Halogen-Containing Resin Binder Separator for High-Voltage Battery
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Solution Overview
Problem
Lithium ion batteries face challenges in achieving high capacity and power while maintaining high-temperature charge characteristics due to oxidative decomposition of resin binders at elevated voltages, which affects electrolyte permeability and retentivity.
Innovation Solution
A separator with a porous layer made of inorganic fine particles and a resin binder, specifically polyimide, polyamide, or polyamideimide with a halogen atom content of 10-30% by weight, is used to enhance electrolyte permeability and retentivity, reducing oxidation and improving high-temperature charge characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the end-of-charge voltage is increased to 4.3 V or more to increase battery capacity, then the utilization factor of the positive electrode is improved, but the resin binder in the porous layer undergoes oxidative decomposition which deteriorates high-temperature charge characteristics
Solution Approach 1:
The patent changes the chemical composition parameters of the resin binder by incorporating halogen atoms (specifically fluorine atoms at 10-30 wt%) into the molecular chain of polyimide, polyamide, or polyamideimide resins. This parameter change reduces the electron density of the resin main chain, making it more resistant to oxidative decomposition at high voltages (4.3 V or more), thereby maintaining high-temperature charge characteristics while enabling increased battery capacity
Solution Approach 2:
The patent creates a composite resin binder system by combining halogen-containing resins with inorganic fine particles in the porous layer. This composite structure provides both the oxidative resistance of halogen-containing polymers and the structural stability of inorganic particles, preventing resin decomposition at elevated charge voltages while maintaining the mechanical integrity needed for high-temperature operation
2Productivity
If a porous layer with resin binder is disposed between electrode and separator to improve electrolyte permeability, then electrolyte supply to electrode interior is improved, but resin oxidation at high voltage reduces electrolyte retentivity
Solution Approach 1:
The patent modifies the chemical parameters of the resin binder by introducing halogen atoms into the molecular chain, which changes the electron density and chemical stability of the resin. This parameter change allows the resin to maintain its pore structure and binding properties at high voltages, preserving electrolyte retentivity while the porous structure continues to provide effective electrolyte permeability to the electrode interior
3Temperature
If conventional resins (polyamide, polyimide, polyamideimide) are used in porous layer to increase heat resistance, then safety is improved, but oxidative decomposition occurs at high voltage which deteriorates battery performance
Solution Approach 1:
The patent changes the chemical composition of conventional resins by incorporating halogen atoms (10-30 wt% fluorine atoms) into the molecular chain of polyimide, polyamide, or polyamideimide. This parameter change simultaneously enhances both heat resistance and oxidative stability by reducing the electron density of the resin main chain, preventing oxidative decomposition at high voltages while maintaining the thermal stability required for safety
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 provides a nonaqueous electrolyte battery with improved high-temperature charge characteristics, large capacity, and high energy density by reducing resin oxidation and maintaining effective electrolyte permeability and retentivity.
Implementation Method 1
the electron density of the resin main chain can be reduced and the electron abstraction reaction due to oxidation can be reduced
Implementation Method 2
a porous layer having an excellent nonaqueous electrolyte permeability is disposed between at least one of the positive and negative electrodes and a separator and allowed to function as a diffusion path for supplying an electrolytic solution
Implementation Method 3
function as a diffusion path for supplying an electrolytic solution present in a remaining space of the battery to the interior of the electrode
Data Source
AI summary
To obtain a separator for a nonaqueous electrolyte battery that has an excellent nonaqueous electrolyte permeability into an electrode and an excellent electrolyte retentivity of the electrode and achieves a large capacity, a high energy density and a good high-temperature charge characteristic. A separator 3 used for a nonaqueous electrolyte battery is formed by disposing a porous layer 2 made of inorganic fine particles and a resin binder on a porous separator substrate 1, the resin binder is made of at least one resin selected from the group consisting of polyimide resins, polyamide resins and polyamideimide resins and the molecular chain of the resin has a halogen atom content of 10% to 30% by weight, and the content of the resin binder in the porous layer is 5% by weight or more.