Layered Lithium Battery Anode Structure for Silicon Expansion Control

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Solution Overview

Problem

Rechargeable lithium batteries experience deterioration and expansion of the negative electrode during charging and discharging, leading to poor cycle-life characteristics and performance degradation.

Innovation Solution

A negative electrode structure comprising a current collector with a three-layer active material configuration: a first layer of crystalline carbon, a middle layer containing silicon-based and crystalline carbon, and a third layer of crystalline carbon, where silicon is exclusively in the middle layer, optimized by specific particle sizes and ratios to minimize expansion and improve adherence.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If silicon-based active material is mixed with carbonaceous material to improve current density, then battery capacity increases, but negative electrode expansion occurs during charging and discharging

Engineering Contradiction:

Improvebattery capacityVSAvoidnegative electrode expansion

Core Design Contradiction:

Quantity of substanceVSStability of the object's composition

Solution Approach 1:

The negative active material layer is divided into multiple layers with different compositions and functions. The first layer (containing silicon-based material) is positioned at the bottom for high capacity, the second layer (carbonaceous material) in the middle to suppress expansion, and the third layer (carbonaceous material) at the top for stability. This segmentation allows each layer to perform its specific function while working together to resolve the contradiction between capacity and expansion.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different regions of the negative electrode are assigned different material compositions tailored to their specific functions. The silicon-based material is concentrated in the first layer where high capacity is needed, while carbonaceous material is distributed in the second and third layers where expansion suppression and structural stability are prioritized. This local optimization resolves the contradiction by placing materials in the most appropriate locations.

Inventive Principle:

Principle #3Local quality

2Productivity

If thick negative active material layer is prepared to improve current density, then battery performance increases, but cycle-life characteristics deteriorate

Engineering Contradiction:

Improvecurrent densityVSAvoidcycle-life characteristics

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The thick negative active material layer is segmented into three functional layers. The first layer provides high capacity with silicon-based material, while the second and third layers with carbonaceous material provide structural stability and expansion suppression throughout cycling. This segmentation maintains high current density while improving cycle-life characteristics through the stabilizing effect of the carbonaceous layers.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The negative electrode uses a composite structure combining silicon-based active material with carbonaceous material in a layered configuration. This composite approach allows the silicon-based material to provide high capacity while the carbonaceous material provides structural stability and expansion suppression, thereby maintaining both high current density and good cycle-life characteristics.

Inventive Principle:

Principle #40Composite materials

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The proposed structure enhances cycle-life characteristics and high capability characteristics by reducing silicon expansion and electrolyte depletion, improving electron transfer and lithium ion intercalation.

Implementation Method 1

a positive electrode and a negative electrode which may include an active material being capable of intercalating and deintercalating lithium ions

Methodology Applied

Scientific EffectIntercalation: Absorption (physical)

Implementation Method 2

it causes to occur the deterioration and expansion of the negative electrode during charging and discharging

Methodology Applied

Scientific EffectVolume expansion: Thermal Expansion

Implementation Method 3

generate electrical energy due to an oxidation and reduction reaction when lithium ions are intercalated and deintercalated

Methodology Applied

Scientific EffectOxidation-reduction reaction: Redox Reactions

Data Source

PatentEP4228025B1Negative electrode for rechargeable lithium battery and rechargeable lithium battery including same

Publication Date: 2026.05.06 SAMSUNG SDI CO LTD

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AI summary

Disclosed is a negative electrode for a rechargeable lithium battery and a rechargeable lithium battery including the same, the negative electrode including a current collector and a negative active material layer including a first active material layer, a second active material layer, and a third active material layer, wherein the first active material layer is positioned to contact the current collector and the second active material layer is positioned between the first active material layer and the third active material layer, the first active material layer includes a first active material of first crystalline carbon, the second active material layer includes a second active material of a silicon-based active material, a second crystalline carbon and third crystalline carbon and third active material layer includes a third active material of fourth crystalline carbon.