Silicon Material Bubble Skeleton for Battery Cyclability
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Solution Overview
Problem
Conventional silicon oxide-based negative-electrode active materials for lithium-ion batteries suffer from poor charge/discharge cyclability due to volumetric expansion and irreversible capacity issues, and the inclusion of metallic elements increases battery weight and cost, making them unsuitable for portable applications.
Innovation Solution
A silicon-containing material with a continuous phase of Si—Si bonds forming a three-dimensionally continuous bubble-shaped skeleton and a dispersion phase of Si—O bonds, allowing lithium to diffuse through the continuous phase without relying on the oxygen-containing phase, thereby reducing irreversible capacity and maintaining high conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If silicon oxide is used as a negative-electrode active material to improve capacity, then charge/discharge cyclability deteriorates due to volumetric expansion and pulverization
Solution Approach 1:
The silicon oxide material is segmented into microfine particles with a core-shell structure, where the core contains silicon phases for lithium sorption and the shell contains silicon oxide phases that constrain volumetric expansion. This segmentation allows the material to maintain high capacity while improving cyclability through the protective shell structure.
Solution Approach 2:
The invention uses a composite material structure combining silicon and silicon oxide phases within microfine particles. The silicon phase provides high lithium-ion capacity while the silicon oxide phase provides structural stability and constrains volumetric expansion during charge/discharge cycles, resolving the contradiction between capacity and cyclability.
2Reliability
If silicon oxide is heat treated to decompose into Si and SiO2 phases to improve cyclability, then irreversible capacity increases due to Li-Si-O system compound formation
Solution Approach 1:
The heat treatment is applied locally to form a silicon oxide shell around silicon cores in microfine particles, rather than uniform decomposition. This local quality approach ensures that the silicon oxide phase forms preferentially at the particle surfaces and interfaces, creating a protective layer that reduces irreversible capacity while maintaining cyclability improvements.
3Stability of the object's composition
If SiO2 phase is used to cover Si phases and relieve volumetric expansion, then lithium-ion diffusion rate decreases due to low electrical conductivity of Li-Si-O compounds
Solution Approach 1:
The silicon oxide phase in the microfine particles is designed with a porous or nanostructured morphology that provides multiple diffusion pathways for lithium ions. This porous structure reduces the effective diffusion distance and increases the surface area for lithium-ion transport, compensating for the low electrical conductivity of the Li-Si-O compounds while maintaining volumetric expansion constraints.
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 novel structure enhances lithium-ion battery performance by improving cyclability and reducing irreversible capacity, making it suitable for lightweight, cost-effective applications in portable devices and vehicles.
Implementation Method 1
allowing lithium to diffuse through the continuous phase without relying on the oxygen-containing phase
Implementation Method 2
a continuous phase including silicon with Si—Si bond, and possessing a bubble-shaped skeleton being continuous three-dimensionally
Data Source
AI summary
Providing a silicon-containing material having a novel structure being distinct from the structure of conventional silicon oxide disproportionated to use.A silicon-containing material according to the present invention includes at least the following: a continuous phase including silicon with Si—Si bond, and possessing a bubble-shaped skeleton being continuous three-dimensionally; and a dispersion phase including silicon with Si—O bond, and involved in an area demarcated by said continuous phase to be in a dispersed state.