Linear Carbonate Preparation for Battery Electrolyte Stability
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Solution Overview
Problem
Existing linear carbonates used in lithium-ion batteries face issues with acidity conversion rates when lithium hexafluorophosphate is dissolved, affecting battery performance and stability.
Innovation Solution
A method to control hydroxyl concentration in linear carbonates, specifically through a process involving ethylene carbonate, alcohol compounds, and catalysts, to maintain a low free acid conversion rate, ensuring stable performance over time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If linear carbonate is used as solvent for lithium-ion battery electrolyte, then energy density and discharge capacity are improved, but acidity conversion rate increases affecting battery safety and service life
Solution Approach 1:
The patent changes the chemical parameters of the linear carbonate by controlling hydroxyl concentration (≤100 ppm) and water content (≤20 ppm) through specific preparation processes. This parameter control prevents excessive acidity conversion when lithium hexafluorophosphate is dissolved, thereby maintaining both high energy density and battery safety throughout the service life.
2Ease of manufacture
If hydroxyl concentration in linear carbonate is not controlled, then manufacturing process is simpler, but acidity conversion rate increases after lithium hexafluorophosphate dissolution
Solution Approach 1:
The patent applies preliminary action by controlling hydroxyl concentration and water content during the preparation process before the linear carbonate is used in the battery. The preparation process includes specific steps to remove hydroxyl groups and control water content, which prevents acidity conversion issues from arising later when lithium hexafluorophosphate is dissolved.
Solution Approach 2:
The patent uses an intermediary approach by introducing a specific preparation process that acts as a mediator between the linear carbonate production and its subsequent use in battery electrolytes. This intermediary process (controlling hydroxyl concentration ≤100 ppm and water content ≤20 ppm) prevents direct harmful interactions between the carbonate and lithium hexafluorophosphate.
3Duration of action of stationary object
If linear carbonate is stored for extended period, then battery service life is extended, but acidity conversion rate increases affecting performance
Solution Approach 1:
The patent applies beforehand cushioning by pre-controlling hydroxyl concentration (≤100 ppm) and water content (≤20 ppm) in the linear carbonate during preparation. This preliminary control creates a buffer that prevents excessive acidity conversion from occurring even after extended storage periods, thereby maintaining performance stability throughout the battery's service life.
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 controlled hydroxyl concentration in the linear carbonate results in improved energy density, discharge capacity, safety performance, and extended service life of lithium-ion batteries by minimizing acidity conversion.
Implementation Method 1
adding the mixture into a reaction rectification tower, and introducing an alcohol compound for transesterification
Implementation Method 2
introducing the linear carbonate obtained in the step 2 into a melting crystallizer after passing through an adsorbent for adsorption
Implementation Method 3
cooling to −50 ̃70° C. at a cooling rate of 1-3° C./h
Implementation Method 4
purifying a crystal obtained in the step 3 by sweating at a controlled sweating temperature of 1-5° C. and a sweating ratio of 3-7% of a mass of the crystal, separating sweating liquor
Data Source
AI summary
The present invention relates to the technical field of chemical engineering, and in particular to a linear carbonate and a preparation method thereof, which includes one or more of compounds of structural formula 1 below:wherein R1 and R2 are respectively selected from one of alkyl groups containing 1˜4 carbon atoms;a hydroxyl concentration of the linear carbonate is no more than 100 ppm, and a free acid conversion rate of a solution with a concentration of 1 mol/L as formulated from the linear carbonate and lithium hexafluorophosphate is less than 1.2 after storage under 25° C. for 30 days. An acidity conversion rate was reduced when lithium hexafluorophosphate is dissolved in the linear carbonate by controlling the hydroxyl concentration, the energy density, discharge capacity, safety performance and service life of a battery can be improved when it's electrolyte solution contains the linear carbonate.