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Unformatted text preview: 10.626 Electrochemical Energy Systems Spring 2011 MIT, M. Z. Bazant Problem Set 1 – Equivalent Circuit Models Due: Lecture 5 1. Fuel cell power optimization. A fuel cell has the following current-voltage relation, 2 I V = V , for I < I s , 1 − I s where V is the open circuit voltage and I s is the short circuit current. (a) What is maximum power output of the fuel cell? (b) What external resistance, R ext , achieves the maximum power? 2. Battery discharge at constant load. Consider a battery whose open-circuit voltage varies with charge Q ( t ) stored in the cathode as V O ( Q ) = V (1 − αQ − βQ 2 ), where α,β > 0. Consider slow discharge against an external resistance R from Q (0) = 0, and neglect any internal resistance. (a) What is the maximum capacity Q max ( α,β ) for galvanic discharge? (b) Solve for the voltage profile, V ( t ). 3. Super-capacitor discharging. As shown in the figure, a super-capacitor, consisting of two parallel-plate porous metal electrodes soaked...
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This note was uploaded on 11/27/2011 for the course CHEMICAL E 20.410j taught by Professor Rogerd.kamm during the Spring '03 term at MIT.
- Spring '03