Silicate Composite Anode Material for Stable Silicon Battery Cycling
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The composite particles used in lithium-ion secondary batteries, which include a lithium silicate phase and silicon particles, suffer from significant expansion and contraction during charging and discharging, leading to stress on the lithium silicate phase, cracks, and reduced charge-discharge cycle characteristics.
Innovation Solution
The use of silicate composite particles that include a lithium silicate phase, a silicon oxide phase, and a silicon phase, where the silicon oxide phase and silicon phase are dispersed in the lithium silicate phase, and the ratio of the maximum intensity of the SiO2 (011) plane to the Si (111) plane in XRD diffraction patterns is between 0.9 and 1.4, enhancing the crystallinity of the silicon oxide phase and reducing stress on the composite particles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If silicon particles are used as negative electrode active material to achieve high theoretical capacity density, then battery energy density is improved, but considerable expansion and contraction during charging and discharging causes cracks and breaks in composite particles
Solution Approach 1:
The patent uses a composite structure consisting of a lithium silicate phase matrix containing dispersed silicon particles and silicon oxide phase. This composite material approach allows the silicon particles to provide high capacity while the lithium silicate phase and silicon oxide phase constrain volume changes and prevent cracking during charging-discharging cycles, thus resolving the contradiction between high energy density and cycle stability
Solution Approach 2:
The patent specifies a particular XRD diffraction peak intensity ratio (IA/IB between 0.9 and 1.4) as a parameter to control the crystallinity and phase composition of the composite particles. By optimizing this parameter, the structural stability during lithium insertion/extraction is improved, reducing expansion-contraction stress and maintaining charge-discharge cycle characteristics while preserving high capacity
2Use of energy by moving object
If silicon particles undergo expansion and contraction during charging and discharging, then lithium absorption and release capacity is improved, but stress on lithium silicate phase causes cracks and breaks
Solution Approach 1:
The lithium silicate phase acts as an intermediary matrix that accommodates the expansion and contraction of silicon particles during lithium absorption and release. The silicon oxide phase dispersed within the lithium silicate phase further mediates stress distribution, preventing direct transmission of mechanical stress that would cause cracking, thus preserving both lithium capacity and structural integrity
Solution Approach 2:
By controlling the XRD diffraction peak intensity ratio (IA/IB) to be between 0.9 and 1.4, the patent optimizes the phase composition and crystallinity of the composite particles. This parameter control ensures the lithium silicate phase has appropriate mechanical properties to withstand expansion-contraction stress while maintaining lithium ion conductivity, thus protecting structural integrity during lithium absorption and release
3Productivity
If composite particles experience large stress during expansion and contraction, then charge-discharge capacity is improved, but binding force with surrounding binder decreases and conductive paths are lost
Solution Approach 1:
The composite particle structure with lithium silicate phase matrix and dispersed silicon/silicon oxide phases provides a stable framework that maintains binding force with surrounding binder even during charge-discharge cycles. The composite structure prevents particle isolation by distributing stress uniformly, preserving conductive paths between particles while enabling high charge-discharge capacity
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
This configuration enhances the charge-discharge cycle characteristics of secondary batteries by reducing cracks and breaks in the composite particles, maintaining the conductive path, and improving the binding force with the surrounding binder.
Implementation Method 1
in a diffraction pattern by X-ray diffraction analysis (XRD) of the silicate composite particles
Implementation Method 2
a ratio IA/IB of a maximum intensity IA of a diffraction peak A attributed to a SiO2 (011) plane of the silicon oxide phase appearing at around 2θ=26°, to a maximum intensity IB of a diffraction peak B attributed to a Si (111) plane of the silicon phase appearing at around 2θ28°
Data Source
AI summary
A negative electrode active material for secondary batteries includes silicate composite particles. The silicate composite particles each include a lithium silicate phase containing lithium, silicon, and oxygen, a silicon oxide phase including SiO2, and a silicon phase, in which the silicon oxide phase and the silicon phase are dispersed in the lithium silicate phase. In a diffraction pattern by X-ray diffraction analysis (XRD), a ratio IA/IB of a maximum intensity IA of a diffraction peak A attributed to the SiO2 (011) plane of the silicon oxide phase appearing at around 2θ=26°, to a maximum intensity IB of a diffraction peak B attributed to the Si (111) plane of the silicon phase appearing at around 2θ=28° is 0.9 or more and 1.4 or less.