Lithium Battery Negative Electrode Alignment to Suppress End Dendrites
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Solution Overview
Problem
The formation of lithium dendrites at the end of the negative electrode composite layer during long-term use under high rate conditions leads to internal short circuits and safety issues in lithium secondary batteries, due to inconsistent N/P ratios and sliding phenomena in the electrode composite layer.
Innovation Solution
A negative electrode design with a flat portion and a sliding portion having a thickness gradient, where the sliding portion has a controlled alignment and orientation of carbon-based negative electrode active material, utilizing near-end X-ray absorption fine structure (NEXAFS) spectroscopy to maintain a specific alignment ratio, and a magnetic field application to align the carbon-based negative electrode active material perpendicular to the current collector.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the negative electrode composite layer is made thicker to reduce sliding phenomenon, then the N/P ratio consistency is improved, but the lithium ion mobility at the end is reduced due to densification
Solution Approach 1:
The patent applies different thickness characteristics to different regions of the negative electrode: the end portion has a greater thickness than the central portion. This local quality variation ensures that the end portion maintains adequate active material coverage to prevent sliding phenomenon and maintain N/P ratio consistency, while the central portion retains sufficient lithium ion mobility. The non-uniform thickness distribution resolves the contradiction by optimizing each region for its specific functional requirements.
2Quantity of substance
If the N/P ratio is reduced below 1 to increase capacity, then the battery capacity is improved, but lithium dendrites form on the negative electrode surface during charging
Solution Approach 1:
The patent makes preliminary action by pre-designing the negative electrode with a non-uniform thickness distribution (greater thickness at the end portion) before battery assembly. This preliminary structural configuration ensures that even when the overall N/P ratio is reduced below 1 to increase capacity, the end portion maintains sufficient active material to prevent lithium dendrite formation. The preliminary thickness optimization prevents the harmful effect of dendrites while allowing high capacity operation.
3Ease of manufacture
If the electrode composite layer thickness is reduced toward the outside to improve manufacturing, then the manufacturing ease is improved, but the sliding phenomenon increases making N/P ratio control difficult
Solution Approach 1:
The patent deliberately introduces asymmetry into the negative electrode structure by making the end portion thicker than the central portion. This asymmetric thickness distribution counteracts the natural sliding phenomenon that occurs during electrode formation. The asymmetric design ensures that the end portion maintains adequate active material coverage even after sliding, thereby maintaining N/P ratio control precision while allowing relatively simple manufacturing processes.
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 design effectively suppresses lithium precipitation, enhancing safety and enabling long-term high-rate charging and discharging by maintaining a stable N/P ratio and reducing electrical resistance.
Implementation Method 1
a magnetic field application to align the carbon-based negative electrode active material perpendicular to the current collector
Implementation Method 2
utilizing near-end X-ray absorption fine structure (NEXAFS) spectroscopy to maintain a specific alignment ratio
Data Source
AI summary
A negative electrode for a lithium secondary battery in which lithium precipitation is suppressed. The negative electrode has a form in which a high degree of alignment of a carbon-based active material contained in a sliding portion of the negative electrode active layer is realized. Accordingly, the negative electrode has an excellent effect of suppressing lithium precipitation at the end of the negative electrode active layer during charging and discharging of the secondary battery, so that a lithium secondary battery including the negative electrode has high safety and can be charged and discharged for a long time under high rate conditions. A lithium secondary battery including the negative electrode is also provided.