Immobilized cation functional gel polymer electrolytes with high lithium transference number for lithium ion batteries

An In Situ Polymerization Gel Polymer Electrolyte Based on Pentaerythritol Tetracrylate for High-Performance Lithium-Ion Batteries

Problems occur frequently during the application of traditional liquid electrolyte batteries, such as fluid leakage and low energy density. As a product of liquid electrolyte transition to solid electrolyte, gel polymer electrolyte has its own advantages for achieving high conductivity and good thermal stability. In this study, pentaerythritol tetracrylate (PETEA) was used as the precursor to prepare polymer-based materials with the assistance of azobis(isobutyronitrile) (AIBN) as the initiator. Because fluorine is beneficial to improving the migration efficiency of Li+ and the electrochemical performance of the gel polymer electrolyte, dodecafluoroheptyl methacrylate (DFHMA) is introduced to the PETEA-based gel polymer electrolyte (GPE) system. The DFHMA-introduced GPE shows better electrochemical performance, battery cycle performance, conductivity, and lithium-ion migration number compared with the pristine PETEA-based GPE. In particular, the DFHMA-introduced GPE exhibits the best performance because the molar ratio of PETEA to DFHMA is 5:1. Herein, the electrochemical window is 4.6 V, the ionic conductivity reaches 1.207 mS cm-1, and the number of lithium-ion migrations reaches the value of 0.663. Because the electric current density is 2 C, the specific capacity of LiNi0.5Co0.2Mn0.3O2 (NCM523)/GPE/Li reaches 143.1 mAh g-1 after 100 cycles.

Electro-Spun P(VDF-HFP)/Silica Composite Gel Electrolytes for High-Performance Lithium-Ion Batteries

This work presents a facile way to fabricate a polymer/ceramics composite gel electrolyte to improve the overall properties of lithium-ion batteries. Lithium salt-grafted silica was synthesized and mixed with P(VDF-HFP) to produce a nanofiber film by the electrostatic spinning method. After coating a layer of SiO2 onto the surface of nanofibers through a sol-gel method, a composite nanofiber film was obtained. It was then immersed in plasticizer until saturation to make a composite gel electrolyte film. Electrochemical test results showed that the obtained gel electrolyte film shows high thermal stability (~450 °C), high ionic conductivity of 1.3 × 10-3 S cm-1 at 25 °C and a lithium-ion transference number of 0.58, and superior cycling stability, providing a new direction for manufacturing secondary batteries with higher safety and performance.

Fluorescent double network ionogels with fast self-healability and high resilience for reliable human motion detection

Fascinating properties are displayed by high-performance ionogel-based flexible strain sensors, thereby gaining increasing attention in various applications ranging from human motion monitoring to soft robotics. However, the integration of excellent properties such as optical and mechanical properties and satisfactory sensing performance for one ionogel sensor is still a challenge. In particular, fatigue-resistant and self-healing properties are essential to continuous sensing. Herein, we design a flexible ion-conductive sensor based on a multifunctional ionogel with a double network using polyacrylamide, amino-modified agarose, 1,3,5-benzenetricarboxaldehyde and 1-ethyl-3-methylimidazolium chloride. The ionogel exhibits comprehensive properties including high transparency (>95%), nonflammability, strong adhesion and good temperature tolerance (about -96 to 260 °C), especially adaptive for extreme conditions. The dynamic imine bonds and abundant hydrogen bonds endow the ionogel with excellent self-healing capability, to realize rapid self-repair within minutes, as well as good mechanical properties and ductility to dissipate input energy and realize high resilience. Notably, unexpected fluorescence has been observed for the ionogel because of the gelation-induced emission phenomenon. Flexible strain sensors prepared directly from ionogels can sensitively monitor and differentiate various human motions, exhibiting a fast response time (38 ms), high sensitivity (gauge factor = 3.13 at 800% strain), good durability (>1000 cycles) and excellent stability over a wide temperature range (-30 to 80 °C). Therefore, the prepared ionogel as a high-performance flexible strain sensor in this study shows tremendous potential in wearable devices and soft ionotronics.

