Alkali Metal Electrode Composite Protective Layer
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Solution Overview
Problem
Existing electrode structures in electrochemical cells are prone to undesirable reactions with electrolytes and suffer from exposure issues, leading to performance degradation and limited cycling stability.
Innovation Solution
A protected electrode structure comprising an alkali metal electrode with a composite protective structure, which includes alloys, fluoride salts, and elemental carbon, forming a stable interface that prevents exposure to electrolytes and accommodates expansion/contraction during cycling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If existing electrode structures are used, then the device complexity is low, but the reliability deteriorates due to undesirable reactions with electrolytes and exposure issues
Solution Approach 1:
The patent applies composite materials by creating a multi-layer protective structure comprising an alloy layer (e.g., Li-Al-Sn alloy) and a fluoride salt layer (e.g., LiF) on the alkali metal electrode. This composite structure provides both chemical stability against electrolyte reactions and mechanical flexibility to accommodate volume changes during cycling, thereby resolving the contradiction between reliability improvement and structure complexity.
Solution Approach 2:
The patent utilizes parameter changes by controlling the composition ratios (e.g., Al:Sn ratio between 1:4 and 4:1, LiF content between 0.1-50 wt%), thickness parameters (protective structure thickness 1-100 micrometers), and processing conditions (heating temperature 50-200°C, time 1-24 hours) to optimize the protective structure's properties, achieving both high reliability and controlled complexity.
2Reliability
If a protective structure is added to prevent electrolyte exposure, then the reliability improves, but the device complexity increases
Solution Approach 1:
The patent employs composite materials by forming an integrated multi-layer protective structure with an alloy layer and fluoride salt layer that work synergistically. The alloy layer provides mechanical stability and volume accommodation, while the fluoride salt layer provides chemical stability and ion transport, achieving effective protection with a controlled number of functional layers.
Solution Approach 2:
The protective structure exhibits multi-functionality where the alloy layer simultaneously provides mechanical stability, volume expansion accommodation, and serves as a substrate for fluoride salt deposition. The fluoride salt layer simultaneously provides chemical protection against electrolyte reactions, ion transport pathways, and contributes to structural stability, reducing the need for additional separate functional layers.
3Reliability
If the protective structure is made more stable to prevent reactions, then the reliability improves, but the adaptability worsens due to limited flexibility during expansion/contraction
Solution Approach 1:
The patent resolves this contradiction through composite materials where the alloy layer (e.g., Li-Al-Sn) provides mechanical flexibility and volume accommodation capability, while the fluoride salt layer (e.g., LiF) provides chemical stability. The combination allows the protective structure to maintain both chemical inertness against electrolytes and mechanical adaptability during electrode expansion and contraction cycles.
Solution Approach 2:
The patent utilizes parameter changes by adjusting the composition ratios (Al:Sn ratio, LiF content), thickness parameters, and processing conditions to optimize the balance between chemical stability and mechanical flexibility. By controlling these parameters, the protective structure achieves both high chemical stability and sufficient adaptability for volume changes during cycling.
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 protected electrode structure enhances cell performance by preventing electrolyte exposure, maintaining stability through ion transport and flexibility, and forming a stable solid electrolyte interface, thereby improving cycling stability and capacity retention.
Implementation Method 1
forming a stable interface that prevents exposure to electrolytes
Implementation Method 2
maintaining stability through ion transport
Implementation Method 3
accommodates expansion/contraction during cycling
Implementation Method 4
forming a stable solid electrolyte interface
Data Source
AI summary
Articles and methods involving protected electrode structures are generally provided. In some embodiments, a protected electrode structure includes an electrode comprising an alkali metal and a protective structure directly adjacent the electrode. In some embodiments, the protective structure comprises elemental carbon and intercalated ions. In some embodiments, the protective structure is a composite protective structure. The composite structure may comprise an alloy comprising an alkali metal, an oxide of an alkali metal, and/or a fluoride salt of an alkali metal.