We have the ability to find a list of closed matters on the matter list.
How to show closed matters on a matter list
On the Matter list screen, you need to click on Filters>Show Available Filters>Change Status to use Closed and it will give you a list of Closed Matters.
Once you have this information, you have the ability to export this to an excel by clicking on More.
Matter List View or Custom Matter Report
Custom List Views - Filters and Copy