Mesoporous Silicon-Carbon Anode Particles for Swelling Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The rapid increase in demand for rechargeable batteries with high capacity and light weight has necessitated the development of high-energy density batteries, which require a high-capacity negative electrode active material. Existing technologies face challenges in effectively utilizing silicon as a high-capacity negative electrode active material due to issues such as volume expansion during charging and discharging.
Innovation Solution
A negative electrode active material is developed, comprising silicon nanoparticles with an amorphous carbon coating layer and pores, specifically designed to have a sphericity of 0.9 to 1.0, a mesopore volume ratio of 30% to 70% relative to the total pore volume, and a span of 1.1 to 1.6. This material also includes a polymer layer on the amorphous carbon coating, enhancing its structural integrity and cycle-life characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If silicon is used as a high-capacity negative electrode active material, then battery capacity is improved, but volume expansion occurs during charging and discharging
Solution Approach 1:
Silicon nanoparticles are encapsulated within a porous carbon core structure, creating a nested configuration where the silicon is contained within the carbon matrix. This nested structure allows the silicon to expand and contract during lithium insertion/extraction cycles without compromising the overall structural integrity, thereby maintaining high capacity while suppressing volume expansion.
Solution Approach 2:
The carbon core is designed with a porous structure that provides void spaces to accommodate the volume expansion of silicon nanoparticles during lithiation. The porous architecture allows the silicon to swell into the pores without generating excessive stress that would lead to particle fragmentation or electrode degradation, thus maintaining structural stability during cycling.
2Use of energy by moving object
If silicon nanoparticles are used to increase capacity, then energy density is improved, but structural stability deteriorates due to volume expansion
Solution Approach 1:
The invention employs a composite material system consisting of silicon nanoparticles embedded in a porous carbon core. The carbon component provides structural stability and mechanical strength, while the silicon provides high capacity. The synergistic combination allows the electrode to maintain structural integrity during cycling while achieving high energy density through the silicon's lithium storage capability.
Solution Approach 2:
The porous carbon core acts as an intermediary between the silicon nanoparticles and the electrolyte, providing a stable structural framework that mediates the volume changes of silicon during cycling. The carbon matrix absorbs and distributes the mechanical stress generated by silicon expansion, preventing direct contact between the expanding silicon and the electrolyte, thereby maintaining structural stability.
3Reliability
If conventional negative electrode materials are used, then structural stability is maintained, but battery capacity is limited
Solution Approach 1:
The invention applies local quality by concentrating the high-capacity silicon material in specific regions (nanoparticles within the porous core) rather than using it uniformly throughout the electrode. This localized placement of silicon within the stable carbon matrix allows the electrode to achieve high capacity where needed while maintaining overall structural stability through the carbon framework.
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 developed negative electrode active material effectively suppresses volume expansion during charging and discharging, improves cycle-life characteristics, and enhances the distribution and stability of the active material within the battery, leading to improved performance and efficiency of rechargeable lithium batteries.
Implementation Method 1
amorphous carbon coating layer on a surface of the silicon nanoparticles... effectively suppresses volume expansion during charging and discharging
Implementation Method 2
pores... including mesopores... ratio of a mesopores volume relative to a total pore volume... about 30% or more and less than about 70%
Data Source
AI summary
A negative electrode active material, including silicon nanoparticles including an amorphous carbon coating layer on a surface of the silicon nanoparticles; and pores, wherein the negative electrode active material has a sphericity as represented by Equation 1 of about 0.9 to about 1.0, and the pores include mesopores, and a ratio of a mesopores volume relative to a total pore volume of the negative electrode active material is about 30% or more and less than about 70%, andSphericity (S)=4π×A/B2[Equation 1]in Equation 1, A is an area of the negative electrode active material and B is a circumference of a shape of the negative electrode active material.