Bi-layer Separator for Lithium-ion Battery Dendrite Resistance
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Solution Overview
Problem
Conventional microporous separators in lithium-ion batteries are prone to penetration by lithium dendrites and metal particles, especially at elevated temperatures, leading to potential short circuits and reduced durability.
Innovation Solution
A bi-layer separator construction is integrated with an electrode, comprising a layer of ceramic particles and a microporous polymer layer, providing enhanced mechanical and thermal resistance, with the ceramic layer resisting penetration and the polymer layer ensuring adhesion and flexibility to accommodate volume changes during charge-discharge cycles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional microporous polymer separator is used, then the battery can operate with basic separation functionality, but the separator is prone to penetration by lithium dendrites and metal particles at elevated temperatures
Solution Approach 1:
The patent applies composite materials by combining a ceramic layer (providing thermal and mechanical stability) with a polymer layer (providing flexibility and adhesion) to create a bi-layer separator that resists penetration by lithium dendrites and metal particles at elevated temperatures while maintaining ion conductivity
2Strength
If the separator is made thicker to improve penetration resistance, then mechanical strength increases, but the battery's energy density decreases
Solution Approach 1:
The patent applies local quality by creating a bi-layer separator where the ceramic layer provides localized penetration resistance and thermal stability, while the polymer layer provides localized flexibility and adhesion, allowing each layer to be optimized for its specific function rather than making the entire separator uniformly thick
3Strength
If a rigid separator structure is used to improve penetration resistance, then mechanical strength increases, but the separator cannot accommodate volume changes during charge-discharge cycles
Solution Approach 1:
The patent applies local quality by assigning different functional properties to different layers: the ceramic layer provides localized rigid support for penetration resistance, while the polymer layer provides localized flexibility to accommodate electrode volume changes during charge-discharge cycles
4Ease of manufacture
If a single-layer separator is used, then the manufacturing process is simple, but the separator cannot provide both thermal resistance and flexibility simultaneously
Solution Approach 1:
The patent applies segmentation by dividing the separator into two distinct layers with different functions: the ceramic layer for thermal stability and penetration resistance, and the polymer layer for flexibility and adhesion, allowing each layer to be optimized independently while maintaining overall manufacturing feasibility
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 bi-layer separator significantly improves the battery's ability to withstand mechanical stress, temperature fluctuations, and extends its operational life by preventing short circuits and maintaining electrical insulation between electrodes.
Implementation Method 1
The first layer 15 comprises a ceramic material and provides improved temperature resistance and improved penetration resistance
Implementation Method 2
The first layer 15 comprises a ceramic material and provides improved temperature resistance and improved penetration resistance
Implementation Method 3
The second layer 30 comprises a microporous polymer material and provides improved adhesion to the electrode
Implementation Method 4
The second layer 30 comprises a microporous polymer material and provides improved adhesion to the electrode and flexibility
Implementation Method 5
assure electrical separation between the anode and cathode of the cell
Data Source
AI summary
A porous bi-layer separator is composed of a first separator layer with a contacting array of non-conducting particles overlaid with a second separator layer of a microporous polymer layer, fabricated on the electrode surface of the anode of a lithium-ion battery to form an integral electrode-separator construction. Exemplary bi-layer separators may be fabricated by deposition of solvent-containing slurries of separator particles followed by solvent evaporation to produce the particle layer with subsequent application of polymer solutions followed by controlled evaporation of solvent to produce the microporous polymer layer. The elevated temperature performance of lithium-ion battery cells incorporating such integral electrode-bi-layer separators was demonstrated to exceed the performance of similar cells using commercial and experimental single layer polymer separators.