Silicon Oxide-Coated Negative Active Material for Conductive Path Stability
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Silicon-based negative electrode active materials in lithium secondary batteries face issues such as volume expansion during charging, leading to disconnection of conductive paths and generation of gases, which deteriorate battery performance and service life.
Innovation Solution
A silicon-based active material coated with a silicon oxide layer containing at least 40% oxygen by atomic percentage, formed through chemical deposition and heat or chemical treatment, to act as a protective layer preventing solvent reactions and uniform lithium intercalation/deintercalation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a silicon-based compound is used as a negative electrode active material to increase capacity, then the discharge capacity is improved, but the volume rapidly expands during charging causing disconnection of conductive paths and deterioration of battery characteristics
Solution Approach 1:
A coating layer comprising silicon oxide and silicon oxynitride is formed on the surface of the silicon-based compound particles. This thin film coating accommodates the volume expansion of the silicon core during charging while maintaining structural integrity and preventing conductive path disconnection, thus resolving the contradiction between high capacity and conductive path stability.
Solution Approach 2:
The coating layer is composed of a composite material system including silicon oxide and silicon oxynitride in specific ratios. This composite structure provides both mechanical flexibility to accommodate volume changes and chemical stability to prevent harmful reactions, enabling the silicon-based material to maintain both high capacity and reliable conductive paths.
2Quantity of substance
If a silicon-based compound is used as a negative electrode active material to increase capacity, then the discharge capacity is improved, but gases are generated due to reaction with slurry solvent causing non-uniform electrode coating and deterioration of service life characteristics
Solution Approach 1:
The coating layer comprising silicon oxide and silicon oxynitride acts as an intermediary barrier between the silicon-based compound and the slurry solvent. This intermediate layer prevents direct contact and harmful chemical reactions between the silicon and solvent, thereby eliminating gas generation while allowing the silicon to maintain its high capacity functionality.
3Reliability
If the particle diameter of the silicon-based compound is reduced to suppress volume expansion, then the conductive path stability is improved, but the manufacturing complexity increases
Solution Approach 1:
Instead of relying solely on reducing particle diameter, the invention changes the approach by modifying the surface composition through coating with silicon oxide and silicon oxynitride. This parameter change in surface chemistry allows larger particles to be used while still maintaining conductive path stability, thereby reducing manufacturing complexity associated with precise particle size control.
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 oxide coating reduces stress on the active material, prevents gas generation, and enhances electrode stability, improving service life and capacity performance.
Implementation Method 1
the generation of gases due to reaction with a solvent still occurs, so that problems such as non-uniform electrode coating and deterioration in service life characteristics occur
Implementation Method 2
the reaction occurs uniformly and the stress applied to the silicon-based active material is reduced
Implementation Method 3
uniform lithium intercalation/deintercalation
Data Source
AI summary
A negative electrode active material, a method for preparing the same, a negative electrode composition and a negative electrode including the same, and a lithium secondary battery including the negative electrode are provided.