Cyclic Sulfonylimide Electrolyte Salt Purity for Heat-Resistant Batteries
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Solution Overview
Problem
Existing methods for producing fluorine-containing cyclic sulfonylimide salts result in impurities that compromise the heat-resistant properties and metal corrosion resistance of non-aqueous electrolyte solutions used in lithium ion batteries, leading to suboptimal performance in terms of initial charging/discharging efficiency and cycle performance.
Innovation Solution
A non-aqueous electrolyte solution comprising a lithium salt and a fluorine-containing cyclic sulfonylimide salt, where the salt is produced through an electrolytic coupling reaction followed by a cyclization and cation exchange step, with a purification process that reduces the content of specific by-products to enhance heat-resistant properties and reduce metal corrosiveness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a fluorine-containing cyclic sulfonylimide salt is produced by conventional electrolytic coupling reaction followed by cyclization and cation exchange, then the salt can be obtained as a final product, but fluorine-containing sulfonamide compounds remain as by-products (impurities) that compromise heat-resistant properties
Solution Approach 1:
The patent applies preliminary action by adding a specific amount of fluorine-containing sulfonamide compound (2) to the reaction mixture during the cation exchange step, before the final product is obtained. This preliminary addition allows the impurity to be present in a controlled amount that prevents harmful by-products from forming while maintaining heat-resistant properties. The impurity acts as a sacrificial agent that protects the final product from degradation.
Solution Approach 2:
The patent converts the harmful effect of fluorine-containing sulfonamide compounds (2) into a beneficial effect. Instead of completely eliminating these compounds as impurities, the invention utilizes them in a controlled manner to prevent the formation of more harmful by-products during the cation exchange reaction. The impurity (2) sacrifices itself to protect the heat-resistant properties of the final fluorine-containing cyclic sulfonylimide salt product.
2Productivity
If conventional production methods are used, then the fluorine-containing cyclic sulfonylimide salt can be produced, but metal corrosion of non-aqueous secondary battery members occurs due to impurities
Solution Approach 1:
The patent applies preliminary action by pre-adjusting the amount of fluorine-containing sulfonamide compound (2) in the reaction mixture before completing the cation exchange reaction. This preliminary control prevents metal corrosion from occurring during battery operation, while maintaining high production efficiency. The controlled impurity level ensures that no excessive purification steps are needed, preserving productivity.
3Device complexity
If the content of fluorine-containing sulfonamide compound is not controlled, then the production process is simpler, but initial charging/discharging efficiency and cycle performance are suboptimal
Solution Approach 1:
The patent applies parameter changes by precisely controlling the amount of fluorine-containing sulfonamide compound (2) present during the cation exchange reaction. Instead of changing the production process complexity, the invention optimizes the concentration parameter of the impurity to achieve both simple production and high reliability. The specific amount range of compound (2) ensures optimal initial charging/discharging efficiency and cycle performance without complicating the production process.
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 achieves improved heat-resistant properties and reduced metal corrosivity, resulting in enhanced initial charging/discharging efficiency and cycle performance of lithium ion batteries.
Implementation Method 1
FO2SCF2CF2SO2F synthesized by an electrolytic coupling reaction of FSO2CF2COOH
Implementation Method 2
a reaction crude product containing FO2SCF2CF2SO2F synthesized by an electrolytic coupling reaction may be purified by a post-treatment such as distillation
Data Source
AI summary
Provided is a non-aqueous electrolyte containing a non-aqueous electrosolvent and a lithium salt, wherein the non-aqueous solvent includes a carbonate solvent, the lithium salt contains a fluorine-containing cyclic sulfonylimide salt represented by general formula (1): (in the formula, Rf each may be the same or different and each represent a fluorine atom or a C4 or lower perfluoro group), and a fluorine-containing sulfonamide compound represented by general formula (2): H(CR2)m—SO2NHM2 (in the formula, R each may be the same or different and each are a fluorine atom or a trifluoromethyl group, M2 is Li, Na, K, H, or NH4, and m is 1 or 2) is contained in an amount of 1,000 mass ppm or less relative to the total amount of non-aqueous electrolyte.