When will they make one for cellphones that will stay charged for a month?..........................
Lithium-ion batteries, specifically lithium cobalt oxide (LiCoO2), the type used in cell phones, have the highest energy density (about 600 Watt-hours per Liter of volume) of any commercially-manufactured battery. While claims have been made of batteries up to 7 times as powerful for a given size, they all have problems that will probably limit their commercial appeal.
We are living in the golden age of battery life, right now.