Carbon-Coated Natural Graphite Anodes With Controlled Porosity
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Solution Overview
Problem
Natural graphite-based negative electrode active materials for secondary batteries face challenges with high porosity and low mechanical strength, leading to side reactions with electrolytes and reduced lifespan.
Innovation Solution
A negative electrode active material is developed using natural graphite particles with a carbon coating layer on their surface and inside, processed through a first baking treatment at 1,130° C. to 1,800° C. and a second baking treatment, resulting in a porosity of 3% to 13%.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If natural graphite is used as negative electrode active material, then output and capacity characteristics are improved, but side reaction with electrolyte solution increases and life characteristic deteriorates
Solution Approach 1:
The patent applies composite materials by combining natural graphite particles with a carbon coating layer. The carbon coating layer is formed by coating liquid pitch onto the natural graphite particles and performing a baking treatment, creating a composite structure that preserves the high output characteristics of natural graphite while adding protective properties to improve life characteristic and reduce side reactions with electrolyte.
Solution Approach 2:
The patent applies parameter changes by controlling the porosity of the natural graphite particles within a specific range of 3% to 13%. By optimizing this physical parameter and performing baking treatment at specific temperatures, the patent achieves a balance between maintaining high output characteristics and reducing side reactions with electrolyte, thereby improving life characteristic.
2Productivity
If natural graphite has high porosity, then output characteristic is improved, but side reaction with electrolyte solution becomes strong
Solution Approach 1:
The patent applies parameter changes by precisely controlling the porosity of natural graphite particles within the range of 3% to 13%. This optimization allows the material to maintain high output characteristics while minimizing excessive porosity that would lead to strong side reactions with electrolyte solution.
Solution Approach 2:
The patent applies composite materials by forming a carbon coating layer on the natural graphite particles. This coating layer modifies the surface properties and internal pore structure, reducing the harmful side reactions with electrolyte while preserving the beneficial output characteristics through controlled porosity.
3Ease of manufacture
If natural graphite has low mechanical strength, then ease of processing is improved, but life characteristic deteriorates
Solution Approach 1:
The patent applies composite materials by creating a carbon-coated natural graphite structure. The carbon coating layer reinforces the mechanical strength of the natural graphite particles, improving life characteristic and durability while maintaining processability through the coating formation process involving liquid pitch and baking treatment.
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 approach significantly reduces side reactions with electrolytes, enhances mechanical durability, and improves both output and life characteristics of the negative electrode active material.
Implementation Method 1
subjecting natural graphite to a first baking treatment at 1,130° C. to 1,800° C.
Implementation Method 2
mixing the first baking-treated natural graphite and a liquid pitch to form a carbon coating layer which coats a surface and an inside of the natural graphite
Implementation Method 3
subjecting the natural graphite having the carbon coating layer formed on the surface and in the inside thereof to a second baking treatment
Data Source
AI summary
A negative electrode active material for a secondary battery including: natural graphite particles; and a carbon coating layer on a surface and in an inside of the natural graphite particles. The negative electrode active material for a secondary battery has a porosity of 3% to 13%.