Battery Separator Porosity and Air Permeability Optimization
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Solution Overview
Problem
Existing batteries face challenges in achieving both high capacity and high power due to issues with separator conductivity and lithium ion distribution, leading to increased inner resistance and difficulty in realizing both performance metrics simultaneously.
Innovation Solution
A battery design incorporating a positive electrode with a specific active material layer and a separator with a predetermined porosity and air permeability, ensuring effective lithium ion distribution and reduced inner resistance, comprising a positive electrode current collector with a positive electrode active material layer having compounds like lithium nickel composite oxides and a porous film with controlled porosity and air permeability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the positive electrode active material layer area density is increased to achieve high capacity, then the battery capacity improves, but the inner resistance increases and power performance deteriorates
Solution Approach 1:
The patent applies parameter changes by precisely controlling the porosity (30-80%) and air permeability (100-10000 sec/100cc) of the separator, as well as the area density (20-50 mg/cm²) of the positive electrode active material layer. These parameter optimizations enable the battery to achieve high capacity while maintaining low inner resistance and high power performance, resolving the contradiction between capacity and power.
2Reliability
If the separator porosity is increased to improve lithium ion distribution, then the lithium ion conductivity improves, but the mechanical strength decreases and short circuit risk increases
Solution Approach 1:
The patent resolves this contradiction by optimizing the porosity parameter within the specific range of 30-80% and controlling air permeability between 100-10000 sec/100cc. This parameter optimization ensures sufficient lithium ion conductivity while maintaining adequate mechanical strength to prevent short circuits, achieving both high reliability and structural integrity.
3Quantity of substance
If the positive electrode active material layer area density is increased beyond 50 mg/cm² to achieve higher capacity, then the capacity increases, but the discharge performance under high-load conditions deteriorates due to increased inner resistance
Solution Approach 1:
The patent applies parameter changes by precisely controlling the area density of the positive electrode active material layer within the range of 20-50 mg/cm². This optimization ensures that the battery achieves high capacity while maintaining low inner resistance and excellent discharge performance under high-load conditions, preventing the deterioration that would occur with higher area densities.
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 enables batteries to achieve both high capacity and high power by optimizing the separator structure and active material layer, suppressing inner resistance and enhancing discharge performance under high-load conditions.
Implementation Method 1
a separator at least including a porous film... The porous film has a porosity ε [%] and an air permeability t [sec/100 cc] which satisfy the following formulae
Implementation Method 2
The positive electrode active material has at least one compound selected from the group consisting of: a lithium nickel composite oxide having nickel as a main component... a lithium manganese composite oxide having a spinel structure... a lithium iron phosphate compound having an olivine structure
Data Source
AI summary
A battery is provided. The battery includes a positive electrode including a positive electrode active material layer provided on a positive electrode current collector; a negative electrode; and a separator at least including a porous film, wherein the porous film has a porosity ε [%] and an air permeability t [sec/100 cc] which satisfy formulae of:t=a×Ln(ε)−4.02a+100 and −1.87×1010×S−4.96≤a≤−40wherein S is the area density of the positive electrode active material layer [mg/cm2] and Ln is natural logarithm.