Lithium Metal Battery Electrolyte for Stable SEI and Longer Cycling
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Solution Overview
Problem
Current lithium metal batteries face challenges in maintaining cycling performance due to the accelerated deterioration of battery performance caused by the consumption of film-forming additives used to promote a stable solid electrolyte interface, leading to reduced safety and capacity over time.
Innovation Solution
A lithium metal battery design that optimizes the molar concentration of lithium salt and mass percentage of solvents in the electrolyte, ensuring a stable and uniform solid electrolyte interface film formation, thereby improving cycling performance and safety by controlling the solubility of lithium salts and the distribution of the electrolyte within the battery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If film-forming additives are added to promote stable solid electrolyte interface formation, then cycling performance is improved, but battery performance deteriorates in later stages due to additive consumption
Solution Approach 1:
The patent changes the chemical composition parameters of the electrolyte by introducing a fluorinated cyclic carbonate compound with specific molecular structure (Formula 1) and controlling its concentration ratio (5-50 wt%) relative to total carbonate solvent. This parameter change enables the formation of a stable SEI film without relying on consumable film-forming additives, thereby improving cycling performance while preventing substance loss.
Solution Approach 2:
The patent replaces traditional film-forming additives (which are consumed during cycling) with a fluorinated cyclic carbonate compound that forms a durable, self-sustaining SEI film. The fluorinated compound acts as a sacrificial agent that forms a protective layer preventing further decomposition of electrolyte and consumption of additives, thus extending battery life without continuous material consumption.
2Reliability
If electrolyte concentration and composition are optimized for stable SEI film formation, then ion conductivity is improved, but electrolyte consumption is reduced
Solution Approach 1:
The patent optimizes the electrolyte composition by controlling the concentration of lithium salt (1.0-3.0 mol/L) and the ratio of fluorinated cyclic carbonate compound to total carbonate solvent (5-50 wt%). These parameter changes create an electrolyte system with high ion conductivity while forming a protective SEI film that reduces electrolyte decomposition and consumption during cycling.
Solution Approach 2:
The patent creates a composite electrolyte system combining fluorinated cyclic carbonate compound (Formula 1) with other carbonate solvents (EC, DMC, DEC, EMC). This composite electrolyte formulation synergistically improves ion conductivity through the fluorinated compound's unique properties while the combined solvent system reduces overall electrolyte consumption by forming a stable protective interface.
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 optimized electrolyte composition results in improved ion conductivity, reduced electrolyte consumption, and enhanced safety performance by ensuring a uniform deposition and peeling process of lithium metal, leading to extended battery life and efficient charge/discharge capabilities.
Implementation Method 1
through the synergistic controlling of the lithium salt concentration and the mass percentage of the first solvent to satisfy the foregoing relations, the structure of the solid electrolyte interface (SEI) film on the negative electrode can be improved
Implementation Method 2
the ion conductivity of the SEI film is improved
Implementation Method 3
solubility of the lithium salt in the first solvent is C g/100 g, satisfying: 0.01≤C≤5
Data Source
AI summary
A lithium metal battery includes a positive electrode plate, a negative electrode plate, and an electrolyte. The electrolyte includes a lithium salt and a solvent. A molar concentration of the lithium salt is A mol/L, where 2≤A≤4. The solvent includes a first solvent. Based on a total mass of the solvent in the electrolyte, a mass percentage of the first solvent is B %, satisfying 10≤B≤50. The lithium metal battery satisfies a relation: 40≤A×B≤100. In the lithium metal battery and the electronic apparatus provided in this application, cycling performance and safety performance of the lithium metal battery are improved through the adjustment of components of a fluorine-containing solvent in the electrolyte and components and structure of an SEI film at a negative electrode side.