Conjugated System of PEDOT:PSS-Induced Self-Doped PANI for Flexible Zinc-Ion Batteries with Enhanced Capacity and Cyclability

Abstract

Owing to its electronic conductivity and electrochemical reactivity, polyaniline (PANI) can serve as the cathode for rechargeable zinc-ion batteries (ZIBs). However, it suffers from fast deactivation and thus performance deterioration because of spontaneous deprotonation during charge/discharge. Here, we report an effective strategy to improve the electrochemical reactivity and stability of the PANI-based cathode by constructing a π-electron conjugated system between PANI and poly­(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) on carbon nanotubes (CNTs). The impressive performance of the post-treated CNTs–PANI–PEDOT:PSS (t-CNTs–PA–PE) cathode is largely attributed to the −SO3 –H+ groups in PSS, which acts as an internal proton reservoir and provides enough H+ for PANI’s protonation, thus promoting its electrochemical activity and reversibility. Besides, the strong interactions between PANI and PEDOT:PSS assist the stretching of π–π conjugation chains, bringing about enhanced electronic conductivity. Consequently, the t-CNTs–PA–PE cathode achieves a high capacity of 238 mA h g–1, together with good rate capability and long-term stability (over 1500 cycles with 100% Coulombic efficiency). Through exerting the freestanding t-CNTs–PA–PE, a flexible ZIB was further constructed with both outstanding electrochemical properties and superior high safety. This work demonstrates the availability of conducting polymer cathodes for high-performance ZIBs, fulfilling the need of flexible electronics.

Design Strategies for High‐Performance Aqueous Zn/Organic Batteries

“…[52][53][54][55][56] They often display bipolar-type redox chemistry in aqueous ZIBs.Inthe case of Zn/PANI batteries, Zn 2+ could serve as the cation species associated with the imine-related redox reaction, while the counter anions will participate in the reaction between the =NH + -a nd -NHmoieties during charge/discharge processes.A lthough they often deliver limited specific capacity (< 200 mAh g À1 )due to their low available doping level, they usually display more stable electrochemical performance in comparison with other most previous reported cathode materials.A saresult, they were usually utilized to act as the electrodes of flexible ZIBs with various configurations. [57][58][59][60][61][62] Thee lectrochemical performance of conductive polymers could be further improved by the optimization of electrolyte, [27,63] hybridization with inorganic materials, [28,[64][65][66][67] morphology regulation [68] and copolymerization. [38,[69][70][71] Forinstance,the conductive polymers could be intercalated into the interlayers of metal oxides to effectively eliminate the structural changes of them during discharge/charge processes,r esulting in excellent rate capability and long cycling life.…”

“…Although they often deliver limited specific capacity (<200 mAh g −1 ) due to their low available doping level, they usually display more stable electrochemical performance in comparison with other most previous reported cathode materials. As a result, they were usually utilized to act as the electrodes of flexible ZIBs with various configurations [57–62] . The electrochemical performance of conductive polymers could be further improved by the optimization of electrolyte, [27, 63] hybridization with inorganic materials, [28, 64–67] morphology regulation [68] and copolymerization [38, 69–71] .…”

Aqueous Rechargeable Zn‐ion Batteries: Strategies for Improving the Energy Storage Performance

“…The cathode materials for ZIB developed in the past few years can be broadly classified into four major categories (Figure 2a): manganese-based materials, [32][33][34][35][36][37][38][39][40][41][42][43][44][45][46][47][48] Prussian blue analogs, [49][50][51][52][53][54][55] vanadium-based materials, and organic redox molecules. [92][93][94][95][96][97][98][99][100][101][102][103] Other materials like cobalt oxide (Co 3 O 4 ), [104,105] carbon, [106,107] and MXene [108,109] have also been studied in the recent past as cathode.…”

“…[96] Conducting polymers, such as, polyaniline (PANI), polypyrrole (PPy), poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) are also used as efficient cathode materials of the ZIB. [99][100][101] Recently, the porous covalent organic frameworks (COFs) have also been examined for ZIB applications as they have a large surface area and selfassembled π-π stacking. The Zn 2 + binding sites of COFs make them suitable for ZIB application.…”

Intrinsically conducting polymers and their combinations with redox-active molecules for rechargeable battery electrodes: an update

“…More than 1000 cycles were recorded. PEDOT:PSS was used as proton source for pH-management in PANI as positive electrode in a flexible zinc-ion battery keeping about 80% of its initial capacitance after 1500 cycles (Liu et al 2019a). A flexible, all-in-one solid-state zinc-ion battery with a composite of PANI and reduced graphene oxide with a solid electrolyte has been described (Zhang et al 2019b).…”