Single Radiation‐Induced Grafting Method for the Preparation of Two Proton‐ and Lithium Ion‐Conducting Membranes

Abstract

Summary: Two distinct types of polymer electrolyte membranes for conducting protons and lithium ions have been prepared by a radiation‐induced grafting method. The polymer electrolyte precursor (PVDF‐g‐PS) is obtained by the simultaneous grafting of styrene onto poly(vinylidene fluoride) (PVDF) followed by one of two specific treatments. This includes sulfonation with a chlorosulfonic acid/dichloromethane mixture to obtain proton (H+)‐conducting membranes, or activation with LiPF6/EC/DC liquid electrolyte to obtain lithium ion (Li+)‐conducting membranes. The chemical structure of the obtained electrolyte membranes is verified by FT‐IR spectroscopy. Differential scanning calorimetry is used to examine the changes in the crystallinity and the thermal properties of both electrolyte membranes during the preparation process. The thermal stability of both electrolyte membranes is also evaluated using thermal gravimetrical analysis. The obtained polymer electrolyte membranes achieve superior conductivity values: 1.61 × 10−3 S · cm−1 for Li+ and 5.95 × 10−2 S · cm−1 for H+ at room temperature at a polystyrene content of 50%. The results of this work suggest that high quality H+‐ and Li+‐conducting membranes can be obtained using a single radiation‐induced grafting method.Schematic representation of the single root for preparation of Li+‐ and H+‐conducting membranes started by radiation‐induced grafting of styrene onto a PVDF film followed by chemical treatment.magnified imageSchematic representation of the single root for preparation of Li+‐ and H+‐conducting membranes started by radiation‐induced grafting of styrene onto a PVDF film followed by chemical treatment.

Preparation of polystyrene-grafted poly(vinylidene fluoride) membranes for lithium secondary batteries

“…The ionic conductivities of PVDF-g-PS membranes increased with the increase in the DOG. This behavior can be generally attributed to the increase in the amorphous polystyrene layer, which can hold more liquid electrolyte with increase in the DOG [7][8][9]. The ionic conductivity reached 2.50 mS/cm for the highest sample at 120% DOG.…”

“…3, the degree of crystallinity was found to decrease with increase in the DOG. The reduction in the degree of crystallinity upon grafting of styrene can be attributed to the dilution of the crystalline PVDF with the amorphous polystyrene [7][8][9]. Fig.…”

“…Although fluoropolymers exhibit relatively good chemical and electrochemical stability, their performance such as electrolyte uptake need to be improved by the use of a grafted copolymerization technique [7][8][9][10][11][12][13]. Graft copolymerization can be achieved by several methods including UV radiation, use of chemical initiator, plasma treatment, and highenergy radiation.…”

“…This technique has many advantages: (i) the polymerization proceeds mildly and thoroughly; (ii) the chemistry of the reaction system is free of contamination; (iii) and the energy consumption is relatively low. Such a versatile nature of this technique is attributed to the ability to control the degree of grafting by proper selection of irradiation conditions [7][8][9][10][11][12][13].…”

Influence of Radiation‐Induced Grafting Process on Mechanical Properties of ETFE‐Based Membranes for Fuel Cells

“…while the chain flexibility of the second type (shell of crystallites, which is grafted) is restricted even if it is assumed that the most of the grafting occurs in the amorphous zone of the base film ( Figure 10) [33]. In addition, it is expected that the brittleness of the grafted films and the resulting membranes increases with the DVB content.…”