Graphite Anode Particle Structuring for Fast-Charging Cycle Life
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing negative electrode active materials for lithium secondary batteries face trade-offs between performance characteristics such as high-speed charging and discharging, cycle lifespan, and volume stability, with improvements in one aspect often leading to deterioration in others, particularly due to irregular particle alignment and increased specific surface area.
Innovation Solution
A method for manufacturing a negative electrode active material using green coke to control particle diameter and shape, with secondary particles having a specific span value and sphericity, and a graphite material with controlled specific surface area and tap density, achieved through controlled graphitization and grinding processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the size of particles of synthetic graphite is reduced to reduce diffusion distance of lithium ions, then high-speed charging and discharging characteristic is improved, but the lifespan of the battery reduces due to increase of specific surface area
Solution Approach 1:
The invention divides graphite particles into primary particles (5-20 μm) that are further assembled into secondary particles (50-150 μm). This segmentation allows the primary particles to maintain small size for short diffusion paths while the secondary particle structure reduces the overall specific surface area, resolving the contradiction between charging speed and battery lifespan
Solution Approach 2:
The invention employs a nested structure where multiple primary particles are assembled into secondary particles. The primary particles (5-20 μm) are nested within the secondary particle framework (50-150 μm), creating a hierarchical structure that simultaneously provides short diffusion paths at the primary particle level while reducing overall specific surface area at the secondary particle level
2Stability of the object's composition
If secondary particles are formed by condensing small diameter particles to suppress volume change, then material volume change is offset, but irregular alignment of particles increases specific surface area and reduces battery lifespan
Solution Approach 1:
The invention specifies precise parameter ranges for primary particles (5-20 μm diameter) and secondary particles (50-150 μm diameter) with controlled span values (1.0-1.32). By controlling the span value and sphericity (0.85-1.00), the invention achieves regular particle morphology that reduces specific surface area while maintaining volume stability, resolving the contradiction between volume stability and battery lifespan
3Quantity of substance
If graphitizing heat treatment is maintained at 2800-3000°C or more to increase graphitizing degree, then high capacity is achieved, but manufacturing complexity and energy consumption increase
Solution Approach 1:
The invention performs preliminary classification and sizing of green coke particles before graphitization. By pre-processing the raw material to achieve uniform particle size distribution (span value 1.0-1.32) and sphericity (0.85-1.00), the invention enables more efficient graphitization at 2800-3000°C, reducing the complexity and energy consumption of the heat treatment process while maintaining high capacity
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 method enhances high-speed charging and discharging efficiency while maintaining a low expansion rate and improving cycle lifespan, with improved electrode density and reduced specific surface area, resulting in better battery performance.
Implementation Method 1
a graphitizing degree is increased by maintaining the graphitizing heat treatment at 2800-3000° C. or more
Implementation Method 2
a heat treatment is performed by adding a catalyst material so as to induce a catalyst graphitizing reaction
Data Source
AI summary
The present invention relates to a negative electrode active material of a lithium secondary battery, a manufacturing method thereof, and a lithium secondary battery using the same. An embodiment of the present invention provides a negative electrode active material for a lithium secondary battery, including a graphite material including secondary particles, wherein the secondary particles are an assembly of a plurality of primary particles, the primary particles include green coke, and a ratio ((D90−D10)/D50) of a difference between a particle diameter D90 and a particle diameter D10 with respect to a particle diameter D50 of the secondary particles is 1.0 to 1.32. An embodiment of the present invention provides a method for manufacturing a negative electrode active material for a lithium secondary battery, including: manufacturing primary particles by using a carbon raw material including green coke; manufacturing secondary particles by mixing the primary particles and a binder; carbonizing the secondary particles; and manufacturing a graphite material by graphitizing the carbonized secondary particles, wherein a particle diameter D50 of the primary particles is 5.5 to 10.0 μm.