appending multiple datasets from the same excel

Question

After uploading into r (with openxlsx) an excel with hundreds of tabs I am left with hundreds of dataframes with 6-9 variables each.

The name of each tab (now dataset) is a date (like 080720).

1. How do I append them all (they are hundreds) in one individual dataset and
2. (if possible) add a variable column with the name of their original dataset (the date)?