Graphite Negative Electrode Orientation for Lower Battery Resistance
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Solution Overview
Problem
Current battery technologies face challenges in reducing battery resistance, which affects the input/output performance of lithium-ion secondary batteries, particularly in high-output and high-capacity applications such as electric vehicles.
Innovation Solution
A negative electrode for lithium-ion secondary batteries is developed, featuring a negative electrode current collector and a negative electrode layer with a high elastic modulus binder and scaly graphite active material, where the binder's elastic modulus is greater than 811 MPa, and the orientation degree of the active material is enhanced by applying a magnetic field during the manufacturing process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If conventional binders with lower elastic modulus are used in the negative electrode, then the manufacturing process is easier and cost is lower, but the battery resistance is higher and input/output performance is poorer
Solution Approach 1:
The patent changes the elastic modulus parameter of the binder from conventional low values to greater than 811 MPa, which fundamentally alters the electrode structure and reduces battery resistance. This parameter change enables better maintenance of active material orientation and improves input/output performance.
Solution Approach 2:
The patent uses a composite binder system comprising polyacrylic acid and polyvinylidene fluoride in specific ratios, creating a material with optimized elastic modulus and binding properties that simultaneously achieves low resistance and manufacturability.
2Quantity of substance
If the negative electrode active material is pressed to increase density, then the battery capacity increases, but the orientation of the active material deteriorates and resistance increases
Solution Approach 1:
The high elastic modulus binder acts as a protective matrix that cushions and maintains the vertical orientation of scaly graphite particles during the pressing process. The binder's rigidity prevents particle reorientation even under high pressure, preserving the low-resistance structure while achieving high density.
Solution Approach 2:
The patent creates local structural quality differences by maintaining vertical orientation of scaly graphite particles in specific regions of the electrode while achieving high overall density. The binder provides localized support to maintain orientation where it is most critical for electron transport.
3Loss of energy
If scaly graphite with high aspect ratio is used to reduce resistance, then the orientation effect is enhanced, but the manufacturing precision and particle distribution become more difficult to control
Solution Approach 1:
The binder serves as an intermediary medium that facilitates the handling and distribution of high aspect ratio scaly graphite particles. It provides a matrix that holds particles in appropriate orientations during manufacturing while allowing for controlled processing, bridging the gap between particle morphology and manufacturability.
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 solution effectively reduces battery resistance and improves input/output performance by maintaining the orientation of the negative electrode active material, even under pressing conditions, thereby enhancing the battery's efficiency and capacity.
Implementation Method 1
a negative electrode for a battery, which is characterized in that a cured layer of a graphite-based negative electrode active material composition is formed on a negative electrode current collector under a magnetic field
Data Source
AI summary
A negative electrode for a lithium-ion secondary battery, wherein the negative electrode includes a negative electrode current collector and a negative electrode layer, and the negative electrode layer includes a negative electrode active material and a binder, wherein an elastic modulus of the binder is larger than a 811 MPa, and an X-ray diffraction intensity of a (110) plane of the negative electrode active material is I (110), and an X-ray diffraction intensity of a (004) plane is I (004). The negative electrode is characterized in that an orientation degree I (110)/I (004) of the negative electrode active material obtained by dividing I (110) by I (004) is larger than 0.23.