Graphite Anode Composition for Single-Press Cycle-Stable Batteries
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Solution Overview
Problem
The production of non-aqueous electrolyte secondary batteries with high energy density faces challenges in maintaining charging/discharging cyclic characteristics due to the need for multiple compression steps, which reduces productivity and can lead to deterioration in battery performance.
Innovation Solution
A non-aqueous electrolyte secondary battery design incorporating a negative electrode active material layer composed of graphite particles with porosities of 5% or less and 8-20%, in a specific mass ratio of 70:30 to 90:10, allowing for a single compression step while maintaining high packing density and suppressing cyclic deterioration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If graphite particles with low porosity (5% or less) are used to suppress deterioration in charging/discharging cyclic characteristics, then reliability is improved, but multiple compression steps are required which reduces productivity
Solution Approach 1:
The patent uses a composite material system consisting of two types of graphite particles with different porosity characteristics. Graphite particles A (5% or less porosity) provide reliability by suppressing cyclic deterioration, while graphite particles B (8-20% porosity) enable high packing density with single compression. The composite mixture achieves both reliability and productivity goals that neither component alone can satisfy.
2Manufacturing precision
If multiple compression steps are carried out to obtain high packing density with low porosity graphite particles, then manufacturing precision is improved, but device complexity and production time increase
Solution Approach 1:
The patent applies local quality by assigning different functional characteristics to different components within the graphite particle mixture. Graphite particles A provide local regions of low porosity for reliability, while graphite particles B provide local regions of appropriate porosity that facilitate packing during compression. This local differentiation allows single compression to achieve the packing density that would otherwise require multiple compression steps.
3Reliability
If the porosity due to closed pores of graphite particles is reduced to suppress deterioration, then reliability is improved, but the ability to collapse by compression is reduced requiring more compression steps
Solution Approach 1:
Graphite particles B act as an intermediary component that facilitates the compression process. Their moderate porosity (8-20%) allows them to collapse during compression, creating space and enabling the overall mixture to achieve high packing density in a single compression step, while graphite particles A maintain their low porosity structure for reliability.
Data Source
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AI summary
The objective of the present disclosure is to provide a non-aqueous electrolyte secondary battery capable of suppressing an increase in man-hour for a compression process in the production of a negative electrode and also suppressing a deterioration in charge/discharge cycle characteristics. A non-aqueous electrolyte secondary battery according to one embodiment of the present disclosure is provided with a negative electrode having a negative electrode active material layer, wherein: the negative electrode active material layer includes graphite particles A and graphite particles B as a negative electrode active material; the internal porosity of the graphite particles A is 5% or less, and the internal porosity of the graphite particles B is 8-20%; and the mass ratio of the graphite particles A to the graphite particles B is 70:30 to 90:10.