Double-Layer Silicon Anode Structure for Stable Li-Ion Cycling

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Solution Overview

Problem

Silicon-based negative electrode active materials in lithium secondary batteries experience rapid volume expansion during charging, leading to disconnection of conductive paths, surface degradation, and non-uniform lithium ion charging, which deteriorates battery capacity and cycle life.

Innovation Solution

A double-layered negative electrode structure with a first layer of SiOx and a second layer of carbon-based or silicon-based materials, where the second layer is coated uniformly and thinly to prevent surface degradation and ensure uniform lithium ion distribution, using specific thickness and non-uniformity criteria to maintain high capacity and cycle performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If silicon-based compounds are used as negative electrode active material to increase capacity, then discharge capacity is improved, but volume expansion during charging causes disconnection of conductive path and deterioration of battery characteristics

Engineering Contradiction:

Improvedischarge capacityVSAvoidbattery characteristics

Core Design Contradiction:

Quantity of substanceVSReliability

Solution Approach 1:

The negative electrode active material layer is divided into two distinct layers: a first layer containing silicon-based compounds for high capacity, and a second layer containing graphite-based materials for structural stability. This segmentation allows each layer to perform its specialized function, resolving the contradiction between high capacity and reliability

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The invention uses a composite structure combining silicon-based compounds (high capacity) with graphite-based materials (structural stability). The composite negative electrode active material layer integrates the advantages of both materials, achieving high discharge capacity while maintaining battery characteristics through the stabilizing effect of graphite

Inventive Principle:

Principle #40Composite materials

2Quantity of substance

If silicon-based compounds are used as negative electrode active material, then discharge capacity is improved, but surface degradation accelerates during charging and discharging cycles

Engineering Contradiction:

Improvedischarge capacityVSAvoidsurface degradation

Core Design Contradiction:

Quantity of substanceVSObject-affected harmful factors

Solution Approach 1:

The graphite-based material layer acts as an intermediary between the silicon-based compounds and the electrolyte. This intermediate layer protects the silicon-based material from direct exposure to the electrolyte, reducing surface degradation while allowing lithium ion transport, thus resolving the contradiction between high capacity and surface stability

Inventive Principle:

Principle #24Intermediary (Mediator)

3Quantity of substance

If silicon-based compounds are used as negative electrode active material, then discharge capacity is improved, but lithium ion distribution becomes non-uniform in the depth direction

Engineering Contradiction:

Improvedischarge capacityVSAvoidlithium ion distribution uniformity

Core Design Contradiction:

Quantity of substanceVSManufacturing precision

Solution Approach 1:

The invention applies local quality by assigning different functional characteristics to different layers: the first layer (silicon-based) provides high capacity where needed, while the second layer (graphite-based) ensures uniform lithium ion distribution. This local differentiation resolves the contradiction between high capacity and uniform lithium ion distribution

Inventive Principle:

Principle #3Local quality

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 double-layered structure enhances capacity retention and cycle life by preventing surface degradation and ensuring uniform lithium ion distribution, maintaining optimal performance even with high silicon content.

Implementation Method 1

The negative electrode includes a negative electrode active material for intercalating and deintercalating lithium ions to and from the positive electrode

Methodology Applied

Scientific EffectIntercalation: Absorption (physical)

Implementation Method 2

a second negative electrode active material layer provided on a surface of the first negative electrode active material layer opposite to a surface of the first negative electrode active material layer facing the negative electrode current collector layer

Methodology Applied

Scientific EffectCoating/Deposition: Deposition (physical)

Data Source

PatentUS20260074190A1Negative electrode for lithium secondary battery, method for manufacturing negative electrode for lithium secondary battery, and lithium secondary battery comprising negative electrode

Publication Date: 2026.03.12 LG ENERGY SOLUTION LTD

AI summary

A negative electrode for a lithium secondary battery, a method for manufacturing a negative electrode for a lithium secondary battery, and a lithium secondary battery including a negative electrode, are provided. The negative electrode includes a negative electrode current collector layer, a first negative electrode active material layer provided on a surface of the negative electrode current collector layer, and a second negative electrode active material layer provided on a surface of the first negative electrode active material layer opposite to a surface of the first negative electrode active material layer facing the negative electrode current collector layer.