Spherical Graphite Anode Material for Lithium Battery Expansion Control
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Solution Overview
Problem
Lithium secondary batteries face challenges with anode active material expansion during charge and discharge, leading to battery deformation and reduced cycle-life, especially with high-density electrodes.
Innovation Solution
The use of a specific composition of spherical graphite with varying particle sizes and shapes, including coarse-grained, medium-grained, and fine-grained spherical graphite, optimized to maintain polydispersity and isotropy, which suppresses volume expansion and improves cycle-life characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high-density electrodes are used to increase energy density, then productivity and energy density are improved, but anode expansion during charge and discharge occurs, leading to battery deformation and reduced cycle-life
Solution Approach 1:
The patent applies parameter changes by precisely controlling the particle size distribution parameters (D10, D50, D90) and their differences to fall within specific ranges. This optimization of particle size parameters enables high-density electrode configuration while maintaining structural stability during charge-discharge cycles, thus improving energy density without compromising cycle-life
Solution Approach 2:
The patent uses composite materials by combining spherical graphite particles with different grain sizes (fine-grained, medium-grained, and coarse-grained) in a specific distribution. This multi-size composite structure allows dense packing for high energy density while the varied particle sizes work together to suppress overall anode expansion, preventing battery deformation and maintaining reliability
2Reliability
If anode active material volume expansion is suppressed to prevent battery deformation, then reliability is improved, but this may limit the density of the electrode
Solution Approach 1:
The patent optimizes the particle size distribution parameters (specifically D90-D10 between 10-30 μm and D10/D50/D90 ratios) to achieve a balance where the anode can accommodate volume changes during charge-discharge without deforming the battery. This parameter optimization allows high electrode density while maintaining structural integrity and preventing deformation
Solution Approach 2:
The patent employs a composite structure of spherical graphite particles with varying sizes (fine-grained 3-6 μm, medium-grained 8-12 μm, coarse-grained 15-20 μm). The smaller particles fill voids between larger particles, achieving high packing density, while the spherical shape and size distribution allow coordinated expansion and contraction that suppresses overall anode volume change, preventing battery deformation
Data Source
AI summary
Provided are an anode active material for a lithium secondary battery and a lithium secondary battery comprising the same, wherein the anode active material comprises at least three types of spherical graphite, and a difference between a 90% volume cumulative diameter (D90) and a 10% volume cumulative diameter (D10) is in the range of 13.0 μm≤(D90−D10)≤35.0 μm.