With this tool you can open a Dyson battery from a V6 cordless vacuum cleaner without causing any damage to the battery casing. It will press on just the right spots to release the internal tabs.
You just need to slide both left and right side tools onto the battery, with the arrows pointing up, and squeeze the tool using some Quick-Grip type clamps. There are another two tabs on the upper neck of the battery so you will also need to squeeze there. The casing should then be released.
There are probably other Dyson batteries that this will work with.