Lithium-Silicon Composite Oxide Anodes With Controlled Phase Balance
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Solution Overview
Problem
Lithium secondary batteries face challenges with silicon oxide anode active materials that exhibit low initial efficiency and lifespan due to irreversible phase formation during the initial charge stage, requiring an improvement in both initial efficiency and lifespan properties.
Innovation Solution
The development of lithium-silicon composite oxide particles with a specific phase fraction ratio, particle size distribution, and the inclusion of amorphous carbon, which are synthesized through a controlled firing process to enhance the anode active material's performance, including improved electrical conductivity and reduced swelling during charging and discharging.
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 the battery capacity increases, but the initial efficiency deteriorates due to formation of irreversible phase
Solution Approach 1:
The patent changes the chemical composition parameters of the silicon oxide material by introducing lithium to form lithium-silicon composite oxide (Li2SiO3 and Li2Si2O5 phases). This compositional modification transforms the material properties to reduce irreversible phase formation while maintaining high capacity, thereby improving initial efficiency without sacrificing battery capacity
Solution Approach 2:
The patent creates a composite material system by combining lithium, silicon, and oxygen to form lithium-silicon composite oxide with specific phase compositions (Li2SiO3 and Li2Si2O5). This composite approach leverages the beneficial properties of both lithium oxide and silicon oxide while mitigating their individual drawbacks, achieving both high capacity and improved initial efficiency
2Quantity of substance
If silicon oxide is used as an anode active material to achieve high capacity, then the battery capacity increases, but the lifespan deteriorates due to formation of irreversible phase
Solution Approach 1:
The patent modifies the chemical composition by introducing lithium to form lithium-silicon composite oxide, changing the material's structural and electrochemical parameters. This composition change reduces irreversible phase formation during cycling, thereby extending battery lifespan while maintaining high capacity
Solution Approach 2:
The lithium-silicon composite oxide composite material combines the high capacity characteristics of silicon oxide with the structural stability provided by lithium oxide phases, creating a material that delivers both high capacity and extended lifespan through reduced degradation mechanisms
3Reliability
If lithium-silicon composite oxide particles with specific phase ratio are used to improve initial efficiency, then the initial capacity efficiency increases, but the manufacturing complexity increases due to controlled phase fraction ratio requirement
Solution Approach 1:
The patent establishes specific parameter ranges for phase fraction ratios (I(225)/I(213) ≤ 1.0) and particle size distribution (D50 between 4-10 μm, with controlled micro-powder content). These defined parameters provide clear manufacturing targets that simplify process control while ensuring improved initial capacity efficiency, transforming a complex optimization problem into a targeted parameter specification
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 lithium-silicon composite oxide particles with a phase fraction ratio of 1.0 or less and controlled micro-powder content improve the anode's capacity and power properties, maintaining capacitance while suppressing swelling and enhancing initial capacity efficiency and lifespan.
Implementation Method 1
The lithium-silicon composite oxide particles comprise at least one selected from the group consisting of Li2SiO3 and Li2Si2O5 and have a phase fraction ratio defined by Equation 1 of 1.0 or less
Implementation Method 2
The lithium-silicon composite oxide particles may further include an amorphous carbon. Preferably, the amorphous carbon is coated onto the lithium-silicon composite oxide particles
Implementation Method 3
silicon oxide may have a low volume expansion ratio to provide enhanced life-span property
Data Source
AI summary
An anode active material for a secondary battery according to an embodiment of the present application includes lithium-silicon composite oxide particle. The lithium-silicon composite oxide particles include at least one selected from the group consisting of Li2SiO3 and Li2Si2O5 and have a phase fraction ratio defined by Equation 1 of 1.0 or less. A content of particles having a diameter of less than 3 μm is 5 vol % or less based on a total volume of the lithium-silicon composite oxide particles.