Separator Thickness Control for Battery Safety
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing nonaqueous electrolyte secondary batteries cannot prevent the occurrence of internal short circuits caused by foreign substances introduced into the electrode body, leading to safety deterioration and production yield issues.
Innovation Solution
The battery design includes a separator with a specific thickness change of 50% or more at 10 MPa compression, which prevents foreign substances from causing internal short circuits by collapsing pores and preventing electrolyte elution, thereby maintaining battery safety and increasing production yield.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional separator is used, then the battery structure is simple and manufacturing is easy, but internal short circuits occur when foreign substances are introduced
Solution Approach 1:
The separator's thickness is specifically controlled to be 15 µm or less, and its compression characteristics are optimized to achieve at least 40% thickness reduction at 10 MPa. This parameter optimization enables the separator to effectively prevent internal short circuits while maintaining structural simplicity and ease of manufacturing.
2Reliability
If the separator thickness is reduced to prevent short circuits, then safety improves, but electrolyte retention capability deteriorates
Solution Approach 1:
The separator's compression characteristics are optimized to achieve at least 40% thickness reduction at 10 MPa applied load. This specific parameter control enables the thin separator to maintain both safety (by preventing short circuits) and electrolyte retention capability through controlled pore collapse under compression.
3Quantity of substance
If a thick separator is used, then electrolyte retention is good, but internal short circuits cannot be prevented when foreign substances are introduced
Solution Approach 1:
The separator thickness is controlled to be 15 µm or less, which is sufficiently thin to allow compression-induced pore collapse that prevents foreign substance penetration and internal short circuits, while still maintaining adequate electrolyte retention through optimized compression characteristics.
Solution Approach 2:
The separator is pre-compressed during battery assembly to achieve the desired thickness reduction and pore collapse before foreign substances can be introduced. This preliminary compression action creates a barrier that prevents subsequent internal short circuits while maintaining electrolyte retention.
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 prevents internal short circuits and maintains battery safety, even when foreign substances are introduced, suitable for large-sized batteries, and optimizes electrolyte retention capability to prevent performance deterioration.
Implementation Method 1
When a load of 10 MPa is applied to a nonaqueous electrolyte secondary battery in the state where a foreign substance is inserted between a positive electrode and a separator, the thickness of the separator is reduced by 40% or more
Implementation Method 2
the thickness of the separator is reduced by 40% or more, thereby occurrence of an internal short circuit can be prevented
Data Source
AI summary
A nonaqueous electrolyte secondary battery includes an electrode body that has a positive electrode, a negative electrode, and a separator provided between the positive electrode and the negative electrode. A nonaqueous electrolyte is held at least in the separator. In at least a part of the separator, an amount of change in a thickness of the separator at a time of restraint at 10 MPa is 50% or more.