In situ Synthesis of Gel Polymer Electrolytes for Lithium Batteries

Abstract

Gel polymer electrolytes (GPEs) are considered as a promising solution to replace organic liquid electrolytes for safer lithium (Li) batteries due to their high ionic conductivity comparable to liquid electrolytes, no risk of leakage, and high flexibility. However, poor interfacial contact between electrodes and GPEs leads to high interfacial impedance and unsatisfactory electrochemical performance. The emerging in situ synthesized GPEs can fully infiltrate into porous electrodes and form intimate interfaces, improving interfacial contact and electrochemical performance. This perspective covers recent advances of in situ GPEs in design, synthesis, and applications in lithium (Li) batteries. Polyester and polyether-based GPEs are mainly discussed followed by a brief introduction of GPEs with other polymer matrices, such as poly(ionic liquid)s, cyanoethyl polyvinyl alcohol, poly(vinyl acetal) and single-ion conductors. Then, the recent progress in Li batteries using in situ GPEs are summarized, including Li-ion battery, Li-metal battery, Li-sulfur battery, and Li-air battery. Finally, the remaining challenges and future perspectives of in situ GPEs are discussed. We hope this perspective can offer guidance for in situ synthesis of GPEs and facilitate their applications in high-performance Li batteries.

In-situ Crosslinked Gel Polymer Electrolytes Based on Ionic Monomers as Charge Carriers for Lithium-Ion Batteries

“…34 On the other hand, the vast majority of research articles on in-situ polymerized GPEs, where the gelation occurs following cell assembly, include conventional lithium salt in the formulation and thus also frequently achieve ionic conductivities of ∼10 -3 S cm −1 . 35,36 The number of examples of true in-situ polymerized gel electrolytes lacking conventional salt is limited. In fact, a number of so-called in-situ polymerized GPEs involve polymerization inside of the separator but outside of the coin cell, sometimes so UV-light can be leveraged for quick gelation; 37,38 application of that approach for large-scale LIB manufacturing would demand sufficient mechanical properties of the GPE for assembly.…”

Applications of Polymer Electrolytes in Lithium-Ion Batteries: A Review

“…The resulting GPEs exhibit improved ionic conductivity, mechanical stability, electrochemical stability, and compatibility with electrode materials. Additionally, in situ chemical methods enable the fabrication of GPEs directly within the battery system, ensuring good contact and compatibility with the electrodes [88][89][90].…”