In my hard science world there is a character that can output electrons around 30000 volts and around 50,000 amps.The problem is that they would instantly die every time they use their ability. So I had an idea and thought superconducting cells would work but there aren’t any ways this could work so can somebody please help. Thank you in advance.
You're forgetting Ohm's Law in your design.
By defining the Voltage and the Amperage, you have inadvertently defined the resistance too. V=IR, so 30,000=50,000*0.6. So you have to have 0.6 Ohms of total resistance for your equation to come out right. No superconductor or other substance will fundamentally change this fact.
Additionally, I think you might be a little ambitious about how much power your character in a hard science world can output. Your character can generate 1,500 MW of power (Power=Volts*Amps), while Hoover Dam only provides 700 MW.
One of the fun things about electricity is that it repels itself. It's all negatively charged, and like charges repel. That's why your hair sticks out when you touch an electrostatic generator.
Your character doesn't need superconductivity through his entire body, he just needs it on his skin. This would make his skin an effective Tesla cage. How the electricity gets from inside his body to his skin is up to you.
There would be unusual side-effects of this. Superconductivity isn't just for electricity. For instance, if he touched a hotplate, the heat would immediately be distributed across his entire skin. You could theoretically extend that to kinetic energy, too. I've seen examples of superfluids that, when you spin the container, the superfluid inside the container breaks down into numerous vortices in order to evenly distribute the kinetic energy.
But really, this is superheroes, so you decide how far you want to take it.
We have Electric Eels on planet earth, Whilst they aren't outputting the energy that you are talking about (toping out at about 800 volts) - As of time of writing, we don't definitively know why they don't shock themselves.
Some theories have suggests that they contort their bodies in such a way that any charges don't traverse their heart. Other theories point to the fact their vital organs are contained within the first 1/5th of their body, the rest being used for Electricity generation...
But we still don't know how they do it
And if we don't know how it works on a real life creature in the real world, then perhaps you don't need a hard science explanation, other than something like 'they seem to have some way of not being affected, just like an Electric Eel'
Assuming that they were not just gifted with this power one day at full capacity, this is a level of power that they had to work up to. They have built up their ability to harness power safely over the course of years to be able to output that kind of power.
The final result of the training is not only do they control the lightning to do what the user wants to do with it, they also control it so it does not give them a lethal feedback.
In one aspect, this works because they still have to control the electricity entirely and are actively doing it. Should their concentration lapse enough, then that power will take the shortest route to ground. Likewise they are always controlling it so that it can't hurt them -- doubly so if they have some internal source of their electric powers.
As a demonstration of training, I offer Pokemon -- specifically good ol' #25. Pikachu has fairly good control over its electric powers. By contrast, it's pre-evolution Pichu does not. Pokedex lore specifically states that it does not have good control over its electricity and it is reflected inthe games by only learning weak electric attacks. Also, the Smash Brothers games actually show this lore tidbit by the little mouse taking damage when it uses its electric attacks.
The comparison is that your electrokinetic does not control power well in the beginning. However, through experience, training, and likely a few unpleasant shocks, they have learned how to control the power at their command until they too can Thunderbolt with the best of them.