Silicon-Lithium Aluminate Anode Composite for Low Irreversible Capacity
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Solution Overview
Problem
Lithium silicate-based negative electrode active materials for non-aqueous electrolyte secondary batteries suffer from poor alkali resistance and side reactions with Li ions, leading to reduced initial charge-discharge efficiency.
Innovation Solution
A negative electrode active material comprising composite particles with a lithium aluminate phase and a silicon phase dispersed within, enhancing alkali resistance and ion conductivity, thereby suppressing side reactions and improving initial charge-discharge efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If lithium silicate phase is used as negative electrode active material, then irreversible capacity is reduced and initial charge-discharge efficiency is improved, but alkali resistance deteriorates and side reactions with Li ions occur
Solution Approach 1:
The patent uses a composite material consisting of lithium aluminate phase and silicon phase. The lithium aluminate phase provides excellent alkali resistance and structural stability, while the silicon phase contributes high theoretical capacity. This composite structure resolves the contradiction by combining materials with complementary properties, achieving both low irreversible capacity and high alkali resistance simultaneously.
Solution Approach 2:
The patent changes the chemical composition parameter from lithium silicate (Li2SiO3) to lithium aluminate (LiAlO2). This parameter change fundamentally alters the material's chemical properties, providing superior alkali resistance while maintaining the desired electrochemical performance. The substitution of silicon with aluminum in the oxide phase resolves the alkali resistance issue.
2Quantity of substance
If silicon particles are dispersed in SiO2 phase, then high theoretical capacity density is achieved, but initial charge-discharge efficiency deteriorates due to large irreversible capacity
Solution Approach 1:
The patent creates a composite structure where silicon particles are dispersed in lithium aluminate phase instead of SiO2 phase. The lithium aluminate phase provides a more stable and reactive environment that reduces irreversible capacity formation during initial charging, thereby improving initial charge-discharge efficiency while maintaining the high capacity benefits of silicon dispersion.
Solution Approach 2:
The patent changes the matrix phase composition from SiO2 to lithium aluminate. This parameter change in the surrounding phase modifies the electrochemical behavior during initial cycles, reducing the irreversible capacity loss and improving the initial charge-discharge efficiency while preserving the high theoretical capacity of the silicon phase.
3Stability of the object's composition
If lithium silicate phase is used, then structure stability is improved compared to pure Si, but side reactions with Li ions occur reducing initial efficiency
Solution Approach 1:
The patent changes the chemical composition from lithium silicate to lithium aluminate. This parameter change provides even greater structure stability and alkali resistance than lithium silicate, while simultaneously reducing side reactions with Li ions. The lithium aluminate phase forms a more stable protective environment that prevents harmful reactions during initial charging.
Solution Approach 2:
The lithium aluminate phase acts as an intermediary between the silicon particles and the Li ions. It provides a stable, reactive interface that facilitates controlled Li ion insertion while preventing direct contact between silicon and electrolyte, thereby reducing side reactions and improving initial charge-discharge efficiency while maintaining structure stability.
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 aluminate-based composite particles effectively suppress the deterioration of initial charge-discharge efficiency and capacity, achieving higher battery performance and improved cycle characteristics.
Implementation Method 1
a material containing silicon (Si) that forms an alloy with lithium
Implementation Method 2
enhancing alkali resistance and ion conductivity
Data Source
AI summary
A negative electrode active material for a non-aqueous electrolyte secondary battery includes composite particles containing a lithium aluminate phase, and a silicon phase dispersed in the lithium aluminate phase.