Li-Ion Battery Negative Electrode Tuning for Lower Self-Discharge
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Solution Overview
Problem
Lithium-ion batteries experience significant self-discharge, which affects their performance and capacity retention, despite existing improvements in the field.
Innovation Solution
A lithium-ion battery negative electrode with specific parameters such as compaction density, application weight, thickness, diffusion resistance, and composition, including artificial graphite and silicon-carbon material, is developed to reduce self-discharge current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the negative electrode material compaction density is increased to improve capacity retention, then the self-discharge current increases, but the capacity retention rate decreases
Solution Approach 1:
The patent optimizes the compaction density parameter of the negative electrode material within a specific range (1.3-1.7 g/cm³) to achieve the best balance between capacity retention and self-discharge current. This parameter optimization resolves the contradiction by finding the optimal value that simultaneously improves both metrics rather than simply increasing density.
Solution Approach 2:
The patent uses a composite negative electrode material containing both artificial graphite and silicon-carbon materials in specific ratios. This composite structure allows the electrode to maintain good capacity retention while controlling self-discharge current, as the two materials complement each other's properties to resolve the technical contradiction.
2Quantity of substance
If the negative electrode material thickness is increased to improve capacitance, then the diffusion resistance increases, but the electrochemical performance deteriorates
Solution Approach 1:
The patent optimizes the thickness parameter of the negative electrode material within a specific range (20-50 μm) to achieve the best balance between capacitance and diffusion resistance. This parameter optimization ensures that the electrode has sufficient capacitance while maintaining low diffusion resistance for good electrochemical performance.
Solution Approach 2:
The patent applies different material compositions and properties to different regions of the negative electrode. By creating local variations in material composition (graphite and silicon-carbon ratios) and structure, the electrode achieves uniform lithium ion diffusion and maintains good electrochemical performance across the entire electrode area.
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 optimized negative electrode effectively reduces self-discharge current, improving capacity retention rates to 83.2% - 86% after 30 days at 60°C, with reduced internal resistance and enhanced capacitance.
Implementation Method 1
the negative electrode has a diffusion resistance of 2.5 - 4 Ω*cm2
Data Source
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AI summary
The present invention relates to the field of batteries, in particular to a lithium-ion battery negative electrode and a lithium-ion battery. A negative electrode for a lithium-ion battery comprises a negative electrode current collector and a negative electrode material applied to the negative electrode current collector, characterized in that a compaction density of the negative electrode material is 1.3 - 1.7 g/cm3, a single-side application weight of the negative electrode material on the negative electrode current collector is 3.5 - 6.5 mg/cm2, and a single-side negative electrode material thickness of the negative electrode is 20 - 50 µm. The negative electrode for a lithium-ion battery can improve the self-discharge current of a lithium-ion battery.