In the last post, A New, Modern Li-ion Battery Platform, I published the third excerpt from an article “A New and Innovative 3D Architecture for Lithium Batteries.” Ashok Lahiri, Enovix co-founder and CTO, authored the article that appears in the latest issue of Applied Wireless Technology. Following is the fourth excerpt that describes the unique construction of our 3D silicon lithium-ion battery.
Photolithography and Wafer Production
The Enovix battery manufacturing process combines an established photolithographic mask and etch process with standard solar-cell fabrication equipment to achieve high-volume, low-cost battery production. The 1-mm (depth or thickness) wafer die can be configured in different perimeter plane sizes (width and height) and shapes (square, rectangular, round, oval, hexagonal, etc.).
The figure below illustrates the five major steps in the production process.
- A photolithographic mask and etch process is applied to a solar-grade silicon (SG-Si) wafer.
- The 100% silicon that remains after wet etching forms the anode and backbone of the interlaced cell structure.
- Thin layers of metal films are applied to the anode and backbone to form current collectors.
- A ceramic separator is deposited around the anode current collectors.
- A cathode coating fills the remaining voids in the wafer die.
The individual cells are laser sliced from the multiple-cell (full) wafer, die stack tabs are attached, the dies are baked, and 1-mm cells are stacked to the desired thickness and packaged in a pouch or case.