Self‐supported VO2 on polydopamine‐derived pyroprotein‐based fibers for ultrastable and flexible aqueous zinc‐ion batteries

• Published in: Carbon energy Vol. 6; no. 7
• Main Authors: Yeon, Jeong Seok, Park, Sul Ki, Kim, Shinik, Mohite, Santosh V., Il Kim, Won, Jang, Gun, Jang, Hyun‐Seok, Bae, Jiyoung, Lee, Sang Moon, Hong, Won G., Kim, Byung Hoon, Kim, Yeonho, Park, Ho Seok
• Format: Journal Article
• Language: English
• Published: Beijing John Wiley & Sons, Inc 01.07.2024; Wiley
• Subjects: Adhesive strength; Adhesives; aqueous battery; binder free; Binders; Carbon; conducting agent‐free; Dopamine; Electrical conductivity; Electrical resistivity; Electrochemical analysis; Electrochemistry; Electrode materials; Electrodes; Electrolytes; Electrons; Energy storage; Fibers; flexible electrode; Metals; Microscopy; Polymerization; Power sources; Reagents; Rechargeable batteries; Spectrum analysis; Substrates; Vanadium oxides; Voltammetry; Zinc; zinc‐ion battery
• ISSN: 2637-9368; 2637-9368
• DOI: 10.1002/cey2.469

A conventional electrode composite for rechargeable zinc‐ion batteries (ZIBs) includes a binder for strong adhesion between the electrode material and the current collector. However, the introduction of a binder leads to electrochemical inactivity and low electrical conductivity, resulting in the decay of the capacity and a low rate capability. We present a binder‐ and conducting agent‐free VO2 composite electrode using in situ polymerization of dopamine on a flexible current collector of pyroprotein‐based fibers. The as‐fabricated composite electrode was used as a substrate for the direct growth of VO2 as a self‐supported form on polydopamine‐derived pyroprotein‐based fibers (pp‐fibers@VO2(B)). It has a high conductivity and flexible nature as a current collector and moderate binding without conventional binders and conducting agents for the VO2(B) cathode. In addition, their electrochemical mechanism was elucidated. Their energy storage is induced by Zn2+/H+ coinsertion during discharging, which can be confirmed by the lattice expansion, the formation of by‐products including Znx(OTf)y(OH)2x−y·nH2O, and the reduction of V4+ to V3+. Furthermore, the assembled Zn//pp‐fibers@VO2(B) pouch cells have excellent flexibility and stable electrochemical performance under various bending states, showing application possibilities for portable and wearable power sources. The developed current collector‐free pp‐fibers@VO2(B) cathode exhibits a high specific capacity, excellent rate capability, and an invisible capacity fading rate of 0.001% per cycle after even 20,000 cycles. The reversible H+/Zn2+ cointercalation mechanism on the cathode surface during cycling has a high capacity by providing an abundant Zn2+ storage site.