Should the cell phone battery be fully charged (or emptied) if it is not used for a long time?

Many people have multiple mobile phones or batteries in their homes, and some batteries will not be used for a long time. Many people use two extreme methods - fully charged or discharged. In fact, both of these methods will affect the life of the mobile phone. The correct way is to charge the battery of the mobile phone to 40~60% and store it in a cool and dry place.
3： The first charge takes more than 12 hours
In 2013, most mobile phones used lithium batteries. Unlike the former NiMH batteries, lithium batteries have no memory effect (to be correct, the memory effect is very weak), and there is no activation. Long-term charging will cause certain damage to the battery. So what is the best time to control the first charge? It also depends on the capacity of the battery. Generally speaking, it takes 2 to 4 hours, and the mobile phone shows that it can be charged for another half an hour after charging.