Non-aqueous Electrolyte Battery Positive Electrode Particle Distribution
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Solution Overview
Problem
Non-aqueous electrolyte secondary batteries face issues with electrolyte solution uniformity and internal resistance due to positive electrode active material particle breakage during charge/discharge, especially when high capacity is sought or silicon oxide is used as the negative electrode, leading to capacity deterioration and increased internal resistance.
Innovation Solution
A non-aqueous electrolyte secondary battery design featuring a positive electrode active material layer with a broad particle size distribution and high proportion of particles ≥15 μm in diameter, ensuring reduced particle breakage and enhanced electrolyte permeability, thereby maintaining capacity and reducing internal resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the packing density of the positive electrode active material is increased to achieve high capacity, then the battery capacity is improved, but the positive electrode active material particles are more likely to break during charge/discharge
Solution Approach 1:
The patent changes the particle size distribution parameters of the positive electrode active material, specifically setting D90-D10 > 13 μm and ensuring 20% or more of particles have diameter ≥15 μm with high sphericity (area ratio ≥0.8). This parameter optimization reduces particle breakage while maintaining high capacity by creating a more resilient electrode structure that can accommodate volume changes during charge/discharge cycles.
2Quantity of substance
If silicon oxide is used as negative electrode active material to increase capacity, then the battery capacity is improved, but the internal resistance increases due to large volume change
Solution Approach 1:
The patent optimizes the particle size distribution parameters of the positive electrode active material (D90-D10 > 13 μm, with 20% or more particles having diameter ≥15 μm and area ratio ≥0.8), creating a more resilient electrode structure that can accommodate the large volume changes of silicon oxide during charge/discharge, thereby reducing internal resistance while maintaining high capacity.
Solution Approach 2:
The patent creates a heterogeneous particle size distribution with a specific proportion of large, highly spherical particles (≥15 μm diameter with area ratio ≥0.8) that serve as structural anchors in the positive electrode. These particles provide localized structural stability that compensates for the volume expansion/contraction of silicon oxide in the negative electrode, reducing internal resistance while maintaining overall electrode integrity.
3Stability of the object's composition
If the positive electrode active material particles are broken into smaller pieces, then the particle size distribution changes, but the entry and exit of the electrolyte solution becomes more difficult
Solution Approach 1:
The patent sets specific parameters for particle size distribution (D90-D10 > 13 μm) and sphericity (area ratio ≥0.8 for particles ≥15 μm), which maintains optimal pore structure within the electrode. This controlled particle morphology ensures sufficient void spaces for electrolyte penetration while preserving the overall particle size distribution needed for high capacity, preventing the electrode from becoming too dense.
Data Source
AI summary
A non-aqueous electrolyte secondary battery according to one mode of the present disclosure is provided with: a positive electrode including a positive-electrode active material layer; a negative electrode; and a non-aqueous electrolyte, wherein the positive-electrode active material layer includes positive-electrode active material particles having a particle size distribution in which the difference (D90-D10) between a 90% diameter (D90) and a 10% diameter (D10) measured with a laser diffraction method is larger than 13 μm. In addition, the positive-electrode active material layer is characterized in that, on an arbitrarily defined cross section thereof, the total area of positive-electrode active material particles A, each of which has a particle size not smaller than 15 μm and has a particle area at least 0.8-fold the area of a circle circumscribing the positive-electrode active material particle, is 20% or larger with respect to the total area of the cross section.