How a Two-Layer Coating Protects Lithium Battery Anodes

This patent describes a lithium battery cell design that uses two special protective layers on the anode to stop harmful growths called dendrites and make the battery last longer and work better, especially in solid-state batteries.

What it covers

This patent describes a specific design for a lithium battery cell, focusing on its anode. The anode has an "anode current collector" (like a metal sheet) covered by two distinct "ad-layers" (thin coatings). The first ad-layer sits directly on the current collector and is designed to let lithium ions pass through while blocking electrical current, using materials like amorphous carbon or graphene oxide (Claim 1). The second ad-layer, which is also conductive to lithium ions, acts as a protective shield, often made from metal oxide or nitride derivatives (Claim 2). These layers work together to prevent "dendrites," which are tiny, tree-like metal growths that can damage the battery and cause it to fail. For example, a battery built with these layers could maintain over 99.9% "coulombic efficiency" for 2000 charge/discharge cycles (Claim 13).

What it doesn't cover

• —Battery cells that do not include both a first ad-layer that is electrically insulating and a second ad-layer that is a protective layer, as described in Claim 1.
• —Anode protective layers that are not conductive to lithium ions, as both the first and second ad-layers are specified to be (Claim 1).
• —Battery cells using liquid electrolytes, as the separator is specified to be a solid polymer, ceramic, or a combination thereof (Claim 1).
• —Protective layers made from materials outside the specific groups listed for the first ad-layer (amorphous carbon, boron nitride, graphene oxide) or the second ad-layer (metal oxide, nitride, phosphide derivatives) (Claim 1, 2).
• —Battery designs where the protective layers are not positioned between the anode current collector and the solid-state separator.

The clever bit

The novelty lies in the specific combination and arrangement of two distinct ad-layers on the anode. One layer is specifically designed to be electrically insulating but lithium-ion conductive, while the second is a general protective layer also conductive to lithium ions. This dual-layer approach, with specific material choices, offers a robust defense against dendrite formation and degradation.

Why it matters

Solid-state batteries promise safer, higher-energy power sources, but a major challenge is the growth of lithium dendrites on the anode. These dendrites can pierce the solid separator, causing short circuits and battery failure. This patent addresses this fundamental problem by introducing a specific multi-layer anode protection strategy. By preventing dendrites and improving "coulombic efficiency," this technology is crucial for making solid-state batteries practical for widespread use in demanding applications like electric vehicles.

Real-world examples

• 1.Solid-state batteries for electric vehicles
• 2.High-energy density batteries for portable electronics
• 3.Long-life batteries for grid storage
• 4.Next-generation smartphone batteries