Silicon-Silicate Anode Material for Higher Initial Li-Ion Efficiency
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Solution Overview
Problem
Existing non-aqueous electrolyte secondary batteries, particularly lithium ion batteries, require further improvement in initial charge and discharge efficiency to meet the demands of advanced portable electronic devices.
Innovation Solution
A negative electrode material comprising a silicate phase with dispersed silicon particles and a crystal phase containing a rare earth element, silicon, and oxygen, which reduces irreversible capacity by minimizing reactive sites with lithium ions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a silicate phase containing fine silicon particles is used as a negative electrode active material, then the theoretical capacity density is improved, but the initial charge and discharge efficiency deteriorates due to increased irreversible capacity
Solution Approach 1:
The invention applies local quality by creating a composite structure where silicon particles are dispersed in a silicate phase matrix. The silicate phase provides different local chemical environments: regions with silicon particles offer high lithium insertion capacity, while the silicate matrix regions provide stability and reduced irreversible reactions. This spatial differentiation of material properties allows simultaneous achievement of high capacity and good initial efficiency.
Solution Approach 2:
The invention uses composite materials by combining silicon particles with a silicate phase to create a hybrid negative electrode active material. The composite structure leverages the high theoretical capacity of silicon while the silicate phase component reduces irreversible capacity formation. The synergistic effect of these two materials resolves the contradiction between achieving high capacity and maintaining good initial charge-discharge efficiency.
2Use of energy by moving object
If more silicon is dispersed in the silicate phase to increase capacity, then the energy density is improved, but the irreversible capacity increases and initial efficiency worsens
Solution Approach 1:
The invention applies parameter changes by optimizing the composition parameters of the silicate phase, specifically controlling the ratio of elements and the crystalline structure. By adjusting these parameters, the silicate phase achieves an optimal balance between providing structural support and minimizing irreversible lithium reactions, allowing higher silicon content while maintaining acceptable initial efficiency.
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
Enhances initial charge and discharge efficiency by reducing irreversible capacity and improving lithium ion conductivity, leading to improved battery performance.
Implementation Method 1
a material containing silicon (Si) that forms an alloy with lithium has been expected to be utilized as a negative electrode active material having a high theoretical capacity density
Implementation Method 2
the crystal phase containing a rare earth element, silicon, and oxygen... By allowing a crystal phase whose reactivity with lithium ions is low to be dispersed in the matrix of the silicate phase, the number of sites that may react with the lithium ions in the silicate phase are decreased, resulting in a reduced irreversible capacity
Data Source
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AI summary
A negative electrode material for a non-aqueous electrolyte secondary battery, including a silicate phase, silicon particles dispersed in the silicate phase, and a crystal phase dispersed in the silicate phase. The silicate phase contains at least one element E1 selected from the group consisting of alkali metal elements and Group 2 elements. The crystal phase contains a rare earth element, silicon, and oxygen.