Coordination Nanosheet-Based Electrochromic Supercapacitor with High Energy Storage, Switching Durability, and Long Optical Memory Properties

Susmita Roy; Sayan Halder; Sarda Sharma; Karumbaiah N Chappanda; Chanchal Chakraborty; Masayoshi Higuchi

doi:10.1021/acsami.5c13795

Coordination Nanosheet-Based Electrochromic Supercapacitor with High Energy Storage, Switching Durability, and Long Optical Memory Properties

ACS Appl Mater Interfaces. 2025 Nov 12;17(45):62499-62509. doi: 10.1021/acsami.5c13795. Epub 2025 Oct 29.

Authors

Susmita Roy^{1

2}, Sayan Halder¹, Sarda Sharma³, Karumbaiah N Chappanda⁴, Chanchal Chakraborty^{1

5}, Masayoshi Higuchi²

Affiliations

¹ Department of Chemistry, Birla Institute of Technology & Science (BITS) Pilani, Hyderabad Campus, Jawaharnagar, Samirpet, Hyderabad, Telangana 500078, India.
² Electronic Functional Macromolecules Group, National Institute for Materials Science (NIMS), 1-1 Namiki, Tsukuba 305-0044 ,Japan.
³ Department of Electronics and Communication Engineering, Amrita School of Engineering, Bengaluru, Amrita Vishwa Vidyapeetham, Bengaluru 560035, India.
⁴ Sensors and Nano Electronics (SANE) Lab, School of Applied Engineering and Technology, Southern Illinois University Carbondale, Carbondale, Illinois 62901, United States.
⁵ Materials Center for Sustainable Energy & Environment (McSEE), Birla Institute of Technology and Science, Hyderabad Campus, Hyderabad 500078, India.

Abstract

Electrochromic (EC) supercapacitors have attracted considerable attention as energy storage systems integrated with optical functions. EC supercapacitors with high-performance and long-term optical memory properties were successfully fabricated by a combination of coordination nanosheets (CONASH), composed of Fe(II) ions and a tristerpyridine ligand having a nonconjugated linker, and nickel hexacyanoferrate (NiHCF) as a redox-complementary counter material. The EC supercapacitor exhibited EC changes between purple and pale yellow with large optical contrast (57.4% at 556 nm), short switching times (1.28/1.69 s), exceptionally high coloration efficiency (619 cm² C^-¹), significantly small energy consumption (3.6 mJ/cm²), and excellent EC switching stability of more than 50,000 cycles. The EC supercapacitor also demonstrated high volumetric capacitance (248.1 F/cm³), energy density (29.37 mW h/cm³), and power density (7.5 W/cm³), maintaining stable performance over 40,000 galvanostatic charge-discharge cycles. Most notably, the device showed a drastically reduced self-discharge property as only 33% optical contrast was returned after 36 h under open-circuit conditions, paving the way for an efficient energy storage solution by exploiting the long optical memory of the device. Combining superior EC functionality with robust supercapacitive performance, this study offers a foundation for sustainable energy technology.

Keywords: coordination nanosheets; electrochromic supercapacitor; metallo-supramolecular polymers; optical memory; redox-complementary counter material.