Negative Electrode Active Mass Optimization for Lithium Batteries
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Solution Overview
Problem
Rechargeable lithium batteries face challenges in achieving high energy density and improved cycle-life characteristics due to limitations in the Young's modulus and active mass density of negative electrode materials, particularly when using amorphous carbon which results in low capacity and efficiency.
Innovation Solution
A negative electrode with an active mass layer comprising artificial graphite as the negative active material, having a Young's modulus of 10 GPa to 35 GPa and an active mass density of 1.65 g/cc to 1.85 g/cc, along with a binder and conductive material, to enhance current density and cycle-life characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If amorphous carbon is used as negative active material, then ease of manufacture is improved, but energy density and cycle-life characteristics deteriorate due to low Young's modulus and low active mass density
Solution Approach 1:
The patent applies parameter changes by specifying a Young's modulus range of 10-35 GPa for the negative active material. This parameter optimization resolves the contradiction by selecting materials that balance manufacturability with improved cycle-life characteristics, moving away from traditional amorphous carbon while maintaining processing feasibility.
Solution Approach 2:
The patent employs composite materials by combining negative active material with binder and conductive material in specific ratios. This composite approach achieves both ease of manufacture and improved reliability by creating a synergistic structure that maintains mechanical integrity and electrical conductivity while enhancing cycle-life performance.
2Ease of manufacture
If amorphous carbon is used as negative active material, then ease of manufacture is improved, but energy density deteriorates due to low active mass density
Solution Approach 1:
The patent optimizes the active mass density parameter by specifying a range of 1.65-1.85 g/cc for the negative electrode. This parameter change resolves the contradiction by selecting materials and structures that achieve higher energy density while maintaining ease of manufacture through controlled density optimization.
3Quantity of substance
If negative electrode active mass density is increased, then energy density is improved, but manufacturing precision deteriorates due to compression challenges
Solution Approach 1:
The patent applies parameter changes by specifying a Young's modulus range of 10-35 GPa that optimizes the balance between achieving high active mass density (1.65-1.85 g/cc) and maintaining manufacturability. This parameter optimization ensures the material is compressible enough for manufacturing while dense enough for high energy density.
Solution Approach 2:
The patent uses composite materials with binder and conductive material to achieve high active mass density while maintaining manufacturing precision. The composite structure allows controlled compression and densification during manufacturing while achieving the target density range for high energy density.
4Quantity of substance
If negative electrode active mass density is increased, then energy density is improved, but swelling characteristics deteriorate
Solution Approach 1:
The patent optimizes the Young's modulus parameter (10-35 GPa) to balance active mass density (1.65-1.85 g/cc) with swelling resistance. This parameter change ensures the material achieves high energy density while maintaining structural stability and resisting swelling during battery cycling.
Data Source
AI summary
A negative electrode for a rechargeable lithium battery may include a negative electrode active mass layer including a negative active material having a Young's modulus of about 10 GPa to about 35 GPa and having an active mass density of greater than or equal to about 1.65 g/cc and a current density of greater than or equal to about 3.2 mAh/cm2.