Artificial Graphite Secondary Particles for Rapid Charging
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Solution Overview
Problem
Lithium secondary batteries using carbon-based negative electrodes face challenges in rapid charging performance due to increased electrode orientation during the roll-pressing process, which affects the inflow and outflow of lithium ions, leading to deteriorated charging properties.
Innovation Solution
The use of artificial graphite secondary particles with a specific particle size distribution, where the average particle diameter ranges from 10 nm to 9 μm, and a controlled ratio of minimum to average particle diameter, is employed to minimize electrode orientation and enhance rapid charging capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If natural graphite is used as negative electrode active material, then capacity per unit weight is large, but electrode orientation increases during roll-pressing, deteriorating lithium ion inflow/outflow properties and rapid charging performance
Solution Approach 1:
The invention changes the particle size parameter of graphite from conventional large particles (1-10 μm) to ultra-fine particles (10 nm to 1 μm). This parameter change reduces electrode orientation during roll-pressing while maintaining high capacity, thereby resolving the contradiction between capacity and rapid charging performance
Solution Approach 2:
The invention segments the graphite particle size distribution into two ranges: 10 nm to 1 μm (70-90 wt%) for reducing orientation and 1 μm to 10 μm (10-30 wt%) for maintaining capacity. This segmentation allows simultaneous achievement of low orientation and high capacity
2Ease of manufacture
If artificial graphite secondary particles with larger initial particle size are used, then manufacturing is easier, but rapid charging performance deteriorates due to increased electrode orientation
Solution Approach 1:
The invention changes the particle size parameter to ultra-fine range (10 nm to 1 μm) which inherently reduces orientation during roll-pressing. This parameter change improves rapid charging performance while the controlled size distribution (70-90 wt% in this range) ensures ease of manufacture
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 results in improved rapid charging properties and extended lifespan of lithium secondary batteries by optimizing the size and distribution of artificial graphite particles, ensuring efficient lithium ion diffusion and intercalation.
Implementation Method 1
artificial graphite secondary particles comprising artificial graphite primary particles having an average particle diameter (D50) of 10 nm to 9 μm, the artificial graphite secondary particles being formed by granulating the artificial graphite primary particles
Implementation Method 2
ensuring efficient lithium ion diffusion and intercalation
Implementation Method 3
exhibits excellent electrode cycle life properties due to highly reversible charge and discharge behavior caused by uniaxial orientation of a graphene layer
Data Source
AI summary
A negative electrode active material including artificial graphite secondary particles comprising artificial graphite primary particles having an average particle diameter (D50) of 10 nm to 9 μm, said artificial graphite secondary particles being formed by granulating said artificial graphite primary particles, wherein a value (V1) obtained by dividing a minimum particle diameter (Dmin) of the secondary particles by the average particle diameter (D50) of the initial particles is 0.50 to 0.8, and a value (V2) obtained by dividing the minimum particle diameter (Dmin) of the secondary particles by an average particle diameter (D50) of the secondary particles is 0.23 to 0.4.