Battery Separator Coating for Low-Temperature Electrolyte Penetration
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Solution Overview
Problem
Lithium-ion batteries exhibit decreased performance and restricted application in low-temperature environments due to inadequate low-temperature performance, necessitating an enhancement in their cold weather capabilities.
Innovation Solution
A separator with a first coating of polymer secondary particles having a melting point of 130° C. to 150° C. and a second coating of high molecular polymer, strategically applied to improve electrolyte penetration and adhesion, along with an optional inorganic coating for mechanical strength, is used to enhance the battery's low-temperature performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the melting point of polymer secondary particles is increased to improve adhesion, then adhesion improves, but electrolyte penetration decreases
Solution Approach 1:
The patent optimizes the melting point parameter of polymer secondary particles to a specific range (130-150°C) to achieve the best balance between adhesion and electrolyte penetration. This parameter optimization resolves the contradiction by finding the optimal value that satisfies both requirements simultaneously.
2Reliability
If the melting point of polymer secondary particles is decreased to improve electrolyte penetration, then electrolyte penetration improves, but adhesion deteriorates
Solution Approach 1:
The patent determines the optimal melting point range (130-150°C) for polymer secondary particles through parameter optimization. This resolves the contradiction between electrolyte penetration and adhesion by identifying the specific parameter value that achieves both goals.
3Reliability
If polymer secondary particles with excessively low melting point are used, then electrolyte penetration improves, but the polymer swells or dissolves leading to decreased adhesion
Solution Approach 1:
The patent establishes a lower bound (130°C) for the melting point parameter to prevent polymer swelling and dissolution while maintaining adequate electrolyte penetration. This parameter constraint resolves the contradiction by eliminating values that cause harmful effects.
4Strength
If polymer secondary particles with excessively high melting point are used, then adhesion improves, but kinetic performance deteriorates
Solution Approach 1:
The patent sets an upper bound (150°C) for the melting point parameter to maintain good adhesion while preserving kinetic performance. This parameter limitation resolves the contradiction by preventing values that would harm kinetic performance.
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 results in improved adhesion and electrolyte penetration, leading to better low-temperature performance and energy density of lithium-ion batteries, while maintaining mechanical strength and cycling performance.
Implementation Method 1
the secondary particles have many internal voids, and the electrolyte can more easily penetrate into these voids
Implementation Method 2
the polymer is prone to over-swelling or even dissolving in the electrolyte, which leads to a decrease in the adhesion of the first coating
Data Source
AI summary
A separator includes a separator substrate, and a first coating and a second coating respectively disposed on two surfaces of the separator substrate, where the first coating includes polymer secondary particles, and the secondary particles have a melting point of 130° C. to 150° C. The first coating in the separator has good adhesion and resistance to electrolyte swelling, and the secondary particles have many internal voids, which facilitates the penetration of the electrolyte, thus improving electrolyte penetration into the first coating and enhancing the low-temperature performance of the electrochemical apparatus.