Battery Separator Structure to Suppress Heat-Induced Micro-Shorts
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional nonaqueous electrolyte secondary batteries are prone to micro-short circuits when excessive heat causes the separator's thermoplastic resin to melt, potentially leading to contact between the positive and negative electrodes, due to insufficient suppression of thermal shrinkage and melting effects.
Innovation Solution
The energy storage device incorporates a separator with a base material layer containing thermoplastic resin and an inorganic layer, where the mass ratio of the base material layer to the negative composite layer's spatial volume is optimized to 0.26 or more, and the mass per unit area is set to 0.085 (g/100 cm²) or more, ensuring the inorganic layer opposes the positive electrode and the base material layer opposes the negative electrode, thereby preventing through-hole formation and micro-short circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a separator with inorganic layer and thermoplastic resin base material layer is used to suppress thermal shrinkage, then thermal stability is improved, but the base material layer may melt at high temperature causing through-hole formation and micro-short circuits
Solution Approach 1:
The separator is constructed as a composite material combining an inorganic layer and a thermoplastic resin base material layer. The inorganic layer provides thermal stability and prevents shrinkage at elevated temperatures, while the base material layer maintains structural integrity even when melted, preventing through-hole formation. This composite structure resolves the contradiction by integrating materials with complementary properties that simultaneously address thermal stability and reliability.
2Reliability
If the mass ratio of base material layer to negative composite layer is optimized to prevent penetration, then reliability is improved, but separator structure complexity increases
Solution Approach 1:
The invention optimizes specific parameters of the separator structure, particularly the mass ratio of the base material layer to the negative composite layer and the mass per unit area of the base material layer. By establishing quantitative thresholds (mass ratio ≥ 0.26, mass per unit area ≥ 0.085 g/100 cm²), the patent simplifies the design process while ensuring penetration resistance. This parameter-based approach resolves the contradiction by providing clear design criteria that prevent excessive 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
This configuration effectively suppresses micro-short circuits during heat generation by preventing the molten base material layer from penetrating into the negative composite layer, maintaining electrical insulation and ensuring the battery's safety and performance.
Implementation Method 1
the inorganic layer functions as the backbone of the separator to suppress shrinkage of the separator
Implementation Method 2
when the temperature of the base material layer becomes equal to or higher than the melting point, it is concerned that the base material layer may melt
Data Source
Figure 1~2
Figure 3~4
AI summary
An energy storage device in which a micro-short circuit at the time of heat generation is suppressed is provided. The energy storage device includes: a positive electrode; a negative electrode containing a negative composite layer; and a separator disposed between the positive electrode and the negative electrode. The separator contains a base material layer containing a thermoplastic resin and an inorganic layer formed on the base material layer, the inorganic layer opposes to the positive electrode, the base material layer opposes to the negative electrode, and a ratio of a mass of the base material layer per unit area to a spatial volume of the negative composite layer is 0.26 or more.