a "protected" Li-Ion has a small electronic circuit integrated into the cell packaging. It protects against common dangers, such as overcharge, overdischarge, short-circuit (overcurrent), and temperature. These cells are safer to use, both individually and in batteries. They are less likely to ignite and cause personal or property damage, a phenomenon known as "venting with flame." Unprotected cells do not have this protection circuit, so they can have more capacity and current capability than protected cells. Some cells, such as 10440 (AAA), are too small to accomodate a protection circuit and are only available in unprotected form. Users must decide whether they prefer to stick with protected cells or accept the bigger responsibility and danger associated with unprotected cells.
It's alway's good safe practice to A) Always use a decent intelligent battery charger. B) Never leave batteries charging unattended I.e leaving the house, same practice that you'd use with a tumble dryer.
Like mentioned previously I highly recommend the Protected Panasonic NCR18650B batteries, they will be perfectly suited for your needs.