3D Cell Architecture & Silicon Anode

Our 3D Silicon Lithium-ion battery uses a patented 3D cell architecture. While this is a novel approach for battery design, it is a proven approach for high-density disk drive read-write heads, 3D MEMS contact technology for semiconductor wafer testing, and 3D MEMS sensors.

The 3D cell is inherently flat, utilizes much thinner distributed metal-plated current collectors (rather than thicker foil), and eliminates the dead space in the inner-cell winding core and outer edges of a conventional Li-ion battery. This significantly increases the proportion of active to inactive materials, so that only about 25% of the total battery volume is inactive, versus over 40% of the total battery volume in a conventional Li-ion cell. The improved ratio of active-to-inactive elements—about 3:1 (75:25) versus about 3:2 (60:40)—produces a corresponding increase in volumetric energy density.

3D cell architecture more effectively utilizes advances in conventional battery technology, especially electrode material science. For example, a silicon anode has the potential to store ten times more lithium than a graphite anode. However, silicon’s absorption of lithium during charging can lead to its expansion, swelling, and eventual disconnection of the anode from the current collector in conventional Li-ion battery structure. Our battery uses patented porous silicon for its anode that, along with other proprietary methods, contains expansion within the structural voids and prevents external swelling. This maintains structural integrity of the connection between the anode and its external porous current collector during repeated charge-discharge cycles.