Safe, Flexible, and High-Performing Gel-Polymer Electrolyte for Rechargeable Lithium Metal Batteries

Abstract

The use of gel polymer electrolytes (GPEs) is of great interest to build high-performing rechargeable lithium metal batteries (LMBs) owing to the combination of good electrochemical properties and improved safety. Herein, we report a facile and scalable one-pot preparation method of a GPE based on highly safe polyethylene glycol dimethyl ether (PEGDME) plasticizer in a poly­(vinylidenefluoride-co-hexafluoropropylene) (PVDF-HFP) polymer matrix. The prepared GPE exhibits excellent safety (nonflammability and thermal stability up to 250 °C) and outstanding electrochemical properties at room temperature (high ionic conductivity of 3.4 × 10–4 S cm–1 and high lithium transference number). Moreover, high loading LiFePO4 (6–7 mg cm–2) LMB using such GPE delivers a good C-rate response and high capacity (ca. 1 mAh cm–2 at C/10) with an excellent retention of 98% after 60 cycles in coin cell configuration. Notably, the prototype pouch cell (ca. 19 mAh at C/10) provides remarkable safety, mechanical flexibility, and strong tolerance toward bending and cutting. These results suggest that the prepared GPE is a promising candidate for the development of high performance, flexible, and safe LMBs that operate at room temperature, as well as for other energy storage systems beyond lithium-ion technologies.

Novel poly(epichlorohydrin)-based matrix for monolithic ionogel electrolyte membrane with high lithium storage performances

“…The MIEMs exhibit high ionic conductivities of 1.21 and 4.49 mS cm −1 at 20 and 70 °C, respectively, higher than those of the counterparts as reported in literatures. 5,42–47 This trend could be ascribed to the increase in the flexibility of the MIEM and faster diffusion of the ions with increasing temperatures. The ionic conductivity of LIBs should exceed 0.1 mS cm −1 in the working temperature ranges of 20–70 °C, and the MIEM prepared herein fulfilled this requirement.…”

“…[1][2][3] However, current commercial LIBs still using ammable organic solvents as the electrolyte components have unavoidable drawbacks such as ammability and leakage, which limit their further development, especially in exible and wearable devices. 4,5 In order to overcome these safety limitations, continual research efforts have been carried out for decades. Polymer-based electrolytes have been widely studied since Fenton et al 6 rst reported them in 1973.…”

Current Insight into 3D Printing in Solid‐State Lithium‐Ion Batteries: A Perspective

“…In some polymer electrolytes, lithium salts are solvated by the polymer chains, while in others, a solvent is added to form a polymer gel. [66] In general, the former is mechanically stronger, allowing for the formation of a free-standing film. Unlike polymer gels, which require mechanical support from other battery components, polymer gels have higher conductivities.…”

“…Polymer electrolytes provide advantages over ceramics in terms of processibility and flexibility while also retaining the advantages of solid electrolytes, such as dimensional stability and safety and the ability to prevent lithium dendrite formation. In some polymer electrolytes, lithium salts are solvated by the polymer chains, while in others, a solvent is added to form a polymer gel [66] . In general, the former is mechanically stronger, allowing for the formation of a free‐standing film.…”

Gel Polymer Electrolytes Based on Crosslinked Networks by the Introduction of an Ionic Liquid Crosslinker with Ethylene Oxide Arms

“…Gel polymer electrolytes (GPEs), which are composed of a polymer containing a large volume of a liquid ionic conductor, can be a compromise between liquid and solid electrolytes. , GPEs have high ionic conductivity and good interfacial contact, comparable with that of the liquid electrolytes while exhibiting a higher thermal stability than these electrolytes. In addition to the conventional liquid electrolytes, , ionic liquids are also employed as liquid ionic conductors owing to their high thermal stability and nonvolatility. , Several polymers such as poly­(vinylidene fluoride) and poly­(acrylonitrile) have been employed as ex situ polymers to hold the liquid ionic conductor in GPEs; , However, externally formed polymers have difficulty in enough contact with the uneven surface of electrodes, and then, it causes a higher interfacial resistance. On the other hand, an in situ polymer network, which is prepared by thermal crosslinking of a liquid-state precursor in a contact state with the electrode, can minimize the interfacial resistance.…”