Negative Electrode Current Collector Roughness for Strong Layer Adhesion
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Solution Overview
Problem
Existing rechargeable lithium batteries face challenges in achieving improved battery characteristics such as lifecycle, high-rate performance, and efficiency due to insufficient adherence between the active material layer and the current collector, which is often caused by inadequate surface roughness of the current collector.
Innovation Solution
A negative electrode design with a current collector that exhibits a specific X-ray diffraction peak at the (111) plane and a defined PCR value of 5.0 or less, ensuring sufficient surface roughness and adherence, is used in conjunction with a carbonaceous active material, including graphite composites and Si-including active materials, to enhance battery performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the current collector surface is made smoother for easier manufacturing, then the manufacturing process becomes simpler, but the adherence between the active material layer and the current collector deteriorates
Solution Approach 1:
The invention changes the surface roughness parameter of the current collector to a specific range (Ra 0.3-3.0 μm) to optimize both manufacturability and adherence. This parameter optimization allows the active material layer to bond effectively to the current collector surface while maintaining reasonable manufacturing complexity.
Solution Approach 2:
The invention applies different surface roughness characteristics to different regions or aspects of the current collector. The surface is engineered to have enhanced roughness features specifically at the interface with the active material layer, while other portions of the current collector maintain smoother surfaces for ease of handling and manufacturing.
2Reliability
If the current collector surface is made rougher to improve adherence, then the adherence between the active material layer and the current collector improves, but the manufacturing complexity increases
Solution Approach 1:
The invention optimizes the surface roughness parameter within a specific range (Ra 0.3-3.0 μm) to achieve the desired adherence without excessive complexity. This controlled parameter change ensures that the surface is rough enough for good bonding but not so rough as to create manufacturing difficulties.
Solution Approach 2:
The invention employs a composite surface structure on the current collector, combining base material with surface treatments or coatings that provide the necessary roughness. This composite approach achieves enhanced adherence while keeping the base current collector structure relatively simple and manufacturable.
3Reliability
If a complex surface treatment is applied to the current collector to enhance adherence, then the adherence improves, but the manufacturing process becomes more complex and costly
Solution Approach 1:
The invention modifies the surface roughness parameter to an optimal range (Ra 0.3-3.0 μm) that can be achieved through relatively simple manufacturing processes such as controlled rolling, brushing, or chemical etching, avoiding the need for complex multi-step surface treatments while still achieving good adherence.
Solution Approach 2:
The invention incorporates surface roughness features into the current collector during the initial manufacturing process rather than applying complex surface treatments afterward. This preliminary action of creating the appropriate surface texture during base manufacturing simplifies the overall production process while ensuring good adherence from the start.
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
The proposed design improves cycle-life characteristics and high-rate characteristics by ensuring strong adherence between the active material layer and the current collector, resulting in a longer cycle life and enhanced efficiency.
Implementation Method 1
a PCR (Plane angel Change Ratio) value defined by Equation 1 below is about 5.0 or less. In Equation 1, the peak intensity is a value from an X-ray diffraction measurement by using a CuKα ray.
Data Source
AI summary
The current disclosure includes a negative electrode for a rechargeable lithium battery and a rechargeable lithium battery including the negative electrode. The negative electrode for the rechargeable lithium battery includes a negative active material layer including a negative active material and a current collector on the negative active material layer, wherein a PCR (Plane angel Change Ratio) value is about 5.0 or less.