Separator with Phase-Separated Adhesive Layer for Thermal Stability
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Solution Overview
Problem
Lithium ion polymer batteries face challenges with low capacity and insufficient discharge at low temperatures, and conventional separators exhibit heat shrinking issues leading to potential short-circuits and safety concerns due to their material properties.
Innovation Solution
A separator with a porous polymer substrate coated with a porous organic-inorganic layer and an adhesive porous layer formed through phase separation, using inorganic particles and binder polymers, which enhances adhesion and reduces resistance while maintaining porosity and mechanical stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a polyolefin-based porous substrate is used as a separator, then it provides basic separation function, but it shows severe heat shrinking behavior at 100°C or higher causing short-circuit between cathode and anode
Solution Approach 1:
The patent applies composite materials by forming an organic-inorganic coating layer on the polyolefin-based porous substrate. The coating layer comprises inorganic particles (such as alumina, silica, or boehmite) dispersed in a binder polymer matrix. This composite structure combines the thermal stability of inorganic materials with the flexibility of the polymer substrate, preventing heat shrinking at high temperatures while maintaining the separator's basic functions.
2Reliability
If a porous organic-inorganic coating layer is formed by applying a mixture of excessive inorganic particles and binder polymer, then heat shrinking is reduced, but adhesion with electrode deteriorates and resistance increases
Solution Approach 1:
The patent applies local quality by creating a coating layer with controlled inorganic particle distribution and concentration. Instead of using excessive inorganic particles uniformly, the coating layer is designed with optimized local composition where inorganic particles are dispersed at appropriate concentrations within the binder polymer matrix. This localized optimization maintains thermal stability while preserving electrode adhesion and minimizing resistance by ensuring sufficient polymer continuity for ion transport.
3Reliability
If a porous organic-inorganic coating layer is formed with excessive inorganic particles, then heat shrinking is reduced, but manufacturing complexity increases
Solution Approach 1:
The patent applies parameter changes by optimizing the composition ratios and physical parameters of the coating layer. Specific parameters include the weight ratio of inorganic particles to binder polymer (controlled within specific ranges), particle size distribution, and coating thickness. By controlling these parameters within optimized ranges, the patent achieves thermal stability without requiring excessive inorganic particles, thereby simplifying the manufacturing process and reducing production complexity.
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 improves adhesion with electrodes, reduces resistance, and enhances safety by maintaining porosity and mechanical stability, addressing the low capacity and safety concerns of lithium ion polymer batteries, particularly at low temperatures.
Implementation Method 1
an adhesive porous layer formed on at least one surface of the separator base and including an adhesive resin which shows adhesive property through heating at a temperature lower than the melting point of the porous polymer substrate
Implementation Method 2
the adhesive porous layer is provided with a porous structure formed by phase separation caused by the evaporation rate of a solvent and that of a non-solvent, when applying and drying a coating composition including the adhesive resin, the solvent and the non-solvent
Implementation Method 3
the adhesive porous layer is provided with a porous structure formed by phase separation caused by the evaporation rate of a solvent and that of a non-solvent
Data Source
AI summary
Disclosed are a separator and an electrochemical device including the same. The separator includes: a porous polymer substrate having a plurality of pores; a separator base including a porous coating layer formed on at least one surface of the porous polymer substrate, and including a plurality of inorganic particles and a binder polymer disposed partially or totally on the surface of the inorganic particles to connect and fix the inorganic particles with each other; and an adhesive porous layer formed on at least one surface of the separator base and including an adhesive resin which shows adhesive property through heating at a temperature lower than the melting point of the porous polymer substrate, wherein the adhesive porous layer is provided with a porous structure formed by phase separation caused by the evaporation rate of a solvent and that of a non-solvent, when applying and drying a coating composition including the adhesive resin, the solvent and the non-solvent on at least one surface of the separator base.