Battery Separator Pore Diameter Ratio for Rate Capability
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional nonaqueous electrolyte solution secondary battery separators, particularly those using the interface separation method, face challenges in achieving high rate capability and cyclability due to issues with pore uniformity and impurity content, leading to inefficiencies in ionic conductivity and corrosion.
Innovation Solution
A nonaqueous electrolyte solution secondary battery separator is developed using a thermoplastic resin-based porous film with a controlled filler particle size distribution and reduced impurity levels, specifically targeting a ratio of average to maximum pore diameter of 0.6 or more and minimizing halogen and iron elements, to enhance rate capability and cyclability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the interface separation method is used to produce porous film, then productivity is improved and waste fluid processing is reduced, but pore uniformity deteriorates and manufacturing precision decreases
Solution Approach 1:
The patent applies parameter changes by precisely controlling the particle size distribution of the filler within specific ranges (d10: 0.5-2.0 μm, d50: 2.0-5.0 μm, d90: 5.0-10.0 μm) and adjusting the ratio of average pore diameter to maximum pore diameter to 0.55 or more. These parameter optimizations resolve the contradiction by achieving both high productivity through interface separation and improved pore uniformity through controlled filler characteristics.
2Reliability
If filler with large particle size is used, then porosity increases and ionic conductivity improves, but pore uniformity deteriorates and manufacturing precision decreases
Solution Approach 1:
The patent applies local quality by using a multi-modal particle size distribution with different filler particles serving different functions: smaller particles (d10: 0.5-2.0 μm) create uniform fine pores for good ionic conductivity, while larger particles (d90: 5.0-10.0 μm) create larger pores for adequate porosity. This local differentiation of filler particle sizes resolves the contradiction between ionic conductivity and pore uniformity.
Solution Approach 2:
The patent optimizes the particle size distribution parameters of the filler, specifically controlling d10, d50, and d90 values within defined ranges and ensuring the average pore diameter to maximum pore diameter ratio is 0.55 or more. These parameter changes enable simultaneous achievement of high ionic conductivity and uniform pore structure.
3Reliability
If impurity content in filler is reduced, then battery performance and cyclability improve, but manufacturing complexity increases
Solution Approach 1:
The patent applies parameter changes by specifying strict impurity content limits for the filler materials (halogen elements: 50 ppm or less, iron elements: 100 ppm or less) and incorporating these specifications into the manufacturing process. This approach improves cyclability while managing manufacturing complexity through standardized quality control parameters rather than complex processing steps.
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 results in a battery with improved rate capability, achieving 60% or more of the discharge capacity at 6C compared to C/3, and stable performance at high temperatures by ensuring uniform pore distribution and reducing impurity-related corrosion.
Implementation Method 1
not preventing ionic conduction between the electrodes
Implementation Method 2
retaining the electrolyte solution
Data Source
AI summary
An object of this invention is to improve battery performance such as a rate capability of a nonaqueous electrolyte solution secondary battery using a separator constituting a thermoplastic resin-based porous film containing a filler.This invention provides a nonaqueous electrolyte solution secondary battery separator which is formed from a porous film containing a thermoplastic resin and a filler contained in the thermoplastic resin and has a ratio of an average pore diameter (μm) to a maximum pore diameter (μm) defined by ASTM F316-86 of 0.6 or more as well as relates to a nonaqueous electrolyte solution secondary battery using this separator.