Silicon Electrode Active Material for Battery Volume Expansion
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Solution Overview
Problem
Silicon-based electrode materials for secondary batteries face challenges due to volume expansion during lithium ion intercalation/deintercalation, leading to mechanical strain, degradation, and reduced lifespan, as well as difficulties in controlling the solid electrolyte interphase layer and maintaining charge/discharge characteristics.
Innovation Solution
An electrode active material comprising secondary particles made of silicon-containing primary particles, an electrically conductive material, and a chemically cross-linked water-insoluble polymer, which controls lithium ion reaction and diffusion without blocking electron transport, thereby improving charge/discharge characteristics and lifespan.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If silicon-based material is used as electrode active material to achieve high capacity, then theoretical capacity reaches about 3,570 mAh/g, but volume expansion of up to 300% occurs during lithium ion intercalation/deintercalation
Solution Approach 1:
The silicon-based electrode active material is divided into primary particles (1-100 nm) that are aggregated to form secondary particles (1-10 μm). This segmentation allows the material to accommodate volume expansion at the primary particle level while maintaining overall structural integrity at the secondary particle level, resolving the contradiction between high capacity and volume expansion.
Solution Approach 2:
The invention creates a composite structure where primary silicon-containing particles are aggregated into secondary particles with controlled morphology. This composite approach enables the material to achieve high theoretical capacity while the aggregated structure provides space to accommodate volume expansion, preventing mechanical degradation.
2Stability of the object's composition
If volume expansion is controlled to maintain structural integrity, then mechanical strain and degradation are reduced, but charge/discharge characteristics and lifespan deteriorate
Solution Approach 1:
The invention applies different structural characteristics to different levels: primary particles (1-100 nm) provide flexibility to accommodate local volume changes, while secondary particles (1-10 μm) maintain overall structural integrity. This local quality differentiation allows the material to simultaneously achieve structural stability and good charge/discharge characteristics.
3Volume of stationary object
If primary fine particles are sintered to form composite particles, then material density increases, but control over solid electrolyte interphase layer and charge/discharge characteristics becomes difficult
Solution Approach 1:
The invention creates a dynamic hierarchical structure where primary particles can move and rearrange within the secondary particle framework during lithium ion intercalation and deintercalation. This dynamic structure allows the material to maintain density while adapting to volume changes, enabling better control over the solid electrolyte interphase layer and charge/discharge characteristics.
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 proposed solution enhances the charge/discharge performance and extends the lifespan of silicon-based secondary batteries by effectively managing lithium ion reactions and diffusion, maintaining capacity and cycle stability.
Implementation Method 1
controls a reaction and diffusion of lithium ions
Implementation Method 2
during intercalation/deintercalation of lithium ions
Data Source
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AI summary
An electrode active material including a secondary particle, the secondary particle including: a plurality of primary particles including a silicon-containing material; an electrically conductive material; and a chemically cross-linked water-insoluble polymer. Also an electrode, and a secondary battery, both of which include the electrode active material, and a method of preparing the electrode active material.