Ionic Conductivity in Solid Electrolytes

The ion transport in crystalline electrol5de is controlled primarily by the vacancy diffusion or hopping diffusion mechanism discussed in Section 7.1. Vacancy spots are created in crystalline base electrol5de material by doping it with an impurity or alloy element. The ion concentration distribution in the electrol)4 e is controlled by the density of tire doping element in the base electrolyte material. 

Substituting Equation 7.29 for diffusion coefficient into Equation 7.42 for ionic conductivity, we get 

Equation 7.45 is similar to Equation 7.40 and gives a direct relation between the charge conductivity and the ion concentration. In a crystalline electrolyte, the ion concentrations and the number of vacancy sites are controlled by doping the base material with an impurity element. 

The purpose of the polymer electrolyte is to transport the positively charged proton from the anode to the cathode side. One of the most popular polymer membranes is the Nafion-117, which is made of material structure that has 

The proton conduchvity is then obtained from Equation 7.42 with 2 =1 for hydrogen ion (H+) as 

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