Negative electrode plate and secondary battery

The negative electrode plate design with a graphite layer and Si-based particle distribution alleviates stress from Si expansion and contraction, enhancing peel strength and conductivity in secondary batteries.

JP2026084581APending Publication Date: 2026-05-21TOYOTA BATTERY CO LTD
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Patent Information

Authority / Receiving Office
JP Β· JP
Patent Type
Applications
Current Assignee / Owner
TOYOTA BATTERY CO LTD
Filing Date
2024-11-11
Publication Date
2026-05-21

AI Technical Summary

Technical Problem

Si-based particles in negative electrode plates of secondary batteries expand and contract during charge-discharge cycles, causing stress that leads to delamination from the foil and disruption of conductive paths, reducing peel strength and increasing resistance.

Method used

A negative electrode plate design featuring a graphite layer with large and small graphite particles and Si-based particles, where Si-based particles are predominantly on the side opposite to the current collector, with specific particle size and volume ratios, and a thin graphite layer to relieve stress and maintain contact.

Benefits of technology

The design effectively reduces stress and peeling, maintaining conductive paths and reducing resistance in the electrode plate.

✦ Generated by Eureka AI based on patent content.

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Abstract

To provide a negative electrode plate in which stress due to expansion and contraction of Si-based particles is relieved, and a secondary battery including the negative electrode plate. [Solution] A negative electrode plate comprising a negative electrode current collector and a graphite layer laminated on the negative electrode current collector, wherein the graphite layer contains large graphite particles with an aspect ratio of 1.5 or more, small graphite particles with an aspect ratio of 1.5 or more, and Si-based particles, wherein in the graphite layer, there are more Si-based particles on the side opposite to the side in contact with the negative electrode current collector than on the side in contact with the negative electrode current collector, the average particle size D50 of the Si-based particles is 0.4 to 1 times the length of the smaller of the average major axis diameter a1 of the large graphite particles - the average major axis diameter a2 of the small graphite particles, or the average minor axis diameter b2 of the small graphite particles, and the Si-based particle content is 10 volume% or less of the total volume of the graphite layer.
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