Electrolyte Films Research Articles

Mechanisms of Secondary Spreading and Micro Droplet Formation on Steel

Abstract A new theory for secondary spreading based on the wetting theory of thin films is presented. It explains how micro droplets within the spreading zone and the primary droplet retain their shape, although connected by a thin electrolyte film and how humidity and salt concentration affect the growth rate of micro droplets. The trigger for secondary spreading, polarization or alkalization, is identified by using droplets of sodium hydroxide solution. Secondary spreading thus occurs on steel from pH 13.5 without corrosion or external polarization. The limiting pH value found explains why secondary spreading on steel only occurs when certain salts are used. 
The effect of the substrate is investigated by changing the microstructure of the steel. By comparing the sizes of micro droplets and micro structural phases and by scanning electron microscopy/energy-dispersive X-ray analysis measurements of the spreading zone, the existence of an electrolyte film connecting the micro droplets is supported. Ecorr potential profiles of secondary spreading droplets of sodium chloride solution on steel acquired by means of SKP are used to assess the contribution of secondary spreading to the total corrosion current, which is estimated to be low compared to that of the cathodic zone at the edge of the droplet

Coordination‐Driven Crosslinking Electrolytes for Fast Lithium‐Ion Conduction and Solid‐State Battery Applications

AbstractRechargeable batteries paired with lithium (Li) metal anodes are considered to be promising high‐energy storage systems. However, the use of highly reactive Li metal and the formation of Li dendrites during battery operation would cause safety concerns, especially with the employment of highly flammable liquid electrolytes. Herein, a general strategy by engineering coordination‐driven crosslinking networks is proposed to achieve high‐performance solid polymer electrolytes. Through the coordination of metal‐organic polyhedra (MOPs) with cellulose‐based copolymers, the Li+‐conducted hypercrosslinked MOP (CHMOP‐Li) polymer network is capable of enabling the rapid transport of Li+. In addition to the high Li+ conductivity (1.02×10−3 S cm−1 at 25 °C), CHMOP‐Li electrolyte also exhibits a high Li+ transference number (0.75) and a wide electrochemical stability window. Benefiting from the thermally stable and mechanically strong CHMOP‐Li electrolyte film, the short‐circuiting of the symmetric batteries is prevented even after 3200 h of cycling and a high specific energy of 300 Wh kg−1 is achieved for the Li‐metal battery. The solid‐state Li−O2 batteries fabricated with CHMOP‐Li electrolyte also show good cycling performance (500 cycles) and high discharge capacity (15740 mAh g−1). The proposed coordination‐driven crosslinking strategies offer an alternative route to design high‐performance next‐generation sustainable battery chemistries.

Coordination-Driven Crosslinking Electrolytes for Fast Lithium-Ion Conduction and Solid-State Battery Applications.

Rechargeable batteries paired with lithium (Li) metal anodes are considered to be promising high-energy storage systems. However, the use of highly reactive Li metal and the formation of Li dendrites during battery operation would cause safety concerns, especially with the employment of highly flammable liquid electrolytes. Herein, a general strategy by engineering coordination-driven crosslinking networks is proposed to achieve high-performance solid polymer electrolytes. Through the coordination of metal-organic polyhedra (MOPs) with cellulose-based copolymers, the Li+-conducted hypercrosslinked MOP (CHMOP-Li) polymer network is capable of enabling the rapid transport of Li+. In addition to the high Li+ conductivity (1.02×10-3 S cm-1 at 25 °C), CHMOP-Li electrolyte also exhibits a high Li+ transference number (0.75) and a wide electrochemical stability window. Benefiting from the thermally stable and mechanically strong CHMOP-Li electrolyte film, the short-circuiting of the symmetric batteries is prevented even after 3200 h of cycling and a high specific energy of 300 Wh kg-1 is achieved for the Li-metal battery. The solid-state Li-O2 batteries fabricated with CHMOP-Li electrolyte also show good cycling performance (500 cycles) and high discharge capacity (15740 mAh g-1). The proposed coordination-driven crosslinking strategies offer an alternative route to design high-performance next-generation sustainable battery chemistries.

