Overcoming the Four Killer Problems of Silicon to Create a Better Battery

Conventional Wound “Jelly-roll” Battery Architecture
Enovix Novel 3D Architecture

Uniquely Enabling Silicon Anodes

Looking at a problem from a different perspective often yields new opportunities and solutions that would otherwise not be possible. This is the case with the Enovix 3D cell architecture. Rather than having long, wound electrodes that run parallel to the face of the battery, Enovix cells have many small electrodes that are orthogonal to the largest face of the battery. This seemingly small difference has huge benefits. Specifically, the 3D cell architecture is well-suited to accommodate the use of a silicon anode and therefore capitalize on the higher energy density it provides.

  • 1. Formation expansion. “Formation” is the term for the first charging of the battery, when lithium moves from the cathode, through the separator, to the anode. When fully charged, a silicon anode can more than double in thickness, resulting in significant swelling that can physically damage the battery, causing failure.​
  • 2. Formation efficiency. When first charged, a silicon anode can absorb and permanently trap as much as 50%-60% of the original lithium in the battery, reducing the battery’s capacity by 50%-60%.​
  • 3. Cycle swelling. A silicon anode will swell and shrink when the battery is charged and discharged, respectively, causing damage to both the package and the silicon particles in the anode, which can crack, and further trap lithium on the fresh silicon surfaces exposed by the crack.​
  • 4. Cycle life. Silicon particles can become electrically disconnected from the electrode when the silicon anode is in its shrunken state and can crack when the silicon anode is swollen, both of which can lower cycle life. In addition, when silicon particles become disconnected from the electrode, they are no longer able to accept lithium and neighboring particles must absorb the excess, causing over charging and further opportunities for physical damage.​

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Enovix

Enovix

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Enovix, based in Fremont, California, is the first company capable of volume production of advanced Lithium-ion batteries with a 100% active silicon anode.