Nikkei Electronics Asia. Panasonic will begin volume production of its new 4.0Ah Li-ion secondary batteries featuring an enhanced nickel (Ni) cathode and silicon (Si) alloy anode (earlier post) in fiscal 2012. At its announcement of the cells in December 2009, Panasonic had said volume production would begin in fiscal 2013 (ending March 2013).
Initially intended for use in notebook PCs, the 18650 format cells offer a high volumetric energy density of 800 Wh/L, compared to the 620 Wh/L in the current 2.9 Ah cells; however, the gravimetric density is about 252 Wh/kg—comparable with existing graphite designs. The new high energy density cells weigh about 54 g per cell, about 10 g more than the NCR18650A model.
Although silicon offers a very high capacity as an anode material, lithium ion insertion into and extraction from silicon are accompanied by a volume change of up to 300%, which induces a strong stress on the silicon particles and causes pulverization and rapid capacity fading.
Panasonic claims to have addressed that issue through its fabrication techniques and made other unspecified modifications in the material, and that after 500 charge/discharge cycles, the cells retain at least 80% capacity.