Negative Electrode Particle Screening for Energy Density and Cycle Life
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Solution Overview
Problem
Current secondary batteries face a challenge in balancing the compaction density of negative electrode sheets to achieve high energy density while maintaining dynamic performance and cycle life, as increased compaction density leads to reduced dynamics and irregular particle shapes affect both compaction and cycling performance.
Innovation Solution
A negative electrode sheet with a specific ratio of equivalent average spherical diameter (R50) to median particle diameter (Dv50) of 0.7≤R50/Dv50≤0.95 is used, ensuring the energy density and dynamic performance are controlled to an equilibrium state, with the equivalent spherical diameter calculated to exclude internal pores, using materials like graphite, soft carbon, or silicon-based compounds, and a screening method to select appropriate particles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the compaction density of the negative electrode sheet is increased to achieve high energy density, then the energy density is improved, but the dynamic performance deteriorates
Solution Approach 1:
The patent applies parameter changes by precisely controlling the ratio of equivalent spherical diameter to median particle diameter (R50/Dv50) within the range of 0.7-0.95, and controlling the particle diameter distribution (Dv10, Dv50, Dv90 values). This optimization of particle size parameters enables the negative electrode sheet to achieve high compaction density while maintaining good dynamic performance, resolving the contradiction between energy density and rate capability.
2Quantity of substance
If the compaction density is increased to improve energy density, then the energy density is improved, but the cycle life deteriorates
Solution Approach 1:
The patent optimizes particle size parameters including controlling the R50/Dv50 ratio between 0.7-0.95 and specifying Dv10, Dv50, and Dv90 values. This parameter optimization achieves high compaction density for improved energy density while simultaneously ensuring long cycle life by preventing particle structure degradation during cycling.
3Shape
If the equivalent spherical diameter ratio (R50/Dv50) is increased to make particles more spherical, then the particle shape regularity is improved, but the dynamic performance deteriorates
Solution Approach 1:
The patent identifies an optimal range for the R50/Dv50 ratio (0.7-0.95) that balances particle sphericity with dynamic performance. By controlling this parameter within the specified range along with particle diameter distribution, the patent achieves sufficient particle regularity for high compaction density while maintaining adequate dynamic performance for ion transport.
4Adaptability or versatility
If the equivalent spherical diameter ratio (R50/Dv50) is decreased to allow irregular particle shapes, then the particle shape flexibility is improved, but the compaction density deteriorates
Solution Approach 1:
The patent optimizes the R50/Dv50 ratio to fall within 0.7-0.95, which provides sufficient particle shape regularity to achieve high compaction density. Additionally, the patent controls the particle diameter distribution (Dv10, Dv50, Dv90 values) to ensure particles can pack efficiently while retaining adequate shape flexibility for ion transport pathways.
Data Source
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AI summary
A negative electrode sheet and a screening method thereof, a battery and an electric equipment are provided. The negative electrode sheet comprises a current collector and a negative active material layer arranged on the current collector. The negative active material layer has negative active particles, and the negative active particles satisfy the relation: 0.7≤R50/Dv50≤0.95; R50 is an equivalent average spherical diameter of the negative active particles, and Dv50 is a corresponding particle diameter when a cumulative volume fraction in a volume-based distribution reaches 50% in the particle diameter distribution measurement by a laser scattering method.