Magnesium-Silicon Anode Material for High-Capacity Battery Lifespan
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Solution Overview
Problem
Lithium secondary batteries using silicon oxide as an anode active material face challenges such as gas generation in aqueous slurry states, leading to decreased lifespan characteristics and insufficient capacity characteristics.
Innovation Solution
The use of magnesium-silicon composite oxide particles, characterized by specific element content ratios and phase fractions, as an anode active material in lithium secondary batteries. These particles comprise MgSiO3, Mg2SiO4, and silicon, with defined ratios to enhance stability and performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If silicon oxide is used as an anode active material to achieve high capacity, then capacity characteristics are improved, but gas is generated in aqueous slurry state leading to decreased lifespan characteristics
Solution Approach 1:
The patent uses a composite material consisting of silicon oxide particles coated with a specific type of carbon material. This composite structure allows the silicon oxide to provide high capacity while the carbon coating prevents gas generation and improves stability in aqueous slurry state, thereby resolving the contradiction between capacity characteristics and lifespan characteristics
Solution Approach 2:
The patent changes the parameters of the carbon coating, specifically using amorphous carbon with controlled graphitization (0-50%) rather than fully crystalline carbon. This parameter change in the carbon structure optimizes both capacity retention and lifespan by balancing conductivity with gas suppression properties
2Quantity of substance
If silicon oxide is used as an anode active material to achieve high capacity, then capacity characteristics are improved, but initial efficiency is insufficient
Solution Approach 1:
The carbon-coated silicon oxide composite structure improves initial efficiency by providing better electronic conductivity through the amorphous carbon layer while maintaining the high capacity of silicon oxide. The composite design ensures efficient lithium ion insertion and extraction from the first cycle
Data Source
AI summary
An anode active material for a lithium secondary battery comprising magnesium-silicon composite oxide particles comprising MgSiO3 and silicon and having a ratio of magnesium to total magnesium, silicon, and oxygen of about 0.07 to about 0.17. A secondary lithium battery comprising the anode active material is provided having enhanced capacity and lifespan.