ALD Protection Layers for Lithium Metal Anodes
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Solution Overview
Problem
Highly reactive metal anodes in batteries, such as lithium (Li) metal, face challenges due to corrosion and dendrite formation, leading to battery degradation and failure, especially when exposed to atmospheric conditions, and existing protection methods like organic molecules and polymeric coatings have limited success in controlling thickness and composition.
Innovation Solution
Atomic layer deposition (ALD) is used to form a protection layer on the anode with a thickness of 1 nm to 200 nm, allowing ion conduction while inhibiting electron transport and preventing air and water passage, thereby reducing corrosion and enhancing battery performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If organic molecules and polymeric coatings are used to protect Li metal anodes, then some protection is achieved, but thickness and composition control is poor
Solution Approach 1:
The patent applies atomic layer deposition (ALD) to precisely control the thickness and composition of the protection layer on Li metal anodes. ALD enables atomic-level precision in depositing inorganic materials such as Al2O3, TiO2, and Li3PO4, allowing thickness control within nanometer ranges (e.g., 2-20 nm) and stoichiometric composition control, thereby resolving the manufacturing precision issue while maintaining reliable protection against corrosion and dendrite formation.
2Reliability
If sputtered solid electrolyte films are deposited on Li metal electrodes, then electrolyte decomposition is prevented, but large cell overpotentials occur during recharge due to large thicknesses and low ionic conductivity
Solution Approach 1:
The patent employs atomic layer deposition (ALD) to create ultra-thin protection layers (2-20 nm) of inorganic materials on Li metal anodes, replacing the thick sputtered solid electrolyte films. The ALD process enables precise thickness control at the nanometer scale, ensuring the protection layer is thin enough to maintain low ionic resistance and minimal cell overpotential while still providing effective protection against electrolyte decomposition and corrosion.
Solution Approach 2:
The patent substitutes the sputtering process with atomic layer deposition (ALD) to form protection layers. ALD provides superior conformal coverage and atomic-level thickness control compared to sputtering, enabling the formation of ultra-thin, uniform layers that maintain low ionic resistance while providing effective protection, thereby reducing cell overpotential during recharge.
3Quantity of substance
If Li metal anodes are used to achieve high energy density, then battery capacity increases, but corrosion reactions occur due to high reactivity with electrolytes and atmospheric conditions
Solution Approach 1:
The patent introduces an inorganic protection layer deposited by atomic layer deposition (ALD) as an intermediary between the highly reactive Li metal anode and the electrolyte/atmosphere. This protection layer acts as a stable barrier that prevents corrosion reactions while allowing ionic transport, enabling the Li metal anode to maintain its high capacity benefits without suffering from degradation due to reactivity with electrolytes or atmospheric exposure.
Solution Approach 2:
The patent creates a composite structure consisting of the Li metal anode combined with an inorganic protection layer (such as Al2O3, TiO2, or Li3PO4) deposited by ALD. This composite structure combines the high capacity advantage of Li metal with the stability and protective properties of inorganic materials, resulting in an anode that maintains both high battery capacity and long-term stability during cycling.
4Ease of manufacture
If Li metal anodes are exposed to atmospheric conditions, then battery assembly is simplified, but oxidation and corrosion occur from exposure to H2O and CO2
Solution Approach 1:
The patent applies atomic layer deposition (ALD) to form a protective inorganic layer on the Li metal anode surface before battery assembly. This preliminary protection step enables the anode to withstand exposure to atmospheric conditions during handling and assembly without oxidizing or corroding, thereby simplifying the manufacturing process by eliminating the need for stringent inert atmosphere requirements while maintaining anode integrity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The ALD protection layer effectively delays and reduces corrosion, maintains anode integrity, and improves battery capacity and Coulombic efficiency, allowing for more relaxed purity requirements in battery assembly and operation.
Implementation Method 1
The protection layer is formed on the anode to a thickness of between 1 nm and 200 nm, inclusive, using atomic layer deposition (ALD)
Data Source
AI summary
A protection layer is formed on a highly-reactive substantially-pure metal anode to a thickness of between 1 nm and 200 nm, inclusive, using atomic layer deposition (ALD). The ALD protection layer allows the conduction of ions of the metal of the anode therethrough but suppresses electron transport therethrough. The ALD protection layer may also be effective to inhibit passage of air and/or water therethrough. The ALD protection layer can allow more relaxed purity requirements for subsequent battery assembly, electrolyte specifications, and/or cathode gas purity. Fabrication methods for the protection layers, protected metal anodes, and systems and devices incorporating such protected metal anodes are also disclosed herein.