Third party LI90 battery
I hope it works out for you, but the three 3rd party batteries I've used have all gone tits up in three months or so, at which point they start self-discharging within hours of getting a full charge. No more for me...
I've bought four so far, for my K20D. All are at least a couple of years old. One I threw away because it wouldn't hold a charge. Another is sometimes unreliable, so I always keep it in the grip. The camera is set to select the grip first. The other two generics are reliable, but don't last anywhere near as long as the Pentax battery.
I tend to always shoot with the third party battery first and save the Pentax for backup. That way I get all the shots the knock-off can deliver, and I am secure, knowing I have a solid backup if I need it. I cycle the Pentax periodically so that it gets some use.
I have had no concerns about safety with the cheap imitations, just longevity.