Li2Si2O5-Coated SiOx Anode Material for Stable Water-Based Processing
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Solution Overview
Problem
Current lithium-ion battery negative electrode materials face challenges with poor processability and low initial efficiency due to the formation of strongly alkaline by-products during pre-lithiation, which affects water-based processing and cycling performance.
Innovation Solution
A silicon-oxygen composite negative electrode material is developed, comprising SiOx, a non-Li2Si2O5 lithium-containing compound coated with Li2Si2O5, which prevents the generation of strongly alkaline by-products and improves processing stability, allowing for higher initial efficiency and long cycle life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If pre-lithiation is performed to improve initial efficiency, then initial coulombic efficiency is improved, but strongly alkaline by-products are generated causing poor processability
Solution Approach 1:
The patent introduces water as an intermediary substance to react with strongly alkaline by-products (such as Li2SiO3 and Li4SiO4) generated during pre-lithiation, converting them into weakly alkaline substances. This mediator approach allows the system to maintain high initial efficiency while eliminating the harmful effects of strong alkalinity on processability
Solution Approach 2:
The patent converts the harmful strongly alkaline by-products into beneficial weakly alkaline substances through water treatment. The strongly alkaline by-products that originally caused poor processability are transformed into substances that do not interfere with water-based slurry preparation, thereby turning a disadvantage into an advantage
2Reliability
If lithium powder is dispersed in water-based slurry for pre-lithiation, then pre-lithiation is achieved, but gas production occurs reducing processability
Solution Approach 1:
The patent changes the chemical environment parameters by introducing water to react with strongly alkaline by-products, transforming them into weakly alkaline substances. This parameter change prevents gas production during slurry preparation while maintaining the pre-lithiation effect, as the modified chemical environment no longer supports gas-generating reactions
3Reliability
If pre-lithiated materials are prepared with high lithium content, then initial efficiency is improved, but viscosity decreases causing tailing during application
Solution Approach 1:
The patent uses water as a mediator to react with strongly alkaline by-products that cause viscosity reduction. By converting these by-products into weakly alkaline substances, the slurry maintains appropriate viscosity for application even when high lithium content is present, thus preserving both initial efficiency and application performance
4Reliability
If pre-lithiation is performed to improve initial efficiency, then initial coulombic efficiency is improved, but pinholes or air pores appear in dried electrode sheet
Solution Approach 1:
The patent converts harmful strongly alkaline by-products into beneficial weakly alkaline substances through water treatment. This transformation eliminates the formation of pinholes and air pores during drying, as the modified chemical environment prevents the gas-generating reactions that originally caused these defects, thereby improving electrode sheet quality while maintaining 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
The silicon-oxygen composite negative electrode material enhances processing stability and initial efficiency by preventing alkalinity issues, enabling stable water-based processing and improved cycling performance, making it suitable for industrial-scale production.
Implementation Method 1
Li2Si2O5 covers a surface of the non-Li2Si2O5 lithium-containing compound... prevents the generation of strongly alkaline by-products
Implementation Method 2
a large amount of Li2SiO3 and Li4SiO4 phases, even Li2O and LixSi, are present in the materials after pre-lithiation, and these components are easily soluble in water to exhibit strong alkalinity
Data Source
AI summary
The present application provides a silicon-oxygen composite negative electrode material and method for preparation thereof and lithium-ion battery. The silicon-oxygen composite negative electrode material comprises a silicon-oxygen composite negative electrode material comprising SiOx, non-Li2Si2O5 lithium-containing compound, and Li2Si2O5; said Li2Si2O5 is coated on the surface of the non-Li2Si2O5 lithium-containing compound; 0≤x≤1.2. The preparation method comprises: mixing a first silicon source with a reducing lithium source and roasting, to obtain a composite material containing a non-Li2Si2O5 lithium-containing compound; the composite material containing the non-Li2Si2O5 lithium-containing compound is fused with a second silicon source and then subjected to heat treatment to obtain a silicon-oxygen composite negative electrode material. The silicon-oxygen composite anode material provided by the present application is coated with Li2Si2O5, solving the problem in the prior art of a negative electrode material producing strong alkaline or easily soluble by-products in water after pre-lithiation and affecting subsequent processing.