Negatively Charged Polymerizable Monomer for High-Voltage Lithium Battery Stability
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Solution Overview
Problem
High-capacity batteries with high charging voltage suffer from reduced cathode stability and increased electrolyte decomposition, leading to decreased discharge capacity, especially when stored at high temperatures.
Innovation Solution
An organic electrolytic solution comprising a lithium salt, an organic solvent, and a negatively charged linear or cyclic polymerizable monomer that forms a rigid film on the cathode, preventing solvent decomposition and ion elution, thereby enhancing battery stability and cycle life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If high charging voltage is used to achieve high capacity, then battery capacity is improved, but cathode stability deteriorates and electrolyte decomposition increases
Solution Approach 1:
A polymer coating layer is introduced as an intermediary between the cathode active material and the electrolyte solution. This coating layer, formed by polymerizing a vinylene monomer on the cathode surface, acts as a protective barrier that prevents direct contact between the electrolyte and cathode, thereby suppressing electrolyte decomposition and cathode material degradation while maintaining high charging voltage operation
Solution Approach 2:
The invention changes the chemical and physical parameters of the electrolyte system by introducing a polymer coating with specific properties (formed from vinylene monomers with particular functional groups). This coating modifies the interface properties between electrolyte and cathode, creating a stable environment that enables high voltage operation without excessive decomposition
2Quantity of substance
If high charging voltage is used to achieve high capacity, then battery capacity is improved, but electrolyte decomposition increases
Solution Approach 1:
The polymer coating layer serves as a mediator that physically separates the electrolyte from the high-voltage cathode surface. This intermediate layer prevents direct electrochemical reactions between the electrolyte and cathode active material, significantly reducing electrolyte decomposition even at high charging voltages
Solution Approach 2:
The invention converts the potentially harmful high voltage stress into a beneficial effect by using it to drive in-situ polymerization of vinylene monomers on the cathode surface. This creates a protective coating that subsequently prevents further decomposition, turning the harsh high-voltage environment into a mechanism for self-protection
3Quantity of substance
If battery is stored at high temperature to maintain performance, then discharge capacity is maintained, but decomposition reactions accelerate
Solution Approach 1:
The polymer coating layer acts as a thermal and chemical buffer between the cathode and electrolyte during high-temperature storage. This intermediate barrier suppresses thermally activated decomposition reactions by preventing direct interaction between reactive species, allowing the battery to be stored at elevated temperatures without excessive degradation
4Reliability
If polymerizable monomer is added to form protective film, then stability is improved, but device complexity increases
Solution Approach 1:
The vinylene monomer is pre-added to the electrolyte solution before battery assembly. During initial charging cycles, the monomer automatically polymerizes on the cathode surface to form the protective coating. This preliminary action eliminates the need for separate coating application steps, maintaining manufacturing simplicity while achieving enhanced stability
Solution Approach 2:
The system uses the battery's own operating conditions (charging voltage, temperature) to drive the polymerization of the monomer on the cathode surface. The battery essentially coats itself during normal operation, eliminating the need for external coating equipment or complex manufacturing processes while achieving the protective effect
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 effectively inhibits solvent decomposition and metal ion precipitation, maintaining battery performance and capacity retention even after multiple cycles and at elevated temperatures.
Implementation Method 1
a linear or cyclic polymerizable monomer that is negatively charged due to the location of electrons on the monomer
Implementation Method 2
an organic electrolytic solution includes a lithium salt, an organic solvent and a polymer of a linear or cyclic polymerizable monomer
Data Source
AI summary
An organic electrolytic solution including a lithium salt, an organic solvent, and a linear or cyclic polymerizable monomer that is negatively charged due to localization of electrons on the monomer, and a lithium battery employing the same. Since the organic electrolytic solution prevents decomposition of an electrolyte and elution from or precipitation of metal ions, the lithium battery employing the organic electrolytic solution has excellent lifetime characteristics and cycle characteristics.