Intercalation Mechanism of Surfactants in Vanadium Pentoxides Interlayer Framework for Improving Electrochemical Performance of Zinc Metal Batteries

Abstract

Zinc metal batteries have aroused great discussion among researchers because of their advantages of abundant resource reserves, environmental protection, and inexpensive. At low current densities, the vanadium-based cathode materials in zinc metal batteries exhibit poor rate performance, slow diffusion of Zn²⁺, and easy structural collapse severely hinder their industrial practical applications. Hence, there is an urgent need to find a method to stabilize the microstructure and orderly coordinate insertion/extraction of Zn²⁺ on the vanadium-based cathode. Surfactants have abundant hydrophilic groups and hydrophobic groups, which makes them as additives to maintain the stability of the main system. In this paper, polyethylene glycol, sodium dodecyl benzene sulfonate, and hexadecyl trimethyl ammonium bromide were chosen as non-ionic, anionic, and cationic surfactants, respectively. They were inserted into the interlayer skeleton of vanadium pentoxide using hydrothermal method and heat treatment (in air), and the intercalation mechanisms of different surfactants in vanadium pentoxide cathode material is investigated. Among them, polyethylene glycol is cross inserted in the form of molecules, and compared with the other two surfactants, the cathode has outstanding electrochemical properties and stable structure, while also increasing the transfer rate of Zn²⁺. In particular, after adding polyethylene glycol, an excellent rate capability of 342.3 mA h g^-1 was achieved at a low current density of 0.2 A g^-1. Moreover, even when the current density reaches 5.0 A g^-1, it is able to sustain an excellent capacity of 173.8 mA h g^-1. After 700 cycles, it also maintains a good capacity retention rate.