Electrolyte Composition for High-Voltage Lithium-Ion Batteries
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Solution Overview
Problem
Lithium ion batteries face limitations in performance and cycle life when operating at high cathode potentials due to decomposition of existing non-aqueous electrolyte solvents, particularly above 4.35 V, which affects the battery's ability to efficiently discharge and charge multiple times.
Innovation Solution
The development of an electrolyte composition comprising a cyclic carbonate as the first solvent, a non-fluorinated acyclic carbonate as the second solvent, and an electrolyte component such as a fluorinated acyclic carboxylic acid ester, fluorinated acyclic carbonate, or fluorinated acyclic ether, which are present in specific weight percentages to enhance the stability and performance of the battery at high potentials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If conventional non-aqueous electrolyte solvents (cyclic carbonate and linear carbonate mixtures) are used, then the battery can operate at high cathode potentials above 4.35 V, but the electrolyte decomposes resulting in limited cycling performance and reduced cycle life
Solution Approach 1:
The patent changes the chemical composition parameters of the electrolyte by introducing fluorinated carbonates and carboxylic acid esters with specific molecular structures. These compositional changes modify the electrolyte's electrochemical stability window and decomposition behavior, enabling operation at higher cathode potentials while maintaining cycling performance through reduced decomposition reactions.
Solution Approach 2:
The patent creates a composite electrolyte system by combining multiple solvent components (fluorinated cyclic carbonate, fluorinated linear carbonate, and fluorinated carboxylic acid ester) in specific ratios. This composite formulation synergistically improves both the stability at high potentials and the cycling performance, resolving the contradiction between operating voltage and reliability.
2Power
If conventional electrolyte solvents are used to achieve high cathode potential operation, then the battery voltage can exceed 4.35 V, but the solvent decomposes leading to loss of battery performance
Solution Approach 1:
The patent modifies the electrolyte's chemical composition by incorporating fluorinated compounds with specific functional groups. These parameter changes in molecular structure increase the electrochemical stability of the electrolyte, raising its decomposition potential above 4.35 V and enabling high-voltage operation without significant solvent decomposition.
Solution Approach 2:
The patent converts the potential harm of high-voltage operation (which would normally cause electrolyte decomposition) into a benefit by using fluorinated electrolyte components that are specifically designed to be stable at high potentials. The fluorinated compounds' inherent stability at high voltages transforms the high-voltage condition from a harmful factor into an advantageous operating parameter.
Data Source
AI summary
Disclosed herein are electrolyte compositions comprising: a) a first solvent comprising a cyclic carbonate; b) a second solvent comprising a non-fluorinated acyclic carbonate; c) at least one electrolyte component selected from: i) a fluorinated acyclic carboxylic acid ester; ii) a fluorinated acyclic carbonate; iii) a fluorinated acyclic ether; or iv) a mixture thereof; and d) an electrolyte salt; wherein the electrolyte component is present in the electrolyte composition in the range of from about 0.05 weight percent to about 10 weight percent, based on the total weight of the first and second solvents.