Spherical SiOx Anode Particles for Low-Expansion Li-Ion Cycling
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Solution Overview
Problem
SiOx negative electrode materials for lithium ion batteries face challenges with high volume expansion during cycling, leading to instability and reduced performance due to non-uniform particle shapes causing electrolyte infiltration and SEI film fractures.
Innovation Solution
A silicon oxygen material with spherical primary particles having a Wadell sphericity greater than 0.92, potentially doped with reducing metals or metal compounds, is developed to maintain structural stability and minimize volume expansion by uniform contraction and expansion, reducing electrolyte infiltration and SEI film generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If SiOx negative electrode material is used, then high capacity is achieved, but volume expansion rate reaches about 200% during cycling
Solution Approach 1:
The SiOx particles are divided into primary particles (1-10 μm) that aggregate into secondary particles (10-50 μm). This segmentation allows the primary particles to undergo uniform volume expansion during lithium insertion/extraction, preventing structural collapse while maintaining high capacity. The secondary particle structure provides additional space to accommodate expansion.
Solution Approach 2:
Primary SiOx particles are nested within secondary particle structures, creating a hierarchical architecture. The primary particles are distributed within the secondary particles, allowing each primary particle to expand independently while the secondary particle structure provides overall structural support and accommodates total volume changes.
2Ease of manufacture
If non-spherical particles are used, then manufacturing is easier, but structural stability deteriorates due to non-uniform stress distribution
Solution Approach 1:
The SiOx particles are designed with high sphericity (Wadell sphericity ≥0.92). Spherical shapes ensure uniform stress distribution during volume expansion and contraction, preventing the formation of weak spots and structural collapse. The spherical morphology is achieved through controlled aggregation of primary particles into secondary particles.
3Productivity
If high surface area particles are used, then reactivity is improved, but SEI film generation increases causing irreversible capacity loss
Solution Approach 1:
The particle system is segmented into primary particles (1-10 μm) and secondary particles (10-50 μm). This segmentation optimizes the balance between surface area and SEI film generation. The small primary particles provide high reactivity, while their aggregation into secondary particles reduces the total exposed surface area, minimizing SEI film formation and irreversible capacity loss.
4Volume of moving object
If particle structure collapses during cycling, then volume expansion is reduced, but electrolyte infiltration increases causing continuous SEI film generation
Solution Approach 1:
The spherical particle structure with high sphericity ensures uniform stress distribution during volume expansion, preventing structural collapse and the formation of weak spots. This maintains particle integrity throughout cycling, preventing electrolyte infiltration and continuous SEI film generation while accommodating the necessary volume expansion for 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 spherical silicon oxygen material enhances cycling performance and reduces irreversible capacity loss by maintaining structural integrity and minimizing SEI film growth, leading to improved capacity retention and rate performance.
Implementation Method 1
The spherical particles have an isotropic feature so that they are uniformly contract and expand outward along a radial direction during a cycling process
Implementation Method 2
feeding raw materials for preparing a silicon oxygen material into a plasma stream to react
Implementation Method 3
cooling the reacted product to obtain a silicon oxygen material including silicon oxide
Implementation Method 4
The silicon oxide is primary particles of the spherical silicon oxide
Data Source
AI summary
A silicon oxygen material, a negative electrode material, and its preparation method, and a lithium ion battery is disclosed. The silicon oxygen material includes a silicon oxide having a chemical formula SiOx, where 0<x<2, wherein the silicon oxygen material is primary particles having a Wadell sphericity greater than 0.92. The negative electrode material provided by the present disclosure includes the silicon oxide having a high sphericity, the silicon oxide has a more stable structure during a cycling process, so that it is capable of avoiding the problem of cracking of particles of the material due to repeated generation of the SEI film, thereby improving cycling performance of the material and reducing the volume expansion due to SEI film generation.