Metal-Doped Silicon Oxide Anode Material for Expansion Damage Control
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Solution Overview
Problem
Silicon-based negative electrode active materials in lithium secondary batteries face issues with volume expansion and damage during charge/discharge cycles, leading to reduced lifespan and capacity performance.
Innovation Solution
A negative electrode active material is developed using silicon-based oxide particles with a metal distributed on their surface or inside, featuring a compressive fracture strength of 170 MPa to 380 MPa and Si crystal grains of 3 nm to 20 nm, which are heat-treated with a metal-containing material to enhance structural stability and prevent damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If silicon-based negative electrode active material is used to achieve high capacity and high energy density, then capacity and energy density are improved, but volume expansion and particle damage occur during charge/discharge cycles
Solution Approach 1:
The patent uses a composite structure consisting of silicon-based oxide particles embedded in a porous carbon matrix. The carbon matrix provides structural support and prevents particle damage during volume expansion, while the silicon-based oxide particles provide high capacity. This composite approach resolves the contradiction by combining materials with complementary properties.
Solution Approach 2:
The patent employs porous carbon material as the matrix structure. The porous structure accommodates volume expansion of silicon-based oxide particles during lithiation, preventing particle cracking and maintaining structural integrity. The pores act as buffer spaces that absorb expansion stress, thereby preserving particle integrity while maintaining high capacity.
2Quantity of substance
If silicon-based negative electrode active material is used to achieve high capacity, then energy density is improved, but lifespan properties deteriorate due to volume expansion and particle damage
Solution Approach 1:
The composite structure of silicon-based oxide particles in a porous carbon matrix provides both high capacity and long lifespan. The carbon matrix protects silicon particles from degradation during cycling, while the porous structure accommodates volume changes. This combination maintains structural integrity over many cycles, resolving the contradiction between capacity and lifespan.
Solution Approach 2:
The patent applies different material properties to different regions: silicon-based oxide particles provide high capacity in specific locations, while the surrounding porous carbon matrix provides structural stability and protection. This local differentiation allows the system to achieve both high capacity and long lifespan by optimizing each region for its specific function.
3Quantity of substance
If conventional silicon-based active material is used, then high capacity is achieved, but cracks and damage to active material particles occur during charge/discharge
Solution Approach 1:
The patent creates a composite where porous carbon matrix surrounds and supports silicon-based oxide particles. The carbon matrix provides mechanical strength and prevents particle cracking, while silicon-based oxide particles maintain high capacity. This composite structure resolves the contradiction between capacity and particle strength.
Solution Approach 2:
The porous carbon matrix acts as a flexible protective shell around silicon-based oxide particles. This shell can accommodate volume expansion and contraction during charge/discharge cycles without breaking, thereby protecting the internal particles from mechanical damage while maintaining their high capacity.
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 effectively prevents active material damage and improves lifespan performance by controlling volume expansion and maintaining high capacity properties, resulting in enhanced battery performance.
Implementation Method 1
heat-treated with a metal-containing material to enhance structural stability and prevent damage
Data Source
AI summary
The present invention relates to a negative electrode active material including silicon-based oxide particles and a metal distributed on a surface, inside, or on the surface of and the inside the silicon-based oxide particles, wherein compressive fracture strength measured at a pressure of 100 mN is 170 MPa to 380 MPa, and the silicon-based oxide particles contain Si crystal grains having a crystal grain size of 3 nm to 20 nm.