Plasma-Assisted Surface Modification on the Electrode Interface for Flexible Fiber-Shaped Zn–Polyaniline Batteries

• Published in: ACS applied materials & interfaces Vol. 12; no. 5; pp. 5820 - 5830
• Main Authors: Yu, Hyunjin, Liu, Guicheng, Wang, Manxiang, Ren, Ren, Shim, Gayoung, Kim, Ji Young, Tran, Minh Xuan, Byun, Dongjin, Lee, Joong Kee
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 05.02.2020
• Subjects: electron cyclotron resonance O2-plasma treatment; fiber-shaped Zn−polyaniline battery; surface modification of carbon fibers; electrodeposition of polyaniline; high electrochemical performance
• ISSN: 1944-8244; 1944-8252
• DOI: 10.1021/acsami.9b19172

A novel flexible fiber-shaped zinc–polyaniline battery (FZPB) is proposed to enhance the electrochemical performance, mass loading, and stability of polyaniline cathodes. To this end, electron-cyclotron-resonance oxygen plasma-modified carbon fibers are employed. During plasma treatment, on the carbon-fiber surface, O2 + plasma breaks the C–C, C–H, and C–N bonds to form C radicals, while the O2 molecules are broken down to reactive oxygen species (O+, O2+, O2 +, and O2 2+). The C radicals and the reactive oxygen species are combined to homogeneously form oxygen functional groups, such as −OH, −COOH, and −CO. The surface area and total pore volume of the treated carbon fibers increase as the plasma attacks. During electrodeposition, aniline interacts with the oxygen functional groups to form N–O and N–H bonds and π–π stacking, resulting in a homogeneous and high-loading polyaniline structure and improved adhesion between polyaniline and carbon fibers. In an FZPB, the cathode with plasma-treated carbon fibers and a polyaniline loading of 0.158 mg mgCF –1 (i.e., 2.36 mg cmCF –1) exhibits a capacity retention of 95.39% after 200 cycles at 100 mA g–1 and a discharge capacity of 83.96 mA h g–1 at such a high current density of 2000 mA g–1, which are ∼1.67 and 1.24 times those of the pristine carbon-fiber-based one, respectively. Furthermore, the FZPB exhibits high flexibility with a capacity retention of 86.4% after bending to a radius of 2.5 mm for 100 cycles as a wearable energy device.