Silicon-Carbon Anode Active Material for Crack-Resistant Output

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Solution Overview

Problem

Lithium secondary batteries face issues with mechanical stability and output characteristics due to volume expansion of silicon-based anode active materials during charging and discharging, leading to cracks and hindered lithium ion intercalation.

Innovation Solution

An anode active material composition comprising a carbon-based material and a silicon-based material with controlled carbon content and Raman peak intensity ratio, along with optimized pore volume and expansion rate, is used to suppress volume expansion and enhance mechanical stability and output.

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 occurs during charging and discharging leading to mechanical instability

Engineering Contradiction:

Improveenergy densityVSAvoidmechanical stability

Core Design Contradiction:

Quantity of substanceVSStability of the object's composition

Solution Approach 1:

Silicon-based active material particles are embedded within a three-dimensional porous carbonaceous material structure. The carbonaceous material acts as a container or matrix that holds the silicon particles, allowing the silicon to expand and contract during lithium insertion/extraction without compromising the overall structural integrity. This nesting approach enables high capacity from silicon while maintaining mechanical stability through the carbon framework.

Inventive Principle:

Principle #7Nested doll (Nesting)

Solution Approach 2:

The three-dimensional porous carbonaceous material functions as a flexible matrix that can accommodate volume changes of silicon particles. The porous structure provides space for expansion and contraction, while the carbonaceous material itself maintains structural coherence through its three-dimensional network, effectively acting as a flexible container that preserves mechanical stability during cycling.

Inventive Principle:

Principle #30Flexible shells and thin films

2Quantity of substance

If silicon-based active material is used to increase capacity, then energy density is improved, but cracks form during repeated charging and discharging

Engineering Contradiction:

Improveenergy densityVSAvoidlifespan

Core Design Contradiction:

Quantity of substanceVSReliability

Solution Approach 1:

Inventive Principle:

Principle #7Nested doll (Nesting)

Solution Approach 2:

The three-dimensional porous carbonaceous material structure is prepared in advance to provide cushioning space and structural support for silicon particles before volume expansion occurs. The porous structure anticipates and accommodates the expansion, preventing crack formation during subsequent charging and discharging cycles, thereby extending battery lifespan.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

3Stability of the object's composition

If carbon content in silicon-based active material is increased to suppress volume expansion, then mechanical stability is improved, but output characteristics deteriorate

Engineering Contradiction:

Improvemechanical stabilityVSAvoidoutput characteristics

Core Design Contradiction:

Stability of the object's compositionVSPower

Solution Approach 1:

Instead of uniformly increasing carbon content throughout the silicon-based active material (which would reduce output), the invention locally contains silicon particles within a carbonaceous matrix. The silicon particles maintain their high capacity properties while the surrounding carbonaceous material provides mechanical stability. This local differentiation of quality allows simultaneous achievement of high output characteristics and mechanical stability.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The invention creates a composite structure where silicon-based active material particles are combined with three-dimensional porous carbonaceous material. This composite approach allows the silicon component to provide high capacity and output characteristics while the carbonaceous component provides mechanical stability and structural integrity, achieving both goals without compromising either.

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 anode active material composition improves mechanical stability, reduces resistance, and enhances the capacity and efficiency of lithium secondary batteries by preventing cracks and facilitating lithium ion diffusion.

Implementation Method 1

a peak intensity ratio of a Raman spectrum of the second anode active material defined by Equation 1 below is 0.5 to 2.3: In Equation 1, I(520) may be a peak intensity of the second anode active material at a Raman shift of 520 cm -1

Methodology Applied

Scientific EffectRaman spectroscopy:

Implementation Method 2

facilitating lithium ion diffusion

Methodology Applied

Scientific EffectIon diffusion: Diffusion

Data Source

PatentEP4654274A1Anode active material for lithium secondary battery, anode for lithium secondary battery and lithium secondary battery

Publication Date: 2025.11.26 SK ON CO LTD

Figure 1~2

AI summary

An anode active material for a lithium secondary battery according to embodiments of the present disclosure includes a first anode active material which includes a carbon-based active material; and a second anode active material which includes a silicon-based active material with a carbon content of 1% by weight or less, wherein a content of the second anode active material is 0.1% by weight to 9% by weight based on the total weight of the anode active material, and a peak intensity ratio of a Raman spectrum of the second anode active material defined by a predetermined equation is 0.5 to 2.3. Accordingly, the resistance and expansion rate of the anode are reduced, and the output characteristics of the lithium secondary battery are improved.