Recent Progress in Functional Hydrogel Electrolyte-Based Flexible Lithium-Ion Batteries: Preparation, Modifications, Fabrication, and Applications

In today’s fast-paced world, electronic devices possess multi-functionality and flexibility to keep up with the demands of modern life. This ensures convenience and high-quality performance. To achieve this goal, developers focus on developing energy reservoirs that are both wearable and flexible. Today, aqueous lithium-ion batteries (LIBs) have emerged as highly promising options for wearable electronics due to their impressive electrochemical performance, ability to control their function, and affordability. Polymer hydrogel electrolytes (HEs) are introduced and designed to enhance the functionalities of traditional LIBs. This review examines functional HEs and their potential use in LIBs. Characteristics such as mechanical strength, temperature adaptability, flexibility, and electrochemical stability of HEs for LIBs are evaluated. These findings contribute to the development of cell-level LIBs that utilize multifunctional HEs. The structure, ionic conductivity, and properties of HEs are also examined. This review discusses different HEs in LIBs, highlighting that HE batteries are our future, in the end, a comprehensive summary is provided for these examples, along with a thorough evaluation of the challenges, alternatives to lithium like sodium-ion batteries (SIB) and aqueous zinc-ion batteries, why they are a better alternative, and prospects for functional LIBs and HEs.