I think short circuit current for this small 4mA cell is best measured with a transimpedance amplifier.
The only way to have zero voltage across the cell at any current.
A simple LM358 with Arduino's 1.1volt Aref could do that.
Add a negative supply voltage for the opamp, and generate a 0 to -1volt with the second half of the opamp from a PWM signal. Feed that to the +input of the transimpedance opamp, and you can make voltage/current traces.
Leo..