Non-aqueous Electrolyte Solution Using Fluorinated Solvent and LiBOB
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Solution Overview
Problem
Non-aqueous electrolyte solutions with fluorinated solvents face challenges in suppressing both oxidative and reductive decomposition, leading to decreased battery capacity due to the low solubility of LiBOB, which is essential for forming a protective SEI film and preventing decomposition.
Innovation Solution
A method involving the preparation of a highly concentrated LiBOB solution in a highly polar solvent and subsequent mixing with a fluorinated solvent to achieve sufficient LiBOB dissolution, maintaining its solvated state and ensuring adequate SEI film formation, thereby balancing oxidation and reduction resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a fluorinated solvent is used as the main component of the non-aqueous solvent to suppress oxidative decomposition, then oxidation resistance is improved, but LiBOB solubility deteriorates
Solution Approach 1:
The patent introduces a highly polar solvent as an intermediary substance to mediate between the fluorinated solvent and LiBOB. The highly polar solvent serves as a bridge that enhances LiBOB solubility in the fluorinated solvent system without compromising the oxidation resistance provided by the fluorinated solvent. This intermediary substance resolves the contradiction by enabling sufficient LiBOB dissolution while maintaining the protective oxidation-resistant environment.
Solution Approach 2:
The patent creates a composite electrolyte solution system combining fluorinated solvent, highly polar solvent, and LiBOB in specific proportions. This composite approach leverages the oxidation resistance of fluorinated solvents while utilizing the high LiBOB solubility of highly polar solvents. The synergistic combination of multiple components resolves the contradiction between oxidation resistance and LiBOB solubility that cannot be achieved with a single solvent type.
2Reliability
If LiBOB concentration is increased to form sufficient SEI film and suppress reductive decomposition, then reduction resistance is improved, but manufacturing complexity increases
Solution Approach 1:
The patent optimizes the concentration parameters of LiBOB and highly polar solvent within specific ranges to achieve sufficient SEI film formation without excessive complexity. By establishing precise parameter specifications (LiBOB concentration and highly polar solvent content), the patent simplifies the manufacturing process while ensuring adequate reduction resistance through proper SEI film formation.
3Quantity of substance
If highly polar solvent content is increased to improve LiBOB solubility, then LiBOB concentration is improved, but oxidation resistance deteriorates
Solution Approach 1:
The patent establishes optimal parameter ranges for highly polar solvent content and LiBOB concentration that balance solubility and oxidation resistance. By controlling these parameters within specific boundaries, the patent achieves sufficient LiBOB concentration for SEI film formation while maintaining adequate oxidation resistance through limited but effective highly polar solvent content.
Solution Approach 2:
The patent creates a balanced composite electrolyte system where fluorinated solvent provides oxidation resistance and highly polar solvent provides LiBOB solubility. The specific compositional ratios in this composite system resolve the contradiction between LiBOB concentration and oxidation resistance by leveraging the complementary strengths of different solvent types in controlled proportions.
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
This approach effectively suppresses both oxidative decomposition at full charge and reductive decomposition during initial charging, maintaining battery capacity by ensuring sufficient LiBOB concentration and oxidation resistance.
Implementation Method 1
some of the non-aqueous electrolyte solution undergoes reductive decomposition during initial charging and a coating film known as a solid electrolyte interface (SEI) film is formed on a surface of the negative electrode active substance
Implementation Method 2
Because such fluorinated solvents exhibit high resistance to oxidation, it is possible to advantageously suppress oxidative decomposition at full charge even in cases where a high potential positive electrode active substance is used
Implementation Method 3
preparing a highly concentrated LiBOB solution by dissolving LiBOB in a highly polar solvent
Data Source
AI summary
A non-aqueous electrolyte secondary battery which uses a non-aqueous electrolyte solution in which a main component of a non-aqueous solvent is a fluorinated solvent, and by which it is possible to suitably prevent a decrease in battery capacity. A method for producing the non-aqueous electrolyte solution disclosed here includes a fluorinated solvent provision step for preparing the fluorinated solvent, a highly polar solvent provision step for preparing a highly polar solvent having a relative dielectric constant of 40 or more, a LiBOB dissolution step for preparing a highly concentrated LiBOB solution by dissolving LiBOB in the highly polar solvent at a concentration that exceeds the saturation concentration in the fluorinated solvent, and a mixing step for mixing the fluorinated solvent with the highly concentrated LiBOB solution.