Organic/Inorganic Composite Separator for Battery Safety
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Solution Overview
Problem
Lithium secondary batteries face safety issues due to ignition and explosion risks from internal short circuits, particularly during external impacts, which conventional polyolefin-based separators fail to adequately address, and they also have low discharge capacity at low temperatures and insufficient lithium ion conductivity.
Innovation Solution
An organic/inorganic composite porous separator is developed by coating a mixture of inorganic particles and a binder polymer onto a polyolefin-based separator substrate, creating a uniform pore structure that enhances thermal safety, electrochemical safety, and lithium ion conductivity, preventing complete short circuits and allowing for a high degree of swelling with electrolyte.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a polyolefin-based separator is used, then the battery can be manufactured with conventional processes, but the thermal safety and electrochemical safety are insufficient due to ignition and explosion risks from internal short circuits
Solution Approach 1:
The patent applies composite materials by combining polyolefin-based separator substrate with an inorganic particle layer to create a composite separator structure. This composite structure integrates the thermal safety benefits of inorganic materials (high temperature stability, resistance to thermal shrinkage) with the functional properties of the polyolefin substrate, thereby improving overall thermal and electrochemical safety while maintaining manufacturability through conventional coating processes
Solution Approach 2:
The patent utilizes porous materials by forming an inorganic particle layer with controlled porosity (30-80%) on the separator substrate. The porous structure allows efficient lithium ion transport while the inorganic particles provide thermal stability and prevent complete short circuits. The pore size (0.01-10 μm) and porosity are optimized to balance ion conductivity with safety functions
2Temperature
If conventional inorganic particles are coated on the separator, then thermal stability is improved, but lithium ion conductivity decreases significantly
Solution Approach 1:
The patent applies porous materials by creating a highly porous inorganic particle layer with porosity of 30-80% and pore sizes of 0.01-10 μm. This porous structure provides continuous pathways for lithium ion transport through the inorganic layer, maintaining high lithium ion conductivity while the inorganic particles themselves provide thermal stability and structural integrity at elevated temperatures
Solution Approach 2:
The patent applies parameter changes by optimizing key parameters of the inorganic particle layer including porosity (30-80%), pore size (0.01-10 μm), and inorganic particle content (1-50 wt%). These parameter optimizations ensure that the inorganic layer provides thermal stability while maintaining sufficient lithium ion conductivity, resolving the trade-off between thermal stability and ion transport
3Reliability
If the inorganic particle layer is made thicker to improve safety, then thermal safety improves, but the mechanical integrity and ion transport are compromised
Solution Approach 1:
The patent applies parameter changes by optimizing the thickness of the inorganic particle layer within specific ranges (1-50 μm) and controlling the inorganic particle content (1-50 wt%). This optimized thickness provides sufficient thermal safety and short-circuit prevention while maintaining adequate mechanical integrity and lithium ion transport capability, avoiding the trade-off between safety and mechanical 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 organic/inorganic composite porous separator significantly improves the safety and quality of lithium secondary batteries by preventing internal short circuits, maintaining mechanical integrity, and ensuring stable lithium ion conductivity, even under extreme conditions, thus enhancing their thermal and electrochemical performance.
Implementation Method 1
coating a mixture of inorganic particles and a binder polymer onto a polyolefin-based separator substrate
Implementation Method 2
lithium ions reciprocate between the cathode and the anode
Implementation Method 3
the inorganic particles and a binder polymer, wherein the inorganic particles are interconnected among themselves and are fixed by the binder polymer
Data Source
AI summary
Disclosed is an organic/inorganic composite porous separator comprising: (a) a polyolefin-based separator substrate; and (b) an active layer formed by coating at least one region selected from the group consisting of a surface of the substrate and a part of pores present in the substrate with a mixture of inorganic particles and a binder polymer, wherein the inorganic particles in the active layer are interconnected among themselves and are fixed by the binder polymer, and interstitial volumes among the inorganic particles form a pore structure. A method for manufacturing the same separator and an electrochemical device including the same separator are also disclosed. An electrochemical device comprising the organic/inorganic composite porous separator shows improved thermal and electrochemical safety and quality, simultaneously.