I posted this on HoFo before the D4 release. It might help:
"OK. I think I'm starting to be able to piece together this battery puzzle. True polymer batteries are super, except they have to stay really hot to work well. The RAZR & D4 will use a foil pouch Lithium-hybrid polymer design. As such it has no significant performance advantage over regular Lithium ion batteries. What makes it useful in a handheld device is that it can be made really skinny. Since the hybrid battery is soft, you can break it. That's one reason to lock it away. Another reason is that polymer hybrid Li-ion batteries are more prone to gassing, so Motorola may have felt that double covers would better resist its ballooning tendencies. However, nobody wants a battery you can't replace yourself, especially since Lithium batteries are known to start to degrade after a year or so, even if not in use. So we get a key and instructions on how to - carefully! - install a new battery when the original gets too weak. That new battery may be expensive since it's a new technology in low production.
Essentially, this is all being done just to make the phone a tad (0.2mm or 1.55% v. D3) skinnier. There is no other performance benefit to the user. And you lose the ability to "just pull the battery" to reset the phone when it freezes,up, gets loopy aftet a minor spill, or if you're stuck trying to root it.
This is mostly supposition but it is consistent with what we know."
After release, we now know that the battery is not designed *ever* to be removed and there is no approved vzw or Moto replacement battery. Essentially, as far as vzw is concerned, the $550 (outright) D4 is like a disposable flashlight -- when the battery wears out, it's trash. That's true even if you've only had it 13 months and you're still under contract.
Perspective instantiates reality.
( By DX w/DF app. )