In situ XRD and operando spectra-electrochemical investigation of tetragonal WO3-x nanowire networks for electrochromic supercapacitors

• Published in: NPG Asia materials 2021-07, Vol.13 (1), Article 51
• Main Authors: Wang, Shen, Xu, Hongbo, Hao, Tingting, Wang, Peiyuan, Zhang, Xiang, Zhang, Hongming, Xue, Junying, Zhao, Jiupeng, Li, Yao
• Format: Article
• Language: English
• Subjects: 140/133; 140/146; 639/301/299/161; 639/638/161; Biomaterials; Chemistry and Materials Science; Cycles; Electrochemical analysis; Electrochromism; Energy storage; Energy Systems; Fluorine; Intercalation; Materials Science; Modulation; Nanowires; Optical and Electronic Materials; Reaction mechanisms; Structural Materials; Supercapacitors; Surface and Interface Science; Thin Films; Tin oxides; Vanadium pentoxide
• ISSN: 1884-4049; 1884-4057
• DOI: 10.1038/s41427-021-00319-7

Electrochromic supercapacitors (ESCs) are appealing for smart electronic device applications due to their advantages of dual-function integration. Unfortunately, the synchronous dual-function evaluation and the essential reaction mechanism are ambiguous. Herein, we constructed a 3D WO 3-x nanowire networks/fluorine-doped tin oxide (WO 3-x NWNs/FTO) bifunctional electrode for ESCs by a solvothermal self-crystal seeding method. The synchronous correspondence relationship between the optical and electrochemical performances of the WO 3-x NWNs/FTO electrode was explored using an operando spectra-electrochemical characterization method. It reveals an excellent areal capacity of 57.57 mF cm −2 with a high corresponding optical modulation (ΔT) of 85.05% and high optical-electrochemical cycling stability. Furthermore, the synergistic reaction mechanism between the Al 3+ ion intercalation behavior and the surface pseudocapacitance reaction during electrochemical cycling is revealed utilizing in situ X-ray diffraction. Based on these results, an ESC device was constructed by pairing WO 3-x /FTO as the cathode with V 2 O 5 nanoflowers/FTO (V 2 O 5 NFs/FTO) as the anode, which simultaneously deliver high capacity and large optical modulation. Moreover, the energy storage level of the ESC device could be visually monitored by rapid and reversible color transitions in real time. This work provides a promising pathway to developing multi-functional integrated smart supercapacitors. The synchronous correspondence relationship between the optical and charge storage performances, and the synergistic intrinsic mechanism between the Al 3+ ion intercalation and the surface pseudocapacitance reaction affecting the electrochromic-energy storage performance are revealed using in-situ/operando techniques.