Porous Separator Coating for Battery Overcharge Heat Dissipation
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Solution Overview
Problem
Existing electrochemical devices, such as lithium secondary batteries, face safety issues due to overcharge leading to rapid temperature increases and potential explosions, which existing heat-conductive pads or foils cannot adequately address while maintaining high energy density.
Innovation Solution
A separator for electrochemical devices featuring a porous polymer substrate with a porous coating layer containing inorganic particles and a binder polymer, where the binder polymer concentration gradient increases towards the electrode, enhancing adhesion and heat conductivity without additional devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a pad or foil having high heat conductivity is introduced to the cell surface, then heat-radiating capability is improved, but energy density per unit volume is reduced
Solution Approach 1:
The patent merges the heat dissipation function with the separator by forming a porous coating layer containing inorganic particles directly on the separator surface. This integration eliminates the need for separate heat-radiating pads or foils, allowing heat dissipation functionality to be incorporated within the existing cell structure without adding external components that would reduce energy density.
Solution Approach 2:
The patent employs a porous coating layer with controlled porosity (30-70%) containing inorganic particles. The porous structure provides thermal conductivity for heat dissipation while maintaining ion permeability for battery operation. The porosity allows the coating to facilitate heat radiation without requiring a dense, thick layer that would occupy valuable cell volume and reduce energy density.
2Reliability
If additional heat dissipation devices are introduced, then overcharge safety is improved, but device complexity increases
Solution Approach 1:
The patent combines multiple functions into the separator component: ion separation, heat dissipation, and overcharge protection. By integrating the heat-radiating porous coating layer directly onto the separator, the invention eliminates separate heat dissipation devices and simplifies the overall cell structure while maintaining or enhancing safety performance.
Solution Approach 2:
The separator is designed to perform multiple functions simultaneously: it acts as an ion separator, a heat dissipation medium through its porous coating layer, and an overcharge protection mechanism. This multi-functionality reduces the need for additional specialized components, thereby decreasing device complexity while improving overall reliability.
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 improved overcharge safety and heat-radiating properties, maintaining conventional energy density by increasing adhesion between the electrode and separator, thereby reducing heat resistance and preventing explosions.
Implementation Method 1
each of the binder polymer contained in the first region and the second region has a concentration gradient increasing from the porous polymer substrate toward the outermost the porous coating layer
Implementation Method 2
a porous coating layer positioned on at least one surface of the porous polymer substrate and including inorganic particles and a binder polymer
Data Source
AI summary
A separator for an electrochemical device and a method for manufacturing the same. Particularly, the drying rate of a composition for forming a second porous coating layer is controlled to be higher than the drying rate of a composition for forming a first porous coating layer. In this manner, it is possible to improve the interfacial adhesion between an electrode and the separator, while ensuring adhesion strength between a porous polymer substrate and a porous coating layer.