Nonaqueous Electrolyte Additives for Stable SEI and Low Initial Resistance
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing nonaqueous electrolyte solutions in lithium secondary batteries suffer from decreased battery performance due to the formation of films on electrodes, which inhibit lithium ion migration and cause swelling, leading to poor cycle characteristics and initial input-output characteristics.
Innovation Solution
A nonaqueous electrolyte solution containing specific compounds represented by general formulas (1), (2), (3), and (4), along with solutes and nonaqueous organic solvents, forms a film on electrodes that enhances cation conductivity and reduces initial resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a nonaqueous electrolyte solution is used in lithium secondary batteries, then high capacity and high energy density can be achieved, but the nonaqueous organic solvent is reductively decomposed on the negative electrode surface during charging, forming films and generating gases that inhibit electrochemical reactions and deteriorate cycle characteristics
Solution Approach 1:
The patent introduces specific additives (compounds with formulas (1)-(4)) as intermediary substances that mediate between the nonaqueous organic solvent and the negative electrode. These additives preferentially react with lithium ions to form stable SEI films, preventing direct contact and harmful reactions between the solvent and electrode, thus resolving the contradiction between achieving high energy density and maintaining good cycle characteristics
Solution Approach 2:
The patent changes the chemical composition parameters of the electrolyte by incorporating specific compounds (formulas (1)-(4)) with particular molecular structures containing fluorine atoms and specific functional groups. This parameter change modifies the properties of the formed SEI film, making it more stable and conductive, thereby improving cycle characteristics while maintaining high energy density
2Quantity of substance
If lithium metal or alloy materials are used as negative electrode to achieve high initial capacity, then pulverization occurs during cycles, increasing initial irreversible capacity and decreasing charge/discharge efficiency and battery performance
Solution Approach 1:
The patent applies preliminary action by having the additive compounds react first during initial charging cycles to form a stable protective SEI film on the negative electrode surface before the harmful pulverization and solvent decomposition occur. This pre-formed film prevents subsequent degradation, maintaining both high capacity and efficient charge/discharge performance
Solution Approach 2:
The patent converts the potentially harmful reaction between electrolyte and electrode into a beneficial process by controlling the formation of SEI film through additive compounds. The initial irreversible capacity loss is directed toward forming a stable, conductive protective layer rather than allowing uncontrolled solvent decomposition, thus converting harm into benefit for long-term performance
3Reliability
If films are formed on electrode surfaces to suppress solvent decomposition, then the films contain lithium oxide, lithium carbonate, or lithium alkyl carbonate that can inhibit lithium ion migration and cause electrode swelling
Solution Approach 1:
The patent changes the compositional parameters of the SEI film by introducing compounds with specific molecular structures (formulas (1)-(4)) containing fluorine atoms and particular functional groups. This modifies the film's physical and chemical properties, achieving both solvent decomposition suppression and maintained ion conductivity, preventing electrode swelling
Solution Approach 2:
The patent creates a composite SEI film structure combining traditional components (lithium oxide, lithium carbonate) with new components from the additive compounds. This composite structure leverages the protective properties of traditional SEI while incorporating the beneficial properties of the additive-derived compounds, achieving both protection and conductivity
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 solution improves the initial input-output characteristic of nonaqueous electrolyte batteries by forming a film that prevents solvent decomposition and reduces electrode contact, thereby enhancing battery performance.
Implementation Method 1
the nonaqueous organic solvent in the nonaqueous electrolyte solution is reductively decomposed on the surface of the negative electrode during charging
Implementation Method 2
When lithium cations are inserted into the negative electrode during the first cycle charging, the negative electrode and the lithium cations or the negative electrode and the electrolyte solution solvent react with each other to form a film
Implementation Method 3
the film on the surface of the electrode is called solid electrolyte interface (SEI), and the properties thereof greatly affect the battery performance, through suppression of reductive decomposition of the solvent, suppression of deterioration of the battery performance
Implementation Method 4
when the temperature becomes high in the charged state, oxidative decomposition of the nonaqueous organic solvent occurs locally and partially at the interface between the positive electrode material and the nonaqueous electrolyte solution
Data Source
AI summary
A nonaqueous electrolyte solution capable of exhibiting an excellent initial input-output characteristic when used for a nonaqueous electrolyte solution battery, a nonaqueous electrolyte solution battery capable of exhibiting an excellent initial input-output characteristic, and a compound suitably used for the nonaqueous electrolyte solution are provided. A nonaqueous electrolyte solution containing (I) at least one compound selected from the group consisting of a compound represented by the general formula (1), a compound represented by the general formula (2), a compound represented by the general formula (3), and a compound represented by the general formula (4) described in the specification, (II) a solute, and (III) a nonaqueous organic solvent, a nonaqueous electrolyte solution battery containing the nonaqueous electrolyte solution, and the compound represented by any of the general formulae (1) to (4) described in the specification.