electrochemical cell problem - when to use platinum?

why is a platinum electrode used if there is a conductive surface for the 2nd equation?it goes in the forward direction, as it is more positive (or less negative) E so the reactants would be Li+ (aq) and MnO2(s) MnO2 is a solid, so why is it not used as the electrode?can only pure metals be used as electrodes?


thanks for any help in advance, I appreciate it