Question: First of all I just started doing barre chords after learning ordinary non-barre chords. Problem is they don't sound so well, so my question is, will training with hand grippers help me achieve this? Because I've been applying equal pressure and they still sound a bit off, only a bit off.

Answer: 
No. Simple answer. Your hands could be stronger than a weightlifter's and still not play barre chords, or any other chords, well.

Actually, hardly any finger strength is needed. Putting fingers as close as possible to the fretwire helps, accurate fingering helps, and a good action helps. If the strings are a long way above the fingerbaord, strength will help, but a better solution is to improve the action, or change guitars.

If any muscles help, it's the arm muscles, as they should be used a little as levers, using the thumb as a fulcrum point - which also doesn't need to be clamped to the neck.
No, training with hand grippers won't help you execute barre chords. Firstly, time spent squeezing grippers is time that you could be using to actually practise barre chords. Secondly, the physical action is markedly different and not about finger placement and subtleties of pressure. But hey, you could end up with a really impressive handshake, and all the other musicians will ask you to carry their gear. It's early days; hang in there and your barre chords will improve.