Mines are an automated solution of the old days... one just does not have enough troops to protect all sides of ones boundary, this is where mines come into play, they are deterrent for those that would choose to go that direction to attack you. They were cheap and effect at the job of killing individuals willing to pass through that way.
In modern times, there can be automated defense systems that can accomplish the same job more efficiently / effectively. Automated drones would be a better solution than mines themselves. It appears one would like a drone that sits in a location and looks for a craft and ram the opposing craft for massive amounts of damage.
But this leads to simple solutions by the opposing team. I'm sure every craft would be equipped with anti-asteroid weapons, just to vaporize these objects before they get close enough to do damage (shields would stop many smaller asteroids, but some larger varieties would need a little help to destroy them). Thus, any mine field (which can't be hidden too effectively in space) and can be destroyed immediately upon contact (no real hidden factor, a necessity since the old days of mines. If you can see it, then it isn't effective).
What would be the case is that one would want to build and forget system of deploying drones. Simply put, it would be nice to implement a drone command center that allows the player to build any number of short ranged drones at an upkeep cost for the drone facility and the cost of each drone individually. But the upkeep doesn't increase upon large numbers of drones. 1 Drone upkeep - 5bc, 10 Drones upkeep - 5bc. Of course one could flesh out this idea, but it is simply put that a military starbase would have an ability to create a drone protection grid on a 1 hex radius, where you can produce a number of drones to initiate a battle, to protect an area.
But to the mine question... No. I don't think space explosives are the way to go here.