional outlook for fabricating GPEs-based Li-S batteries with outstanding performance are outlined.

A novel permselective organo-polysulfides/PVDF gel polymer electrolyte enables stable lithium anode for lithium–sulfur batteries

Lithium-sulfur(Li-S)battery can satisfy the need of the future power battery market because of its high energy density,but the hidden dangers caused by lithium anode have seriously hindered their commercialization.Herein,an innovative gel polymer electrolyte(GPE)composed of polyvinylidene fluoride(PVDF)and organo-polysulfide polymer(PSPEG)is proposed,which could be used in semisolid-state Li-S batteries for protection of Li anodes.Particularly,organo-polysulfide polymer could chemically/electrochemically generate both inorganic and organic components simultaneously in-situ once contacting fresh Li metal surface and/or during discharging processes.And these inorganic/organic components could participate in the formation of the SEI layer and finally constitute a stable and flexible hybrid SEI layer on the surface of Li metal anode.Moreover,the organic components were permselective to lithium ions against anions.Therefore,PVDF/PSPEG GPE ensures the ideal chemical and electrochemical properties for Li-S batteries.Our work demonstrates an effective solution to solve the problems about Li anodes and contributes to the development of the safe Li metal batteries.

Thermotolerant and fireproof gel polymer electrolyte toward high-performance and safe lithium-ion battery

Poly(ethylene oxide)(PEO)and its derivatives based gel polymer electrolytes(GPEs)are severely limited in advanced and safe lithium-ion batteries(LIBs)owing to the intrinsically high flammability of liquid electrolytes and PEO.Directly adding flame retardants to the GPEs can suppress their flammability and thus improve the safety of LIBs,but results in deteriorative electrochemical performance.Herein,a novel GPE with chemically bonded flame retardant(i.e.diethyl vinylphosphonate)in cross-linked polyethylene glycol diacrylate matrix,featuring both high-safety and high-performance,is designed.This as-prepared GPE storing the commercial 1 mol L^(-1) LiPF6 electrolyte resists high temperature of 200℃and cannot be ignited as well as possesses a high ionic conductivity(0.60 m S cm^(-1))and good compatibility with lithium.Notably,the LiFePO_(4)/Li battery with this GPE delivers a satisfactory capacity of 142.2 m A h g^(-1) and a superior cycling performance with a capacity retention of 96.3%and a coulombic efficiency of close to 100%for 350 cycles at 0.2 C under ambient temperature.Furthermore,the battery can achieve steady charge–discharge for 100 cycles with a coulombic efficiency of 99.5%at 1 C under 80℃and run normally even at a high temperature of 150℃or under the exposure to butane flame.Differential scanning calorimetry manifests significantly improved battery safety compared to commercial battery systems.This work provides a new pathway for developing next-generation advanced LIBs with enhanced performance and high safety.

Fibrous gel polymer electrolyte for an ultrastable and highly safe flexible lithium-ion battery in a wide temperature range

Replacement of flammable liquid electrolytes with gel polymer electrolytes(GPEs)is a promising route to improve the safety of lithium-ion batteries(LIBs).However,polymer-based electrolytes have limited suitability at low/high temperatures due to the instability of the polymer at high temperatures and the low ionic conductivity of the gel state at low temperatures.Herein,an integrated design of electrodes/fibrous GPEs modified with graphene oxide(GO)is reported.Due to the integrated structure of electrodes/GPEs,the strong interface affinity between electrodes and GPEs ensures that the GPEs spun on electrodes do not shrink at high temperatures(160-180℃),thus preventing a short circuit of electrodes.Moreover,after GO modification,oxygen-containing functional groups of GO can accelerate Li^(+)transport of GO-GPEs even at a low temperature of−15℃.When these GPEs are applied to flexible LIBs,the LIBs show excellent electrochemical performance,with satisfactory cycling stability of 82.9%at 1 C after 1000 cycles at 25℃.More importantly,at a high temperature of 160℃,the LIBs can also discharge normally and light the green light-emitting diode.Furthermore,at a low temperature of−15℃,92.7%of its room-temperature capacity can be obtained due to the accelerated Li^(+)transport caused by GO modification,demonstrating the great potential of this electrolyte and integrated structure for practical gel polymer LIB applications.

A HYBRID POLYMER GEL AND ITS STATIC NONERGODICITY

We used a thermally reversible hybrid gel made of billions of physically jam-packed swollen thermally sensitivepoly(N-isopropyl-acrylamide) chemical microgels. Laser light scattering study on a series of such hybrid gels formed atdifferent gelling rates and temperatures revealed that the position-dependence of the scattering speckle pattern(staticnonergodicity) came from large voids formed during the sol-gel transition. With a proper preparation, such a nonergodicitycould be completely removed, indicating that the static nonergodicity generally observed in a gel is not indinsic, but comesfrom the clustering "island" structure formed during the gelation process.

A review of nuclear magnetic resonance(NMR) technology applied in the characterization of polymer gels for petroleum reservoir conformance control

Polymer gel systems have been widely applied to control excessive water and improve oil recovery(IOR)in petroleum reservoirs.They are usually divided into two main types,in-situ cross-linked polymer gels,and pre-formed polymer gels.In recent years,nuclear magnetic resonance(NMR) technology has been gradually applied to the research of polymer gel systems due to its unique analysis advantages.This paper is intent to review these works systematically.For in-situ cross-linked polymer gel systems,NMR can be used to characterize the chemical structure changes of the polymer,the cross-linker,and the auxiliary agent in the formulation of the polymer gel systems.Moreover,the gelation time and the gel strength of the in-situ cross-linked polymer gel systems can also be measured by NMR.For pre-formed polymer gels,NMR can be employed to detect the chemical structure of the designed products.Last,the NMR method can evaluate the plugging,water control,and oil improvement performance of the polymer gels in porous media without using dopants.This review can help readers build a more systematic understanding of the application of NMR technology in polymer gel systems for IOR and help re searchers to more deeply study the performance of polymer gel systems.

