Carbon Negative Electrode Material for Lithium Secondary Battery
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Solution Overview
Problem
Lithium secondary batteries face issues with battery short circuits and explosion risks due to dendrite formation, and the use of carbon-based active materials leads to particle deformation during the rolling process, deteriorating the battery's lifespan characteristics.
Innovation Solution
A carbon-based negative electrode active material is developed, satisfying specific density and sphericity criteria to minimize particle deformation during the rolling process, using natural or artificial graphite with a Raman R value of 0.01 to 1.4, and including hard or soft carbon in 5-15 wt%, which reduces resistance and improves capacity retention.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If carbon-based active material is used for negative electrode, then battery safety is improved (no dendrite formation), but particle deformation occurs during rolling process leading to deteriorated lifespan characteristics
Solution Approach 1:
The invention changes the physical parameters of the carbon-based active material particles, specifically controlling sphericity (0.7-1.0), pellet density (1.0-1.5 g/cm³), and tap density (0.8-1.2 g/cm³) to satisfy a specific relational expression. These parameter adjustments minimize particle deformation during the rolling process while maintaining battery safety, thereby improving lifespan characteristics without sacrificing reliability.
2Duration of action of stationary object
If particle deformation is minimized during rolling, then lifespan characteristics are improved, but manufacturing process complexity increases due to specific density and sphericity requirements
Solution Approach 1:
The invention establishes specific parameter ranges for sphericity (0.7-1.0), pellet density (1.0-1.5 g/cm³), and tap density (0.8-1.2 g/cm³) that satisfy a relational expression. By defining these parameters upfront, the manufacturing process becomes more controlled and predictable, reducing variability and actually simplifying quality assurance while achieving minimal particle deformation and improved lifespan characteristics.
Data Source
AI summary
Provided is a negative electrode active material for a secondary battery including a carbon-based active material. The negative electrode active material satisfies the following Relational Expression 1, [Relational Expression 1] 0.1≤(Dp−DT)/sphericity≤0.28 where Dp is a pellet density (g/cm3) of the carbon-based active material, DT is a tap density (g/cm3) of the carbon-based active material, and the sphericity is a sphericity of a particle of the carbon-based active material.