defrag on sd cards on phones are not a good idea.
___Fragmentation is only a problem on moving hard drives - it slows down access to a file if it's spread all over the drive in small fragments. This doesn't matter with the solid state internal memeory of a phone - no moving parts = no delay retrieving different parts of the file.___
So on a hdd the storage closest to the center og the spinning disc inside will be the fastest part aka the operating system.
But in an sd (solid state storage) all files are spread over a little area witch will cause no lag or delay.
Defragmenting will maby help, but do it only once, not many times, that will kill the thing.
I had my ssd since january this year, and was on 58% fragmented in july, i degragmentet it and has been on 1-3% since, same with my sd card on my phone.