Interconnected Hollow Porous Polyacrylonitrile-Based Electrolyte Membrane for a Quasi-Solid-State Flexible Zinc–Air Battery with Ultralong Lifetime

Abstract

Quasi-solid-state flexible zinc–air batteries (FZABs) have received enormous attention due to their low cost and high safety. However, the constraints in lifetime resulting from the lack of stable quasi-solid-state electrolyte membranes and efficient bifunctional electrocatalysts toward oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) hinder the large-scale manufacture and commercialization of FZABs to power electric devices. Herein, a polyacrylonitrile (PAN)-based membrane (HPPANP) fabricated via facile coaxial electrospinning, water dissolution, lyophilization, and KOH preimmersion method was utilized as the quasi-solid-state electrolyte membrane. The interconnected hollow porous structure based on PAN nanofibers endows HPPANP with outstanding electrolyte-uptake/retention capabilities for high ionic conductivity and nanolevel wetted electrolyte/anode interface for uniform Zn dissolution/deposition, thus prolonging the lifespan of the FZABs. In addition, the in situ alkaline hydrolysis of KOH solution supplies HPPANP with abundant oxygen-containing groups, which also improves its ionic conductivity. Additionally, we synthesized a Co/N-doped hollow carbon sphere (CoN-CS) electrocatalyst that exhibits superior ORR and OER electrocatalytic activities with a low potential difference (ΔE) of 0.73 V. Such favorable ORR and OER performances can be mainly attributed to the hierarchical hollow micro/nanostructures with abundant active sites, long-term stability, and favorable electron/ion diffusion pathway. As a result, the assembled FZAB equipped with the CoN-CS catalyst and HPPANP displays high power density (123.8 mW cm–2) and preferable long-term cycling performance (more than 50 h at 3 mA cm–2).

Electrode|electrolyte interface enhancement in quasi-solid-state zinc–air batteries through an anion conducting polymer electrolyte interlayer by in situ polymerization

“…Overall, in terms of the performance based on a few key indicators, the current system shows distinct advantages over the previously reported AEPEM-based ZAB systems in the literature (Table S3 †), with a clear novelty in the present case of having the in situ generated ionomer buffer layer as a means to extend the active interface at the cathode. 21,40,48,50 The choice of the catalyst for the demonstration of the present strategy is not limited only to the Pt/C-RuO 2 catalyst pair; instead, many other 3D-structured bifunctional electrocatalysts could also be suitable.…”

“…S9a†), which is significantly low for commercial applications and approximately four-fold lower than the specific capacity value achievable in earlier reported liquid electrolyte-based ZABs. 48 This is the major bottleneck in the case of replacing the liquid electrolyte with quasi-solid-state systems because the solid electrolyte fails to form an effective interface with the electrode and substantially reduces catalyst utilization, and builds up an overpotential. Also, a careful analysis of the discharge plot presented in Fig.…”

Enhanced zinc reversibility enabled by zinc–bromide complexation of a quasi-solid electrolyte for high-performance flexible zinc–air batteries

“…4h, Tables S1 and S2 †). 31,[45][46][47][48][49][50][51][52][53][54] The cycling stability of FZABs assembled with PAM/CS-BT-KBr under different operating conditions has also been tested, as presented in Fig. 4i.…”

Flexible Solid‐State Metal‐Air Batteries: The Booming of Portable Energy Supplies

“…Metal foils, such as Zn, Al, and Mg foil, provide decent electrochemical stability under deformation and can be directly applied as metal anodes of FSSMABs in most cases. To achieve a higher degree of flexibility, one common approach is to electrodeposit metals on flexible substrates such as carbon cloth [39,46c] or carbon fiber [59b,80] . Under certain practical application scenarios, FSSMABs are required to be fully flexible and capable of enduring dynamic deformation.…”