# 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. - **Patent:** US 11271251 - **Original title:** Battery cell with anode protective layer - **Owner:** Robert Bosch - **Granted:** 2022 - **Status:** Active - **Times cited:** 0 - **Field:** consumer_electronics, automotive, energy, materials, semiconductors ## What it does 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 does NOT 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. ## 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 ## 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. ## Frequently asked questions ### What does How a Two-Layer Coating Protects Lithium Battery Anodes cover? 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. ### Who owns patent US 11271251? Robert Bosch owns this patent, granted in 2022. ### When does this patent expire? This patent is expected to expire on June 7, 2038, when the invention enters the public domain. ### What problem does this patent solve? 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. ### What does this patent NOT 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. **Full plain-English explainer:** https://patentbrief.org/patent/us/11271251/battery-cell-with-anode-protective-layer **Original patent:** https://patents.google.com/patent/US11271251 --- _Source: PatentBrief — https://patentbrief.org. Patent facts are from public records; the plain-English explanation is PatentBrief's._ ## Related patents Semantically similar inventions in the PatentBrief corpus: - [How a Hybrid Layer Stops Metal Growths in Lithium Batteries](https://patentbrief.org/patent/us/10566652/lithium-metal-battery-with-hybrid-electrolyte-system) — This patent describes a special multi-layered electrolyte system for lithium metal batteries that uses a stiff, hybrid material to block dangerous metal growths, aiming for safer, higher-energy batteries. - [Boosting Solid-State Batteries with a Capacitor Interlayer](https://patentbrief.org/patent/us/11145922/solid-state-battery-having-a-capacitor-assisted-interlayer) — This patent describes a solid-state battery design that includes a special capacitor-like layer between the main battery parts to improve performance and stability. - [Improving Lithium Battery Life with a Built-in Lithium Source](https://patentbrief.org/patent/us/10593988/electrochemical-cell-for-lithium-based-batteries) — This patent describes a method for building rechargeable lithium-based batteries with a special extra lithium source electrode inside that helps the main battery parts work better and last longer by giving them an initial charge of lithium ions. - [Making Solid-State Battery Electrodes That Don't Swell and Crack](https://patentbrief.org/patent/us/11239459/low-expansion-composite-electrodes-for-all-solid-state-batteries) — This patent describes a special design for solid-state battery electrodes that uses tiny internal holes and spaces between particles to prevent them from expanding and cracking during charging and discharging. - [Making Safer Battery Separators with Ceramic Coatings](https://patentbrief.org/patent/us/11094998/ceramic-coated-separators-for-lithium-containing-electrochemical-cells-and-metho) — This patent describes how to make a special ceramic coating for battery separators using specific lithium-containing materials and a precise drying process to improve the safety and performance of lithium-ion batteries.