Lithium ion polymer batteries aren’t that different from standard lithium ion cells. They can be much thinner and designed in many different shapes and perhaps have slightly higher power density, however they are still basically lithium ion batteries.
http://www.batteryuniversity.com/partone-5.htm
i wish Sandisk would use a standard removable 18650 lithium ion battery to power its future high capacity mp3 players. The 18650 batteries are around 2400 mah at 3.6 volts, retail for only around $5 each, and can be charged one or 2 at a time in a charger that retails for only around $10. The 18650 battery is only slightly larger than a AA battery, yet holds more than twice as much energy as a 2900 mah AA nimh battery. I wonder if pc connectivity, charging circuitry, and internal flash memory is removed from the player design(except perhaps a tiny bit for player settings? so it is a Slotmusic player, but still has a basic display, perhaps a player could still be small(but not so thin) and use an 18650 battery? It would be cool if the player came with an external 18650 charger and two 18650 batteries.
How about using a standard sized inexpensive removable battery and design the player around that, rather than designing a weird shaped proprietary battery to fit around the other player components?
