Silicon Oxide Anode Particles With Li States for Longer Cycle Life
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Solution Overview
Problem
Lithium-ion secondary batteries using silicon materials face challenges in achieving cycle characteristics equivalent to those of carbon-based active materials, with silicon materials exhibiting inferior cycle characteristics and no proposed solutions offering equivalent performance.
Innovation Solution
A negative electrode active material comprising a silicon compound particle with a Li compound, where at least part of Si is present in oxide states of Si2+ to Si3+ and compounds containing Li and Si2+ to Si3+, along with a carbon material coating, to improve battery capacity and cycle characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If silicon material is used as negative electrode active material to improve battery capacity, then battery capacity increases, but cycle characteristics deteriorate due to material breakage and electrolyte decomposition
Solution Approach 1:
The invention uses a composite material structure where silicon oxide particles are coated with carbon material. The silicon oxide core provides high capacity while the carbon coating prevents breakage and electrolyte decomposition, resolving the contradiction between capacity and cycle characteristics
Solution Approach 2:
The invention changes the chemical state of silicon from metallic silicon to silicon oxide, and controls the oxygen content to 30-70 at%. This parameter change stabilizes the material structure during charging-discharging cycles, improving cycle characteristics while maintaining high capacity
2Reliability
If silicon oxide particles are used to improve cycle characteristics, then reliability improves, but battery capacity decreases compared to metallic silicon
Solution Approach 1:
The invention optimizes the oxygen content parameter to a specific range (30-70 at%) rather than using stoichiometric silicon oxide. This parameter optimization maintains structural stability for good cycle characteristics while preserving enough silicon for high capacity
3Reliability
If carbon coating is applied to silicon oxide particles to improve conductivity and safety, then electric conductivity improves, but manufacturing complexity increases
Solution Approach 1:
The invention uses thermal decomposition of organic substance at high temperature to form carbon coating on silicon oxide particles. This phase transition approach creates a protective carbon layer that improves conductivity and safety while being integrated into the material synthesis process
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 solution enhances battery capacity and cycle characteristics by stabilizing the phase structure during charging and discharging, reducing irreversible capacity, and improving electric conductivity, resulting in high-capacity and efficient lithium-ion secondary batteries.
Implementation Method 1
stabilizing the phase structure during charging and discharging
Implementation Method 2
improving electric conductivity
Data Source
AI summary
Methods for producing a negative electrode active material particle which includes a silicon compound particle containing a silicon compound that contains oxygen. The methods including preparing a silicon compound particle containing a silicon compound that contains oxygen; inserting Li into the silicon compound particle; and heating, while stirring, the Li-inserted silicon compound particle in a furnace to produce a negative electrode active material particle, wherein at least part of Si constituting the silicon compound particle is present in at least one state selected from oxide of Si2+ to Si3+ containing no Li, and compound containing Li and Si2+ to Si3+.