Battery Separator Coating for Electrode Adhesion and Heat Resistance
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing secondary battery separators face issues with reduced adhesion to electrodes and insufficient heat resistance, leading to safety concerns such as thermal runaway and short-circuits.
Innovation Solution
A separator for secondary batteries featuring a porous polymer substrate with a porous coating layer containing inorganic particles and a urethane bond-containing crosslinked polymer, which is crosslinked during the battery activation process, ensuring improved adhesion and heat resistance without the need for additional crosslinking steps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a porous organic-inorganic coating layer is formed by applying a mixture of inorganic particles with a binder polymer onto a porous polymer substrate, then heat resistance is improved, but adhesion to electrode is reduced
Solution Approach 1:
The patent changes the chemical structure parameters of the binder polymer by introducing urethane bonds and controlling the glass transition temperature to -50°C or lower. This parameter modification allows the binder to maintain flexibility and adhesion at low temperatures while providing sufficient heat resistance for the separator coating layer.
Solution Approach 2:
The patent creates a composite coating layer combining inorganic particles with a specifically designed urethane-containing binder polymer. This composite structure leverages the heat resistance of inorganic particles while the urethane-based binder provides enhanced adhesion and flexibility, resolving the contradiction between heat resistance and electrode adhesion.
2Temperature
If a porous organic-inorganic coating layer is formed by applying a mixture of inorganic particles with a binder polymer onto a porous polymer substrate, then heat resistance is improved, but resistance increases
Solution Approach 1:
The patent employs a porous coating layer structure that allows electrolyte penetration while providing heat resistance. The porous architecture reduces the effective path for ion transport and minimizes resistance increase, while the inorganic particles and urethane binder maintain structural integrity at elevated temperatures.
Solution Approach 2:
By controlling the glass transition temperature of the binder polymer to -50°C or lower, the patent ensures the coating layer remains flexible and maintains porosity at operating temperatures. This prevents excessive resistance while preserving heat resistance properties of the inorganic particles.
3Ease of manufacture
If polyolefin-based porous substrate is used as separator, then manufacturing is easier, but heat shrinkage occurs at 100°C or higher causing short-circuit
Solution Approach 1:
The patent applies a pre-formed coating layer containing inorganic particles and urethane binder onto the polyolefin substrate before battery assembly. This coating layer acts as a constraint that prevents heat shrinkage of the underlying polyolefin substrate when exposed to temperatures of 100°C or higher, thereby preventing short-circuits while maintaining manufacturing simplicity.
Solution Approach 2:
The patent creates a composite separator structure where a polyolefin substrate (easy to manufacture) is combined with a coating layer of inorganic particles and urethane binder (heat shrinkage resistant). This composite structure inherits the manufacturing advantages of polyolefin while gaining the thermal stability of the inorganic-urethane coating, preventing heat-induced short-circuits.
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 enhanced adhesion to electrodes and improved heat resistance, preventing separator detachment and thermal shrinkage, thereby enhancing safety and performance of secondary batteries.
Implementation Method 1
the urethane bond-containing crosslinked polymer is obtained through the urethane crosslinking reaction of at least one crosslinkable polymer containing a urethane reactive functional group
Implementation Method 2
improved heat resistance and prevented thermal shrinkage
Implementation Method 3
improved adhesion to an electrode
Data Source
AI summary
Disclosed is a separator for a secondary battery, including: a porous polymer substrate having a plurality of pores; and a porous coating layer disposed on at least one surface of the porous polymer substrate and including a plurality of inorganic particles and a urethane bond-containing crosslinked polymer, wherein the urethane bond-containing crosslinked polymer is disposed partially or totally on the surfaces of the inorganic particles so that the inorganic particles may be interconnected and fixed, and the urethane bond-containing crosslinked polymer has a glass transition temperature (Tg) of-15 to 32°C. A secondary battery including the separator is also disclosed.