一种浸渍燃料电池用石墨双极板的新方法

New method of impregnating graphite bipolar plates used in fuel cell

石墨板虽然具有良好的导电、导热以及耐腐蚀等性能,但在制造过程中不可避免地产生气孔,含有气孔的石墨板作为质子交换膜燃料电池双极板会使H2和O2互相渗透,降低电池性能。采用真空加压方法以硅酸钠浓溶液浸渍石墨双极板,然后加酸加热使之转变为SiO2,使石墨板气孔率由18.2%降低至3.3%以下,在0.3MPaH2压力下不透气。经硅酸钠溶液浸渍后的石墨板电阻没有增加,而用其做的石墨双极板使电池性能在同样电流密度下约增加40mV以上。浸渍工艺保证了燃料电池的性能。

Graphite is charactered by good conductivity, good heat conduction and rust-resistance, but graphite contains many pores during their manufacturing process inevitably. H_2 and O_2 will be mixed if the graphite bipolar plates which contain pores are used in PEMFC (proton exchange membrane fuel cell), and the performance of fuel cell is low. Graphite bipolar plates were impregnated by thick Na_2SiO_3 solution in vacuum and pressure. Na_2SiO_3 in graphite plate was turned into SiO_2 after being reacted with acid and heated. Porosity of graphite plate dropped to 3.3% from 18.2%. No H_2 leakage occurred at the pressure of (0.3) MPa. The resistance of graphite plate after impregnation did not rise. The voltage of fuel cell used the graphite plates added 40 mV at the same current density. Performances of fuel cell were guaranteed.