Negative Electrode Binder Distribution for Low-Temperature Battery Performance
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Nonaqueous electrolyte secondary batteries face increased internal resistance in low-temperature environments due to high viscosity of the electrolytic solution, which affects lithium ion supply and battery performance, and existing methods fail to effectively address this issue while maintaining productivity and cost-effectiveness.
Innovation Solution
The battery design incorporates a negative electrode with a cellulose-based binder, specifically carboxymethyl cellulose, where the binder content is adjusted to 35% to 50% by mass in the region near the negative electrode core, reducing steric hindrance and improving electrolyte permeation, and a multilayer structure with varying binder concentrations in the negative electrode mixture layers to enhance low-temperature performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the viscosity of the electrolytic solution is reduced to improve low-temperature performance, then the internal resistance decreases, but the battery structure and electrolyte composition require significant modification
Solution Approach 1:
The patent applies local quality by creating a non-uniform binder distribution within the negative electrode mixture layer. The binder concentration is specifically controlled to be higher (35-50% by mass) in the first region near the negative electrode core compared to the second region farther from the core. This localized modification optimizes electrolyte permeation and lithium ion supply at the critical electrode-core interface without requiring changes to the entire battery structure or electrolyte composition.
2Strength
If the binder content in the negative electrode mixture layer is increased to improve adhesion, then the layer structure is maintained better, but the electrolyte permeation and lithium ion supply are hindered
Solution Approach 1:
The patent resolves this contradiction by implementing spatially varying binder content. In the first region near the negative electrode core where electrolyte permeation is critical, the binder content is controlled to 35-50% by mass of total binder, providing sufficient adhesion while maintaining adequate porosity for electrolyte penetration. This localized optimization allows the electrode structure to maintain strength where needed while permitting electrolyte flow where required.
Solution Approach 2:
The patent applies parameter changes by precisely controlling the binder content parameter within a specific range (35-50% by mass of total binder in the first region). This quantitative parameter optimization balances the competing requirements of adhesion strength and electrolyte permeation, achieving both goals simultaneously through numerical control of material composition.
3Ease of manufacture
If a uniform binder distribution is used in the negative electrode mixture layer, then the manufacturing process is simpler, but the low-temperature internal resistance cannot be effectively suppressed
Solution Approach 1:
The patent implements local quality by designing a controlled non-uniform binder distribution. The binder content varies through the thickness of the negative electrode mixture layer, with higher concentration (35-50% by mass) in the first region near the negative electrode core and lower concentration in the second region farther from the core. This spatial variation is achieved through controlled application of slurry with different solid content, optimizing both manufacturing feasibility and low-temperature performance.
4Manufacturing precision
If the solid content of cellulose-based binder in the first negative electrode mixture slurry is increased to improve binder content control, then the binder distribution is better controlled, but the slurry viscosity increases and application becomes more difficult
Solution Approach 1:
The patent applies parameter changes by precisely controlling the solid content parameter of the cellulose-based binder in the first negative electrode mixture slurry. By optimizing this parameter within appropriate ranges, the invention achieves accurate binder content control (35-50% by mass in the first region) while maintaining slurry processability for effective application. This numerical optimization balances precision requirements with manufacturing ease.
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 significantly reduces internal resistance and improves low-temperature input-output characteristics while maintaining good productivity and preventing contamination of the compression roller during the manufacturing process.
Implementation Method 1
reducing steric hindrance and improving electrolyte permeation
Data Source
AI summary
A nonaqueous electrolyte secondary battery according to an embodiment of the present disclosure includes a negative electrode including a negative electrode core and negative electrode mixture layers formed on both surfaces of the negative electrode core. Each of the negative electrode mixture layers contains a cellulose-based binder composed of at least one of carboxymethyl cellulose and a salt thereof. When each of the negative electrode mixture layers is divided in half, at the center in the thickness direction, into a first region near the negative electrode core and a second region far from the negative electrode core, the content of the cellulose-based binder present in the first region is 35% by mass or more and less than 50% by mass of the total mass of the cellulose-based binder contained in the entire of each of the negative electrode mixture layers.