燃料电池局部燃料饥饿条件下电流密度分布和电压分布的测量：阴阳极电压和电流密度分布的相互作用

Dynamics of anode–cathode interaction in apolymer electrolyte fuel cell revealed by simultaneous current and potentialdistribution measurements under local reactant－starvation conditions

A． Manokaran

S． Pushpavanam

P． Sridhar

Abstract

Low stoichiometry operation of fuel cellsinduces nonuniformities in the current generation and electrode potentialsacross the active electrode area． In this study， current and potentialdistributions are measured simultaneously in a fuel cell operating underreactant （fuel／air）－starvation conditions． During the galvanostaticoperation under local reactant starvation， the localized increase ofcurrent density is observed closer to the inlet． Here under air starvation，cathode potentials dropped uniformly across the electrode area． However， duringfuel starvation， a nonuniform cathode potential profile is observed． Duringthe potentiostatic mode of operation under air－starvation condition， cathodepotentials remained uniform and constant across the electrode area． However，under fuel starvation， the cathode potential profile is influenced by the anodepotential profile． Electrode–electrode interaction especially during fuelstarvation is captured by simultaneous measurements of current and potentialdistribution．

Fig． 1 Schematic of the current sensor  plate

Fig． 2 Exploded view of potential  distribution measurement setup

Fig． 3 Schematic of reference electrodes  position in the serpentine flow field plate

Fig． 4 a Overall response of a fuel cell  at different hydrogen stoichiometries under constant voltage  operation． b Variation of normalized current density at different hydrogen  stoichiometries under constant voltage operation． c Variation of  electrode potentials at different hydrogen stoichiometries under constant  voltage operation （solid line anode potential， dashed line cathode  potential）

Fig． 5 a Overall response of a fuel cell  at different hydrogen stoichiometries under constant current  operation． b Variation of normalized current density at different hydrogen  stoichiometries under constant current operation． c Variation of  electrode potentials at different hydrogen stoichiometries under constant  current operation （solid line anode potential， dashed line cathode  potential）

Fig． 6 a Overall response of a fuel cell  at different air stoichiometries under constant voltage  operation． b Variation of normalized current density at different air  stoichiometries under constant voltage operation． c Variation of  electrode potentials at different air stoichiometries under constant  voltage operation （solid line anode potential， dashed line cathode  potential）

Fig． 7 a Overall response of a fuel cell  at different air stoichiometries under constant current operation．  b Variation of normalized current density at different air stoichiometries  under constant current operation． c Variation of electrode potentials  at different air stoichiometry under constant current operation （solid  line anode potential， dashed line cathode potential）

Conclusions

In this study， current and potential  distribution measurement techniques were employed simultaneously to measure  the internal characteristics of a fuel cell operating under fuel and air－starvation  conditions． Fuel－ and air－starvation operations demonstrated the utility of  the combined measurement of potential and current distribution measurement．

During fuel－starvation experiments， a  disturbance was introduced on the anode side externally by varying fuel stoichiometry．  The disturbance induced a change in the anode potential profile which in turn  altered the current distribution． The changes in current distribution  dictated the cathode potential． This coupling， anode potential influencing cathode  potential via current distribution， between two electrodes under local  fuel－starvation conditions， was explicitly captured by simultaneous  measurements of current and potential distributions in this study．

During air－starvation experiments，  external disturbances were introduced on the cathode side． Though the anode–cathode  interactions were implicitly captured by the current distribution， the  influence of the cathode potential on the anode potential was not captured．  Since the hydrogen－oxidation reaction is facile and sufficient hydrogen was  supplied during air starvation， the anode potential was not affected by the cathode  potential． Capturing of the influence of the cathode potential on the anode  potential via current distribution would be possible only when the anode  kinetics is sluggish， i．e．， when methanol is used as a fuel instead of  hydrogen．

This combined potential and current  distribution study captured the anode–cathode interaction under different operating  conditions even in the presence of ohmic drop in the cathode potential and  the zero－shift voltage on the anode potential． The distribution measurements  reported in this study can serve as benchmark for multidimensional theoretical  investigations． This will help in designing more durable and reliable fuel  cell systems．

电流密度是归一化的。

也不知道有没有别人做过氢空进口位置和流向不同的，这些结果很宝贵。