Polymer electrolyte with inorganic and organic salts for Na-Ion supercapacitor

The optimized high ion conducting polymer electrolyte film containing copolymer PVdF-HFP, 10 wt.% inorganic salt {sodium bis(trifluoromethane sulfonyl)imide (NaTFSI)} and 70 wt.% organic salt {1-butyl-1-methypyrrolidinium bis(trifluoromethane sulfonyl) imide ([BMPYr] [TFSI])} have been used for the fabrication of Na-ion supercapacitor. The optimized composition of the electrolyte film possesses maximum room temperature (RT) ionic conductivity (∼0.87 mS/cm), excellent mechanical stability and large operating potential window (∼5.5 V). Using this film and activated carbon electrode (ACE (AC∼0.8 mg/cm2)), electrochemical double layer capacitor (EDLC)/Na-ion supercapacitor has been fabricated. The bulk resistance of this cell is found to be 22.9 Ω which is an evidence of good electrode-electrolyte contact. The cyclic voltammetric (CV) results of the EDLC-cell displays almost rectangular shape which demonstrates their capacitive behavior. The fabricated Na-ion supercapacitor has delivered specific capacities of ∼173 F/g, 151.91 F/g, 145.32 F/g and 122.33 F/g at different areal current densities (∼0.5, 0.8, 1.0 and 2.0 mA/cm2, respectively) along with the coulombic efficiency ranging from 97.6% to 99.9% upto 4500 cycles at 1 mA/cm2. The obtained value of the specific capacitance(s) of the EDLC cell from cyclic voltammetry is in good agreement with the value obtained from galvanostatic charge-discharge (GCD) measurements. Also, a nearly stable cycling performance has been obtained at 1 mA/cm2 upto 2500 cycles and after that the value of the specific capacitance (CSP/CD) decreases slightly upto 4500 cycles. This decrease in CSP/CD value may be because of increased thickness of solid electrolyte interface (SEI) layer and its corresponding interfacial resistance. The maximum specific energy and power density at 0.5 mA/ cm2 areal current density for first cycle are 31.52 Wh/Kg and ∼472.8 kW/Kg, respectively. On using ACE having AC∼1.6 mg/cm2, the fabricated Na-ion EDLC-cell has given maximum value of specific capacitance as ∼72.6 F/g at 0.5 mA/cm2 alongwith coulombic efficiency in the range of 96.5 % to 99.5 %. For the first cycle, the energy as well power density increase (∼40.31 Wh/Kg and ∼499.12 kW/Kg, respectively) and show stable cyclability upto 3000 cycles.

Polyvinyl Butyral Solid Electrolyte Film and Its Electrochromic Laminated Safety Glass.

In recent years, the application of electrochromic laminated safety glass has attracted more and more attention, relying on polyvinyl butyral (PVB) solid electrolyte film. Herein, the ionic conductivity (σ) of the PVB film has been improved by a cross-linked structure and blended with LiClO4, which can reach as high as 1.78 × 10-4 S cm-1 at room temperature. In addition, their excellent comprehensive characteristics have been confirmed, such as mechanical strength, high visible light transmittance (>90%), high bond strength (4.2 MPa), and excellent thermal stability. Based on the PVB film above, WO3-laminated electrochromic devices with 5 × 5 cm2 and 10 × 10 cm2 areas are constructed. They can remain stable after 20 000 cycles monitored by cyclic voltammetry curves, indicating the PVB solid polymer electrolyte (PSPE) with a cross-linked structure has the potential commercial viability of large-area electrochromic devices (ECDs).

Ionic liquid (1-Ethyl-3-methylimidazolium tricyanomethanide) incorporated corn starch polymer electrolyte for solar cell and supercapacitor application

Taking into account energy demand a new highly conducting ionic liquid (IL) c (EmImTCM) mixed corn starch (CS) biopolymer electrolyte is synthesized for dual electrochemical application electric double layer capacitor (EDLC) and the dye-sensitized solar cell (DSSC) application. Electrical, structural, thermal, and optical studies are carried out in detail and presented in this communication. Maximum conducting IL-incorporated biopolymer electrolyte film has been sandwiched between electrodes to develop EDLC and DSSC. The sandwich-structured EDLC delivers a high specific capacitance of 250 F/gram while DSSC shows 1.44 % efficiency at one sun condition.

Ultrasensitive Flexible Organic Synaptic Transistors Modulated by a Chemically Cross-Linked Solvent-Resistive Ion Composite.

