Sci-Hub is a paywall-bypassing website that uses "shared" user credentials to provide PDF or HTML scientific papers. The website itself doesn't store any papers. (There are interesting comments on your [same question on another site][1].)

But [LibGen (via wayback machine)][2] [is said to archive each PDF retrieved by Sci-Hub](https://engineuring.wordpress.com/2019/03/31/sci-hub-and-alexandra-basic-information/).

http://gen.lib.rus.ec has a downloads page - (click the tab to show more options)

+ Torrent - books and text books - http://libgen.io/repository_torrent/

+ Torrent - scientific papers - http://gen.lib.rus.ec/scimag/repository_torrent/

+ Usenet - http://libgen.io/repository_nzb/

+ DB dump - http://gen.lib.rus.ec/dbdumps/


[![enter image description here][3]][3]


  [1]: https://academia.stackexchange.com/q/63330
  [2]: https://web.archive.org/web/20190330215241/https://engineuring.wordpress.com/2019/03/31/sci-hub-and-alexandra-basic-information/
  [3]: https://i.sstatic.net/j3cEq.png