Versatile, Adaptable, and Stretchable Electrochromic Energy Storage Systems

ABSTRACT Electrochromic energy storage devices (EESDs) have emerged as innovative technologies in energy storage and smart materials, generating considerable interest for numerous applications, such as wearables, smart windows, and color‐changing sunglasses. EESDs consist of two primary categories: electrochromic supercapacitors (ESCs) and electrochromic batteries (ECBs). These devices are particularly appreciated for their multifunctional features, which allow them to alter color in response to different charge densities. The performance and efficiency of EESDs rely on three essential components: (I) the current collector or substrate (cc/substrate), which serves as the conductive base for the device; (II) the electrolyte, which supports ion movement and improves overall electrochemical performance; and (III) the electrochromic materials (ECMs), responsible for the color changes and energy storage functions. Careful selection and optimization of these components are crucial for enhancing the devices' efficiency, stability, and lifespan. Advanced flexible and stretchable EESDs have shown significant potential. Their natural flexibility facilitates seamless incorporation into curved surfaces and diverse shapes, making them especially suitable for wearable technologies and other cutting‐edge applications. However, this flexibility also brings challenges, including concerns related to delamination, material dissociation, and degradation over time. A thorough investigation of materials for flexible EESDs is essential for progressing energy conversion and storage systems. Grasping these materials is vital for creating sustainable energy solutions and improving smart capabilities.