Hello Mr.Kapiti, I want you to know that China is having the best marketplace for used lead acid battery scrap. Moreover, if you see the statistics of export this item from India to overseas then the best marketplace is - Sweden, Brazil & Malaysia.
There are some b2b sourcing company exists who can help you like connect 2india and all.
But I'll suggest do your own R&D for the marketplace, try to search buyers over there and start the business by having correct payment terms.
All the best.