We demonstrate a flexible organic synaptic transistor (FOST) with an ion-composite electrolyte film resistant to chemical reagents, which uses a three-dimensionally cross-linked polyimide matrix to accommodate a high-concentration ionic liquid. FOST shows versatile synaptic plasticity for classical conditioning, high-pass filtering, and the learning-forgetting process. The device achieves low-energy consumption down to 1.02 femtojoule per synaptic event with an ultrasensitive impulse to presynaptic spike down to 0.5 mV. Moreover, the electrical performance of the device is still stable after 1000 mechanical bending cycles. These results demonstrate that the device can be applied to future flexible neuromorphic electronics.

Na3Zr2Si2PO12-Polymer Composite Electrolyte for Solid State Sodium Batteries.

The integration of the flexibility of organic polymer electrolyte and high ionic conductivity of the ceramic electrolyte is attempted in search of efficient and safer battery. Composite solid polymer electrolyte (CSPE) provides high ionic conductivity with a sustainable thin film of electrolyte having the synergistic effect of ionic liquid and active inorganic filler. The CSPE is synthesized by the solution cast technique using Na3Zr2Si2PO12 (NZSP) as ceramic and poly(vinylidene fluoride-hexafluoropropylene) with Salt-Ionic liquid as polymer electrolyte. X-ray diffraction (XRD) of CSPE includes amorphous nature due to the polymer part as well as crystalline peaks of ceramic NZSP, simultaneously. The prepared CSPE sample shows homogeneous and interconnected surface morphology is observed by Scanning electron microscopy (SEM) image. Thermogravimetric analysis (TGA) shows electrolyte is thermally stable up to 200 °C and differential scanning calorimetry (DSC) reveals decrease in degree of crystallinity due to NZSP addition in the CSPE. By complex impedance spectroscopy (CIS), room temperature ionic conductivity of the prepared CSPE is found ~1.03 mS/cm. The dielectric behaviour of the prepared electrolyte is also studied to investigate the ion dynamics within the sample. The cationic transference number is 0.53 and the electrochemical stability window (ESW) of the CSPE is 4.9 V which is suitable for sodium solid-state batteries applications.

A PVB electrolyte film and its application in electrochromic laminated glass

In recent years, the electrochemical study of solid electrolyte polymer films has been attracted more and more attentions due to their importance in electrochromic components. In this work, a solid polymer electrolyte (SPE) film based on the Polyvinyl butyral (PVB) has been successful constructed by hybrid process. Its conductivity at room temperature is 6.0 × 10−4 S cm−1, with an activation energy of 0.02 eV. The tensile strength at break reaches up to 43 MPa, while the shear strength is 3.8 MPa. Additionally, the impact energy is 3.1756 J. The corresponding electrochromic laminated glass (ELGs) with 10 × 10 cm2 and 2 × 2 cm2 are obtained through hot pressing process. These glasses exhibit electrochromic properties and safety performance. They can change colors within 4 s at voltages greater than 1 V, with an optical contrast ratio of (ΔT)≈64 %. Additionally, their high stability and good reversibility has been confirmed by 10,000 cycles of cyclic voltammetry (CV) testing. It provides a new possibility for the application of electrolyte films in electrochromic.

Exploring the synergistic potential of PVB: KCl composite electrolyte films for enhanced performance in solid-state potassium batteries

Exploring the synergistic potential of PVB: KCl composite electrolyte films for enhanced performance in solid-state potassium batteries

An electrical double-layer supercapacitor based on a biomass-activated charcoal electrode and ionic liquid with excellent charge-discharge cycle stability 

Supercapacitors that exhibit high power density and safety are emerging as alternative energy storage devices. The construction and performance of a supercapacitor using the ionic liquid, triethylammonium thiocyanate, as the electrolyte and biomass-activated charcoal films as the electrode are described. Enhancements in both energy and power density were observed even for 10,000 charge-discharge cycles. The fabricated supercapacitor with ionic liquid and activated charcoal-based electrodes showed an impressive specific capacitance retention of 142% even after 10,000 cycles at a scan rate of 500 mv s-1, which is attributed to the clearing of ion conducting pathways and enhanced charge transport with increasing temperature. Impedance analysis confirmed the reduction of resistive losses with increasing cycle numbers. The initial energy and power densities of the Electrical double-layer capacitance (EDLC) were 0.926 W h kg-1 and 5681 W kg-1, and they showed 42.2 % and 60.6 % increments after supercapacitors cycles. The study reveals low-cost biomass-based activated carbon electrodes and trimethylamine thiocyanate can be used to prepare supercapacitors with remarkable cycling performances.

