Layered Graphite Anode Structure for Fast-Charging Cycle Life

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Solution Overview

Problem

Lithium secondary batteries face challenges with decreased lifespan characteristics and conductivity due to volume expansion and low conductivity of silicon-based anode materials during fast charging.

Innovation Solution

An anode structure comprising a first anode active material layer with natural graphite and a second anode active material layer with artificial graphite, where the difference in pore aspect ratios and porosity between the layers is controlled within specific ranges, enhancing structural stability and fast charging performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If silicon-based material is included in the anode active material to achieve high capacity, then energy density is improved, but lifespan characteristics are decreased due to volume expansion rate and low conductivity

Engineering Contradiction:

Improveenergy densityVSAvoidlifespan characteristics

Core Design Contradiction:

Quantity of substanceVSReliability

Solution Approach 1:

The anode active material layer is divided into multiple layers with different pore aspect ratios. The first layer has a first pore aspect ratio and the second layer has a second pore aspect ratio different from the first, allowing each layer to serve different functions in managing silicon expansion and maintaining conductivity throughout charging cycles

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different regions of the anode active material layer are given different pore structures. The first layer near the current collector has one pore aspect ratio configuration while the second layer has another configuration, creating local variations that optimize both capacity retention and structural stability in different zones

Inventive Principle:

Principle #3Local quality

2Productivity

If fast charging is performed to improve charging speed, then productivity is improved, but lifespan characteristics are decreased due to volume expansion of silicon

Engineering Contradiction:

Improvecharging speedVSAvoidlifespan characteristics

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The multi-layer pore structure dynamically manages the expansion and contraction of silicon particles during fast charging cycles. The different pore aspect ratios allow the structure to adapt to the changing volume requirements of silicon at different charging stages, maintaining integrity during rapid ion insertion and extraction

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The anode active material layer incorporates porous structures with controlled aspect ratios in different layers. These porous structures provide buffer space for silicon volume expansion during fast charging while maintaining electrical conductivity pathways, enabling high charging speeds without sacrificing lifespan

Inventive Principle:

Principle #31Porous materials

Data Source

PatentEP4579790A1Anode for lithium secondary battery and lithium secondary battery including the same

Publication Date: 2025.07.02 SK ON CO LTD

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AI summary

An anode for a lithium secondary battery according to embodiments of the present disclosure includes an anode current collector, a first anode active material layer formed on at least one surface of the anode current collector and including first pores, a second anode active material layer formed on the first anode active material layer and including artificial graphite and second pores, wherein a difference between the first pore aspect ratio and the second pore aspect ratio is 0.5 to 3.0.