Optimization strategies for flexible aqueous rechargeable sodium-ion batteries (ARSIBs)

Flexible aqueous rechargeable sodium-ion batteries (ARSIBs) have emerged as promising energy storage systems for flexible and wearable electronics due to their safety, eco-friendliness, flexibility, and low cost, especially for large-scale and high-throughput storage needs. However, the design of flexible ARSIBs with high performance and excellent mechanical performance still faces challenges including the structural stability of electrodes, narrow electrochemical stability window of electrolytes, various side reactions, and structural design. It is urgent to design and develop ARSIBs with superior electrochemical performance, excellent mechanical performance and broader application scenarios. While there have been numerous reviews on sodium-ion batteries, there is a scarcity of exclusive reviews focusing on flexible ARSIBs. This review systematically introduces the advancements in electrode materials, electrolytes, and their optimization strategies for flexible ARSIBs. In addition, the recent advancements of batteries are discussed in terms of design strategies, multifunctional applications, and damage resistance. To manufacture flexible ARSIBs with coordinated high energy density and multi-functionality, not only the active materials and electrolytes should be optimized, but also the structural design should be improved. This review aims to evaluate the challenges and future prospects, and offer valuable references for designing advanced and high-performance flexible ARSIBs.