Long‐lifespan 522 Wh kg‐1 Lithium Metal Pouch Cell Enabled by Compound Additives Engineering

Matching high‐voltage cathodes with lithium metal anodes represents the most viable technological approach for developing secondary batteries with ultra‐high energy density exceeding 500 Wh kg‐1. Nevertheless, the instability of electrolyte/electrode interface film and commercial electrolytes with cut‐off voltage above 4.3 V is still a major concern. Herein, we present that excellent cycling stability with an ultra‐high cut‐off voltage of up to 5.0 V can be obtained by using three‐component additives containing fluoroethylene carbonate (FEC), hexadecyl trimethylammonium chloride (CTAC), and tri(pentafluorophenyl)borane (TPFPB). Excellent ionic conductivity, robust interfacial films on both electrodes, and long‐lasting uniform Li+ regulation ability can be obtained in the modifying electrolyte. Consequently, using a high plating/stripping capacity of 3 mAh cm‐2 under the current density of 1 mA cm‐2, lithium symmetric cells demonstrate stable cycling performance exceeding 800 hours. Meanwhile, the 7.3 Ah‐class Li[NixCoyMn1‐x‐y]O2 (x=0.83, NCM83)| Li pouch cells are assembled, which show a high energy density of 522 Wh kg‐1 and present excellent stability over 178 cycles with a high initial coulombic efficiency (CE) of 98.0%.

Long-Lifespan 522 Wh kg-1 Lithium Metal Pouch Cell Enabled by Compound Additives Engineering.

Matching high-voltage cathodes with lithium metal anodes represents the most viable technological approach for developing secondary batteries with ultra-high energy density exceeding 500 Wh kg-1. Nevertheless, the instability of electrolyte/electrode interface film and commercial electrolytes with cut-off voltage above 4.3 V is still a major concern. Herein, we present that excellent cycling stability with an ultra-high cut-off voltage of up to 5.0 V can be obtained by using three-component additives containing fluoroethylene carbonate (FEC), hexadecyl trimethylammonium chloride (CTAC), and tri(pentafluorophenyl)borane (TPFPB). Excellent ionic conductivity, robust interfacial films on both electrodes, and long-lasting uniform Li+ regulation ability can be obtained in the modifying electrolyte. Consequently, using a high plating/stripping capacity of 3 mAh cm-2 under the current density of 1 mA cm-2, lithium symmetric cells demonstrate stable cycling performance exceeding 800 hours. Meanwhile, the 7.3 Ah-class Li[NixCoyMn1-x-y]O2 (x=0.83, NCM83)|Li pouch cells are assembled, which show a high energy density of 522 Wh kg-1 and present excellent stability over 178 cycles with a high initial coulombic efficiency (CE) of 98.0 %.

Tuning Electrochemical Performance of Polymer Electrolyte Films through Metal Oxide Incorporation

AbstractWith the escalating global energy demand, the exploration of alternative, easily accessible, and cost‐effective energy sources has become imperative. The diminishing reserves of conventional energy resources underscore the urgency to transition towards renewable energy. Solid polymer electrolytes (SPEs) have gained prominence for energy storage electrochemical devices due to their high flexibility and favorable electrode–electrolyte interactions. This study focuses on synthesizing nano cuprous oxide (CuO) semiconductors via the precipitation method. The prepared CuO nanofiller is homogeneously dispersed into a polymer electrolyte solution. Utilizing the solution cast method, free‐standing polymer electrolyte films are fabricated, exhibiting commendable mechanical stability. Polyvinyl alcohol (PVA) serves as the host material, with potassium iodide (KI) salt, forming the basis for the polymer electrolyte. The resultant electrolyte films underwent comprehensive characterization for their electrical and optical properties. The investigation aims to identify the optimal composition of the electrolyte film with superior conductivity. The selected composition will be employed in the fabrication of various electrochemical devices, demonstrating the potential for enhanced energy storage applications. This work not only contributes to the synthesis of advanced solid polymer electrolyte films but also paves the way for the development of efficient and sustainable energy storage solutions in the realm of renewable energy technologies.

