Thank you, but unfortunately Diablo battery is not mentioned
It is, under "iDSD micro range".
AFAIK all version (including the "red label" and the "red label") used the same spec & size battery (and share many other things). It looks like this:
There were probably vendor changes through the decade+ production run of this platform since 2013, but even in 2013 the tech for kind of battery used was mature. So vendor and model changes would have had low impact on the electrical parameters and size.
Under the black wolf clothing is a generic "sheep silver" battery, similar (but not identical) to this one:
Simply locate one of the correct size and capacity (more capacity is ok, slightly less also, but not a lot less) and swap. You may be able to find with the correct wires, but that's unlikely.
Alternatively, remove the protection PCB from the old battery and fit it to the new one, using spot welds on the battery nickel contact strips (do not solder) or solder the old battery's wire tail to the new PCB.
All batteries are pretty much generic standard, just needs 3-wires for the thermistor. If that's missing the battery doesn't charge.
Please let me know how your inquiry goes in regards to getting a new battery for the Diablo 1 or the process thereof.
Many thanks. I have a Diablo 1 as well and I get about 3 hrs of battery life in turbo mode.
"I get about 3 hrs of battery life in turbo mode"
The battery is around 18 Wh 4,800mAh / 3.7V or 3.8V). The idle consumption in "turbo" is well over 5W, so 3 Hours or so sounds about right.
I will check this weekend if the original battery seems easy to dismount (if not, I'll keep it as it is

...)
It simply plugs into the Power PCB.
Teardown here:
https://sandalaudio.blogspot.com/2021/02/ifi-audio-idsd-diablo.html
This is very similar overall to the silver iDSD Micro discussed here:
https://www.head-fi.org/threads/need-help-to-disassembly-an-ifi-micro-idsd-v1.967067/
As said, all part of the same family.
Thor