Lithium secondary battery

The lithium secondary battery addresses the rapid degradation issue by optimizing the composition of Si-C composites in the negative electrode and electrolyte, ensuring stable performance and cost-effectiveness through controlled porosity and FEC content, thereby enhancing lifespan and energy density.

WO2026142244A1PCT designated stage Publication Date: 2026-07-02LG ENERGY SOLUTION LTD
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Patent Information

Authority / Receiving Office
WO · WO
Patent Type
Applications
Current Assignee / Owner
LG ENERGY SOLUTION LTD
Filing Date
2025-12-22
Publication Date
2026-07-02

AI Technical Summary

Technical Problem

Lithium secondary batteries using pulverized Si-C composites face rapid performance degradation and reduced lifespan due to irreversible phase transitions and volume changes during charging and discharging, leading to sudden cell death when used with commercially available electrolytes.

Method used

A lithium secondary battery design that includes a negative electrode with a specific composition of pulverized Si-C composite, controlled porosity, and an electrolyte with fluoroethylene carbonate (FEC) content, satisfying conditions defined by Equation (1), to suppress volume expansion and improve lifespan characteristics.

Benefits of technology

The battery achieves excellent lifespan characteristics and cost-effectiveness by using low-cost pulverized Si-C composites, with the optimized composition and electrolyte additives forming a film to stabilize the Si-C composite, preventing sudden performance degradation.

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Abstract

The present invention relates to a lithium secondary battery comprising a positive electrode, a negative electrode, and an electrolyte, wherein the negative electrode includes a pulverized Si-C composite as a negative electrode active material, and A defined by Equation (1) is 9 or more. Equation (1): In Equation (1), WSiC is the weight percentage of the pulverized Si-C composite relative to the total weight of the negative electrode active material, RSiC is the average particle size measured in μm of the pulverized Si-C composite, P is the porosity of the negative electrode, and WFEC is the weight percentage of fluoroethylene carbonate in the electrolyte.
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