Silicon-Composite Anode Structure to Limit Cracking in Li Batteries

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Solution Overview

Problem

Lithium secondary batteries face issues with anode cracking and electrolyte exposure due to volume expansion differences between silicon and carbon-based active materials during charging and discharging, leading to reduced capacity and lifespan.

Innovation Solution

An anode design incorporating a carbon-based active material, a first silicon-based active material with a carbon-silicon composite, and a second silicon-based active material with silicon oxide, optimized in weight percentages and layering, to manage volume changes and enhance lithium ion mobility.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If silicon-based active material is used to increase capacity, then energy density is improved, but volume expansion causes cracks and reduces lifespan

Engineering Contradiction:

ImprovecapacityVSAvoidlifespan

Core Design Contradiction:

Quantity of substanceVSReliability

Solution Approach 1:

The patent applies nested doll by placing silicon-based active material particles inside a porous carbon matrix structure. The carbon matrix acts as a container that accommodates the silicon particles, allowing the silicon to expand and contract during charging-discharging cycles without causing structural damage. This nested configuration enables high capacity from silicon while maintaining structural integrity through the carbon framework.

Inventive Principle:

Principle #7Nested doll (Nesting)

Solution Approach 2:

The patent employs composite materials by combining silicon-based active material with carbon-based materials to form a composite anode structure. The silicon provides high capacity while the carbon component provides structural stability and conductivity. This composite approach allows the benefits of both materials to work together, achieving high capacity without the detrimental volume expansion effects of pure silicon.

Inventive Principle:

Principle #40Composite materials

2Quantity of substance

If silicon and carbon are used together to increase capacity, then energy density is improved, but volume expansion ratio difference causes cracks

Engineering Contradiction:

ImprovecapacityVSAvoidstructural integrity

Core Design Contradiction:

Quantity of substanceVSStrength

Solution Approach 1:

The patent applies local quality by creating regions with different compositions and properties within the anode structure. The porous carbon matrix provides a flexible, expandable framework in regions where silicon particles are located, while maintaining overall structural integrity. This local differentiation allows each region to accommodate volume changes appropriately, preventing cracks from propagating through the entire structure.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent utilizes flexible shells by employing a porous carbon matrix that can flexibly expand and contract to accommodate silicon volume changes. The carbon matrix acts as a flexible container that moves with the silicon particles during charging-discharging cycles, preventing mechanical stress concentration and crack formation that would occur with rigid structures.

Inventive Principle:

Principle #30Flexible shells and thin films

3Quantity of substance

If anode structure is optimized for high capacity, then energy density is improved, but cracks lead to electrolyte exposure

Engineering Contradiction:

ImprovecapacityVSAvoidelectrolyte exposure

Core Design Contradiction:

Quantity of substanceVSObject-affected harmful factors

Solution Approach 1:

The patent applies intermediary by introducing a protective carbon coating and porous carbon matrix as intermediate layers between the silicon-based active material and the electrolyte. These intermediate structures prevent direct contact between the silicon particles and electrolyte, even when cracks occur during volume expansion. The carbon matrix acts as a buffer that absorbs mechanical stress and prevents electrolyte penetration to the silicon surface.

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS20260031338A1Anode for lithium secondary battery and lithium secondary battery including the same

Publication Date: 2026.01.29 SK ON CO LTD

AI summary

An anode for a lithium secondary battery includes an anode current collector, and an anode active material layer formed on at least one surface of the anode current collector. The anode active material layer includes a carbon-based active material, a first silicon-based active material including a carbon-silicon composite active material, and a second silicon-based active material including a silicon oxide (SiOx, 0<x<2). A content of the first silicon-based active material is in a range from 2 wt % to 40 wt % based on a total weight of the anode active material layer.