Improving the stability of poly(arylene piperidinium)-based membranes by capturing free radicals with the crosslinker of aminated lignin

The stability of ionic conducting membranes is a crucial concern for using as the electrolyte in electrochemical devices. Herein, aminated lignin (AL) is used as the cross-linker and free radical scavenger to enhance the properties of anion exchange membranes (AEMs) based on quaternized poly (terphenyl piperidinium-co-trifluoroacetophenone) (QPTPT). The prepared membranes achieve a hydroxide conductivity of 112 mS cm−1 and a proton conductivity of 210 mS cm−1 at 80 °C. The presence of AL obviously improves the resistance of the AEMs to the attack of both OH− ions and free radicals. A conductivity retention rate of about 80 % is achieved by the prepared membranes after soaking in 2 mol L−1 KOH solutions at 80 °C for 1500 h. Meanwhile, the retained tensile stress at break of these aged membranes is within the range of 26 to 37 MPa. The amphoteric water electrolytic cell using the proposed membrane as the diaphragm achieves a current density of 954 mA cm−2 under 2 V at 80 °C. This electrolytic cell can work stably at a current density of 100 mA cm−2 at 20 °C for 83 h with an initial energy consumption of 2.8 kWh m−3 for hydrogen production.