I have to have a layer (shapefile) with a polygon that has a 100-m buffer zone around each polygon of my original file. With the `QGIS` `Buffer (fixed distance)` tool, I get polygons that include the original polygon. But I only want the outside for each polygon.  
If the buffer for polygon A intersects the buffer for polygon B, I don't want to lose that part of the "outside" buffer (so I can't use the `différenciation symétrique` tool (sorry, I'm on a French version of software and I don't know it's equivalent in English). Alternative would be a smart intersection that is polygon-to-polygon based on an ID to get rid of the inner part.

My original datafile is the green and the buffers are underneath in blue.

[![enter image description here][1]][1] 

Just the buffer layer that I tried in blue.

[![enter image description here][2]][2]


  [1]: https://i.sstatic.net/Mw38Z.png
  [2]: https://i.sstatic.net/Gks2X.png