Electrode Assembly Inner-Layer Notches to Cut Inactive Battery Material
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Solution Overview
Problem
In secondary batteries, the active substance on the innermost winding of the negative electrode plate does not participate in lithiation/delithiation, leading to waste of active materials, increased weight, and reduced energy density.
Innovation Solution
The electrode assembly design includes a negative electrode plate with a first inner layer section and a positive electrode plate with a second inner layer section, where the first inner layer section has notch portions that allow the second inner layer section to be exposed, ensuring lithiation/delithiation occurs between them, thereby reducing material waste and enhancing energy density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the negative electrode plate is designed as a complete inner layer in the innermost winding, then the structural integrity is maintained, but active material waste occurs and energy density decreases
Solution Approach 1:
The patent extracts the problematic complete inner layer of active material from the negative electrode plate at the innermost winding position. By removing this non-functional active material layer that cannot participate in lithiation/delithiation, the invention eliminates waste while maintaining the necessary structural framework through the current collector alone.
Solution Approach 2:
The patent applies local quality by creating an asymmetric structure where the negative electrode plate has different configurations at different radial positions. Specifically, the innermost winding lacks the active material inner layer that would normally be present, while outer windings maintain the complete layered structure. This localized modification optimizes performance where it matters most without compromising overall structural integrity.
2Quantity of substance
If the innermost negative electrode active material is removed, then energy density increases, but structural completeness deteriorates
Solution Approach 1:
The invention extracts the non-functional active material from the innermost negative electrode layer, removing only the portion that cannot contribute to energy storage. This selective extraction increases the effective energy density by ensuring all remaining active material participates in electrochemical reactions.
Solution Approach 2:
The current collector in the innermost winding serves multiple functions: it maintains structural integrity, provides electrical conductivity, and acts as the complete negative electrode where active material is absent. This multi-functional design compensates for the removed active material layer.
3Ease of manufacture
If the electrode assembly uses conventional complete winding structure, then manufacturing simplicity is maintained, but active material utilization efficiency decreases
Solution Approach 1:
The patent implements local quality by modifying only the innermost winding structure while keeping the rest of the electrode assembly conventional. The asymmetric design where the negative electrode lacks an active material inner layer at the core is applied locally, allowing most of the manufacturing process to remain unchanged while significantly improving active material utilization.
Solution Approach 2:
Instead of the conventional approach where the negative electrode plate has a complete active material layer throughout, the invention inverts this approach by deliberately creating an asymmetric structure where the innermost layer lacks active material. This inversion resolves the utilization efficiency problem while maintaining manufacturing feasibility.
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 design reduces material waste and increases energy density by ensuring active materials on both layers participate in the electrochemical reaction, optimizing the structural integrity and performance of the secondary battery.
Implementation Method 1
During charging and discharging of the secondary battery, lithium ions undergo lithiation/delithiation between the negative electrode plate and the positive electrode plate, thereby producing electrical energy.
Data Source
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AI summary
This application provides an electrode assembly, a secondary battery, and a battery-powered apparatus. The electrode assembly includes a negative electrode plate, a positive electrode plate, and a separator, and the negative electrode plate, the separator, and the positive electrode plate are laminated and wound around a winding center, where the negative electrode plate includes a first inner layer section, the positive electrode plate includes a second inner layer section, and the first inner layer section and the second inner layer section are immediately adjacent to the winding center; and the first inner layer section is provided with a notch portion, and the first inner layer section is disposed opposite the second inner layer section through the notch portion.