Silicon Oxide Negative Electrode Slurry Segmentation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Silicon oxide materials used as negative electrode active materials in non-aqueous electrolyte secondary batteries suffer from high irreversible capacity loss and decreased cycling performance due to the interference of alkali-modified carboxymethylcellulose (CMC) when used in aqueous slurries with lithium-doped silicon oxide.
Innovation Solution
A method involving the concurrent use of undoped and lithium-doped silicon oxide materials in a negative electrode composite, where undoped silicon oxide is dispersed in an aqueous CMC solution, mitigating CMC modification and allowing a strong binder like styrene-butadiene rubber to maintain effective binding, thereby reducing irreversible capacity loss and enhancing cycling performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If lithium-doped silicon oxide is used in aqueous CMC slurry, then irreversible capacity loss decreases and initial capacity increases, but cycling performance deteriorates due to alkali-modified CMC interference
Solution Approach 1:
The patent segments the silicon oxide material into two distinct components: lithium-doped silicon oxide (for reducing irreversible capacity loss) and undoped silicon oxide (for preventing CMC modification). This segmentation allows each material to fulfill its specific function without interfering with the other, resolving the contradiction between initial capacity and cycling performance.
Solution Approach 2:
The undoped silicon oxide acts as an intermediary material that prevents direct contact between CMC and lithium-doped silicon oxide. By serving as a physical barrier, it mediates the interaction between the binder and the doped material, preventing alkali modification of CMC while allowing the doped material to maintain its low irreversible capacity loss properties.
2Stability of the object's composition
If CMC is used as dispersion stabilizer in aqueous slurry, then dispersion stability improves, but binding force decreases due to weak binding capability of CMC
Solution Approach 1:
The patent employs CMC for its primary function as a dispersion stabilizer while introducing a dedicated binder (such as styrene-butadiene rubber or carboxymethyl starch) to handle the binding function. This multi-functional approach allows each material to specialize in one task, with CMC ensuring stable dispersion and the dedicated binder providing strong adhesion.
3Stability of the object's composition
If alkali-modified CMC is formed on lithium-doped silicon oxide surface, then dispersion stability improves, but binding action is interfered with and cycling performance decreases
Solution Approach 1:
The patent converts the potential harm of CMC modification into a benefit by using undoped silicon oxide as a sacrificial material. The undoped silicon oxide prevents CMC from modifying the lithium-doped silicon oxide surface, thereby protecting the electrochemical performance while still allowing CMC to perform its dispersion stabilizing function on the undoped material surface.
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 approach increases the initial capacity of non-aqueous electrolyte secondary batteries while maintaining good cycling performance by minimizing the formation of alkali-modified CMC, ensuring a desired binding force and improved battery performance.
Implementation Method 1
preparing a dispersion by dispersing the first silicon oxide material in an aqueous carboxymethylcellulose solution
Data Source
AI summary
A first silicon oxide material and a second silicon oxide material are prepared. A dispersion is prepared by dispersing the first silicon oxide material in an aqueous carboxymethylcellulose solution. A negative electrode composite material slurry is prepared by dispersing the second silicon oxide material and a binder in the dispersion. A negative electrode is produced by applying the negative electrode composite material slurry to a surface of a negative electrode current collector and then performing drying. The binder includes no carboxymethylcellulose. The first silicon oxide material has not been pre-doped with lithium. The second silicon oxide material has been pre-doped with lithium.