Multilayer Battery Separator for Abnormal Heat Suppression
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Solution Overview
Problem
Non-aqueous electrolyte secondary batteries face heat generation issues when exposed to abnormal conditions such as overcharging or internal short circuits, leading to increased battery temperature and potential safety risks.
Innovation Solution
A non-aqueous electrolyte secondary battery with a separator having a multilayer structure, including a porous resin substrate, a first filler layer with phosphate particles having a specific BET surface area, and a second filler layer with inorganic particles of higher heat resistance, where the first filler layer faces the negative electrode, effectively suppressing heat generation by forming a phosphate polycondensation coating film and preventing electrode contact.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a separator with a single filler layer is used, then the structure is simple, but the heat resistance and heat generation suppression are insufficient under abnormal conditions
Solution Approach 1:
The separator is divided into multiple functional layers: a porous base material layer and two distinct filler layers. The first filler layer (containing phosphate particles with BET specific surface area of 5-50 m²/g) contacts the negative electrode to suppress heat generation through polycondensation reactions. The second filler layer (containing inorganic particles with higher melting points) contacts the positive electrode to provide thermal stability. This segmentation allows each layer to perform its specific function optimally, resolving the contradiction between reliability and structural simplicity.
Solution Approach 2:
The separator employs a composite structure combining organic porous base material with inorganic filler particles of different properties. The phosphate particles (lower melting point) and high-melting-point inorganic particles are distributed in separate layers, creating a composite material system that leverages the heat-absorbing polycondensation of phosphate while the high-melting-point particles maintain structural integrity at elevated temperatures. This composite approach achieves superior heat resistance without excessive complexity.
2Reliability
If phosphate particles with high BET specific surface area are used, then heat generation suppression is improved, but the particles may deform at lower temperatures
Solution Approach 1:
Different regions of the separator are assigned different filler materials with complementary properties. The first filler layer uses phosphate particles with moderate BET specific surface area (5-50 m²/g) that provide effective heat suppression through polycondensation. The second filler layer uses inorganic particles with significantly higher melting points for thermal stability. This local differentiation of material properties resolves the contradiction between heat suppression efficiency and thermal stability.
Solution Approach 2:
The dual-layer filler structure creates a composite system where phosphate particles handle heat absorption through controlled polycondensation, while the high-melting-point inorganic particles in the second layer prevent structural collapse at elevated temperatures. This composite material strategy allows the use of phosphate particles with optimal surface area for heat suppression without compromising overall thermal stability.
3Reliability
If the separator uses only basic phosphate as filler, then heat generation is suppressed, but the structural stability at high temperature is insufficient
Solution Approach 1:
The filler components are segmented into two separate layers with distinct functions. The first filler layer contains phosphate particles that suppress heat generation through polycondensation reactions. The second filler layer contains inorganic particles with higher melting points that provide structural stability at high temperatures. This functional segmentation resolves the contradiction between heat suppression and structural stability.
Solution Approach 2:
The separator uses a composite filler system combining phosphate particles and high-melting-point inorganic particles in separate layers. The phosphate provides chemical heat suppression mechanisms, while the inorganic particles provide thermal-structural stability. This composite material approach achieves both heat generation suppression and maintained structural integrity under abnormal thermal conditions.
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 effectively suppresses heat generation and temperature increase in batteries exposed to abnormal conditions, enhancing safety by reducing exothermic reactions and maintaining electrode integrity.
Implementation Method 1
the phosphate particles undergo polycondensation to form a phosphate polycondensation coating film
Implementation Method 2
a separator disposed between the positive electrode and the negative electrode
Data Source
Figure 1
Figure 2~3
AI summary
A non-aqueous electrolyte secondary battery includes a positive electrode, a negative electrode, and a separator disposed between the positive electrode and the negative electrode. The separator has a multilayer structure in which a first filler layer containing phosphate particles, a porous resin substrate, and a second filler layer containing inorganic particles having higher heat resistance than the phosphate particles are stacked in this order from the negative electrode side. The first filler layer is disposed on the porous resin substrate in such a manner that the surface of the first filler layer faces the surface of the negative electrode. The phosphate particles have a BET specific surface area in the range of 5 m2/g or more and 100 m2/g or less.