Positive Electrode Particle Mix for Output and Gas Suppression
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Solution Overview
Problem
Non-aqueous electrolyte secondary batteries face a contradiction between enhancing output characteristics and storage characteristics due to the increased specific surface area of hollow structured positive electrode active material particles, which can lead to gas generation.
Innovation Solution
A positive electrode for non-aqueous electrolyte secondary batteries is designed with a combination of first and second positive electrode active material particles, where the first particle has a solid structure with a smaller diameter and low void rate, and the second particle has a hollow structure with a larger diameter and high void rate, optimized by adjusting their mass ratio to balance output and storage characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the positive electrode active material particle is made to have a hollow structure to increase specific surface area, then the output characteristic is enhanced, but gas is easily generated inside the case
Solution Approach 1:
The positive electrode active material is divided into two distinct types of particles: first particles with solid structure (low void rate <10%) and second particles with hollow structure (high void rate ≥10%). This segmentation allows each particle type to fulfill different functions - the solid particles provide structural stability and suppress gas generation, while the hollow particles increase specific surface area for enhanced output characteristic.
Solution Approach 2:
Different regions of the positive electrode are populated with different particle types having different properties. The first solid particles are distributed throughout to provide overall structural stability, while the second hollow particles are distributed to provide high surface area. This local quality differentiation resolves the contradiction by having different structures in different locations within the electrode.
2Productivity
If the specific surface area of the positive electrode active material particle is increased, then the electrolytic solution and particle response is enhanced, but gas generation is facilitated
Solution Approach 1:
The particle population is segmented into two groups with different surface area characteristics. The second hollow particles provide high specific surface area for rapid electrolytic solution response, while the first solid particles with lower surface area suppress gas generation. The combined effect achieves both rapid response and reduced gas generation.
Solution Approach 2:
The void rate parameter is changed to create two distinct particle populations: first particles with void rate <10% (low gas generation) and second particles with void rate ≥10% (high surface area). By controlling the mass ratio and size distribution of these particles, both response speed and gas generation are optimized.
3Speed
If the particle size is reduced to shorten lithium diffusion distance, then the output characteristic is enhanced, but the specific surface area is increased leading to gas generation
Solution Approach 1:
The particle population is segmented by size into two groups: first particles with smaller diameter (1-7 μm) that provide short lithium diffusion paths, and second particles with larger diameter (8-14 μm) that have lower specific surface area. The first particles enhance output through fast diffusion, while the second particles suppress gas generation through reduced surface area.
Solution Approach 2:
Different size ranges are assigned to different particle types: first particles are kept small (1-7 μm) for fast lithium diffusion, while second particles are made larger (8-14 μm) to reduce specific surface area and gas generation. This local quality differentiation in particle sizing resolves the contradiction between diffusion speed and gas generation.
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 approach effectively enhances both the output and storage characteristics of the battery by reducing lithium diffusion distance and specific surface area, thereby minimizing gas generation.
Implementation Method 1
an average particle diameter which is based on a laser diffraction scattering method
Implementation Method 2
an average particle diameter which is based on the laser diffraction scattering method
Data Source
AI summary
Provided a technique capable of a non-aqueous electrolyte secondary battery in which both of an outstanding output characteristic and storage characteristic. The positive electrode active material layer contains a first and a second positive electrode active material particle. The first positive electrode active material particle is a solid particle whose average particle diameter based on a laser diffraction scattering method is equal to or more than 1 μm and not more than 7 μm. The second positive electrode active material particle includes an outer shell part and a hollow part surrounded by the outer shell part, and average particle diameter is equal to or more than 8 μm and not more than 14 μm. A mass M1 of the first positive electrode active material particle and a mass M2 of the second positive electrode active material particle satisfy a formula: 0<M1/(M1+M2)≤0.6.