Reinforced Battery Separator Structure Against Dendrite Piercing
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Solution Overview
Problem
Current separators in batteries face challenges in preventing short circuits caused by dendrite piercing, which is exacerbated by high-power output and fast charge/discharge requirements, leading to safety concerns.
Innovation Solution
The separator includes a reinforced fiber layer and/or coating layer, composed of materials like glass fiber and inorganic particles, to enhance piercing resistance and elastic modulus, inhibiting dendrite growth and reducing shear stress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a conventional separator is used, then the battery can operate with basic separation function, but the separator has low piercing resistance and cannot prevent dendrite penetration
Solution Approach 1:
The separator is constructed as a composite structure combining a base separator layer with a reinforced layer containing inorganic particles (such as Al2O3, SiO2, TiO2) dispersed in a binder polymer. This composite structure significantly enhances piercing resistance while maintaining the necessary porosity for ion transport, directly resolving the contradiction between strength and complexity.
Solution Approach 2:
The reinforced layer is designed with controlled porosity (20-60%) to maintain ion conductivity while providing mechanical reinforcement. The porous structure allows lithium ion transport through the separator without compromising the piercing resistance provided by the inorganic particle network, addressing both strength and functional requirements.
2Strength
If the separator thickness is increased to improve piercing resistance, then dendrite penetration is reduced, but ion conductivity decreases due to longer transport path
Solution Approach 1:
The separator design applies local reinforcement by adding the reinforced layer only on specific sides of the base separator (either one side or both sides), rather than uniformly increasing thickness throughout. This localized approach enhances piercing resistance at critical interfaces while minimizing the impact on overall ion transport pathways, effectively resolving the contradiction between strength and conductivity.
Solution Approach 2:
The reinforced layer uses a composite of inorganic particles and binder polymer with optimized composition ratios to provide high mechanical strength at minimal thickness. The inorganic particles (Al2O3, SiO2, TiO2) create a rigid scaffold that resists dendrite penetration without significantly increasing the separator's overall thickness, thus maintaining ion conductivity while improving piercing resistance.
3Strength
If a reinforced layer is added to improve piercing resistance, then dendrite growth is inhibited, but the separator's flexibility and processability deteriorate
Solution Approach 1:
The binder polymer in the reinforced layer is selected with specific glass transition temperatures and molecular weights to balance rigidity and flexibility. By adjusting these parameters, the reinforced layer maintains sufficient flexibility for battery assembly processes (winding, stacking, calendaring) while providing adequate piercing resistance, thus resolving the contradiction between strength and processability.
Solution Approach 2:
The porous structure of the reinforced layer (20-60% porosity) provides both mechanical reinforcement and flexibility. The interconnected pores allow the layer to deform elastically during processing while maintaining its structural integrity for dendrite resistance, effectively balancing piercing resistance with ease of operation.
Data Source
AI summary
A separator, a battery including the separator, and an electric apparatus including the battery. The separator includes a separator substrate, and the separator substrate satisfies at least one of the following conditions: the separator substrate includes a reinforced fiber layer; and at least one side surface of the separator substrate has a reinforced coating layer.