and also if there are any free cloud storage devices which offer more data storage ?
They don't.
What are you looking for? "Free" usually requires a credit cards so they can bill you for anything you go over the free limit. Without credit card verification, it would get abused.
Actually I do have 2 free accounts, on two platforms, both over 10 GB. One I was lucky to find out in their early days and they were giving huge space.
The other is well known, it's Dropbox. If one starts using Dropbox from a referral, he already gets more than the default 2 GB (gets 2.5 GB?). When I've made my Dropbox account, if one has made certain "learning" steps, has got more storage, I don't know if it still happens. But: by getting others make Dropbox account under your referral, you'll get 512 MB (I think) for each new person (I don't know under what limits). Yes, it can be abused if one has too much time (it needs to actually install and run Dropbox for those accounts) . But it doesn't need credit card.
So I expect that one, especially if he's knowledgeable and determined, can get over 5 GB at Dropbox without paying and without giving out card info. How safe is Dropbox privacy wise? Well.. I don't have too big expectations.