High Density Battery Separator Optimizing Ion Permeability
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Solution Overview
Problem
Existing batteries face deterioration in capacity due to repeated charging and discharging, particularly when the area density of the positive electrode active material layer exceeds a certain threshold, leading to decreased energy density and cycle lifespan.
Innovation Solution
A battery design incorporating a positive electrode with a lithium cobalt composite oxide, a porous separator with specific structural parameters, and a gel electrolyte, where the area density of the positive electrode active material layer is maintained at 27 mg/cm² or greater, and the separator's film resistance, thickness, porosity, and tortuosity are optimized to mitigate over-voltage and enhance ion permeability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the area density of the positive electrode active material layer is increased to improve energy density, then the battery capacity deteriorates due to repeated charging and discharging
Solution Approach 1:
The patent applies parameter changes by precisely controlling the area density of the positive electrode active material layer to be 27 mg/cm² or more, while simultaneously optimizing separator parameters (film resistance, thickness, porosity, tortuosity) to resolve the contradiction between high energy density and good cycle characteristics
Solution Approach 2:
The patent uses a porous separator with specifically controlled porosity (30-80%) and pore size (0.03-1 μm) to improve ion permeability while maintaining structural integrity during repeated charging and discharging, thereby preventing capacity deterioration despite high area density
2Quantity of substance
If the area density of the positive electrode active material layer is increased, then energy density is improved, but over-voltage occurs leading to electrolyte solution decomposition
Solution Approach 1:
The patent introduces the separator as an intermediary component between the positive electrode and negative electrode, with optimized film resistance (0.01-10 μm) and porosity parameters that mediate ion transport to prevent over-voltage and electrolyte solution decomposition while maintaining high area density
Solution Approach 2:
The patent changes the physical parameters of the separator (film resistance, thickness, porosity, tortuosity) to create optimal ion transport conditions that prevent over-voltage generation, allowing the battery to operate with high area density without electrolyte decomposition
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
This configuration improves the cycle characteristics by maintaining energy density and reducing capacity deterioration, while preventing electrolyte solution decomposition and clogging, thus extending the battery's lifespan.
Implementation Method 1
the separator's film resistance, thickness, porosity, and tortuosity are optimized to mitigate over-voltage and enhance ion permeability
Implementation Method 2
application of an electrolyte solution as an electrolyte and a matrix polymer compound that retains the electrolyte solution has been performed for the sake of liquid leakage resistance
Data Source
Figure 1
Figure 2
Figure 3A~3B
AI summary
Provided is a battery in which an area density S (mg/cm2) of a positive electrode active material layer is 27 mg/cm2 or greater, and a porous film included in a separator has a structure satisfying the following Expressions.