In one of my application i need to charge/Discharge 12V battery upto 50A . So need what is the thickness of pcb and track width to support high current and how can i increase the current with less space available over PCB.

 

Search "PCB Calculator". Many PCB makers have a on line tool.
current calculator
You can see what happens with 1oz verses 2oz copper.
Use both sides of the board if you can.
Look at temperature rise. 20C?

 

As scoty says ( not ) the laws of physics can not be changed.

To make a track that can take more current, you need to give the current more copper. i.e. either make the track thicker or wider.


many calculators on line

https://www.7pcb.com/trace-width-calculator.php

the thickness of the PCB doe snot contribute to the current capacity ,

for 1/2 oz copper, you need a trace about 140 mm wide,
for 2 oz copper , you need trace about 40 mm wide.

Remember , if you have any vias etc through the trace, that decreases the trace width.

the answer if yo can not use tracks, is to use a soldered on wire,

 

I've seen some higher current distribution panels built on a PCB, and one thing to remember is that the wide/thick tracks are on both sides and also have dozens of vias between the top and bottom trace (same line, current split between two layers). That is, to handle high current, the board used both sides of the board to make a parallel trace top/bottom with vias between them. That trace was about 1/2" wide on both sides, but not sure of what copper weight it used. It was rated for around 35A