Silicon-Graphite Anode Composition for Slurry Viscosity Control
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Solution Overview
Problem
Current negative electrode materials for lithium secondary batteries face challenges such as increased slurry viscosity, reduced electrode coating quality, and volume expansion issues during charge and discharge, which affect battery capacity and lifespan.
Innovation Solution
A negative electrode active material comprising a carbon-based material and a silicon-based material, where the carbon-based material is artificial or natural graphite, and the silicon-based material is Si, SiOx, or a silicon-carbon composite, with a specific ratio of 50th percentiles of diameter distributions to control slurry viscosity and improve electrode coating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If silicon-based material is added to graphite-based negative electrode material to increase capacity, then the energy capacity increases, but the volume expansion problem occurs during charge and discharge
Solution Approach 1:
The silicon-based material particles are embedded within the graphite-based material matrix, creating a nested structure where silicon particles are surrounded by graphite. This nesting approach allows the higher capacity silicon to be utilized while the graphite outer layer constrains volume expansion and maintains structural stability during charge-discharge cycles.
Solution Approach 2:
The invention creates a composite negative electrode material consisting of both graphite-based material and silicon-based material in specific weight ratios (silicon: 0.1-10 wt%, graphite: 90-99.9 wt%). This composite structure combines the high capacity advantage of silicon with the structural stability of graphite, resolving the contradiction between energy density and volume stability.
2Stability of the object's composition
If artificial graphite is used to prevent volume expansion, then the structural stability increases, but the manufacturing cost increases due to additional processing
Solution Approach 1:
The invention optimizes the weight ratio parameters of silicon-based material (0.1-10 wt%) and graphite-based material (90-99.9 wt%) to achieve the desired structural stability without requiring full artificial graphite processing. By adjusting these compositional parameters, the patent reduces manufacturing complexity and cost while maintaining volume stability.
3Quantity of substance
If silicon-based material is used in higher amounts to increase capacity, then the energy density improves, but the charge and discharge efficiency decreases
Solution Approach 1:
The invention optimizes the weight ratio of silicon-based material to graphite-based material, specifying silicon content between 0.1-10 wt%. This parameter optimization ensures sufficient energy density improvement from silicon while maintaining charge-discharge efficiency by limiting excessive silicon content that would cause severe volume expansion and capacity fading.
Data Source
AI summary
The present disclosure relates to a negative electrode active material including a carbon-based material and a silicon-based material, and as the carbon-based material has a characteristic of controlling a viscosity of a slurry, excellent electrode coating quality may be implemented. A lithium secondary battery including the negative electrode active material of the present disclosure may have high-capacity characteristics, may effectively prevent electrical isolation and peeling phenomena caused by volume expansion of silicon, and may implement excellent lifespan characteristics at a low temperature.