Lookup tables in LTspice
Not sure whether that is what you really need, but I will give it a try. Since your inputs consist of I and V, I suppose you are simulating how this fuel cell is charged. Although not technically correct, you could map one of your variables (e.g. the current) to the time, and import it into LTSpice. 

For example:

Let's say your I-V characteristic looks like the following, where the first column is the current and the second one the voltage. The csv file can be renamed to IV.txt

0,0
1,2
2,3
3,4
4,6
6,7
7,16


By reading out this file as a PWL file with a voltage source, the second collumn is mapped to the voltage. In order to recreate the current behavior, you can model a resistor to limit the current based on the time (current) you need, as depicted below: