Gradient Conductor Distribution in Silicon Negative Electrodes
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Lithium secondary batteries with silicon-containing materials as negative electrode active materials face challenges in achieving superior charge-discharge cycle performance.
Innovation Solution
A lithium secondary battery design with a negative electrode active material layer having a higher concentration of conductor particles on its surface than in its center, utilizing a mixture slurry with specific viscosity and drying conditions to enhance liquid retention and adhesion, and employing a polyimide binder for improved mechanical strength and adhesion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If silicon-containing material is used as negative electrode active material, then battery capacity is improved, but charge-discharge cycle performance deteriorates
Solution Approach 1:
The patent applies local quality by creating a non-uniform distribution of conductor particles within the active material layer. The concentration of conductor particles is specifically increased in the inner region (closer to the current collector) compared to the surface region, establishing a gradient structure that optimizes both capacity and cycle performance locally within different zones of the electrode
2Ease of manufacture
If uniform distribution of conductor particles is used, then manufacturing simplicity is maintained, but lithium ion supply efficiency deteriorates
Solution Approach 1:
The patent implements local quality through a controlled gradient distribution of conductor particles. By positioning higher concentrations of conductor particles in the inner region near the current collector and lower concentrations at the surface, the structure optimizes lithium ion transport pathways while maintaining manufacturability through a systematic deposition approach
3Quantity of substance
If high concentration of conductor particles at surface is used, then liquid retention is improved, but adhesion between active material and current collector deteriorates
Solution Approach 1:
The patent resolves this contradiction by applying local quality principles to the conductor particle distribution. The inner region near the current collector maintains higher conductor particle concentration to ensure strong adhesion and electrical connectivity, while the surface region has lower concentration to provide adequate liquid electrolyte retention, creating an optimized gradient structure
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 design results in superior cycle performance and extended battery life by ensuring efficient lithium ion supply and maintaining adhesion between the active material and current collector.
Implementation Method 1
drying the applied negative electrode mixture slurry with an initial drying temperature set to 100° C. to 150° C.
Data Source
AI summary
A lithium secondary battery with superior cycle performance is provided. The lithium secondary battery includes a negative electrode including a negative electrode active material layer disposed on a negative electrode current collector and containing negative electrode active material particles, negative electrode conductor particles, and a negative electrode binder; a positive electrode containing a positive electrode active material; and a non-aqueous electrolyte. The concentration of the negative electrode conductor particles in a surface layer of the negative electrode active material layer facing away from the negative electrode current collector is higher than the concentration of the negative electrode conductor particles in a center of the negative electrode active material layer.