Polyolefin Separator Coating with Mixed Particle Sizes for Thermal Conductivity
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current separators for electrochemical batteries face challenges in achieving high thermal conductivity and stability, which can lead to overheating and short circuits, particularly when using inorganic particles of a single average particle size, resulting in inadequate heat dissipation and adhesion.
Innovation Solution
A porous separator with a coating layer formed on a polyolefin porous base film, utilizing a mixture of inorganic particles with different average particle sizes (150 nm to 600 nm and 5 nm to 90 nm) and a binder polymer, providing a thermal conductivity of 0.3 W/m·K or more, and an adhesive strength of 10 gf/cm2 or more to electrodes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a coating layer with inorganic particles of a single average particle size is used, then the manufacturing process is simple, but the thermal conductivity and heat dissipation are insufficient
Solution Approach 1:
The patent changes the particle size parameter of inorganic particles from a single size to a multi-size distribution (ranging from 1 nm to 10 μm). This parameter change creates better packing density and thermal contact between particles, significantly improving thermal conductivity and heat dissipation while maintaining a relatively simple coating process
Solution Approach 2:
The patent creates a composite coating layer containing inorganic particles of different sizes (fine particles 1-100 nm, intermediate particles 100 nm-10 μm, and coarse particles 10 μm-100 μm) combined with binder polymers. This composite structure optimizes both thermal performance and mechanical adhesion without substantially complicating the manufacturing process
2Temperature
If inorganic particles are used to improve thermal conductivity, then heat dissipation improves, but adhesion to electrodes deteriorates
Solution Approach 1:
The patent applies local quality by using different particle sizes in different regions of the coating layer. Fine particles (1-100 nm) provide thermal conductivity near the electrode surface, intermediate particles (100 nm-10 μm) provide structural framework, and coarse particles (10 μm-100 μm) enhance mechanical interlocking with electrodes. This spatial differentiation of particle functions simultaneously improves thermal conductivity and adhesion
Solution Approach 2:
The patent combines inorganic particles of various sizes with binder polymers to create a composite coating material. The binder polymer matrix provides strong adhesion to electrodes while the embedded inorganic particles provide thermal conductivity pathways, achieving both objectives simultaneously
3Temperature
If a thick coating layer is applied to improve thermal stability, then thermal conductivity increases, but the separator's porosity and ionic conductivity decrease
Solution Approach 1:
The patent employs porous inorganic particles (such as porous alumina, porous silica, or hollow glass beads) in the coating layer. These porous particles provide thermal mass for thermal stability while their internal voids and the inter-particle spaces maintain porosity pathways for ion transport, thus preserving ionic conductivity even with a thicker coating layer
Solution Approach 2:
The patent optimizes the thickness parameter of the coating layer to a specific range (1 μm to 10 μm) and adjusts the particle size distribution parameter to maximize thermal conductivity while minimizing impact on porosity. This parameter optimization achieves thermal stability without substantially compromising ionic conductivity
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 enhances thermal stability and adhesion, preventing short circuits and improving the lifespan and stability of electrochemical batteries by achieving efficient heat dissipation and maintaining strong attachment to electrodes.
Implementation Method 1
The separator has a thermal conductivity of 0.3 W/m·K or more
Data Source
AI summary
A polyolefin porous separator includes a polyolefin porous base film, and a coating layer formed on one or both sides of the base film. The coating layer includes inorganic particles. The inorganic particles include first inorganic particles having an average particle size ranging from 150 nm to 600 nm, and second inorganic particles having an average particle size ranging from 5 nm to 90 nm. The separator has a thermal conductivity of 0.3 W/m·K or more.