It's all in the temperature regarding Li-Ion. From Wikipedia:
At a 100% charge level, a typical Li-ion laptop battery that is full most of the time at 25 Â°C or 77 Â°F will irreversibly lose approximately 20% capacity per year.
Standard performance on old Li-Ions, should be way better these days.
However, a battery in a poorly ventilated laptop may be subject to a prolonged exposure to much higher temperatures, which will significantly shorten its life. Different storage temperatures produce different loss results: 6% loss at 0 Â°C (32 Â°F), 20% at 25 Â°C (77 Â°F), and 35% at 40 Â°C (104 Â°F). When stored at 40%â€“60% charge level, the capacity loss is reduced to 2%, 4%, 15% at 0, 25 and 40 degrees Celsius respectively
Lithium-ion polymer batteries are somewhat in the same results.