Negative Electrode Particle Size Optimization for Battery Adhesion
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Solution Overview
Problem
Existing negative electrodes with artificial graphite secondary particles suffer from poor cohesion between particles and adhesion to current collectors due to insufficient binder distribution on irregular surfaces, leading to degraded charging and discharging performance and mechanical stability.
Innovation Solution
Incorporating second active material particles with an average particle size between 14% to 95% of the primary particles' size, along with 0.5 wt% to 15 wt% pitch as a binder, to enhance binder distribution and contact between artificial graphite particles and the current collector, thereby improving cohesion and adhesion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If artificial graphite is used as negative electrode active material, then charging and discharging characteristics are improved, but cohesion between particles and adhesion to current collector deteriorate
Solution Approach 1:
The patent changes the particle size parameter by introducing a dual-size particle system where fine particles (D50: 5-12 μm) fill the concave portions of coarse particles (D50: 15-35 μm). This parameter optimization ensures that binder can effectively contact the current collector while maintaining good particle cohesion, thus improving both adhesion and cohesion simultaneously.
Solution Approach 2:
The patent creates a composite particle structure by combining coarse artificial graphite particles with fine artificial graphite particles. The fine particles act as a filler in the concave portions of coarse particles, forming a composite structure that improves binder distribution and contact with the current collector, thereby enhancing both cohesion and adhesion properties.
2Strength
If binder is disposed in concave portion of artificial graphite surface, then adhesion is improved, but binder distribution becomes insufficient
Solution Approach 1:
The patent applies the nesting principle by placing fine particles inside the concave portions of coarse particles. This nested structure allows the binder to be distributed more effectively throughout the particle aggregate, ensuring sufficient binder contact with the current collector while maintaining strong adhesion. The fine particles nest within the irregular surfaces of coarse particles, optimizing binder utilization.
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
This approach significantly enhances the charging and discharging performance and mechanical stability of the battery by ensuring sufficient binder contact and filling concave surface areas, resulting in improved electrode adhesion and reduced binder displacement.
Implementation Method 1
second active material particles having an average particle size (D 50 ) equal to or less than an average particle size (D 50 ) of the primary particles... ensuring sufficient binder contact and filling concave surface areas
Data Source
Figure 1~2
AI summary
The present invention relates to a negative electrode and a secondary battery including the same, and particularly, to a negative electrode which includes a negative electrode active material layer including first active material particles each in the form of a secondary particle in which a plurality of primary particles are agglomerated; and second active material particles, wherein the second active material particles have an average particle size (D50) equal to or less than an average particle size (D50) of the primary particles, the first active material particle is artificial graphite, and the second active material particle is a graphite-based particle, and a secondary battery, a battery module, and a battery pack including the same.