Ion Conduction Mechanism in Polymer Blend Electrolyte Films

AbstractThis paper presents the development of the blend polymer solid electrolyte films (BPSE) for potential applications in electrochemical devices. Two host polymers, polyvinyl alcohol (PVA) and polymethyl methacrylate (PMMA), along with the salt KI, are employed to create the solid polymer electrolytes (SPEs). The synthesis involves varying the weight percentage of salt within the SPEs to investigate its impact on the material properties. Conductivity measurements are conducted using AC impedance spectroscopy, unveiling the conductivity behavior of the BPSEs. Additionally, surface morphology is characterized using polarized optical microscopy (POM) at 10 pixel resolution, offering a detailed examination of the film's microstructure. This comprehensive study not only contributes to the understanding of the fundamental properties of BPSEs but also opens avenues for their utilization in various electrochemical applications.

Binary Biomass-Based Electrolyte Films for High-Performance All-Solid-State Supercapacitor.

Solid-state electrolytes have received widespread attention for solving the problem of the leakage of liquid electrolytes and effectively improving the overall performance of supercapacitors. However, the electrochemical performance and environmental friendliness of solid-state electrolytes still need to be further improved. Here, a binary biomass-based solid electrolyte film (LSE) was successfully synthesized through the incorporation of lignin nanoparticles (LNPs) with sodium alginate (SA). The impact of the mass ratio of SA to LNPs on the microstructure, porosity, electrolyte absorption capacity, ionic conductivity, and electrochemical properties of the LSE was thoroughly investigated. The results indicated that as the proportion of SA increased from 5% to 15% of LNPs, the pore structure of the LSE became increasingly uniform and abundant. Consequently, enhancements were observed in porosity, liquid absorption capacity, ionic conductivity, and overall electrochemical performance. Notably, at an SA amount of 15% of LNPs, the ionic conductivity of the resultant LSE-15 was recorded at 14.10 mS cm-1, with the porosity and liquid absorption capacity reaching 58.4% and 308%, respectively. LSE-15 was employed as a solid electrolyte, while LNP-based carbon aerogel (LCA) served as the two electrodes in the construction of a symmetric all-solid-state supercapacitor (SSC). The SSC device demonstrated exceptional electrochemical storage capacity, achieving a specific capacitance of 197 F g-1 at 0.5 A g-1, along with a maximum energy and power density of 27.33 W h kg-1 and 4998 W kg-1, respectively. Furthermore, the SSC device exhibited highly stable electrochemical performance under extreme conditions, including compression, bending, and both series and parallel connections. Therefore, the development and application of binary biomass-based solid electrolyte films in supercapacitors represent a promising strategy for harnessing high-value biomass resources in the field of energy storage.

High-temperature anodization route to nanoporous niobium oxides with enhanced supercapacitive properties in aqueous electrolytes

Relatively little work has been done on Nb2O5 pseudocapacitive behaviors in aqueous solutions. Here, the galvanostatic anodization of niobium in K2HPO4-containing glycerol electrolyte at high temperature is fully explored. The anodically grown films on niobium have ordered nanoporous morphology and are composed of a low-crystalline orthorhombic Nb2O5, which can be directly employed as supercapacitor electrodes without any posttreatment process. To further improve their supercapacitive performances, a facile technique to generate Fe-doped Nb2O5 films is developed, where the as-anodized films are treated by an electrochemical doping in FeCl3 ethylene glycol solution. The Fe-doped Nb2O5 films show a wider potential window and higher capacitance than that of the as-anodized films in aqueous electrolytes. They present a maximum areal capacitance of 168.1 mF cm−2 at 1 mV s−1 and excellent cycling stability with 85.8 % capacitance retention after 10,000 cycles. The charge storage in the Fe-doped Nb2O5 is believed to occur by the incorporation of Li+ ions with concomitant reduction of Nb5+ to Nb4+ in aqueous lithium-containing solutions. Unlike nonaqueous media, Li+ intercalation/deintercalation in aqueous media is a diffusion-controlled process, leading to the comparatively slower pseudocapacitive processes. Nevertheless, in terms of an industrial applicability the Fe-doped Nb2O5 films deserve special attention.

