Lithium-Ion Conductive Separator Structure for Lower Cell Impedance
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Solution Overview
Problem
Conventional separators in electrochemical cells, particularly lithium-ion batteries, suffer from poor lithium-ion transportation due to non-conductive ceramic layers and increased thickness, leading to higher impedance and potential delamination issues, which affect battery performance and safety.
Innovation Solution
A separator with embedded lithium-ion conductive inorganic particles, such as Li1+xAlxTi2−x(PO4)3 or Li7La3Zr2O12, within a polymer layer to enhance conductivity and reduce thickness, thereby improving lithium-ion transport and cell integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If conventional non-conductive ceramic layers are used in separators, then thermal stability is improved, but lithium-ion conductivity deteriorates
Solution Approach 1:
The patent changes the key parameter of ceramic material from non-conductive to lithium-ion conductive by selecting specific ceramic compositions (e.g., LLZO, LATP, LAGP) that exhibit high lithium-ion conductivity while maintaining thermal stability. This parameter change resolves the contradiction by finding materials that satisfy both thermal stability and lithium-ion conductivity requirements simultaneously.
Solution Approach 2:
The patent uses composite structures combining polymer matrices with lithium-ion conductive ceramic particles. The polymer provides flexibility and processability while the conductive ceramic particles provide thermal stability and lithium-ion conductivity pathways. This composite approach resolves the contradiction by combining the advantages of different material systems.
2Strength
If conventional separator thickness is increased, then mechanical strength is improved, but cell impedance increases
Solution Approach 1:
The patent changes the functional properties of the separator by incorporating lithium-ion conductive ceramic particles, which enable the use of thinner separator designs. The conductive particles create efficient lithium-ion transport pathways that compensate for the reduced thickness, allowing the separator to maintain mechanical strength while reducing impedance.
Solution Approach 2:
The patent employs porous structures with controlled pore sizes and distributions that facilitate lithium-ion transport. The porous architecture provides mechanical integrity while creating efficient ion conduction pathways, resolving the contradiction between mechanical strength and low impedance through optimized pore structure design.
3Reliability
If solid state electrolytes are used, then safety is improved, but inter-surface adhesion deteriorates
Solution Approach 1:
The patent uses composite structures combining polymer matrices with ceramic particles, where the polymer phase provides excellent inter-surface adhesion and flexibility, while the ceramic particles provide safety benefits. This composite approach resolves the contradiction by allowing the polymer to bond well with electrodes while the ceramic particles enhance safety through thermal stability and controlled ion transport.
Solution Approach 2:
The patent applies different material properties to different regions or phases within the separator structure. The polymer matrix provides adhesion at the inter-surface interfaces, while the ceramic particles provide safety properties in the bulk structure. This local differentiation of material functions resolves the contradiction between adhesion and safety.
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 embedded inorganic particles improve lithium-ion conductivity, reducing cell impedance and thickness, leading to longer cycle life and enhanced safety with a nearly 50% reduction in separator thickness.
Implementation Method 1
particles of inorganic material that is lithium-ion conductive embedded within the layer of material
Data Source
AI summary
A separator for an electrochemical cell has a layer of one or more polymer material, the layer having a thickness, and particles of one or more inorganic material that is lithium-ion conductive. The particles of the lithium-ion conductive inorganic material are embedded within the thickness of the layer of polymer material, each particle having a diameter ranging between 100 nm and 600 nm.