Two-Layer Graphite Anode Structure for Adhesion and Fast Charging

Solution Overview

Problem

Conventional lithium secondary batteries face limitations in energy density, leading to long charging times and inadequate lifespan and adhesion to the current collector, particularly when using mixed graphite as the negative electrode active material.

Innovation Solution

A negative electrode with a two-layer structure comprising a first and second carbon-based negative electrode active layer, where the second layer has an orientation index of 6 or less, and a specific particle diameter ratio, along with the use of carbon structures and thickening agents to enhance adhesion and orientation, is employed.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If natural graphite is used as negative electrode active material, then adhesion to current collector is improved, but high-rate charge and discharge performance deteriorates

Engineering Contradiction:

Improveadhesion to current collectorVSAvoidhigh-rate charge and discharge performance

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The negative electrode active material is segmented into two distinct layers: a first layer containing natural graphite particles (5-20 μm) for adhesion, and a second layer containing artificial graphite particles (15-30 μm) for high-rate performance. This segmentation allows each layer to specialize in its respective strength without compromise.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different regions of the negative electrode are assigned different material qualities: the first layer near the current collector uses natural graphite with excellent adhesion properties, while the second layer uses artificial graphite with fewer surface defects and better high-rate characteristics. This local differentiation optimizes overall performance.

Inventive Principle:

Principle #3Local quality

2Productivity

If artificial graphite is used as negative electrode active material, then high-rate charge and discharge performance is improved, but adhesion to current collector deteriorates

Engineering Contradiction:

Improvehigh-rate charge and discharge performanceVSAvoidadhesion to current collector

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The negative electrode active material is segmented into two distinct layers: a first layer containing natural graphite particles (5-20 μm) for adhesion, and a second layer containing artificial graphite particles (15-30 μm) for high-rate performance. This segmentation allows each layer to specialize in its respective strength without compromise.

Inventive Principle:

Principle #1Segmentation

3Productivity

If mixed graphite is used as negative electrode active material, then both adhesion and high-rate performance are improved, but lifespan characteristics and impact resistance stability deteriorate

Engineering Contradiction:

Improvehigh-rate charge and discharge performanceVSAvoidlifespan characteristics

Core Design Contradiction:

ProductivityVSDuration of action of stationary object

Solution Approach 1:

The negative electrode active material is segmented into two distinct layers: a first layer containing natural graphite particles (5-20 μm) for adhesion, and a second layer containing artificial graphite particles (15-30 μm) for high-rate performance. This segmentation allows each layer to specialize in its respective strength without compromise.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The negative electrode uses a composite structure combining natural graphite and artificial graphite in distinct layers, rather than a homogeneous mixture. This composite approach maintains the advantages of each material while avoiding the destabilizing effects of mixing, thereby improving lifespan and impact resistance stability.

Inventive Principle:

Principle #40Composite materials

Data Source

PatentEP4712157A1Anode and manufacturing method therefor

Publication Date: 2026.03.18 LG ENERGY SOLUTION LTD

AI summary

A negative electrode may include a first negative electrode active layer and a second negative electrode active layer on a negative electrode current collector. An orientation index (O.I.) of each of the negative electrode active layers may satisfy a predetermined range, and thus adhesion of the negative electrode active layers to the negative electrode current collector is highly implemented, thereby having excellent lifespan characteristics. In addition, a secondary battery including the same has excellent output characteristics and can be charged in a short time even at a 1C-rate.