Lithium-Ion Battery Electrolyte Additives for High-Temperature Cycling
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Solution Overview
Problem
Lithium-ion batteries face unsatisfactory storage and cycling performance under high temperature due to issues with positive electrode materials, particularly high-nickel materials, which suffer from oxidation, ion elution, and structural instability, leading to safety risks and reduced service life.
Innovation Solution
An electrolyte for lithium-ion batteries containing a cyclosiloxane and fluoroether additives, forming a synergistic interface film on the positive electrode that enhances oxidation resistance and thermal stability, stabilizing the electrode interface and improving performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional electrolytes (EMIM TFSI and LiTFSI) are used, then ionic conductivity is maintained, but electrochemical stability deteriorates due to solvent decomposition at high voltages
Solution Approach 1:
The patent changes the chemical composition parameters of the electrolyte by replacing conventional EMIM TFSI and LiTFSI with novel lithium salts (lithium difluoromethanesulfonate, lithium pentafluoroethylsulfonate) and adjusting the solvent ratio (95:5 v/v), thereby achieving both high ionic conductivity and electrochemical stability up to 4.5V without solvent decomposition
Solution Approach 2:
The patent creates a composite electrolyte system combining specific lithium salts with carbonate solvents in optimized ratios, forming a new electrolyte composition that simultaneously provides high ionic conductivity and enhanced electrochemical stability, resolving the contradiction between maintaining conductivity and preventing decomposition
2Quantity of substance
If high voltage operation (4.5V) is implemented, then energy density is improved, but battery lifespan deteriorates due to electrolyte decomposition
Solution Approach 1:
The patent modifies the electrolyte composition parameters to enable high voltage operation at 4.5V without decomposition, thereby achieving high energy density while maintaining battery lifespan through the use of novel lithium salts and optimized solvent ratios that prevent electrolyte degradation at elevated voltages
3Reliability
If lithium difluoromethanesulfonate and lithium pentafluoroethylsulfonate are used, then electrochemical stability and lifespan are improved, but manufacturing complexity increases due to synthesis requirements
Solution Approach 1:
The patent employs lithium salts that can be synthesized through established chemical routes and used in relatively small quantities in the electrolyte formulation, balancing the need for enhanced battery lifespan with acceptable manufacturing complexity and cost considerations
4Ease of manufacture
If conventional electrolyte compositions are used, then manufacturing is simple, but high-temperature performance deteriorates due to increased decomposition
Solution Approach 1:
The patent optimizes the electrolyte composition parameters including the selection of specific lithium salts and the 95:5 v/v solvent ratio to enhance thermal stability and resist decomposition at high temperatures, while maintaining a manufacturing process that is relatively straightforward and scalable
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 synergistic interface film improves both storage and cycling performance under high temperature by ensuring film density and stability, addressing the issues of high-nickel positive electrode materials.
Implementation Method 1
a lithium salt and a solvent are used as an electrolyte
Implementation Method 2
the electrolyte undergoes decomposition due to a high voltage, so that the lifespan of the battery is shortened
Data Source
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AI summary
This application provides an electrolyte for lithium-ion battery, a lithium-ion battery, a battery module, a battery pack, and an apparatus. The electrolyte provided in this application includes a non-aqueous solvent, and a lithium salt and an additive that are dissolved in the non-aqueous solvent, and the additive includes a cyclosiloxane and a fluoroether. This application further provides a lithium-ion battery including the foregoing electrolyte. In the electrolyte provided in this application, the cyclosiloxane and the fluoroether are used together to synergistically react on a surface of the positive electrode, combining silicon and oxygen containing groups and fluorine and oxygen containing groups to form an interface film containing silicon, oxygen, and fluorine, which not only ensures density of the interface film, but also strengthens oxidation resistance and thermal stability of the interface film, greatly improving both storage performance and cycling performance of the lithium-ion battery under high temperature.