Lithium Metal Battery Protective Layer Reduces Resistance
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Solution Overview
Problem
Existing lithium metal secondary batteries face issues with high reactivity between lithium and the electrolyte, leading to decomposition and the formation of lithium dendrites, which deteriorate coulombic efficiency and electrochemical stability, and increase resistance, thereby reducing battery lifespan.
Innovation Solution
A battery design featuring a negative electrode with a protective layer composed of a copolymer derived from poly(ethylene glycol) diacrylate (PEGDA) and N-hydroxyethyl acrylamide (HEAA), combined with an electrolyte containing a non-fluorinated organic liquid and a fluorinated liquid, which reduces uncompensated resistance and charge transfer resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a protective layer is coated on the lithium metal anode to prevent direct contact with the electrolyte, then the side reaction and dendrite formation are suppressed, but the uncompensated resistance and charge transfer resistance increase significantly
Solution Approach 1:
The patent changes the chemical composition parameters of the protective layer by using a copolymer system (PEGDA and HEAA) with specific functional groups, and adjusts the electrolyte composition to a high concentration (2-6 M LiFSI) with fluorinated additives. These parameter changes reduce the resistance while maintaining protection functionality.
Solution Approach 2:
The patent employs a composite protective layer made from copolymerizing PEGDA and HEAA monomers, creating a material with combined properties: PEGDA provides lithium ion conductivity through ether oxygen atoms, while HEAA contributes to film stability and reduced resistance. The electrolyte is also a composite system combining conventional carbonate solvents with fluorinated liquids and high concentration LiFSI salt.
2Stability of the object's composition
If a polymer protective film is formed on the lithium metal surface to suppress dendrite growth, then the electrode surface stability is improved, but the battery lifespan decreases due to increased resistance
Solution Approach 1:
The patent uses high concentration electrolyte (2-6 M LiFSI) which changes the solvation structure and reduces the formation of thick SEI layers. The fluorinated liquid additives further modify the interface properties, leading to a protective film that maintains low resistance over extended cycling periods, thus improving battery lifespan.
Solution Approach 2:
The protective layer maintains continuous lithium ion conductivity during cycling through the ether oxygen atoms in PEGDA units, ensuring uninterrupted ion transport. The self-healing capability of the copolymer film ensures continuous protection without degradation of performance over time.
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 protective layer acts as a self-healing polymer film, minimizing the formation of a thick solid electrolyte interface layer, resulting in reduced resistance and improved battery performance.
Implementation Method 1
The protective layer acts as a self-healing polymer film, minimizing the formation of a thick solid electrolyte interface layer
Data Source
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AI summary
The present invention relates to a battery comprising a high-concentrated electrolyte and a negative electrode for a battery comprising a metal substrate, and a protective layer disposed directly on at least a part of the metal substrate, wherein the protective layer comprises a copolymer obtainable by the reaction between two or more monomers, a fluoropolymer additive, and a lithium salt. The present inventors have demonstrated that the combination of the electrolyte and the negative electrode results in a reduced resistance within the battery.