Three-Layer Diaphragm Paper for Battery Isolation and Absorption
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Solution Overview
Problem
Existing diaphragm papers for batteries face challenges in preventing internal short circuits while maintaining electrolyte absorption and discharge performance, with issues such as poor interlayer bonding and large pore sizes leading to reduced battery capacity and stability.
Innovation Solution
A three-layer diaphragm paper structure is introduced, comprising a compact middle layer with small pore size for isolation and loose outer layers for high liquid permeability and absorption, using specific fiber materials and a manufacturing process that ensures uniform distribution and bonding strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the diaphragm has smaller pore size to prevent internal short circuit, then the isolation performance is improved, but the electrolyte absorption rate decreases
Solution Approach 1:
The diaphragm is divided into multiple layers with different pore sizes: a first diaphragm layer with larger pores for fast electrolyte absorption, a second diaphragm layer with smaller pores for preventing dendritic crystal penetration, and a third diaphragm layer with moderate pores for balanced performance. This segmentation allows each layer to specialize in one function, resolving the contradiction between isolation and absorption rate.
Solution Approach 2:
Different regions of the diaphragm structure have different pore characteristics tailored to specific functions. The first layer has larger pores (5-15 μm) optimized for absorption speed, the second layer has smaller pores (0.5-5 μm) optimized for isolation, and the third layer has moderate pores (2-10 μm) for overall balance. This local differentiation of quality allows simultaneous optimization of both isolation performance and electrolyte absorption rate.
2Reliability
If the diaphragm has compact structure to improve isolation, then the resistance increases and absorbency decreases
Solution Approach 1:
The diaphragm is segmented into layers with varying compactness: the first layer is less compact with larger pores for low resistance and fast absorption, the second layer is highly compact with smaller pores for excellent isolation, and the third layer has moderate compactness for balanced performance. This segmentation distributes the resistance across layers, allowing the compact second layer to provide isolation without making the entire diaphragm overly resistant.
3Ease of manufacture
If the diaphragm uses single layer structure, then the manufacturing is simpler, but the performance balance between absorption and isolation is poor
Solution Approach 1:
Rather than using a single layer, the invention segments the diaphragm into three functional layers, each with optimized pore sizes for specific tasks. This segmentation enables the diaphragm to simultaneously achieve fast electrolyte absorption, effective dendritic crystal blocking, and good overall performance balance, which cannot be accomplished with a single layer structure.
Solution Approach 2:
The diaphragm uses a composite structure combining three different types of porous layers with distinct pore size characteristics. This composite approach integrates the advantages of different pore size configurations, creating a diaphragm that balances absorption speed, isolation performance, and resistance characteristics better than any single-material or single-structure diaphragm could achieve alone.
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, enhances battery discharge performance, and maintains stability under alkaline conditions, achieving high capacity and reliability.
Implementation Method 1
the second layer is a compact layer, with an average pore size lesser than 5 μm... the intermediate layer has small pore size and good isolation performance, can isolate effectively the positive electrode from the negative electrode
Implementation Method 2
the first layer and the third layer are loose layers, with an average pore size greater than 10 μm... the upper layer and the lower layer have excellent liquid permeability and electrolyte absorptivity
Implementation Method 3
having such alkaline absorption rate that it can meet the demand of ionic conductivity at the continuous discharge time
Data Source
AI summary
Diaphragm paper, and a preparation method and an application thereof. The diaphragm paper comprises a first layer, a second layer, and a third layer, wherein the second layer is located between the first layer and the third layer; the first layer and the third layer are loose layers, of which the average aperture is larger than 10 μm and the basis weight is 5 to 30 g/m2; and the second layer is a compact layer, of which the average aperture is smaller than 5 μm and the basis weight is 2 to 15 g/m2. The compact layer has small aperture and good insulating performance, and is capable of effectively insulating a positive electrode and a negative electrode. The loose layers have good liquid permeability and electrolyte absorptivity, and can guarantee the discharge performance of a battery. The material is further advantageous in having good dimensional stability and being thin, so that a battery can achieve high capacity.