Silicon Anode Composite With Nitride Phase for Cycle Durability
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Silicon compounds in negative electrode active materials for secondary batteries are prone to erosion due to side reactions, leading to capacity degradation and reduced durability.
Innovation Solution
Incorporating a silicon nitride phase dispersed in a silicon compound phase, such as silicon oxide or silicate phase, to enhance durability and improve charge and discharge cycle characteristics by mitigating stress from lithium ion expansion and contraction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If silicon compound phase is used in negative electrode active material, then theoretical capacity density improves, but durability deteriorates due to erosion from side reactions with hydrogen fluoride
Solution Approach 1:
The patent employs a composite material structure consisting of a silicon compound phase (such as silicon oxide or silicate) combined with a silicon nitride phase. The silicon nitride phase acts as a protective component that reduces erosion from hydrogen fluoride while the silicon compound phase provides high theoretical capacity density through lithium alloying. This composite approach allows simultaneous achievement of high capacity and improved durability.
Solution Approach 2:
The silicon nitride phase serves as an intermediary protective layer between the silicon compound phase and the corrosive hydrogen fluoride in the electrolyte. It mediates the interaction by providing chemical stability and resistance to erosion, thereby protecting the reactive silicon compound phase from degradation while allowing lithium ion transport.
2Quantity of substance
If silicon compound phase is used to achieve high capacity, then charge and discharge cycle characteristics worsen due to gradual erosion and capacity deterioration
Solution Approach 1:
The composite structure of silicon compound phase with dispersed silicon nitride phase provides both high capacity and improved cycle characteristics. The silicon nitride phase maintains structural integrity during charge-discharge cycles and protects against gradual erosion, enabling sustained performance over extended cycling.
Solution Approach 2:
The silicon nitride phase is dispersed locally within the silicon compound phase, providing targeted protection at specific locations where erosion is most likely to occur. This local reinforcement strategy maintains overall high capacity while improving durability at critical interfaces.
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 silicon nitride phase effectively suppresses erosion of the silicon compound phase, resulting in improved durability and enhanced charge and discharge cycle characteristics of secondary batteries.
Implementation Method 1
use of a material containing silicon capable of being alloyed with lithium
Implementation Method 2
a silicon nitride phase dispersed in the silicon compound phase, wherein the silicon compound phase is at least one of a silicon oxide phase and a silicate phase
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
A negative electrode active material for a secondary battery includes Si-containing particles, wherein the Si-containing particles include a silicon compound phase, a silicon phase dispersed in the silicon compound phase, and a silicon nitride phase dispersed in the silicon compound phase, and the silicon compound phase is at least one of a silicon oxide phase and a silicate phase.