Carbon-Coated SiOx Anode Material for Cycle-Stable Li-Ion Batteries
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Solution Overview
Problem
Lithium-ion secondary batteries using silicon as a negative electrode active material face issues with low first-time efficiency and cycle stability due to the expansion and shrinkage of the material during charging and discharging, leading to decomposition of the electrolytic solution and reduced cycle characteristics.
Innovation Solution
A negative electrode active material comprising silicon compound particles coated with a carbon layer containing O—C═O and C—C bonds, with a specific ratio of carbon coating and incorporating Li2SiO3, enhances stability and conductivity, reducing irreversible capacity and improving adhesion to binders.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If silicon is used as a negative electrode active material to improve battery capacity, then the theoretical capacity increases ten times or more compared to graphite, but the material expands and shrinks during charging and discharging, causing breakage and reduced cycle characteristics
Solution Approach 1:
The patent applies the nesting principle by placing silicon particles inside a carbon coating layer, forming a core-shell structure where the silicon core provides high capacity while the carbon shell provides structural stability and prevents breakage during expansion and shrinkage cycles
Solution Approach 2:
The patent uses composite materials by combining silicon with carbon to form a composite structure, where the silicon provides high theoretical capacity (4199 mAh/g) and the carbon matrix provides mechanical strength and structural integrity, creating a material that exhibits both high capacity and good cycle stability
2Quantity of substance
If silicon oxide is doped with lithium to improve first-time efficiency and cycle characteristics, then the irreversible component is reduced and capacity increases, but the first-time efficiency remains low compared to positive electrode materials like LiCoO2
Solution Approach 1:
The patent applies parameter changes by precisely controlling the oxygen content parameter in silicon oxide (making it SiOx where 0.5 ≤ x ≤ 1.6) and controlling the carbon coating thickness (0.1-5 μm), thereby optimizing both first-time efficiency and cycle characteristics while maintaining high capacity
3Quantity of substance
If the surface layer of the negative electrode active material breaks during charging and discharging, then a new surface is created increasing the reaction area, but this causes decomposition of the electrolytic solution and consumes electrolyte, reducing cycle characteristics
Solution Approach 1:
The patent converts the harmful effect of surface breakage into a beneficial effect by using carbon coating. The carbon layer allows controlled surface renewal that increases reaction area while preventing excessive electrolyte decomposition, as the carbon-coated surface is more stable and less prone to causing harmful side reactions with the electrolyte
4Reliability
If a carbon coating is applied to silicon compound particles to enhance stability and conductivity, then cycle characteristics improve, but the amount of carbon coating must be precisely controlled to maintain high capacity
Solution Approach 1:
The patent applies parameter changes by optimizing the carbon coating thickness parameter to a specific range (0.1-5 μm) and controlling the carbon content ratio (1-90 mass % of silicon compound). This precise parameter control ensures sufficient structural support and conductivity improvement while minimizing the dilution effect that would reduce overall battery 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 solution results in a high-capacity battery with improved cycle retention and first-time efficiency, suitable for industrial production and use in various applications.
Implementation Method 1
the negative electrode active material particles are at least partially coated with a carbon coating
Implementation Method 2
silicon compound particles containing a silicon compound (SiOx: 0.5≤x≤1.6), wherein the silicon compound particles are a negative electrode active material for a non-aqueous electrolyte secondary battery containing a Li compound
Data Source
AI summary
A negative electrode active material for a non-aqueous electrolyte secondary battery containing negative electrode active material particles which include silicon compound particles containing a silicon compound (SiOx: 0.5≤x≤1.6), wherein the silicon compound particles are a negative electrode active material for a non-aqueous electrolyte secondary battery containing a Li compound, the material particles are at least partially coated with a carbon coating, an amount of the carbon coating relative to a total amount of the silicon compound particles and carbon coating is larger than 0 mass % and 1 mass % or less, the carbon coating contains a coating composed of at least any one of a compound having O—C═O bond and a compound having C—C bond, and the silicon compound particles contain crystalline Li2SiO3 as the Li compound. Thereby, the negative electrode active material for a non-aqueous electrolyte secondary battery having a large capacity, excellent cycle characteristics, and first-time efficiency is provided.