Polyolefin Battery Separator for Dendrite Puncture Resistance
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Secondary batteries face challenges in reliability due to puncture risks from metal dendrites, which affect cycle life and overall performance.
Innovation Solution
A separator with a polyolefin base film having a viscosity-average molecular weight of at least 1,200,000 g/mol and low branching (≤5%) is developed, enhancing molecular chain regularity and puncture strength, and optionally combined with a porous coating for improved heat resistance and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the molecular weight of the polyolefin base film is increased, then the puncture strength is improved, but the manufacturing complexity increases
Solution Approach 1:
The patent changes the molecular weight parameter of the polyolefin base film to ≥1,200,000 g/mol and controls the degree of branching at ≤5%, which fundamentally alters the material properties to achieve high puncture strength without requiring complex structural designs or additional protective layers
2Strength
If the degree of branching is reduced to enhance molecular chain regularity, then the puncture strength is improved, but the manufacturing precision requirements increase
Solution Approach 1:
The patent specifies a precise parameter range for the degree of branching (≤5%) of the polyolefin base film, which standardizes the molecular chain structure to achieve regular arrangement and high puncture strength while providing clear manufacturing guidelines
3Reliability
If a porous coating is added to improve heat resistance and stability, then the reliability is improved, but the device complexity increases
Solution Approach 1:
The patent creates a composite structure by combining the polyolefin base film with a porous coating layer, where each layer performs a specific function (the base film provides mechanical strength and the coating provides heat resistance), achieving enhanced reliability through material composition rather than complex structural design
Data Source
Figure 1~4
Figure 5~7
Figure 8~9
AI summary
The present application provides a separator, a preparation method, a secondary battery, and an electric device. The separator includes a first porous base film, where the first porous base film is polyolefin, and a viscosity-average molecular weight of the first porous base film is greater than or equal to 1,200,000 g/mol, such that the separator has higher puncture strength; a degree of branching of the first porous base film is less than or equal to 5%, molecular chain sequences in the first porous base film are easy to form ordered arrangement, and thus the regularity of the molecular chains is enhanced, thereby further improving the puncture strength of the separator. Therefore, the separator provided by the present application can reduce the risk that the separator is punctured by metal dendrites, prolong the cycle life of the secondary battery, and improve the reliability of the secondary battery.