Dual-Layer Li-Ion Negative Electrode for Fast Charging Durability
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Solution Overview
Problem
There is a demand for improving the charging performance and durability of lithium ion secondary batteries by enhancing the negative electrode structure.
Innovation Solution
The negative electrode includes a dual-layer active material structure with a first active material layer having a smaller BET specific surface area and a second active material layer with a larger BET specific surface area, where the second layer has a lower density and a higher ratio of conductive auxiliary agent, and the first layer contains an Si-based material pre-doped with lithium.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single-layer negative electrode active material is used, then the structure is simple, but the charging performance and durability are insufficient
Solution Approach 1:
The negative electrode active material layer is divided into two distinct layers: a first negative electrode active material layer containing Si-based material pre-doped with lithium, and a second negative electrode active material layer with different density and conductive auxiliary agent content. This segmentation allows each layer to perform specific functions, improving overall battery durability and charging performance while managing structural complexity.
2Productivity
If the BET specific surface area of the second active material is larger than the first, then the charging performance is improved, but the density of the second layer becomes lower
Solution Approach 1:
The patent applies local quality by creating two layers with different BET specific surface areas and densities. The first layer has lower BET specific surface area and higher density, while the second layer has higher BET specific surface area and lower density. This local differentiation allows the second layer to provide enhanced charging performance through increased surface area for lithium ion insertion, while the first layer maintains higher energy density.
3Productivity
If the ratio of conductive auxiliary agent in the second layer is higher than the first layer, then the charging performance is enhanced, but the manufacturing precision requirements increase
Solution Approach 1:
The patent implements parameter changes by varying the conductive auxiliary agent content between layers. The second negative electrode active material layer contains a higher ratio of conductive auxiliary agent compared to the first layer. This parameter differentiation enhances electron conductivity and rapid charging capability in the second layer, while the manufacturing process must precisely control these compositional parameters to achieve the desired performance.
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
This configuration enhances charging performance, particularly rapid charging, and extends the battery life by suppressing side reactions and improving cycle and storage durability.
Implementation Method 1
the negative electrode first active material contains an Si-based material pre-doped with lithium
Data Source
AI summary
A negative electrode for a lithium ion secondary battery can improve charging performance and long life of the battery. The negative electrode for a lithium ion secondary battery includes a negative electrode current collector, a negative electrode active material layer laminated on the negative electrode current collector, in which the negative electrode active material layer includes a negative electrode first active material layer laminated on the negative electrode current collector and a negative electrode second active material layer laminated on the negative electrode first active material layer, in which the negative electrode first active material layer includes a negative electrode first active material, and the negative electrode second active material layer includes a negative electrode second active material, and in which a BET specific surface area of the negative electrode second active material is larger than the BET specific surface area of the negative electrode first active material.