Red electrolytic solution ... and while it is indeed inert at the time of cell manufacture, it can degrade within the battery and release the redox shuttle molecule. Elevated temperatures worsen ...
The battery polarizes the electrolytic cell, that is, the fine platinum wire is. covered with tiny bubbles of oxygen and then the resistance rises so high that the current is nearly reduced to zero.
This constraint adds a layer of complexity and cost to battery and fuel cell design ... point in the development of batteries, fuel cells, and electrolytic cells that operate by using hydrogen." ...