LFP Rechargeable Battery Electrodes for Fast Charging and High Capacity
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Solution Overview
Problem
Rechargeable lithium batteries face challenges in achieving high capacity and rapid charging characteristics due to increased positive electrode mixture density reducing porosity and ionic resistance in the negative electrode, which affects safety and efficiency.
Innovation Solution
The design includes a positive electrode with pores of 0.6 μm to 1 μm and porosity greater than 23%, and a negative electrode with ionic resistance less than 20 Ωcm², using lithium iron phosphate-based materials to ensure safety and capacity while allowing rapid charging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the positive electrode mixture density is increased to achieve high capacity, then the positive electrode active material is more densely positioned, but the porosity and pore size of the positive electrode are reduced, which is disadvantageous for rapid charging
Solution Approach 1:
The patent applies porous materials by designing the positive electrode with controlled porosity (23-40%) and pore size (0.6-1.0 μm) to maintain ion transport pathways while accommodating high active material density. The porous structure allows electrolyte penetration and ion diffusion necessary for rapid charging even when active material is densely packed.
Solution Approach 2:
The patent changes physical parameters by optimizing the porosity range (23-40%) and pore size (0.6-1.0 μm) of the positive electrode, and controlling the mixture density within specific ranges. These parameter adjustments balance the competing requirements of high capacity and rapid charging by tuning the electrode's physical structure.
2Quantity of substance
If the negative electrode mixture density is increased to achieve high capacity, then the negative electrode active material is more densely positioned, but the ionic resistance of the negative electrode increases, which is disadvantageous for rapid charging
Solution Approach 1:
The patent applies porous materials by designing the negative electrode with controlled porosity to maintain ion transport pathways while accommodating high active material density. The porous structure allows electrolyte penetration and ion diffusion necessary for rapid charging even when active material is densely packed.
Solution Approach 2:
The patent changes physical parameters by optimizing the porosity and mixture density of the negative electrode within specific ranges, and controlling the ionic resistance to be less than 20 Ωcm². These parameter adjustments balance the competing requirements of high capacity and low ionic resistance.
3Reliability
If lithium iron phosphate-based oxides are used as positive electrode active material to ensure safety and thermal stability, then the structure is stable and thermal stability is improved, but achieving both high capacity and rapid charging characteristics becomes more challenging
Solution Approach 1:
The patent changes physical parameters by optimizing the porosity (23-40%) and pore size (0.6-1.0 μm) of the positive electrode containing lithium iron phosphate-based oxides. These parameter adjustments enable the safe and thermally stable material to also achieve high capacity and rapid charging characteristics.
Solution Approach 2:
The patent uses composite materials by combining lithium iron phosphate-based oxides with conductive materials and binders in specific ratios, and forming them into a porous electrode structure. This composite approach enhances the inherent safety and thermal stability of lithium iron phosphate while improving electrical conductivity and ion transport for high capacity and rapid charging.
Data Source
AI summary
Disclosed is a rechargeable lithium battery, the rechargeable lithium battery including a positive electrode including a positive electrode current collector and a positive electrode active material layer on the positive electrode current collector and including a lithium iron phosphate-based positive electrode active material, a negative electrode including a negative electrode current collector and a negative electrode active material layer on the negative electrode current collector and including a carbon-based negative electrode active material, and an electrolyte. The positive electrode includes pores with a size of about 0.6 μm to about 1 μm, the positive electrode has a porosity that is greater than or equal to about 23%, and the negative electrode has an ionic resistance that is less than or equal to about 20 Ωcm2.