Zinc Storage Mechanism in Polypyrrole Electrodeposited from Aqueous, Organic, and Ionic Liquid Electrolytes: An In Situ Raman Spectroelectrochemical Study

Abstract

Zinc-ion batteries (ZIBs) are emerging as cheap and safe alternatives to lithium-ion batteries (LIBs). However, due to the divalent nature of Zn ions, it is a challenge to choose suitable cathode materials for ZIBs. Conductive polymers are regarded as promising materials for zinc storage. However, little has been understood regarding the Zn storage mechanism, thereby making it difficult to rationally modify the polymer to improve its performance and stability. In the present study, polypyrrole (PPy) was electrochemically deposited from aqueous, organic, and ionic liquid electrolytes, and the Zn storage mechanism was investigated in PPy using electrochemical methods, X-ray photoelectron spectroscopy (XPS), and in situ Raman spectroscopy. From in situ Raman spectroscopy, it was observed that Zn storage in PPy electrodeposited from ionic liquid took place by a shrinking and stretching mechanism (structural change), whereas a phase transformation mechanism was observed for PPy electrodeposited from aqueous and organic electrolytes. The change in Zn storage mechanisms led to different initial capacities of PPy deposited from different electrolytes. The initial capacity of PPy deposited from 1-ethyl-3-methylimidazolium bis­(trifluoromethylsulfonyl)­amide ([EMIm]­TFSI) can achieve 126 mAh g–1 and the PPy deposited from 1-ethyl-3-methylimidazolium trifluoromethylsulfonate ([EMIm]­TfO) can reach 90 mAh g–1, which is higher than 75 mAh g–1 for the PPy deposited from acetonitrile and 20 mAh g–1 for the PPy deposited from aqueous solution. Furthermore, XPS results showed that an insignificant amount of zinc was trapped in the PPy deposited from [EMIm]­TFSI after 100 charge–discharge cycles. Therefore, the PPy deposited from [EMIm]­TFSI showed better cycling stability, after 100 cycles. The different zinc storage mechanisms of PPy from different electrolytes offer possibilities to improve the cycling stability for a Zn/PPy battery by modulating the electrode and electrolyte compositions.

Construction of Selective Ion Transport Polymer at Anode–Electrolyte Interface for Stable Aqueous Zinc-Ion Batteries

“…397.8 eV). 40,41 After the plating process, the intensity of the Zn−N peak increases obviously, which demonstrates that the zinc ions combined with the Ndoped heterocycles in DA-PPy. The O 1s spectrum shows three peaks related to C−O (ca.…”

Magnetic Core@Shell Fe3O4@Polypyrrole@Sodium Dodecyl Sulfate Composite for Enhanced Selective Removal of Dyestuffs and Heavy Metal Ions from Complex Wastewater

“…The total spectrum shows that there are S, C, N, O, and Na elements at 168.08, 284.08, 400.08, 531.08, and 1071.08 eV, respectively (Figure e). The C 1s spectrum shown in Figure f has four characteristic peaks, including C–C and C–N peaks at 284.88 and 285.48 eV, respectively, and C–O and COOH peaks, respectively, at 287.68 and 290.88 eV, corresponding to the moisture in the air. ,, The N 1s spectrum shown in Figure g is divided into three different states of 398.48, 400.28, and 401.58 eV assigned to C–N, −NH–, and −N + , respectively. Figure h reveals the three main peaks of the O 1s spectrum at 531.48, 532.68, and 533.78 eV of C–O, bound oxygen, and −OH, respectively.…”

Compressible zinc‐ion hybrid supercapacitor and piezoresistive sensor based on reduced graphene oxide/polypyrrole modified melamine sponge

“…The proposed dual‐ion charge storage mechanism of PPy is schematically illustrated in Figure S4d, that is, the insertion/release of SO 4 2− and Zn 2+ during the charging/discharging processes, respectively. [ 21 ] The results indicate that PPy should be a promising positive electrode material in ZHS because it can provide charge storage capacity by accommodating anions and cations.…”

“…Polypyrrole (PPy) is an important conducting polymer, which has been considered an attracting electrode material owing to its high theoretical specific capacitance (620 F g À1 ), good electrical conductivity, easy synthesis, and low cost. [21,22] Compositing carbon materials with PPy has proven to be an effective strategy to enhance the electrochemical performance of electrodes. [23][24][25] Herein, MS is modified by coating rGO on its skeleton and followed by loading PPy to fabricate the compressible positive electrode (PPy/rGO@MS) in this work.…”