Negative Electrode Carbon Gradient for Battery Electrolyte Retention
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Solution Overview
Problem
Non-aqueous electrolyte secondary batteries face challenges in maintaining effective charge-discharge cycle characteristics due to uneven distribution of non-aqueous electrolyte, which affects their performance and durability.
Innovation Solution
The battery design incorporates a negative electrode mixture layer with first carbon particles of higher internal porosity and second carbon particles of lower porosity, where the second carbon particles are more concentrated in the upper half region and first carbon particles in the lower half region, optimizing the electrolyte retention and distribution within the battery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional negative electrode mixture layer is used with uniform carbon particle distribution, then the manufacturing process is simple, but the electrolyte distribution becomes uneven leading to poor charge-discharge cycle characteristics
Solution Approach 1:
The patent applies local quality by creating a non-uniform distribution of carbon particles within the negative electrode mixture layer. Specifically, it uses two types of carbon particles (first and second carbon particles) with different properties and distributes them at different ratios in different regions of the electrode, optimizing electrolyte retention and distribution locally to improve charge-discharge cycle characteristics.
Solution Approach 2:
The patent employs asymmetry by intentionally creating an asymmetric distribution pattern of carbon particles in the negative electrode. The first and second carbon particles are distributed at different ratios in different regions, breaking the symmetry of conventional uniform electrode structures to achieve better electrolyte distribution and cycle performance.
2Quantity of substance
If carbon particles with high internal porosity are used throughout the electrode, then electrolyte absorption capacity increases, but structural stability decreases leading to poor cycle life
Solution Approach 1:
The patent applies local quality by assigning different carbon particle types to different regions of the negative electrode. First carbon particles with higher internal porosity are used in regions where electrolyte retention is prioritized, while second carbon particles with lower internal porosity are used in regions where structural stability is prioritized, achieving both goals simultaneously through spatial differentiation.
Solution Approach 2:
The patent uses composite materials by combining two types of carbon particles with different internal porosity characteristics in the negative electrode mixture layer. This composite approach allows the electrode to simultaneously exhibit high electrolyte absorption capacity (from the porous first carbon particles) and structural stability (from the less porous second carbon particles).
Data Source
AI summary
A non-aqueous electrolyte secondary battery is characterized in that: an electrode body in which a positive electrode and a negative electrode oppose each other through a separator, and a battery case accommodating the electrode body, are provided; the negative electrode has a negative electrode mixture layer containing first carbon particles and second carbon particles having a lower internal porosity than the first carbon particles; the non-aqueous electrolyte secondary battery is used in a fixed state; and when the electrode body in the fixed state is bisected into a top half region and a bottom half region with respect to the vertical direction, the second carbon particles are contained in greater number in the top half region than the bottom half region.