Structural, electrical, and transport properties of a PVB: NH4Br complexed solid polymer electrolyte films for electrochemical cell applications

ABSTRACT Polymer electrolytes are a key development in advancing battery technology, enabling more efficient energy storage. This study focused on developing a solid-state polymer electrolyte film by doping NH4Br with Polyvinyl Butyral (PVB) using a solution-cast method. X-ray diffraction (XRD) was employed to evaluate the amorphousness and crystallinity of the films, while Fourier Transform Infrared Spectroscopy (FTIR) confirmed complex formation between the salt and polymer. The glass transition temperature (Tg) of the electrolyte film was estimated using Differential Scanning Calorimetry (DSC). Ionic conductivity was measured through AC impedance spectroscopy, revealing that the PVB-NH4Br electrolyte doped with 30 wt% NH4Br at 30 °C had an ionic conductivity of 1.47 × 10−7 S cm−1. This conductivity followed an Arrhenius relationship, where conductivity increased with temperature. Dielectric studies showed that at low frequencies, the dielectric constant and loss were higher, while both decreased at higher frequencies. DC Wagner’s polarization technique verified that ion transport was the dominant conduction mechanism. Discharge testing of the electrolyte film using a Swagelok cell showed an open-circuit voltage (OCV) of 1.2 V and a short-circuit current (SCC) of 0.42 mA, indicating promising performance for battery applications.

A Flexible, Bioadhesive, and Breathable On‐Skin Battery Based on Silk Fibroin Hydrogel for Wearable Electronics

AbstractOn‐skin electronics rely on flexible power sources for stable operation and comfortable wearing. However, the current materials and device designs of on‐skin batteries for human‐interface electronic systems suffer from inadequate adhesion and impermeability. In this work, a general design of a bioadhesive and breathable on‐skin flexible metal‐air battery is presented. By laterally loading a conducting polymer‐based cathode and a zinc anode onto a biocompatible silk fibroin ionic hydrogel electrolyte film, the battery exhibits good epidermal adhesions (shear strength exceeds 20 kPa and interface toughness exceeds 150 J m−2) and excellent sweat breathability (3 times greater than commercial 3 M breathable dressing). A singular battery can generate an open circuit voltage of up to 1.4 V and a power density of 72 µW cm−2. It shows stable adhesion to the skin for five days, while simultaneously preserving epidermal respiratory function and facilitating natural skin movement. On‐skin integration of the battery array can be easily conducted to increase the electrical output. This battery design enhances the usability, comfort, and safety of wearable electronics, enabling new applications in healthcare, fitness tracking, and beyond.

Mg‐Ion Conducting Gel Polymer Electrolyte Based on High Flash Point Solvent Adiponitrile for Magnesium Ion Batteries

ABSTRACTDue to some specific properties of adiponitrile (ADN) including high oxidative stability and high flash point, it is proposed as co‐solvent with an ionic liquid (IL) as a promising electrolyte solvent for application in magnesium batteries. Herein, we report a flexible film of gel polymer electrolyte (GPE) comprising a polymer poly(vinylidene fluoride‐co‐hexafluoropropylene) (PVdF‐HFP) in which a liquid electrolyte of Mg‐trifluoromethane sulfonate (Mg‐triflate) in the mixture of ADN:IL (1‐ethyl‐3‐methylimidazolium triflate, EMITf) is immobilized for use in Mg‐batteries. The structural/morphological properties of the GPE film have been characterized via different physical techniques. The high ionic conductivity (σRT = 5.9 mS cm−1), wide potential range of oxidative stability (~4.18 V vs. Mg/Mg2+), high Mg‐ion transport number (tMg2+ = 0.67) and thermal stability up to ~160°C ascertain the compatibility of electrolyte film in magnesium batteries with high voltage cathode materials. The comparative studies of the interfacial‐stability and Mg‐stripping/plating tests on the two symmetrical cells with Mg and Mg/MWCNTs nanocomposite electrodes show the improved reversibility of the electrolyte film with Mg‐MWCNTs powder as anode material, compared with pure Mg‐powder. The overall results indicate that the GPE based on binary solvent mixture ADN:IL is high performance flexible electrolyte for Mg‐batteries with Mg‐MWCNTs powder as anode material.