Composite Negative Electrode Plate for Lightweight Cycle Stability
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Solution Overview
Problem
Existing negative electrode plates in secondary batteries face challenges in achieving high energy density and long cycle performance due to the weight and mechanical limitations of metal current collectors, which can lead to cracking and increased impedance.
Innovation Solution
A negative electrode plate design featuring a metal conductive layer on an organic support layer with a specific active material distribution, where the active material's dimensions in different cross-sections satisfy certain ratios to prevent damage to the conductive layer, ensuring good electrical conductivity and mechanical support, thereby enhancing energy density and cycle performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If metal current collectors with relatively large thickness are used to meet electrical conductivity and current collecting performance requirements, then electrical conductivity is improved, but weight increases which reduces energy density
Solution Approach 1:
The patent employs a composite current collector structure consisting of an organic support layer (such as polyolefin or aromatic polymer) combined with a metal layer (such as aluminum or copper). This composite structure leverages the lightweight property of organic materials to reduce overall weight while the metal component ensures sufficient electrical conductivity and mechanical strength, thereby resolving the contradiction between weight reduction and conductivity maintenance.
Solution Approach 2:
The patent optimizes the thickness parameters of both the organic support layer and the metal layer within specific ranges. By carefully controlling these dimensional parameters, the design achieves the minimum required electrical conductivity while minimizing the total weight of the current collector, thus improving energy density without sacrificing performance.
2Weight of moving object
If thin metal conductive layer is used on organic support layer to reduce weight, then energy density is improved, but cycle performance deteriorates due to mechanical damage
Solution Approach 1:
The composite structure of organic support layer plus metal conductive layer provides both weight reduction and mechanical protection. The organic layer acts as a robust substrate that prevents the thin metal layer from cracking during battery cycling, while the metal layer maintains electrical conductivity. This synergistic combination enables lightweight design without compromising cycle performance.
Solution Approach 2:
The organic support layer serves as a protective cushioning layer that prevents mechanical damage to the thin metal conductive layer before cracking can occur. This preemptive protection mechanism ensures the integrity of the conductive layer throughout the battery's service life, maintaining cycle performance despite the reduced metal thickness.
3Ease of manufacture
If active material with large particle size is used, then manufacturing is easier, but it causes damage to metal conductive layer leading to increased impedance
Solution Approach 1:
The patent specifies optimal particle size parameters for the active material that balance manufacturing ease with protective capability. The particle size is controlled to be large enough for easy handling and processing but small enough to avoid excessive mechanical stress on the metal conductive layer, thereby preventing cracking and maintaining electrical conductivity.
Solution Approach 2:
The active material particles are distributed with specific size characteristics in different regions of the electrode. By optimizing the local particle size distribution, the design achieves ease of manufacture in bulk processing while ensuring that individual particles do not exceed the threshold that would cause damage to the conductive layer, thus maintaining overall electrical performance.
Data Source
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AI summary
The present application discloses a negative electrode plate, a secondary battery, and an apparatus containing the secondary battery. The negative electrode plate includes: a negative electrode current collector, including an organic support layer and a metal conductive layer disposed on the organic support layer; and a negative electrode active material layer, including at least a first active material layer, the first active material layer being disposed on the metal conductive layer and including a first active material; wherein in a first cross section in a thickness direction of the negative electrode plate, the first active material has a size a in a direction parallel to the metal conductive layer, the first active material has a size b in the thickness direction, and a and b satisfy 0.8 ≤ a/b ≤ 20; in a second cross section in the thickness direction of the negative electrode plate, the first active material has a size c in the direction parallel to the metal conductive layer, the first active material has a size d in the thickness direction, and c and d satisfy 0.8 ≤ c/d ≤ 20; and the first cross section is parallel to a first direction, the second cross section is parallel to a second direction, and the first direction intersects the second direction.