Armor is better than warheads

[Psitticine]

You can conceptualize something like a ramming prow with deflector field tech, if'n you like. An extension of repulser field and/or shield technology could be used to project a tightly focused "force field" ahead of the ship that could soak up incoming kinetic energy before it impacted the hull itself. If you want it one-shot, just say it burns out in the process and requires repair before becoming operative again.

It makes a bit more sense then a "superball" substance that would absorb the physical impact and yet not make the ship invulnerable to normal kinetic-based damage.

I agree that it isn't really realistic that anybody could survive a ram at the speeds involved, but I also agree that it is better to just ignore that and enjoy the space opera flavour!