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EECS – Prof. A. Casalegno – 17th July 2019 1 Basic Part (3 points per question, minimum score 12) 1. Write the Nernstian equilibrium potential in generic form for an electrochemical electrode 2. Write the overall current produced by an electrode including the effect of double layer capacitance 3. Depict the charge curve of a Lithium-ion battery at high current with reasonable values 4. Write Faraday’s law applied to electrolyte and both products in an alkaline electrolyzer Name _____________________________ Person N. __________________________ EECS – Prof. A. Casalegno – 17th July 2019 2 Exercise 1 An automotive PEMFC stack, composed of 333 cells, supplies 100 kW at full load (2 A/cm2). Assuming that 3% of H2 is wasted and its performance follows the reported polarization curve, estimate the mass of H2 that is necessary to operate the stack at an average power of 20 kW for 720 Km at an average vehicle speed of 120 km/h. Exercise 2 A Li-ion battery with a capacity of 2.5 Ah operates at ambient pressure and temperature. Assuming: 1. Butler-Volmer kinetics is valid for both electrodes 2. transfer coefficients of both electrodes during discharge are equal to 0.5 3. ion and mass transport effects in electrodes are negligible 4. 𝑎𝐿𝑖𝐶 = [0.7 ∗ 𝑆𝑜𝐶 + 10−6]2 5. 𝑎𝐶 = [1 − 0.7 ∗ 𝑆𝑜𝐶]2 6. 𝐹 ∗ 𝑘− = 10 𝐴 Calculate the overpotential of the negative electrode during discharge at Crate=1 and SoC=30%. Intermediate Part (2.5 points per question) Name _____________________________ Person N. __________________________ ∆𝑉 0 𝑗 0.8 V 0.6 V 0.3 A cm -2 2 A cm -2 EECS – Prof. A. Casalegno – 17th July 2019 3 1. Draw the electrical potential in the double layer of an electrode when Hydrogen Evolution Reaction occurs and compare with the equilibrium one 2. Depict the discharge curve of a…