Silicon-Based Anode Material With Lithium Metasilicate Buffering
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Solution Overview
Problem
Silicon-based materials for secondary batteries suffer from poor cycling performance due to large volume changes during lithium intercalation and deintercalation, and poor structural stability, limiting their large-scale application.
Innovation Solution
A silicon-based material with a core-shell structure is developed, where the core structure includes both a silicon phase and a lithium metasilicate phase with a particle size ≥30nm, and a coating layer is applied to enhance stability and prevent electrolyte contact.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If silicon-based materials are used to increase energy density, then specific capacity is improved, but structural stability deteriorates due to large volume changes during lithium intercalation and deintercalation
Solution Approach 1:
The patent employs a composite material structure consisting of silicon phase particles embedded in a lithium metasilicate phase matrix. The silicon phase provides high specific capacity (theoretically up to 3600mAh/g) while the lithium metasilicate phase acts as a stable matrix that constrains volume expansion during lithium intercalation. This composite approach allows the material to achieve both high energy density and structural stability, resolving the contradiction between specific capacity and structural stability.
2Reliability
If silicon phase particle size is reduced to improve cycling performance, then structural stability is improved, but chemical stability deteriorates due to increased contact areas with water, air, and electrolyte
Solution Approach 1:
The lithium metasilicate phase serves as an intermediary protective matrix that surrounds and isolates the silicon phase particles from direct contact with water, air, and electrolyte. This intermediary layer reduces the harmful chemical interactions while still allowing mechanical support and lithium ion transport, thus improving both cycling performance and chemical stability simultaneously.
Solution Approach 2:
The lithium metasilicate phase forms a thin film-like matrix structure that envelops the silicon particles. This shell-like structure provides protective isolation from the external environment (water, air, electrolyte) while maintaining flexibility to accommodate volume changes during lithium intercalation, thereby protecting the silicon phase from chemical degradation.
3Reliability
If lithium metasilicate phase particle size is reduced to improve lithium ion conduction, then cycling performance is improved, but structural stability deteriorates due to reduced buffering capacity
Solution Approach 1:
The patent optimizes the particle size parameter of the lithium metasilicate phase to a specific range (30-100nm) where it achieves an optimal balance between lithium ion conduction and structural stability. Within this size range, the particles are small enough to provide efficient lithium ion pathways for good cycling performance, yet large enough to maintain sufficient mechanical strength and buffering capacity to constrain silicon phase expansion.
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-based material achieves improved structural and chemical stability, leading to enhanced cycling performance and first-cycle coulombic efficiency of secondary batteries, while increasing energy density.
Implementation Method 1
The lithium metasilicate phase having the above particle size can effectively offset shrinkage and swelling of the silicon phase during intercalation and deintercalation of lithium ions, increasing structural stability of the silicon phase
Implementation Method 2
The lithium metasilicate phase having the above particle size can also allow the silicon-based material to have notable chemical stability, reducing contact areas of the lithium metasilicate phase with water, air, electrolyte, and the like during preparation of the secondary battery
Data Source
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AI summary
This application provides a silicon-based material, a preparation method thereof, and a secondary battery, a battery module, a battery pack, and an apparatus associated therewith. The silicon-based material includes a core structure and a coating layer provided on at least partial surface of the core structure, where the core structure includes both a silicon phase and a lithium metasilicate phase, and a particle size P of the lithium metasilicate phase is ≥30nm. The silicon-based material of this application can not only increase energy density of a secondary battery with the silicon phase, but also improve structural stability and chemical stability of the silicon-based material, so that the secondary battery can deliver satisfactory and balanced cycling performance and first-cycle coulombic efficiency in overall.