Fluorinated Electrolyte Additives for High-Voltage Li-Ion Stability
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Solution Overview
Problem
Existing electrolytes in lithium ion batteries break down at high voltages, leading to poor performance and safety issues, particularly in batteries with high Ni cathodes and silicon anodes.
Innovation Solution
The use of fluorinated ethers such as 1,1,1,3,3,3-hexafluoro-2-methoxypropane (HFMOP) as a reaction solvent to produce fluorinated dialkyl carbonates and sulfites, which are incorporated into the electrolyte to enhance battery performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional carbonate and sulfite compounds are used as electrolyte solvents, then the electrolyte provides basic functionality, but the electrolyte breaks down at battery voltages over 4.4 V leading to poor performance
Solution Approach 1:
The patent introduces fluorinated carbonate and sulfite compounds with modified molecular structures (replacing hydrogen atoms with fluorine atoms) to change the chemical parameters of the electrolyte. This structural modification increases the electrochemical stability window, allowing the electrolyte to withstand voltages over 4.4 V without decomposition, directly resolving the contradiction between reliability and compositional stability.
Solution Approach 2:
The patent employs composite electrolyte formulations combining fluorinated carbonate compounds, fluorinated sulfite compounds, and other additives in specific ratios. This composite approach creates synergistic effects where the fluorinated compounds provide high-voltage stability while other components contribute to overall electrolyte performance, solving the decomposition issue at high voltages.
2Quantity of substance
If high Ni cathodes and silicon anodes are used to increase energy density, then battery capacity improves, but electrolyte breakdown and gassing increase
Solution Approach 1:
The fluorinated carbonate and sulfite compounds act as intermediary substances that form stable interfacial layers between the high Ni cathode/silicon anode and the bulk electrolyte. These intermediary layers prevent direct harmful interactions between the electrodes and electrolyte, reducing gassing and decomposition while allowing the high-capacity electrodes to function properly.
Solution Approach 2:
The patent converts the potentially harmful high reactivity of high Ni cathodes and silicon anodes into a benefit by using fluorinated electrolyte components that preferentially react to form protective surface films. These films stabilize the electrode-electrolyte interface, transforming the harmful high reactivity into a beneficial protective mechanism that reduces overall gassing and improves cycle life.
3Productivity
If fluorinated ethers are used as reaction solvent to produce fluorinated carbonates and sulfites, then manufacturing efficiency improves, but process complexity increases
Solution Approach 1:
The patent employs fluorinated ethers that facilitate self-catalyzed or self-accelerating reactions during the synthesis of fluorinated carbonates and sulfites. The fluorinated solvent system inherently promotes the desired chemical transformations through its unique solvation properties, reducing the need for additional catalysts, harsh conditions, or complex process controls, thereby maintaining high productivity while managing process complexity.
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
Improves the cycle life and safety of batteries with high Ni cathodes and silicon anodes by stabilizing the electrolyte and reducing gassing, resulting in longer cycle life and improved performance.
Implementation Method 1
the reaction is performed in the presence of a fluorinated solvent
Implementation Method 2
Carbonate and sulfite compounds are used as electrolyte solvents and additives respectively for non-aqueous batteries
Data Source
AI summary
The disclosure relates to the use of fluorinated ethers such as 1,1,1,3,3,3-hexafluoro-2-methoxypropane (HFMOP) as a reaction solvent to prepare fluorinated dialkyl carbonate and sulfite compounds useful in batteries, and to electrolytes containing fluorinated compounds for use in batteries containing high Ni cathodes and silicon containing anodes.