Lithium-ion Battery Electrode Compaction Ratio Optimization
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Solution Overview
Problem
Lithium-ion batteries using ternary positive active materials face challenges with surface integrity and cycle life due to volume shrinkage and compression issues between the positive and negative electrode plates, leading to poor dynamics and cycle performance.
Innovation Solution
A lithium-ion battery design that balances the anti-compression capabilities of the positive and negative active materials within specific ratios, using LiaNixCoyMzO2 for the positive electrode and graphite-type carbon for the negative, with optimized particle sizes, compaction densities, and porosities, along with doping and coating modifications to enhance structural stability and electrolyte infiltration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If ternary positive active material is used to increase energy density, then capacity per gram and compaction density improve, but volume shrinkage during cycling causes electrode plate compression and surface destruction
Solution Approach 1:
The patent applies parameter changes by precisely controlling the composition parameters (x, y, z) of the ternary positive active material LiaNixCoyMzO2 and the compaction density ratio KYa/(KYa+KYc) between positive and negative active materials. This parameter optimization resolves the contradiction by achieving high capacity while maintaining volume stability during cycling, preventing electrode compression and surface destruction.
Solution Approach 2:
The patent uses composite materials by combining ternary positive active material with graphite-type carbon negative active material in a specifically designed compaction density ratio. This composite electrode structure balances the volume changes during lithium insertion/extraction, preventing the volume shrinkage of ternary material from compressing and destroying the electrode surfaces, thus improving cycle life while maintaining high energy density.
2Quantity of substance
If positive electrode plate compresses negative electrode plate during cycling, then energy density improves, but surface integrity of both electrodes deteriorates
Solution Approach 1:
The patent changes the compaction density parameter ratio KYa/(KYa+KYc) to a specific range (58-72%), which optimizes the mechanical balance between positive and negative electrode plates during cycling. This parameter control prevents excessive compression while maintaining high energy density, preserving surface integrity of both electrodes.
3Reliability
If compaction density ratio is optimized to prevent electrode compression, then cycle life improves, but energy density may decrease
Solution Approach 1:
The patent optimizes the compaction density ratio KYa/(KYa+KYc) within the range of 58-72%, which is the critical parameter change that simultaneously achieves high cycle performance and high energy density. This precise parameter control prevents electrode compression (improving cycle life) while maintaining sufficient compaction for high energy density.
Data Source
AI summary
The present disclosure provides a lithium-ion battery, the lithium-ion battery comprises a positive electrode plate, a negative electrode plate, a separator and an electrolyte. The positive active material comprises a material having a chemical formula of LiaNixCoyMzO2, the negative active material comprises a graphite-type carbon material, the lithium-ion battery satisfies a relationship 58%≤KYa/(KYa+KYc)×100%≤72%. In the present disclosure, by reasonably matching the relationship between the anti-compression capability of the positive active material and the anti-compression capability of the negative active material, it can make the positive electrode plate and the negative electrode plate both have good surface integrity, and in turn make the lithium-ion battery have excellent dynamics performance and excellent cycle performance at the same time.