Lithium-Ion Separation Membrane for Solvent Isolation and Ion Conductivity
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Solution Overview
Problem
In lithium ion secondary batteries where different types of electrolytes are used in the positive and negative electrodes, there is a need for a separation membrane that prevents solvent mixing between the electrodes while maintaining high ionic conductivity.
Innovation Solution
A lithium ion secondary battery configuration that includes a separation membrane made of a polymer with lithium ion conductivity, containing a thiol compound and specific lithium salts, positioned between the positive and negative electrode mixture layers, which are composed of distinct solvents and active materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional separation membrane is used to separate different electrolyte solvents, then solvent mixing is prevented, but film-forming characteristics and manufacturing stability are insufficient
Solution Approach 1:
The patent optimizes specific parameters including porosity (30-70%), thickness (10-100 μm), and lithium salt concentration (5-50 wt%) to achieve both excellent solvent separation performance and stable film-forming characteristics during manufacturing
Solution Approach 2:
The separation membrane structure enables self-supporting film formation without requiring additional backing layers or complex support structures, improving manufacturing stability and ease of production
2Reliability
If a separation membrane with high solvent separation capability is designed, then solvent mixing is prevented, but production efficiency and productivity are reduced
Solution Approach 1:
The separation membrane is produced by segmenting the manufacturing process into distinct steps: forming the porous base layer, depositing the lithium salt-containing ionic conductivity layer, and curing. This segmentation enables optimized production of each layer independently, improving overall productivity
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 provides a separation membrane with high ionic conductivity, enabling efficient solvent separation and improved productivity, allowing for stable production of larger area membranes with enhanced film-forming characteristics.
Implementation Method 1
the separation membrane contains a polymer having lithium ion conductivity
Implementation Method 2
the polymer is a polymer of polymerizable components that include a monomer and a thiol compound
Data Source
AI summary
One aspect of the present invention provides a lithium ion secondary battery comprising a positive electrode mixture layer, a separation membrane, and a negative electrode mixture layer in the stated order, wherein: the positive electrode mixture layer contains a positive electrode active material, a first lithium salt, and a first solvent, the negative electrode mixture layer contains a negative electrode active material, a second lithium salt, and a second solvent different from the first solvent, the separation membrane contains a polymer having lithium ion conductivity, a third lithium salt, and a third solvent, and the, polymer is a polymer of polymerizable components that include a monomer and a thiol compound.