Silicon Anode Sheet Structure Using Flake Graphite Against Cracking

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Solution Overview

Problem

Conventional lithium-ion batteries with silicon-based negative electrode materials are prone to substrate cracking, leading to increased failure risk due to the brittle nature of silicon-based materials, which can cause damage during the battery cycle process.

Innovation Solution

Incorporating flake graphite into the negative electrode active layer or between the negative electrode active layer and the current collector, with a thickness-to-diameter ratio (t/d) of 0.005 or greater, to enhance the silicon-based material's slippage and reduce substrate damage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If silicon-based material is used as negative electrode active material to improve energy density, then the energy density is improved, but the substrate is prone to cracking resulting in increased failure risk

Engineering Contradiction:

Improveenergy densityVSAvoidfailure risk

Core Design Contradiction:

Use of energy by moving objectVSReliability

Solution Approach 1:

The patent introduces flake graphite as an intermediary layer between the silicon-based active material and the current collector substrate. This intermediary layer absorbs expansion stress and prevents direct transmission of mechanical stress to the substrate, thereby reducing cracking while maintaining the high energy density benefits of silicon-based materials.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent creates a composite negative electrode structure combining silicon-based active material with flake graphite and binder materials. This composite approach leverages the high capacity of silicon while using graphite and binder to provide structural stability and crack prevention, resolving the contradiction between energy density and reliability.

Inventive Principle:

Principle #40Composite materials

2Reliability

If flake graphite is introduced into the negative electrode active layer to reduce substrate damage, then the reliability is improved, but the device complexity increases

Engineering Contradiction:

Improvesubstrate damage resistanceVSAvoidelectrode structure complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent merges the flake graphite into the existing negative electrode active layer formulation, combining it with the silicon-based active material and binder in a single coating process. This integration approach adds protective functionality without requiring separate processing steps or significantly increasing structural complexity.

Inventive Principle:

Principle #5Merging (Combining)

Data Source

PatentUS20250336958A1Negative electrode sheet and preparation method therefor, secondary battery and electric device

Publication Date: 2025.10.30 CONTEMPORARY AMPEREX TECHNOLOGY CO LTD

AI summary

A negative electrode sheet and a preparation method therefor, a secondary battery and an electric device. The negative electrode sheet includes a negative electrode current collector, a negative electrode active layer and a flake graphite. A ratio of a thickness t to a diameter d of the flake graphite is t/d, where t/d≥0.005. The negative electrode active layer includes a negative electrode active material, and the negative electrode active material includes a silicon-based material.