Layered Lithium Battery Anode for Electrolyte Wetting and Energy Density
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Solution Overview
Problem
Natural graphite-based negative electrodes for lithium secondary batteries face issues with electrolyte wetting ability and reduced charge-discharge efficiency due to irregular structure and low wetting ability, limiting their energy density.
Innovation Solution
A layered negative electrode structure with two active layers, where the first layer has higher carbon-based active material alignment and the second layer has lower alignment and controlled porosity, allowing for improved electrolyte wetting and energy density, achieved through a manufacturing process involving magnetic field application and controlled alignment of carbon-based materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If natural graphite is used as negative electrode active material, then lithium-ion storage capacity is improved, but electrolyte wetting ability deteriorates and charge-discharge efficiency is reduced
Solution Approach 1:
The patent applies local quality by creating a surface coating layer on natural graphite particles with different properties from the core. The coating layer has higher electrolyte wettability than the bulk natural graphite, locally improving the wetting interface while preserving the high capacity core material. This resolves the contradiction by making the surface properties different from the bulk properties.
Solution Approach 2:
The patent uses composite materials by combining natural graphite with coating materials that have superior electrolyte wettability. The composite structure integrates the high capacity advantage of natural graphite with the good wettability of coating materials, simultaneously achieving both improved capacity and wetting ability.
2Quantity of substance
If natural graphite is used as negative electrode active material, then lithium-ion storage capacity is improved, but charge-discharge efficiency is reduced
Solution Approach 1:
The surface coating creates a local quality improvement at the electrolyte-contact interface, enabling faster ion transport kinetics without changing the bulk storage capacity. The coating layer facilitates efficient charge-discharge while the core maintains high lithium-ion storage capacity.
Solution Approach 2:
The composite structure combines materials with complementary properties: natural graphite provides high capacity while the coating material provides fast ion transport pathways, achieving both high capacity and high charge-discharge efficiency simultaneously.
3Reliability
If spherization and surface coating treatment are applied to natural graphite, then wetting ability is improved, but electrical properties deteriorate due to low-price competitiveness
Solution Approach 1:
The patent optimizes coating thickness parameters to maintain electrical conductivity while improving wettability. By controlling the coating layer thickness within specific ranges, the patent achieves good wetting ability without excessively degrading electrical properties, making the treatment economically viable.
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 structured negative electrode maintains high electrolyte wetting ability and enhances energy density by providing flow paths for electrolyte movement, resulting in improved charge-discharge efficiency and capacity.
Implementation Method 1
A layered negative electrode structure with two active layers, where the first layer has higher carbon-based active material alignment and the second layer has lower alignment and controlled porosity, allowing for improved electrolyte wetting and energy density, achieved through a manufacturing process involving magnetic field application and controlled alignment of carbon-based materials.
Data Source
AI summary
Disclosed herein relates to a negative electrode for lithium secondary battery and a method for manufacturing the same. The negative electrode has a structure in which a first negative electrode active layer and a second negative electrode active layer are sequentially stacked on a negative electrode current collector. By controlling alignment (O.I) of the carbon-based active material to be lower in the second negative electrode active layer than in the first negative electrode active layer, and by preparing a low percentage of pores in the second negative electrode active layer, it is possible to have a flow path for the electrolyte to move inside the negative electrode active layer even after the rolling process of the negative electrode active layer. The negative electrode also has a high wetting ability to the electrolyte and high energy density.