Flexing the Spectrum: Advancements and Prospects of Flexible Electrochromic Materials.

The application potential of flexible electrochromic materials for wearable devices, smart textiles, flexible displays, electronic paper, and implantable biomedical devices is enormous. These materials offer the advantages of conformability and mechanical robustness, making them highly desirable for these applications. In this review, we comprehensively examine the field of flexible electrochromic materials, covering topics such as synthesis methods, structure design, electrochromic mechanisms, and current applications. We also address the challenges associated with achieving flexibility in electrochromic materials and discuss strategies to overcome them. By shedding light on these challenges and proposing solutions, we aim to advance the development of flexible electrochromic materials. We also highlight recent advances in the field and present promising directions for future research. We intend to stimulate further innovation and development in this rapidly evolving field and encourage researchers to explore new opportunities and applications for flexible electrochromic materials. Through this review, readers can gain a comprehensive understanding of the synthesis, design, mechanisms, and applications of flexible electrochromic materials. It serves as a valuable resource for researchers and industry professionals looking to harness the potential of these materials for various technological applications.

Revealing Phase Transition in Ni-Rich Cathodes via a Nondestructive Entropymetry Method.

With the expanding requirements of recent energy regulations and economic interest in high-performance batteries, the need to improve battery energy density and safety has gained prominence. High-energy-density lithium batteries, employed in next-generation energy storage devices, rely on nickel-rich cathode materials. Since they have extremely high charge/discharge capacity, high operating voltage, prolonged cycle life, and lower cost, nickel-rich cathode materials such as Ni-rich NCM (LiNix > 0.8CoyMnzO2) and Ni-rich NCA (LiNix > 0.8CoyAlzO2) are of particular interest to researchers. Several in situ characterization methodologies are currently used to understand lithium-ion battery electrode response and deterioration better. Nevertheless, in many contexts, these measurement methodologies must be combined with specially designed cells and electrode materials with distinct forms, which is sometimes inconvenient. As an alternative, thermo-voltammetric dynamic characterization may be utilized to describe the thermal internal characteristics of various electrode materials, such as the structural changes and electrode reactions that occur during charging and discharging. In this paper, a nondestructive entropy measurement method demonstrates that phase change occurs for NCM (LiNi0.83Co0.12Mn0.05O2) and NCA (LiNi0.88Co0.09Al0.03O2) at 40-30% of state of charge (SOC) and 90-80% of SOC, respectively. This is confirmed by ex situ X-ray diffraction (XRD) measurements for these highly popular cathodes.