Polarization Studies on High-Temperature Fuel Cells

Abstract

Immobilized‐electrolyte, high‐temperature fuel cells of nonconventional design were operated successfully on a wide variety of fuel gases. This design permits the incorporation of a reference electrode and avoids gasketing problems for low‐pressure operation. The performance of these cells was compared with preliminary results on free electrolyte and solid electrolyte cells. Oscilloscopic observations of polarization decay indicated that ohmic rather than concentration or activation polarization limits the performance of matrix cells in most instances.

Influence of Electrolyte Composition on Electrode Kinetics in the Molten Carbonate Fuel Cell

“…If io is measured in four different fuels, then the four unknowns k*, a, b, and c can be determined. The above equation can be written in the logarithmic form log io = k + a log (H2) + b log (CO2) + c log (H20) [7] where k = log k*. Using io values obtained with fuel gas compositions corresponding to high-, medium,-low-, and very-low-BTU fuel (Table I) Thus, Eq.…”

“…Using io values obtained with fuel gas compositions corresponding to high-, medium,-low-, and very-low-BTU fuel (Table I) Thus, Eq. [7] can be written as io = 104.7 (H2)~ (CO2)~ 0'iTs [9] A variety of approaches can be pursued for the development of the reaction mechanism (13-15). We have followed the general procedure described by Newman (13).…”

“…immersed (6,7) and partially submerged anodes in molten carbonate melts (8,9). This latter work has shown that diffusion of reactants through the thin film electrolyte meniscus can play a significant role in the overall rate of the anodic reaction.…”

Polarization Studies of Molten Carbonate Fuel Cell Electrodes

“…M+O =~-MO+2e- [3] K1 MO + H2 ~-M + H20 [4] where M is a divalent metal. Since these reactions are taking place at 600~ the rate should be very rapid and equilibrium conditions maintained.…”

“…The reactions at the anode as indicated in Eq. [2], [3], and [4] proceed very rapidly, and the electrode-electrolyte interface is in equilibrium at all times independent of current up to 200 amp/ft 2.…”