Silicon Oxide Silicate Composite Anode for Battery Capacity
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Solution Overview
Problem
Lithium-ion batteries face challenges with metal-based negative-electrode active materials due to volume expansion issues leading to cracks and poor cycle characteristics, and silicon-based materials suffer from irreversible reactions with lithium ions, resulting in low charge-discharge efficiency.
Innovation Solution
A negative-electrode active material comprising a silicon oxide (SiOx) and a silicate compound (MaaSic·m(OH)n(H2O)) is developed, where x is between 0 and 2, and M includes transition metal elements, preventing irreversible reactions with lithium ions by incorporating a silicate phase on the surface of silicon oxide particles, enhancing charge-discharge efficiency and capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If metal-based negative-electrode active materials are used, then theoretical capacity is improved, but volume expansion causes cracks and poor cycle characteristics
Solution Approach 1:
The patent uses a composite structure consisting of silicon particles dispersed in a silicon oxide matrix. The silicon oxide matrix (SiOx where 0.5 < x ≤ 2.0) provides structural stability and suppresses volume expansion, while the silicon particles provide high theoretical capacity. This composite approach resolves the contradiction by combining materials with complementary properties.
Solution Approach 2:
The patent creates a heterogeneous structure where silicon particles (high capacity regions) are distributed within a silicon oxide matrix (structural stability regions). This local differentiation allows different parts of the material to fulfill different functions: silicon provides capacity while silicon oxide provides dimensional stability during cycling.
2Quantity of substance
If silicon-based negative-electrode active material is used, then theoretical capacity is improved, but irreversible reaction with lithium ions reduces charge-discharge efficiency
Solution Approach 1:
The silicon oxide matrix acts as an intermediary between the silicon particles and the lithium ion electrolyte. It allows reversible lithium ion insertion/extraction while preventing the harmful irreversible reaction that would otherwise occur between silicon and lithium ions. The silicon oxide composition (0.5 < x ≤ 2.0) is specifically optimized to provide this mediating function.
3Stability of the object's composition
If silicon oxide is used to suppress volume expansion, then structural stability is improved, but irreversible reaction with lithium ions increases and charge-discharge efficiency decreases
Solution Approach 1:
The patent optimizes the silicon oxide composition parameter (x in SiOx) to be in the range 0.5 < x ≤ 2.0. This specific compositional range provides the optimal balance between structural stability (volume suppression) and electrochemical activity (reversible lithium ion insertion/extraction). By precisely controlling this parameter, both structural stability and charge-discharge efficiency are achieved simultaneously.
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 proposed material significantly improves charge-discharge efficiency and capacity by preventing irreversible reactions with lithium ions, leading to enhanced battery performance and durability.
Implementation Method 1
a heat treatment step of heating the mixture in a non-oxidizing atmosphere
Implementation Method 2
allows reversible insertion and extraction of lithium ions
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
A negative-electrode active material characterized by containing a silicon oxide represented by a general formula SiOx (0 < x < 2) and a silicate compound represented by a composition formula MaSibOc-m(OH)-n(H20), and a method for the production of a negative-electrode active material which includes a mixing step of mixing a silicon oxide that is represented by a general formula SiOy (0 < y < 2) and a metal oxide, and a heat treatment step of performing a heat treatment on the mixture that is obtained in the mixing step in a non-oxidizing atmosphere and in which the negative absolute value of the standard Gibbs energy of the oxidation reaction of the metal oxide at the heating temperature in the heat treatment step is smaller than the negative absolute value of the standard Gibbs energy of the oxidation reaction of Si at the heating temperature in the heat treatment step.