Lithium Metal Anode Protective Film Stack for Low-Impedance Handling
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Solution Overview
Problem
Lithium metal poses challenges in processing, storage, and transportation due to its reactivity, and existing protective surface treatments often interfere with subsequent processing or cause issues like irreversible capacity loss in lithium-ion and solid-state batteries.
Innovation Solution
A method involving the formation of a lithium metal film on a copper or stainless steel current collector, followed by a protective film stack comprising a first protective film such as a tin chalcogenide or gallium chalcogenide, and a second protective film like lithium fluoride or a metallic film, which provides surface protection and reduces impedance for ion movement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If lithium metal is coated with a wax layer (e.g., polyethylene wax) for protective surface treatment, then the reactivity of lithium is reduced, but a large amount of coating agent is applied which interferes with subsequent processing of the lithium metal film
Solution Approach 1:
The patent changes the parameters of the protective coating by using inorganic materials (metal oxides, metal nitrides, metal carbides) instead of organic wax materials, and by controlling the coating thickness to be thin (1-100 nm). This allows the coating to provide protection while being transparent to lithium ion transport and not interfering with subsequent processing operations.
Solution Approach 2:
The patent creates an inert protective environment on the lithium metal surface by forming coatings of metal oxides (e.g., Al2O3, SiO2), metal nitrides (e.g., TiN, TaN), or metal carbides (e.g., TiC, SiC). These inorganic materials provide an inert barrier that protects lithium from reaction with moisture and oxygen in the air, eliminating the need for wax-based coatings that interfere with processing.
2Stability of the object's composition
If polymer coatings (e.g., polyurethanes, PTFE, PVC, polystyrene) are applied for protective surface treatment, then lithium metal stability is improved, but these coatings cause problems when prelithiating electrode materials
Solution Approach 1:
The patent changes the material parameters from organic polymers to inorganic materials with specific properties. The inorganic coatings (metal oxides, nitrides, carbides) have different chemical and physical parameters that make them stable for lithium protection while being compatible with electrode materials during prelithiation, unlike polymer coatings which cause irreversible capacity loss.
Solution Approach 2:
The patent uses composite material structures where inorganic protective layers (metal oxides, nitrides, or carbides) are applied on the lithium metal surface. These composite inorganic coatings provide both stability for lithium metal and compatibility with subsequent electrode materials, resolving the conflict between protection and adaptability.
3Ease of operation
If a protective film is formed on lithium metal to enable handling and storage in dry conditions, then processing ease is improved, but the film must not increase impedance for ion movement
Solution Approach 1:
The patent applies the principle of thin films by creating ultra-thin inorganic protective layers (1-100 nm thickness) on the lithium metal surface. These thin inorganic films provide sufficient mechanical protection for handling and storage in dry conditions while remaining thin enough to allow lithium ion transport without significant impedance increase.
Solution Approach 2:
The inorganic protective coatings (metal oxides, nitrides, carbides) create an inert environment at the lithium surface, enabling handling and storage in dry conditions without requiring thick coatings. The inert nature of these materials provides protection while their thin structure maintains ion transport pathways.
Data Source
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AI summary
A method and apparatus for forming metal electrode structures, more specifically lithium-containing anodes, high performance electrochemical devices, such as primary and secondary electrochemical devices, including the aforementioned lithium-containing electrodes. In one implementation, the method comprises forming a lithium metal film on a current collector. The current collector comprises copper and/or stainless steel. The method further comprises forming a protective film stack on the lithium metal film, comprising forming a first protective film on the lithium metal film. The first protective film is selected from a bismuth chalcogenide film, a copper chalcogenide film, a tin chalcogenide film, a gallium chalcogenide film, a germanium chalcogenide film, an indium chalcogenide film, a silver chalcogenide film, a dielectric film, a lithium fluoride film, or a combination thereof.