Carbon-Coated Silicon Anode Structure for Electrolyte Isolation

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Solution Overview

Problem

Lithium ion batteries using silicon-based anode materials face challenges such as side reactions with electrolytes, structure damage, capacity degradation, and reduced cycling stability, making them difficult to commercialize.

Innovation Solution

An anode material composed of a carbon-silicon aggregate with controlled porosity and a carbon layer, where the porosity is ≤2.5% and the quantity proportion of particles with a pore diameter >50 nm is ≤1%, effectively inhibiting electrolyte penetration and side reactions, while the carbon layer enhances protection and conductivity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If silicon-based material is used as anode material to increase energy density, then battery energy density is improved, but side reactions with electrolyte occur causing structure damage and capacity degradation

Engineering Contradiction:

Improvebattery energy densityVSAvoidcycling stability

Core Design Contradiction:

Use of energy by moving objectVSReliability

Solution Approach 1:

A carbon coating layer is applied as an intermediary between the silicon-based material and the electrolyte. This carbon layer prevents direct contact and side reactions while allowing lithium ion transport, thus protecting the silicon structure and improving cycling stability without sacrificing energy density

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The anode is designed as a composite structure combining silicon-based material with carbon materials. The silicon provides high capacity while the carbon matrix provides structural stability and prevents electrolyte penetration, creating a synergistic effect that resolves the contradiction between energy density and cycling stability

Inventive Principle:

Principle #40Composite materials

2Productivity

If porosity of anode material is increased to improve electrolyte penetration, then lithium ion transport is enhanced, but electrolyte directly contacts silicon-based material causing side reactions

Engineering Contradiction:

Improvelithium ion transport rateVSAvoidside reaction between electrolyte and silicon-based material

Core Design Contradiction:

ProductivityVSObject-generated harmful factors

Solution Approach 1:

The carbon coating layer serves as a mediator that allows beneficial lithium ion transport while blocking harmful electrolyte contact. It selectively permits ion diffusion while preventing direct interaction between electrolyte and silicon-based material

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The anode structure exhibits local quality differentiation: the carbon coating layer has properties that allow ion transport but prevent electrolyte penetration, while the interior silicon-based material maintains high capacity. Different regions serve different functions to resolve the contradiction

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 solution significantly improves the cycle performance and stability of lithium ion batteries by preventing electrolyte penetration, reducing volume expansion, and maintaining structural integrity, thus enhancing the batteries' overall performance and lifespan.

Implementation Method 1

The anode material has a porosity W of ≤2.5%, and particles with a pore diameter of >50 nm in the anode material has a quantity proportion P of ≤1%. The porosity of the anode material is obtained by the following test method: a pore volume ΔV of the anode material is tested by using a micro-pores size distribution method; and a true density P of the anode material is tested, and the porosity W of the anode material is calculated to be W=ΔV/(ΔV+1/P).

Methodology Applied

Scientific EffectPhysical barrier effect:

Implementation Method 2

The aggregate has a structure beneficially protecting the silicon-based material particles therein, effectively inhibiting volume expansion of the anode material, reducing expansion rate, and improving cycle performance of the battery.

Methodology Applied

Scientific EffectVolume expansion control:

Implementation Method 3

In an embodiment, the anode material further includes a carbon layer present on at least a part of surface of the aggregate.

Methodology Applied

Scientific EffectProtective coating effect: Coatings

Data Source

PatentUS20250051166A1Anode material, preparation method thereof, and lithium ion battery

Publication Date: 2025.02.13 BTR NEW MATERIAL GRP CO LTD

AI summary

Relating to the field of anode material, an anode material, a preparation method thereof and a lithium ion battery provided. The anode material includes an aggregate, and the aggregate includes a carbon material and a silicon-based material, where the anode material has a porosity W of ≤2.5%, and particles with a pore diameter of >50 nm in the anode material has a quantity proportion P of ≤1%. The porosity of the anode material is obtained by the following test method: a pore volume ΔV of the anode material is tested by using a micro-pores size distribution method; and a true density P of the anode material is tested, and the porosity W of the anode material is calculated to be W=ΔV/(ΔV+1/P). The anode material effectively isolates electrolyte, prevents structure of the anode material from collapsing, and improves cycle performance of the battery.