Negative Electrode Sheet with Segmented Coating for Fast-Charging
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Solution Overview
Problem
Fast-charging lithium ion batteries experience lithium deposition issues on the single-sided coating area of the negative electrode, leading to reduced battery capacity, inflation, and shortened service life due to high current density and low potential.
Innovation Solution
A negative electrode sheet with a specific structure is developed, featuring a first and second negative electrode active material layer with different particle sizes and properties, optimizing the dynamic properties of the single-sided and double-sided coating areas to reduce polarization and prevent lithium deposition without compromising energy density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the negative electrode uses single-sided coating to simplify structure and reduce cost, then device complexity is reduced, but lithium deposition occurs on the single-sided coating area due to high current density and low potential
Solution Approach 1:
The negative electrode is segmented into single-sided coating area and double-sided coating area, with different active material layers configured in each area to address local lithium deposition issues while maintaining overall structural simplicity
Solution Approach 2:
Different active material layers are applied to different areas of the negative electrode: the first active material layer in the single-sided coating area and the second active material layer in the double-sided coating area, creating local quality differences to prevent lithium deposition in specific high-risk zones
2Reliability
If the overall negative electrode dynamic property is increased to prevent lithium deposition, then lithium deposition is reduced, but the power density of the lithium ion battery decreases
Solution Approach 1:
The patent applies different active material layers with different dynamic properties to different areas of the negative electrode. The second active material layer with higher dynamic property is specifically applied to the double-sided coating area where lithium deposition is most severe, while the first active material layer maintains good dynamic properties in the single-sided coating area, thus preventing lithium deposition locally without requiring overall increase in dynamic property that would reduce power density
Solution Approach 2:
The negative electrode is divided into functional segments with different active material characteristics, allowing optimized performance in specific areas without compromising overall battery power density
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 improves the lithium ion battery's cycling lifetime, reduces inflation, and enhances fast-charging performance without decreasing energy density.
Implementation Method 1
a reception speed of lithium ions of the first negative electrode active material is greater than a reception speed of lithium ions of the second negative electrode active material
Data Source
Figure 1~2
AI summary
The present disclosure provides a negative electrode sheet, a preparation method thereof and a lithium ion battery containing the same. The negative electrode sheet includes a negative electrode current collector, where the negative electrode current collector includes a single-sided coating area and a double-sided coating area; in the double-sided coating area, second coating layers are disposed on both side surfaces of the negative electrode current collector, respectively, wherein each of the second coating layers includes a first negative electrode active material layer and a second negative electrode active material layer, the second negative electrode active material layer is disposed on a surface of the negative electrode current collector, and the first negative electrode active material layer is disposed on a surface of the second negative electrode active material layer. The lithium ion battery containing the negative electrode sheet has the following effects: (1) the problem of lithium deposition of a single-sided coating area of a negative electrode of a regular winding structural lithium ion battery can be effectively improved, thereby increasing a circulation lifetime of the lithium ion battery, and reducing a circulation inflation of the lithium ion battery; (2) a compaction density of a negative electrode can be increased and an energy density of a battery cell can be increased; and (3) a dynamic property of the negative electrode and a fast-charging capacity of the battery can be improved.