You can get higher voltages by combining multiple cells. AFAIK there are no 5V batteries. Regulating down from 9V doesn't have to be a waste, if you use a switching regulator (SMPS). For this in/out ratio efficiencies over 90% are attainable.
Are all lithium batteries compatible?
And because cordless tools are designed so they won't accept incompatible (wrong-voltage) battery packs, you're safe using any battery pack from the same manufacturer that fits the tool. The earliest lithium-ion batteries were not backward-compatible with nicad battery tools, but that's changed over time.
Are lithium and lithium-ion batteries the same?
The difference between lithium and lithium-ion batteries is that one is not rechargeable (primary cell) and the other can be recharged (secondary cell). In addition to this, Lithium batteries have a shelf life up to four times longer than lithium-ion batteries and are also much cheaper and easier to make.20 feb 2020
Can you charge a Li ion battery with 5V?
Lithium battery with protection circuit board can be charged with 5V voltage(4.8V to 5.2V can be used). For 3.7V lithium batteries, the charge cut-off voltage is 4.2V and the discharge cut-off voltage is 3.0V. ... Charging with 5V voltage is easy to cause danger of overcharging.17 may 2020
What voltage should I charge a lithium ion battery?
4.2V
Can I charge a battery with a higher voltage charger?
Charging at elevated voltages is OK for very short periods but a lot depends on the temperature of the battery. That is why many modern vehicle charging systems, use a temperature sensor on the battery.16 dic 2018