Artificial Graphite Anode Particles With Higher Tap Density
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Solution Overview
Problem
Conventional artificial graphite secondary particles for lithium secondary batteries have limited tap density, leading to low adhesive force and rolling rate due to irregular shapes, and existing methods to increase tap density either result in swelling or deteriorate charging performance.
Innovation Solution
The use of carbon-based initial particles with different average particle diameters, specifically particle groups A, B, and optionally C, to form secondary particles with enhanced tap density through granulation and graphitization, without requiring additional processing steps, thereby improving adhesive force and high-temperature storage performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If conventional artificial graphite secondary particles with irregular shapes are used, then the manufacturing process is simple, but the tap density is limited (less than 1.1 g/cc) leading to low adhesive force and rolling rate
Solution Approach 1:
The invention changes the particle size distribution parameters by classifying initial particles into different groups (first group with D50 of 5-15 μm, second group with D50 of 15-25 μm, third group with D50 of 25-35 μm) and controlling their mixing ratios. This parameter optimization enables tap density to reach 1.1 g/cc or higher, which in turn improves adhesive force and rolling rate without compromising electrode performance
Solution Approach 2:
The invention creates a composite particle structure by mixing initial particles of different size groups before granulation and graphitization. The multi-group particle composition (with optional fourth group D50 of 35-45 μm) forms a composite secondary particle structure that achieves both high tap density and good adhesive properties, resolving the contradiction between density and strength
2Quantity of substance
If methods to increase tap density are applied, then adhesive force may improve, but swelling phenomenon occurs or rapid charging performance deteriorates due to increased orientation degree
Solution Approach 1:
The invention optimizes the particle size distribution parameters by defining specific D50 ranges for each particle group and controlling their mixing ratios. This controlled parameter change increases tap density while maintaining particle morphology that prevents excessive orientation during electrode manufacturing, thereby preserving rapid charging performance without causing swelling
Solution Approach 2:
The invention applies different particle size characteristics to different portions of the secondary particle structure. The multi-group initial particles create local density variations within secondary particles, where smaller particles fill voids between larger particles, achieving high overall tap density while maintaining local structures that facilitate lithium ion transport and prevent swelling
3Productivity
If particle size-controlled green cokes are used to improve discharge capacity and charge/discharge efficiency, then high speed discharge and charge output characteristics improve, but an additional carbonization process is required
Solution Approach 1:
The invention performs preliminary classification and grouping of initial particles by size before granulation and graphitization. By pre-organizing particles into size groups with controlled mixing ratios, the invention achieves optimal particle distribution in the final secondary particles, improving charge/discharge efficiency while using the existing graphitization process rather than requiring separate carbonization steps
4Quantity of substance
If mixing of initial particles and secondary particles is done to increase tap density, then density improves, but swelling phenomenon occurs due to increased orientation degree of the negative electrode
Solution Approach 1:
The invention changes the particle size distribution parameters by classifying initial particles into multiple groups with specific D50 ranges and controlling their mixing ratios. This optimized parameter configuration increases tap density while the gradual size distribution prevents excessive particle orientation during electrode formation, thereby avoiding swelling phenomenon that occurs with conventional mixing methods
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 approach significantly increases tap density to above 1.1 g/cc, enhancing the adhesive force and rolling rate of the negative electrode, while maintaining high charging performance and reducing electrode damage during the manufacturing process.
Implementation Method 1
cokes, which are materials of initial particles, are granulated as secondary particles, which are graphited through heat treatment
Data Source
AI summary
A negative electrode active material for a lithium secondary battery including artificial graphite secondary particles obtained by granulating carbon-based initial particles having different average particle diameters (D50). The carbon-based initial particles include particle group A having an average particle diameter (D50) of a, and particle group B having an average particle diameter (D50) of b, and b<0.6a. As secondary particles are granulated from carbon-based initial particles having different average particle diameters, the tap density is significantly enhanced, and accordingly, the adhesive force and the high temperature storage performance of the negative electrode become excellent.