Molecular dynamics simulation of alkaline electrolyte diffusion in anion exchange membrane
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lecular dynamics simulation of alkaline electrolyte diffusion in anion exchange membrane *
SONG BingYe, LI Dong, HE YaLing , HUANG Dong & TONG ZiXiang Key Laboratory of Thermo-Fluid Science and Engineering of MOE, School of Energy & Power Engineering, Xi’an Jiaotong University, Xi’an 710049, China Received March 1, 2020; accepted April 27, 2020; published online July 2, 2020
During the operation of alkaline direct liquid fuel cells, the alkaline electrolyte is usually needed in the anode electrode to accelerate the electrochemical reaction kinetics of the liquid fuel. However, the crossover of the alkaline solution in the anode through the anion exchange membrane to the cathode can increase the transfer resistance of the oxygen in the cathode. In order to reduce the crossover of the alkaline solution, the diffusion process of the alkaline solution in the anion exchange membrane needs to be fully understood. In this work, interface models of anion exchange membrane-alkaline electrolytes are established based on the cell structure of the quaternary ammonium polysulfone (QAPS) membrane to simulate the dynamic process of the alkaline solution in the membrane. The effect of the type and the concentration of the alkaline solution on the transportation of the metal + + ions and OH in the membrane are studied. The results show that the agglomeration of Na is formed more easily than K in the + − interface model. Because of the strong interaction of Na on OH , OH ions appear to be concentrated, resulting in that the + + diffusion coefficients of the metal ion and OH in the in Na solution are lower than those in the K solution. In addition, with the raised concentration of electrolyte solution, the aggregation degrees of the metal ions and OH can be increased, which means an enlarged mass transfer resistance of the components. Furthermore, by adding a polytetrafluoroethylene (PTFE) layer on the QAPS membrane, the distribution of metal ions tends to be concentrated, and the number of hydrophilic channels in the QAPS membrane is reduced, which significantly increases the alkali resistance of the anion exchange membrane. direct liquid fuel cells, anion exchange membrane, alkali crossover, QAPS membrane Citation:
Song B Y, Li D, He Y L, et al. Molecular dynamics simulation of alkaline electrolyte diffusion in anion exchange membrane. Sci China Tech Sci, 2020, 63, https://doi.org/10.1007/s11431-020-1615-0
1 Introduction Nowadays, the development of clean and renewable energy is the main technical means to solve environmental problems and achieve sustainable energy development [1]. Among many renewable energy utilization technologies, fuel cell is an important technology to achieve the chemical energyelectric energy conversion without going through the Carnot cycle. Compared with the acid fuel cells, the alkaline fuel cells have been proven to have the following advantages: (1) The alkaline environment can accelerate the electrocatalytic *Correspondenting author (email: [email protected])
reactions of both anode and cath
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