A lithium ion battery got its name from the terminology used in these batteries. Lithium ions present in these batteries move from the negative terminal of the batteries to positive terminal of the batteries during discharge and since these batteries fall under the category of rechargeable batteries, ions travel back to negative terminal while charging. These batteries are made on latest technologies and hence they are replacing the older batteries made of lead acid. AA 3.6 Volt Lithium batteries are light weight and provide the same voltage as lead acid batteries.