Positive Electrode Particle Composition for Battery Output and Storage
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Solution Overview
Problem
Existing non-aqueous electrolyte secondary batteries face a contradiction between enhancing output characteristics through increased specific surface area of positive electrode active material particles and suppressing gas generation to maintain storage characteristics.
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. The first particles have a solid structure with a smaller average particle diameter and low void rate, while the second particles have a hollow structure with a larger average particle diameter and high void rate, optimized to balance output and storage characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the specific surface area of positive electrode active material particles is increased to enhance output characteristic, then the output characteristic is improved, but gas generation inside the case increases and storage characteristic deteriorates
Solution Approach 1:
The positive electrode active material is divided into two distinct particle types: first particles with solid structure and smaller size (1-7 μm) for high power output, and second particles with hollow structure and larger size (8-14 μm) for low gas generation. This segmentation allows each particle type to fulfill different functional requirements simultaneously.
Solution Approach 2:
Different regions of the positive electrode contain particles with locally optimized properties: the first particles provide high surface area for rapid lithium diffusion and high output, while the second particles provide low specific surface area to suppress gas generation. Each particle type is positioned and sized to optimize its local function within the electrode structure.
2Speed
If smaller particle diameter is used to reduce lithium diffusion distance and enhance output characteristic, then the output characteristic is improved, but the specific surface area increases leading to increased gas generation
Solution Approach 1:
The particle population is segmented into two size groups: smaller first particles (1-7 μm) that provide short lithium diffusion paths for high output, and larger second particles (8-14 μm) that provide lower specific surface area to reduce gas generation. This segmentation resolves the contradiction between diffusion speed and gas generation.
Solution Approach 2:
The positive electrode uses a composite particle system combining solid first particles and hollow second particles. The hollow structure of the second particles reduces their effective specific surface area despite their larger size, creating a composite material system that achieves both fast lithium diffusion and low 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 configuration enhances the output characteristic by reducing lithium diffusion distance and increases the storage characteristic by suppressing gas generation, achieving a balance between both performance metrics.
Implementation Method 1
an average particle diameter which is based on a laser diffraction scattering method
Data Source
Figure 1~2
Figure 3
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AI summary
It is to provide a technique capable of implementing a non-aqueous electrolyte secondary battery in which both of an outstanding output characteristic and storage characteristic are achieved. A herein disclosed positive electrode includes a positive electrode current collector 52, and a positive electrode active material layer 54 arranged on a surface of the positive electrode current collector 52. The positive electrode active material layer 54 contains a first positive electrode active material particle 100 and a second positive electrode active material particle 200. The first positive electrode active material particle 100 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 200 includes an outer shell part 210 and a hollow part 220 surrounded by the outer shell part 210, and is a hollow particle whose average grain diameter based on the laser diffraction scattering method 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 100 and a mass M2 of the second positive electrode active material particle 200 satisfy a formula: 0 < M1/(M1 + M2) ≤ 0.6.