Batteries desperately need some major technological improvements. Nothing happened in the last 10 years.
I don't think it's that easy. Adding 1mm of thickness to the iPhone 5S will add a volume of 0.0073 liters. Current battery technology has an energy density of 300 Wh/l. That would add approximately 2 Wh to the battery, so you'd end up with 36% better capacity. Not only is that not really all that much, but it's also not as easy as making the phone bigger and filling the holes with battery. Phones do not only get thinner and thinner because it looks good, but also because electronics are basically two dimensional. As you can see in the images of the interior of the iPhone the engineers need to put battery and logic board side by side. That's because the electronics need to be in one layer (you can't just staple them) and need contact to the display and the back (because of heat dissipation). So yes, you could make the device 1mm thicker, but does that really give you space for more battery? It probably doesn't.How many millions iPhone5 sold? Let's take 50.000.000
Let's think of an iPhone5 1 mm. thicker and 20 gr. heavier with better battery life
How many millions iPhone5 sold? The same 50.000.000, but with 49.999.999 happier customers
(minus 1 because there is always someone that has to say "that is enough for me")
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