Co-solvent induced piezoelectric γ-phase nylon-11 separator for sodium metal battery. (April 2020)

• Record Type: Journal Article
• Authors: Tu, Nguyen Dien Kha; Park, Jaehyun; Na, Sangyun; Kim, Kwang Min; Kwon, Tae-Hyuk; Ko, Hyunhyub; Kang, Seok Ju
• Is Part Of: Nano energy. Volume 70(2020)
• Publication Date: 2020-04
• Subjects: Nylon-11 -- Crystalline phase -- Piezoelectric -- Separator -- Sodium battery; Nanoscience -- Periodicals; Nanotechnology -- Periodicals; Nanostructured materials -- Periodicals; Power resources -- Technological innovations -- Periodicals; Nanoscience; Nanostructured materials; Nanotechnology; Power resources -- Technological innovations; Periodicals; 621.042
• DOI: 10.1016/j.nanoen.2020.104501
• Languages: English
• ISSNs: 2211-2855

Abstract

Abstract: Nylon-11, the most studied member of the odd-numbered nylon family, is a promising functional material for future electronic devices or energy storage systems. To utilize nylon-11 in those applications, it is necessary to control the formation of the applicable metastable crystal phases such as the piezoelectric γ-phase or ferroelectric δ′-phase. Herein, we describe a facile method of fabricating metastable γ-phase nylon-11 fibers via electrospinning with a tailored solvent system. By using a solvent mixture of 1, 1, 1, 3, 3, 3-hexafluoro-2-propanol and trifluoroacetic acid [HFIP:TFA (75:25 mol%)], we could fully eliminate the formation of the most stable α-phase and create metastable γ-phase nylon-11 fibers. The electrospun γ-phase nylon-11 fibrous membrane displayed a typical piezoelectric response when it experienced a periodic external force. Furthermore, the γ-phase nylon-11 fibrous membrane exhibited higher thermal stability, electrolyte wettability, and ionic conductivity than the conventional Celgard separator. Consequently, it achieved decent performance when applied as a separator in a sodium metal half-cell. This study indicates that piezoelectric γ-phase nylon-11 fibrous membranes have great potential for further development in energy harvesting and storage, especially as piezo-separators in self-charging power cells. Graphical abstract: A facile way to produce the pseudo-hexagonal γ-phase nylon-11 nonwoven fibers by electrospinning process with tailored HFIP:TFA (75:25 mol%) solvent mixture was demonstrated. The non-woven mat type γ-phase nylon-11 fibrous membrane allows us to fabricate the piezoelectric device, exhibiting decent electrical output current densities under a periodic vertical pressure. Furthermore, γ-phase nylon-11 fibrous membrane provides stable electrochemical performance when being applied as separator in Na metal battery, suggesting its potential in the energy harvesting and storage fields. Image 1 Highlights: A metastable pseudo-hexagonal γ-phase Nylon-11 fibers was successfully fabricated using the tailored co-solvent system. The electrospun γ-phase Nylon-11 fibrous membrane exhibited a piezoelectric response under a periodic external pressure. The γ-phase Nylon-11 separator showed a decent Na metal battery performance.