Porous Positive Electrode Material for Better Electrolyte Penetration
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Solution Overview
Problem
Existing lithium-ion secondary batteries do not achieve sufficient capacity due to inadequate contact area between the positive-electrode active material and the electrolyte, despite using porous materials with uniform pores, as the electrolyte solution cannot penetrate small pores and the specific surface area does not effectively contribute to increased capacity.
Innovation Solution
A positive-electrode active material with an average pore size of 0.2 µm to 1.0 µm and a proportion of micropores between 70% to 92% is developed, ensuring effective electrolyte penetration and maintaining material strength, thereby enhancing charge and discharge capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If porous positive-electrode active material with small pore size is used to increase specific surface area, then contact area with electrolyte should increase, but electrolyte solution cannot penetrate small pores effectively
Solution Approach 1:
The patent applies parameter changes by optimizing the pore size to a specific range (0.0036 μm to 400 μm) and controlling the average pore size (0.2 μm to 1.0 μm) to balance electrolyte penetration and contact area. This parameter optimization resolves the contradiction by finding the optimal pore dimensions that allow both effective electrolyte access and sufficient surface area for lithium ion interaction.
Solution Approach 2:
The patent applies local quality by creating a hierarchical pore structure with different pore size distributions within the positive-electrode active material. The material contains both small pores (for high surface area) and larger pores (for electrolyte penetration), with the proportion of micropores controlled at 70% to 92%. This local variation in pore quality allows different regions to serve different functions.
2Area of stationary object
If proportion of micropores is increased to increase surface area, then contact area increases, but material strength decreases
Solution Approach 1:
The patent applies parameter changes by precisely controlling the proportion of micropores within the range of 70% to 92% and the average pore size between 0.2 μm to 1.0 μm. This parameter optimization achieves the optimal balance between surface area and material strength, allowing the material to maintain structural integrity while providing sufficient contact area for electrochemical reactions.
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 proposed active material improves battery characteristics by increasing the contact area with the electrolyte, stabilizing pore size, and reducing ineffective pores, resulting in enhanced charge and discharge capacity and efficiency.
Implementation Method 1
When a lithium-ion secondary battery is charged and discharged, lithium ions move between the positive-electrode active material and the electrolyte
Implementation Method 2
it is effective to increase the contact area between the positive-electrode active material and the electrolyte as much as possible and to use particles of a porous positive-electrode active material having a uniform pore on the surface
Data Source
Figure 1
AI summary
A positive-electrode active material for a lithium-ion secondary battery, wherein an average pore size of the positive-electrode active material is 0.2 µm to 1.0 µm when a pore size is measured in a range of 0.0036 µm to 400 µm.