Positive Electrode Particle Layering for Low-Resistance Cycling
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Solution Overview
Problem
The existing positive electrode plates in non-aqueous electrolyte secondary batteries exhibit insufficient cycling performance and high output resistance, as the current designs do not effectively manage the distribution and packing of active material particles, leading to cracks during lithium intercalation and de-intercalation.
Innovation Solution
A positive electrode plate design featuring an active material layer with a higher concentration of large particles on the core body side and small particles on the surface side, where the small particles are single-crystal or polycrystalline and less prone to cracking, and the large particles have a grain boundary, optimizing particle packing density and layer structure to enhance cycling performance and reduce output resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a composite material layer and coating layer with particles of different particle sizes are stacked, then the electrode plate structure is formed, but the cycling performance is insufficient and output resistance is high
Solution Approach 1:
The patent applies local quality by creating distinct deep layer and surficial layer with different particle size distributions. The deep layer contains primarily large particles for structural stability, while the surficial layer contains primarily small particles for performance optimization. This spatial differentiation of particle sizes resolves the contradiction by assigning different functional characteristics to different regions of the active material layer.
Solution Approach 2:
The patent segments the active material layer into two distinct layers: a deep layer and a surficial layer. This segmentation allows independent optimization of each layer's particle composition - the deep layer uses large particles for mechanical strength and cycle stability, while the surficial layer uses small particles for reduced resistance and improved cycling performance.
2Ease of manufacture
If uniform particle distribution is used in the active material layer, then manufacturing is simplified, but cracks form during lithium intercalation and de-intercalation
Solution Approach 1:
Instead of uniform particle distribution, the patent implements local quality by concentrating large particles in the deep layer and small particles in the surficial layer. The large particles in the deep layer provide structural integrity and crack resistance during lithium intercalation and de-intercalation, while still allowing relatively simple manufacturing processes.
3Quantity of substance
If large particles are used throughout the active material layer, then packing density increases, but crack formation occurs during cycling
Solution Approach 1:
The patent segments the particle size distribution by layer, placing large particles in the deep layer to achieve high packing density and small particles in the surficial layer to prevent crack formation during cycling. This segmentation allows the electrode to simultaneously achieve high packing density and good cycle stability.
Solution Approach 2:
The patent creates a composite structure within the active material layer by combining large and small particles in specific spatial arrangements. The deep layer uses large particles for density, while the surficial layer uses small particles for cycle stability, creating a composite particle system that achieves both high packing density and crack resistance.
Data Source
AI summary
The present disclosure relates to a positive electrode plate including an active material layer and a core body, wherein the active material layer includes an active material particle, the active material particle includes a large particle and a small particle, and a larger amount of the large particle is present in a vicinity of a surface of the active material layer on the core body side than in a vicinity of a surface of the active material layer opposite to the core body side. The present disclosure further relates to a non-aqueous electrolyte secondary battery including the positive electrode plate. According to the present disclosure, there are provided: the positive electrode plate having excellent cycling performance and output resistance; and the non-aqueous electrolyte secondary battery including the positive electrode plate.