Battery Separator Porous Layer Aspect Ratio Optimization
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Solution Overview
Problem
Nonaqueous electrolyte secondary batteries with conventional porous layers lack sufficient discharge output characteristics due to low heat resistance and the risk of short circuits caused by melting at elevated temperatures.
Innovation Solution
A nonaqueous electrolyte secondary battery with a porous layer containing an inorganic filler and resin, where the aspect ratio of the inorganic filler's projection image and the degree of orientation are within specific ranges, as determined by X-ray diffraction methods, to enhance discharge output and prevent short circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a porous base material containing polyolefin is used as a separator, then the shutdown function is achieved at approximately 130°C to 140°C, but the heat resistance is low and the material melts at elevated temperatures causing short circuits
Solution Approach 1:
The patent applies composite materials by combining polyolefin porous base material with inorganic fillers (such as alumina, silica, or boehmite) and resins to create a separator that maintains the shutdown function of the polyolefin while adding heat resistance through the inorganic components. The composite structure allows the separator to withstand temperatures above 150°C without melting, preventing short circuits while preserving the clogging shutdown mechanism at 130-140°C.
2Temperature
If a porous layer containing inorganic filler and resin is added to improve heat resistance, then melting and short circuits are prevented, but the discharge output characteristic deteriorates
Solution Approach 1:
The patent applies parameter changes by optimizing the aspect ratio of inorganic filler particles to be within 1.05 to 2.50 and controlling the degree of orientation within 1.10 to 1.80. These specific parameter ranges balance heat resistance with ion permeability, ensuring that the porous structure maintains sufficient channels for ion transport while the inorganic filler provides thermal stability. This resolves the contradiction by tuning physical parameters rather than simply adding more heat-resistant material that would block ion flow.
Solution Approach 2:
The patent utilizes porous materials by maintaining a porosity of 30% to 80% in the separator structure. The porous network formed by the polyolefin base material and the distributed inorganic filler creates interconnected channels that allow efficient ion transport. The pore structure ensures that even with heat-resistant inorganic components present, the separator remains permeable to ions, thus maintaining discharge output characteristics while providing thermal stability.
3Ease of manufacture
If the aspect ratio and degree of orientation of inorganic filler are not controlled, then manufacturing is simpler, but the discharge output characteristic and ion permeability are insufficient
Solution Approach 1:
The patent applies parameter changes by defining specific ranges for aspect ratio (1.05 to 2.50) and degree of orientation (1.10 to 1.80) of inorganic filler particles. These controlled parameters optimize the balance between manufacturing feasibility and performance. The aspect ratio control ensures particles are not too elongated to be easily dispersed, while the orientation control maintains adequate ion transport pathways. By specifying these narrow parameter ranges, the patent makes the manufacturing process more precise but still practically achievable, resolving the contradiction between simplicity and 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 improved porous layer structure enhances the discharge output characteristic of nonaqueous electrolyte secondary batteries by maintaining stability and preventing short circuits, even at elevated temperatures.
Implementation Method 1
The degree of orientation of the inorganic filler is obtained from a ratio of respective peak intensities in any diffraction planes orthogonal to each other, which peak intensities are obtained by measuring the porous layer by a wide-angle X-ray diffraction method
Data Source
AI summary
A nonaqueous electrolyte secondary battery insulating porous layer which has an excellent discharge output characteristic is provided. The insulating porous layer is arranged such that an aspect ratio of a projection image of an inorganic filler at a surface of the insulating porous layer is in a range of 1.4 to 4.0 and respective peak intensities I(hkl) and I(abc) of any diffraction planes (hkl) and (abc) of the insulating porous layer satisfy the following Formula (1). The peak intensities obtained from the diffraction planes (hkl) and (abc) orthogonal to each other are measured using a wide-angle X-ray diffraction method, and a maximum value of the peak intensity ratio is in a range of 1.5 to 300 when calculated by the following Formula (2):I(hkl)>I(abc) (1)I(hkl)/I(abc) (2).