Multi-Layer Lithium Battery Electrode for Low-Resistance Ion Transport
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Solution Overview
Problem
Existing rechargeable lithium batteries face limitations in improving high-rate charge/discharge characteristics due to increased electrode plate resistance caused by reduced porosity and binder migration during the drying process, which affects lithium ion migration.
Innovation Solution
A double-layer or multi-layer electrode structure is implemented, with specific porosity ranges of 8% to 12% for the first active material layer and 16% to 22% for the second layer, using a double slot die coating method to balance compression ratios and reduce electrode plate resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a high compression ratio is applied during electrode manufacturing to increase energy density, then the thickness of the electrode plate is reduced, but the porosity of the active material layer surface decreases, leading to increased resistance to lithium ion migration
Solution Approach 1:
The patent applies porous materials by controlling the porosity of the active material layer to be 30% or more, maintaining a porous structure that facilitates lithium ion migration while achieving high energy density through optimized particle packing and compression ratios
Solution Approach 2:
The patent changes physical parameters by optimizing the compression ratio to 0.45 or less and controlling the porosity at 30% or more, balancing the trade-off between energy density and ionic conductivity to reduce resistance to lithium ion migration
2Reliability
If the electrode plate thickness is reduced to improve high-rate charge/discharge characteristics, then the resistance to lithium ion migration decreases, but the energy density and capacity of the battery are reduced
Solution Approach 1:
The patent transitions from a single-layer electrode structure to a multi-layer electrode structure with alternating high-porosity and low-porosity layers, adding a dimensional aspect to porosity distribution that enables simultaneous optimization of ionic transport pathways and energy density
3Reliability
If the porosity of the active material layer is increased to reduce resistance, then the high-rate charge/discharge characteristics improve, but the binder component migrates during drying, affecting electrode stability
Solution Approach 1:
The patent segments the active material layer into multiple layers with alternating porosity levels, creating distinct zones where binder migration is minimized in low-porosity layers while high-porosity layers maintain low resistance for lithium ion migration
Solution Approach 2:
The patent applies local quality by creating regions with different porosity characteristics within the electrode, where specific layers have optimized porosity for their function (high porosity for ionic transport, low porosity for structural stability), rather than using a uniform structure throughout
Data Source
AI summary
Provided an electrode for a rechargeable lithium battery and a rechargeable lithium battery including the same, the electrode including a current collector and a first active material layer disposed on the current collector and including a first active material, and a second active material layer disposed on the first active material layer and including a second active material, wherein a porosity of the first active material layer is 8% to 12% and a porosity of the second active material layer is 16% to 22%.