Batteries work well in a variety of devices. Ives uses them in an Oral-B electric toothbrush and the controllers for an Oculus Quest. Battery life seems pretty good. I haven't really done extensive testing but I've been happy with the battery life. One thing to be aware of is that the inbuilt voltage regulator does seem to be incompatible with the method that devices use to monitor battery level. My Quest said I had plenty of battery life left but the batteries suddenly died. I'd recommend buying a few extras so you can swap them out with freshly charged ones. All in all I'd recommend the batteries, particularly for travel so you don't need to carry a bulky power adapter.
We decided to try these in place of normal NiMH rechargeable batteries as they said they were 1.5V instead of the normal 1.2V NiMH. They arrived quickly, some were charged other weren't. When we tried them in internal Christmas LED decorations the difference was astounding. It was hard to believe they were that much brighter. We checked in other LED strings, the same brighter result. Only had they batteries a few days so endurance and capacity not yet determined. but we have ordered more, the extra brightness the attraction. I checked the battery voltage, 1.53 - 1.54 compared to 1.24 - 1.28 for NiMH but the difference isge in the LED brightness. Like normal Li ion batteries, when they die, they die fast. One minute good light then a few minutes later almost nothing, we found for some we did not charge on arrival.
Bought theses because my VR remotes have a tendency to stay on after use, works like a charm and saves me going through a new set of batteries every week. They probably last a little more than half as long as a normal battery, but reacharge really quick and are lighter. Honestly can't complain, they work great.