Two-Layer Negative Electrode for Fast-Charging Silicon Batteries
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing secondary batteries face challenges in achieving improved charging performance and service life, particularly with silicon-based active materials that can enhance charging but compromise electrical conductivity and ion mobility.
Innovation Solution
A two-layer negative electrode structure is employed, with a silicon-based active material in the second layer and lithium-substituted carboxymethyl cellulose in both layers, enhancing electrical conductivity and ion mobility, thereby improving charging performance and service life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If silicon-based active material is used in the negative electrode, then charging performance is improved, but electrical conductivity deteriorates
Solution Approach 1:
The negative electrode active material layer is divided into two distinct layers: a first layer containing carbon-based active material with high electrical conductivity, and a second layer containing silicon-based active material with superior charging performance. This segmentation allows each layer to fulfill its specific function without compromising the other, resolving the contradiction between charging performance and electrical conductivity.
Solution Approach 2:
The invention employs a composite structure combining carbon-based active material and silicon-based active material in a two-layer configuration. The carbon-based layer provides a conductive foundation, while the silicon-based layer enhances charging performance. This composite approach allows the negative electrode to simultaneously achieve high electrical conductivity and superior charging performance.
2Duration of action of stationary object
If silicon-based active material is uniformly distributed in the negative electrode, then service life is improved, but charging performance deteriorates due to non-uniform electrical conductivity
Solution Approach 1:
Instead of uniform distribution, the invention applies local quality by concentrating silicon-based active material in the second layer (farther from the current collector) and carbon-based active material in the first layer (closer to the current collector). This non-uniform spatial distribution optimizes both service life and charging performance by placing materials in their most effective positions within the electrode structure.
Solution Approach 2:
The invention transitions from a single-layer uniform distribution to a two-layer stratified structure, adding a dimensional aspect to the material distribution. This vertical stratification allows different materials to occupy different positions in the thickness direction, optimizing both electrical conductivity (via the carbon-based first layer) and service life (via the silicon-based second layer).
3Speed
If lithium-substituted carboxymethyl cellulose is added to the negative electrode, then ion mobility is improved, but manufacturing complexity increases
Solution Approach 1:
Lithium-substituted carboxymethyl cellulose serves multiple functions simultaneously: it acts as a binder holding the active material particles together, provides ion transport pathways for lithium ions, and enhances the overall electrochemical performance. This multi-functionality justifies the additional manufacturing step by delivering multiple benefits from a single additive.
Solution Approach 2:
The invention modifies the chemical composition parameters of the binder by using lithium-substituted carboxymethyl cellulose instead of conventional binders. This parameter change (substituting hydrogen with lithium in the carboxymethyl cellulose structure) enhances ion mobility and electrochemical activity, outweighing the increased manufacturing complexity.
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 two-layer structure with lithium-substituted carboxymethyl cellulose and silicon-based active material improves fast charging performance and secures battery service life by optimizing ion flux and reducing contact resistance.
Implementation Method 1
lithium-substituted carboxymethyl cellulose... has high electrical/ion mobility of Li
Implementation Method 2
the mobility of Li ions is increased
Implementation Method 3
the silicon-based active material accepts lithium ions through alloying
Implementation Method 4
the contact resistance between each layer is decreased
Implementation Method 5
the anode/separator interface experiences a larger ionic flux of lithium ions
Data Source
AI summary
A negative electrode for a secondary battery, including: a current collector; a first negative electrode active material layer provided on the current collector; and a second negative electrode active material layer provided on the first negative electrode active material layer, in which at least one of the first and second negative electrode active material layers includes a lithium-substituted carboxymethyl cellulose, and the second negative electrode active material layers includes a silicon-based active material, and a secondary battery including the same.