Dual-Composition Graphite Anode for Fast-Charge Lithium Plating Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The rapid charging of lithium secondary batteries leads to lithium precipitation imbalance on the negative electrode due to the sliding phenomenon during the manufacturing process, causing uneven lithium deposition rates and affecting battery performance and life.
Innovation Solution
A negative electrode with a first uncoated graphite layer and a second carbon-coated graphite layer, formed on inclined and flat portions respectively, to uniformly occlude and release lithium, improving charge/discharge characteristics and preventing lithium precipitation imbalance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If rapid charging is implemented to meet consumer needs, then charging speed is improved, but lithium precipitation occurs on the negative electrode causing battery life deterioration and swelling
Solution Approach 1:
The patent applies local quality by creating different active material layers at different locations on the negative electrode. Specifically, it forms a first active material layer with uncoated graphite particles and a second active material layer with carbon-coated graphite particles, where each layer has different properties tailored to its function. This allows the electrode to handle rapid charging by preventing lithium precipitation through the carbon-coated layer while maintaining high capacity through the uncoated graphite layer.
2Ease of manufacture
If the electrode active material slurry is coated during manufacturing, then the electrode is formed, but sliding phenomenon causes different coating amounts at different positions leading to uneven lithium deposition rates
Solution Approach 1:
The patent addresses coating uniformity issues by intentionally creating different active material layers at different positions. The first active material layer with uncoated graphite is placed at positions where higher lithium deposition is needed, while the second active material layer with carbon-coated graphite is placed at positions prone to lithium precipitation. This compensates for the sliding phenomenon during coating by strategically distributing different material types across the electrode surface.
Solution Approach 2:
The patent changes the physical and chemical parameters of the active material layers to compensate for coating variations. By using uncoated graphite with higher theoretical capacity in the first layer and carbon-coated graphite with better lithium deposition control in the second layer, the patent adjusts the local electrochemical properties to achieve uniform overall performance despite manufacturing variations.
3Strength
If carbon coating is applied to graphite particles, then particle strength and conductivity are improved, but the coating amount and thickness affect the lithium deposition characteristics
Solution Approach 1:
The patent applies local quality by using carbon-coated graphite particles specifically in the second active material layer where lithium precipitation control is critical. The carbon coating provides mechanical strength and electrical conductivity while regulating lithium deposition at positions prone to precipitation. Meanwhile, the first active material layer uses uncoated graphite to maximize capacity without the lithium deposition control needs.
Solution Approach 2:
The patent uses composite materials by combining carbon-coated graphite particles with other components in the second active material layer. The carbon coating itself forms a composite structure where the graphite core provides capacity and the carbon shell provides strength, conductivity, and lithium deposition control. This composite approach allows simultaneous achievement of multiple desirable properties.
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 lithium deposition uniformity, improves battery performance, and extends the battery's cycle life by using artificial or natural graphite with specific surface areas and porosity, and carbon coating to strengthen particle strength and conductivity.
Implementation Method 1
carbon coating to strengthen particle strength and conductivity
Implementation Method 2
uniformly occlude and release lithium
Data Source
AI summary
The present disclosure relates to a negative electrode for secondary battery in which a negative electrode active material layer is formed on at least one surface of a negative electrode current collector. The negative electrode active material layer includes a first negative electrode active material layer, and a second negative electrode active material layer formed on one side or both sides of the first negative electrode active material layer in a planar. The first negative electrode active material layer includes uncoated graphite as a first negative electrode active material, and the second negative electrode active material layer includes carbon-coated graphite as a second negative electrode active material, and to an electrode assembly and a secondary battery including same.