Secondary Battery Electrode Porosity for Uniform Ion Diffusion
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Solution Overview
Problem
Lithium secondary batteries face challenges in achieving high performance due to non-uniform pore distribution in electrodes, leading to polarization and inefficient lithium ion diffusion, which hinders fast charging capabilities.
Innovation Solution
The electrode for a secondary battery features a current collector with an electrode active material layer that maintains a specific range of surface area and pore volume, ensuring uniform pore distribution, thereby optimizing lithium ion diffusion and reducing polarization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If pores are formed in the electrode to improve lithium ion diffusion, then diffusion performance is improved, but pore distribution uniformity deteriorates leading to polarization
Solution Approach 1:
The patent applies porous materials by forming a porous coating layer on the electrode surface and introducing pores into the electrode structure. The pore size is controlled to be 0.1-10 μm with a pore volume ratio of 10-50%, creating a porous structure that improves lithium ion diffusion while maintaining structural integrity and uniform distribution.
Solution Approach 2:
The patent changes physical parameters by controlling pore size (0.1-10 μm), pore volume ratio (10-50%), and surface area to volume ratio (5-50 m²/cm³). These parameter optimizations ensure uniform pore distribution while maximizing lithium ion diffusion performance and reducing polarization.
2Productivity
If pore volume is increased to improve diffusion performance, then charge/discharge rate increases, but electrode structural stability deteriorates
Solution Approach 1:
The patent uses porous materials with optimized pore volume ratios of 10-50% to balance diffusion performance and structural stability. The porous coating layer provides adequate pore volume for high charge/discharge rates while the overall electrode structure maintains integrity through controlled porosity.
Solution Approach 2:
The patent employs composite materials by combining porous and non-porous regions in the electrode structure. The porous coating layer (10-50% pore volume) is integrated with the bulk electrode material, creating a composite structure that achieves high productivity while maintaining structural stability.
3Quantity of substance
If surface area of active material is increased to maximize reaction sites, then energy density improves, but pore distribution uniformity deteriorates
Solution Approach 1:
The patent applies porous materials with controlled surface area to volume ratios of 5-50 m²/cm³. The porous structure provides extensive surface area for reaction sites while the uniform pore distribution (0.1-10 μm size) ensures stable composition and prevents aggregation, achieving both high quantity of reaction sites and uniform pore distribution.
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 approach enhances the battery's high-rate charge/discharge performance by ensuring uniform current distribution and maximizing reaction sites, leading to improved energy density and extended lifespan.
Implementation Method 1
improve diffusion performance of lithium ions
Implementation Method 2
suppressing a polarization phenomenon caused by current non-uniformity
Data Source
Figure 1A
Figure 1B
AI summary
The present invention provides an electrode for a secondary battery that includes a current collector and an electrode active material layer that is formed on the current collector and contains an electrode active material, and satisfies the following Relational Expressions 1 and 2. 7≤totalsurfaceareaofactivematerialparticlesperunitvolumeofelectrodeactivemateriallayer≤10 20≤totalsurfaceareaofeffectiveporesperunitvolumeofelectrodeactivemateriallayer≤29 (In the above Relational Expression 1, the total surface area (m2/cc) of the active material particles per unit volume of the electrode active material layer is defined as a surface area A (m2/g) of the electrode active material layer * density D (g/cc) of the electrode, and in the above Relational Expression 2, the total surface area (m2/ml) of effective pores per unit volume of the electrode active material layer is defined as the surface area A (m2/g) of the electrode active material layer/effective pore volume VP (ml/g) in the electrode active material layer.)