In order to help reduce costs of ultrabooks, Intel is aggressively pushing two new battery solutions for these systems; the 16650 cylindrical battery and a prismatic lithium-ion battery. Full details at DigiTimes. Acer has already started adopting the 16650 battery while Lenovo's IdePad 530 uses the prismatic li-ion, albeit in limited volumes.
However, only a limited supply of the 16650 cylindrical battery is available, so prismatic lithium-ion battery will have a higher chance to success, but due to issues such as capacity and certification, vendors will not have chance to adopt prismatic lithium-ion batteries for their products until 2013.
The 16650 cylindrical battery has a diameter of 16mm and is only available from Japan-based Sanyo and China-based BAK, but due to vendors being concerned that supply is fully controlled by only two players, and BAK is unlikely to pass most vendors' certification process, there are concerns about the solution.
Although prismatic lithium-ion battery is higher in cost compared to the 16650 cylindrical battery, but the solution's size of 60mmx80mm and thickness of 5-6mm is providing a strong advantage, while the battery also has more suppliers available in the market.