Panasonic just started manufacturing of its latest 3.1 Ah 18650 format lithium ion cells earlier this month but the Japanese company is already hard at work on its next-generation cells. In 2012, it plans to start production of cells with 3.4 Ah output and the following year it is planning 4.0 Ah cells. Both of the new cells retain the same nickel oxide positive electrodes used today. The 3.4 Ah unit also continues to use a carbon anode just like today's cells.
The 4.0 Ah cell goes a different direction with a new silicon-based alloy for the electrode. The result is an energy density of 800 Wh/L compared to the 620 Wh/L of the current generation 2.9 Ah cells and a capacity increase from today's 10.4 Wh to 13.6 Wh. The downside is that the cell voltage drops from 3.6 V to 3.4 V and the mass increases from 44 to 54 g/cell.