Oriented Graphite Negative Electrode for Low-Resistance Li-Ion Cycling
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Solution Overview
Problem
Rechargeable lithium batteries face challenges with high electrical resistance and poor cycle-life characteristics due to the orientation and composition of the negative active material layers, which affect lithium ion transfer and battery performance.
Innovation Solution
A negative electrode design with oriented first and second negative active material layers, each having a controlled peak intensity ratio (I(002)/I(110)) of 150 or less, achieved through magnetic field application and controlled layer thickness, composition, and binder distribution, to enhance lithium ion transfer and reduce electrical resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional negative active material layers are used without controlled orientation, then the battery structure is simple and easy to manufacture, but the electrical resistance is high and cycle-life characteristics are poor
Solution Approach 1:
The patent applies a magnetic field during the coating process to preliminarily orient the negative active material particles before the layer is fully formed. This preliminary orientation action ensures that the (002) planes of the graphite crystals are aligned parallel to the current collector surface, which reduces electrical resistance and improves cycle-life characteristics without requiring complex post-processing steps.
Solution Approach 2:
The patent controls the orientation of negative active material layers by changing the magnetic field parameters during coating. By adjusting the magnetic field strength and direction, the patent achieves optimal orientation of the (002) planes parallel to the current collector, thereby improving electrical conductivity and battery performance while maintaining manufacturing feasibility.
2Productivity
If magnetic field application is used to control layer orientation, then electrical resistance is reduced and lithium ion transfer is enhanced, but the manufacturing process becomes more complex
Solution Approach 1:
The magnetic field is applied during the coating process itself, performing the orientation function preliminarily before the electrode is assembled into the battery. This approach enhances lithium ion transfer rates by ensuring proper crystal orientation while integrating the complexity into the existing manufacturing workflow rather than adding separate processing steps.
Solution Approach 2:
The patent replaces mechanical mixing and random particle arrangement with a magnetic field-based orientation system. This substitution allows for controlled alignment of graphite crystals through magnetic interaction rather than mechanical force, achieving superior lithium ion transfer rates while maintaining process efficiency.
3Reliability
If the peak intensity ratio I(002)/I(110) is not controlled, then the manufacturing process is simpler, but the electrical resistance remains high
Solution Approach 1:
The patent controls the peak intensity ratio I(002)/I(110) by changing the orientation parameters of the negative active material during coating. By adjusting the magnetic field application, the patent achieves a specific orientation where the (002) planes are parallel to the current collector, resulting in a controlled peak intensity ratio that correlates with reduced electrical resistance and improved battery reliability.
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 design results in reduced electrical resistance and improved cycle-life characteristics, enabling rapid charge and discharge capabilities suitable for high-power applications.
Implementation Method 1
applying a magnetic field to the resulting product
Data Source
AI summary
A negative electrode for a rechargeable lithium battery and a rechargeable lithium battery including the same are provided. The negative electrode includes: a current collector; a first negative active material layer on the current collector and including a first negative active material; and a second negative active material layer on the first negative active material layer and including a second negative active material, wherein the first negative active material layer and the second negative active material layer have a peak intensity ratio (I(002)/I(110)) of a peak intensity at a (002) plane relative to a peak intensity at a (110) plane of 150 or less when measured by X-ray powder diffraction (XRD) using a CuKα ray.