Ionic Liquid-Based Electrolytes for Energy Storage Devices: A Brief Review on Their Limits and Applications

Since the ability of ionic liquid (IL) was demonstrated to act as a solvent or an electrolyte, IL-based electrolytes have been widely used as a potential candidate for renewable energy storage devices, like lithium ion batteries (LIBs) and supercapacitors (SCs). In this review, we aimed to present the state-of-the-art of IL-based electrolytes electrochemical, cycling, and physicochemical properties, which are crucial for LIBs and SCs. ILs can also be regarded as designer solvents to replace the more flammable organic carbonates and improve the green credentials and performance of energy storage devices, especially LIBs and SCs. This review affords an outline of the progress of ILs in energy-related applications and provides essential ideas on the emerging challenges and openings that may motivate the scientific communities to move towards IL-based energy devices. Finally, the challenges in design of the new type of ILs structures for energy and environmental applications are also highlighted.

Investigation on Electrochemical Performance of New Flexible Nanocomposite Poly(Vinylidene Fluoride-co-Hexafluoropropylene) Polymer Electrolytes

This research paper as an article investigates electrochemical performance of poly(vinylidene fluoride-co-hexafluoropropylene) (PVdF-co-HFP) flexible nanocomposite polymer electrolytes which have been prepared successfully with incorporation of zinc oxide (ZnO) nanofiller. First, nanofillers are incorporated in a polymer matrix to form the flexible nanocomposite PVdF-co-HFP polymer membranes (PI-CMPM), and it is obtained by phase inversion technique. Contact angles of PI-CMPM have achieved a maximum of 136°. After this procedure, it has been activated by using a 1.0 M LiClO4 containing of DMC/EC (1 : 1 v/v ratio) electrolyte solution to get flexible nanocomposite polymer electrolytes (PI-CMPE). The optimized PI-CMPM has increased the electrolyte uptake by 150%. It reaches the maximum ionic conductivity value of 2.47×10−3 S cm−1 at room temperature. Optimized PI-CMPE achieved a maximum transference number of 0.61, which may be further evidence for the ability to fabricate high-performance lithium ion polymer batteries.

Highly Conductive and Flexible Gel Polymer Electrolyte with Bis(Fluorosulfonyl)imide Lithium Salt via UV Curing for Li-Ion Batteries

A series of new self-standing gel polymer electrolytes (SGPEs) were fabricated by ultraviolet (UV) curing and investigated for application in flexible lithium-ion batteries. Compared with traditional gel polymer electrolytes (combine with solvents or plasticizers), these new SGPEs were prepared simply by curing different weight ratios of lithium bis(fluorosulfonyl)imide (LiFSI) with a methacrylic linear monomer, poly (ethylene glycol) dimethacrylate (PEGDMA). Noticeably, there were no solvents or plasticizers combined with the final SGPEs. Owing to this, the SGPEs showed high flexibility and strong mechanical stability. Some paramount physicochemical and electrochemical characters were observed. The SGPEs demonstrated good thermal stability below 150 °C and an extremely low glass transition temperature (T_g) (around −75 °C). Moreover, plastic crystal behaviors were also identified in this study. Ultimately, the SGPEs demonstrated excellent ionic conductivity at room temperature, which proves that these new SGPEs could be widely applied as a prospective electrolyte in flexible lithium-ion batteries.

Monochromatic "Photoinitibitor"-Mediated Holographic Photopolymer Electrolytes for Lithium-Ion Batteries

A new polymer electrolyte based on holographic photopolymer is designed and fabricated. Ethylene carbonate (EC) and propylene carbonate (PC) are introduced as the photoinert substances. Upon laser-interference-pattern illumination, photopolymerization occurs within the constructive regions which subsequently results in a phase separation between the photogenerated polymer and unreacted EC-PC, affording holographic photopolymer electrolytes (HPEs) with a pitch of ≈740 nm. Interestingly, both diffraction efficiency and ionic conductivity increase with an augmentation of the EC-PC content. With 50 wt% of EC-PC, the diffraction efficiency and ionic conductivity are ≈60% and 2.13 × 10-4 S cm-1 at 30 °C, respectively, which are 60 times and 5 orders of magnitude larger than the electrolyte without EC-PC. Notably, the HPEs afford better anisotropy and more stable electrochemical properties when incorporating N,N-dimethylacrylamide. The HPEs exhibit good toughness under bending, excellent optical transparency under ambient conditions, and astonishing capabilities of reconstructing colored images. The HPEs here open a door to design flexible and transparent electronics with good mechanical, electrical, and optical functions.