It's actually the lithium-ion chemistry, rather than the trickle maintenance voltage required to maintain the charge. The cells are continuously degrading from the point where the chemistry is first activated. The degradation is slowest around 50-60% SoC (State of Charge), fastest at 0% or lower (0% SoC isn't actually empty), but also faster at 100% or higher. If you are storing them on a shelf, about 60% is optimal, but that's not practical for something like a laptop where you want on demand usage. Very low state of charge (below nominal 0%) is dangerous because the copper electrode dissolves in the chemistry, then replates if recharged, potentially leading to short circuit and fire; that's why batteries brick themselves and refuse to charge after overdischarge. Overcharging is also problematic, but doesn't occur so easily due to the charge controller cutting off at a safe level.
Cycling (charge, discharge, charge, discharge, ...) will shorten the life faster than just maintaining them at 100%, with the cells typically having around 500 to 1000 full cycles before they drop below 80% capacity (that varies significantly based on application and the charge/discharge rates).