Preparation of Organic/Inorganic Hybrid Polymer Emulsions with High Silicon Content and Sol-gel-derived Thin Films

A novel polymer/SiO2 hybrid emulsion(PAES)was prepared by directly mixing colloidal silica with polyacrylate emulsion(PAE)modified by a saline coupling agent.The sol-gel-derived thin films were obtained by addition of co-solvents into the PAES.The effects ofγ-methacryloxypropyltrimethoxysilane(KH-570)content and co-solvent on the properties of PAES films were investigated.Dynamic laser scattering(DLS)data indicate that the average diameter of PAES(96 nm)is slightly larger than that of PAE(89 nm).Transmission electron microscopy (TEM)photo discloses that colloidal silica particles are dispersed uniformly around polyacrylate particles and some of the colloidal silica particles are adsorbed on the surface of PAE particles.The crosslinking degree data and Fourier transform infrared(FT-IR)spectra confirm that the chemical structure of the PAES is changed to form Si-O-Si-polymer crosslinking networks during the film formation.Atomic force microscope(AFM)photos show the solvent induced sol-gel process of colloidal silica and the Si-based polymer distribution on the film surface of the dried PAES.Thermogravimetric analysis(TGA)curves demonstrate that the PAES films display much better thermal stability than PAE.

A lithiated gel polymer electrolyte with superior interfacial performance for safe and long-life lithium metal battery

Rechargeable lithium metal batteries(LMBs)have gained much attention recently.However,the short lifespan and safety issues restrict their commercial applications.Here we report a novel gel polymer electrolyte(GPE)based on lithiated poly(vinyl chloride-r-acrylic acid)(PVCAALi)to realize dendritesuppressing and long-term stable lithium metal cycling.PVC chains ensure the quick gelation process and high electrolyte uptake,and lithiated PAA segments enable the increase of mechanical strength,acceleration of lithium-ion transmission and improvement of interfacial compatibility.PVCAALi GPE showed much higher mechanical strength compared with other free-standing GPEs in previous works.It displays a superior ionic conductivity of 1.50 m S cm^(-1) and a high lithium-ion transference number of 0.59 at room temperature.Besides,the lithiated GPE exhibits excellent interfacial compatibility with lithium metal anodes.Lithium symmetrical cells with PVCAALi GPE yield low hysteresis of 50 m V over1000 h at 1.0 m A cm^(-2).And the possible mechanism of the lithiated GPE with improved lithium-ion transfer and interfacial property was discussed.Accordingly,both the Li4Ti5O12/Li and lithium-sulfur(Li-S)cells assembled with PVCAALi GPE show outstanding electrochemical performance,retaining high discharge capacities of 133.8 m Ah g^(-1) and 603.8 m Ah g^(-1) over 200 cycles,respectively.This work proves excellent application potential of the highly effective and low-cost PVCAALi GPE in safe and long-life LMBs.

Performance Improvement of Polyvinyl Formal Based Gel Polymer Electrolyte for Lithium-Ion Batteries by Coating Al2O3

Al2O3/PVFM/Al2O3 trilayer membranes are prepared by means of simple coating of PVA-Al2O3 solution onto both sides of PVFM thin membranes, which is prepared via phase inversion method. The characteristics of the trilayer membranes and gel polymer electrolytes are investigated using FESEM, tensile testing apparatus, thermal shrinkage test, EIS and charge-discharge test. When inorganic Al2O3 particles are used to coat the PVFM membrane, drawbacks associated with gel-type membranes, namely, poor mechanical strength and thermal stability are greatly improved. Lithium ion cell with the Al2O3/PVFM/Al2O3 based GPE matched with LiFePO4 shows excellent electrochemical performance.

Rheological properties of polymer micro-gel dispersions

The influence of swelling time, temperature, NaCl concentration and polymer micro-gel concentration on rheological properties of polymer micro-gel dispersions was studied by using a HAAKE rheometer. The results showed that with increasing swelling time and NaCl concentration, the polymer micro-gel dispersions changed from a shear-thickening fluid to a Newtonian fluid. The polymer micro-gel dispersion show shear-thinning in non-saline water. At higher swelling temperature, the time of the polymer micro-gel dispersion showing shear-thickening was shorter. With increasing polymer micro-gel concentration, the dispersion changed from shear-thickening to shear-thinning.

Preparation and properties of PEO/LiClO_4/KH560-SiO_2 composite polymer electrolyte by sol-gel composite-in-situ method

Composite polymer electrolytes based on polyethylene oxide(PEO) were prepared by using LiClO4 as doping salt and silane-modified SiO2 as filler. SiO2 was formed in-situ in (PEO)8LiClO4 matrix by the hydrolysis and condensation reaction of Si(OC4H9)4. The crystallinity,morphology and ionic conductivity of composite polymer electrolyte films were examined by differential scanning calorimetry,scanning electron microscopy,atom force microscopy and alternating current impedance spectroscopy,respectively. Compared with the crystallinity of the unmodified SiO2 as inert filler,that of composite polymer electrolytes is decreased. The results show that silane-modified SiO2 particles are uniformly dispersed in (PEO)8LiClO4 composite polymer electrolyte film and the addition of silane-modified SiO2 increases the ionic conductivity of the (PEO)8LiClO4 more noticeably. When the mass fraction of SiO2 is about 10%,the conductivity of (PEO)8LiClO4-modified SiO2 attains a maximum value of 4.8×10-5 S·cm-1.