Layered Lithium Battery Anode for Fast Charging and Adhesion
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Solution Overview
Problem
Conventional lithium secondary batteries face limitations in energy density, charging time, and high-rate discharge performance, particularly due to the slow intercalation reaction of graphite-based negative electrode materials, which hinder their application in electric vehicles requiring high capacity and fast charging.
Innovation Solution
A negative electrode for lithium secondary batteries featuring a two-layer structure with distinct carbon-based and silicon-based active materials, utilizing CMC binders of varying molecular weights to control alignment and adhesion, and a manufacturing process involving magnetic fields to optimize the orientation and adhesion of these materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If graphite-based negative electrode materials are used, then the battery structure is stable and manufacturing is easy, but the intercalation reaction is slow and high-rate discharge performance is poor
Solution Approach 1:
The patent uses composite negative electrode materials combining graphite particles with silicon-based materials or other high-capacity materials. This composite structure maintains the stable framework of graphite while incorporating materials that enable faster lithium ion transport, thereby improving high-rate discharge performance without sacrificing manufacturability.
Solution Approach 2:
The patent creates a multi-layer or gradient structure where different regions of the negative electrode have different compositions. The surface or outer layers contain materials optimized for fast kinetics, while inner layers maintain the stable graphite structure, achieving both fast discharge performance and manufacturing ease through localized material optimization.
2Quantity of substance
If silicon-based negative electrode materials are used, then the capacity is high, but the volume changes are large and adhesion is poor
Solution Approach 1:
The patent encapsulates silicon-based materials within graphite particles or uses a core-shell structure where silicon is nested inside a graphite shell. This nested structure allows silicon to expand and contract during charge-discharge cycles while the outer graphite shell maintains structural integrity and prevents excessive volume changes, preserving both high capacity and compositional stability.
Solution Approach 2:
The patent employs flexible binder materials or coating layers that can accommodate the volume expansion of silicon during lithiation. These flexible shells or films maintain adhesion despite volume changes, preventing electrode disintegration while preserving the high capacity benefits of silicon-based materials.
3Quantity of substance
If the negative electrode active layer is made thicker to increase capacity, then the energy density is improved, but the charging time increases
Solution Approach 1:
The patent creates a gradient or multi-layer structure where the composition varies through the thickness of the active layer. Surface or outer regions contain materials with fast lithium ion diffusion coefficients to enable rapid charging, while inner regions contain high-capacity materials, achieving both thick electrode benefits and fast charging performance through localized property optimization.
Solution Approach 2:
The patent divides the thick active layer into multiple thinner sub-layers with different compositions or structures. This segmentation reduces the diffusion distance for lithium ions while maintaining overall high capacity, as each sub-layer can be optimized for specific functions and the cumulative effect achieves both high capacity and acceptable charging time.
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 enhances the battery's charging performance, adhesion, and durability, enabling high capacity and high-rate discharge characteristics, thus addressing the limitations of conventional graphite-based electrodes.
Implementation Method 1
applying a magnetic field in the range of 1,000 to 10,000 G for 5 to 20 seconds
Data Source
Figure 1~2
Figure 3
AI summary
A negative electrode for a lithium secondary battery includes a negative electrode current collector, a first negative electrode active layer provided on at least one side of the negative electrode current collector, and a second negative electrode active layer provided on the first negative electrode active layer. Also provided is a method for manufacturing the negative electrode, and a lithium secondary battery using the negative electrode. The negative electrode applies CMC binders having different molecular weights to the first and second negative electrode active layers and controls the orientation of the negative electrode active materials, respectively. By doing so, the negative electrode has excellent adhesion between the current collector and the active layer and improves the charging performance when applied to a lithium secondary battery.