Positive Electrode Binder Composition to Prevent Plate Cracking
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing rechargeable lithium batteries face challenges in maintaining adhesion, oxidation resistance, and flexibility, leading to cracks in the electrode plates, which affect battery capacity and cycle-life characteristics, particularly with small particle-sized active materials like lithium iron phosphate compounds.
Innovation Solution
A positive electrode design incorporating a binder with a siloxane-based and imide-based repeating units, ranging from 1 wt% to 49 wt%, enhances adhesion, oxidation resistance, and flexibility, reducing crack formation and improving battery performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional binders are used in positive electrodes, then manufacturing is simple, but adhesion and flexibility are insufficient leading to electrode plate cracks
Solution Approach 1:
The patent applies composite materials by combining siloxane-based polymer and imide-based polymer in a specific weight ratio (1:9 to 49:51) to create a binder composite that achieves both adhesion and flexibility. The siloxane-based polymer provides flexibility while the imide-based polymer provides adhesion, resolving the contradiction between these two properties through material composition.
Solution Approach 2:
The patent applies parameter changes by optimizing the weight ratio of siloxane-based polymer to imide-based polymer within the range of 1:9 to 49:51. This parameter optimization allows the binder to achieve the desired balance between adhesion and flexibility, preventing electrode plate cracks while maintaining manufacturability.
2Quantity of substance
If small particle-sized active materials are used, then energy density improves, but adhesion becomes insufficient causing cracks
Solution Approach 1:
The patent uses composite materials (siloxane-based polymer combined with imide-based polymer) to provide sufficient adhesion for small particle-sized active materials. The siloxane-based polymer's flexibility and the imide-based polymer's adhesion work together to bind small particles effectively, enabling high energy density without cracking.
Solution Approach 2:
The patent applies local quality by ensuring the binder composite specifically targets the adhesion needs at the particle level for small particle-sized active materials. The binder's dual-polymer composition provides localized adhesion and flexibility exactly where needed at the electrode plate level, allowing small particles to be effectively bound.
3Strength
If binder with high adhesion is used, then electrode plate strength improves, but flexibility decreases causing brittleness
Solution Approach 1:
The patent applies composite materials by combining siloxane-based polymer (providing flexibility) with imide-based polymer (providing adhesion and strength). This composite binder achieves both electrode plate strength and flexibility simultaneously, preventing the brittleness that would result from using only high-adhesion materials.
Solution Approach 2:
The patent applies parameter changes by optimizing the weight ratio of the two polymers (siloxane-based:imide-based = 1:9 to 49:51) to achieve the desired balance between strength and flexibility. This parameter optimization ensures the electrode plate has sufficient strength while maintaining the flexibility needed to prevent cracking.
Data Source
Figure 1
Figure 2
Figure 3
AI summary
Disclosed are a positive electrode, and a rechargeable lithium battery including the positive electrode, the positive electrode including a positive electrode current collector and a positive electrode active material layer on the positive electrode current collector. The positive electrode active material layer includes a positive electrode active material, a binder, and a conductive material. The binder includes a siloxane-based repeating unit and an imide-based repeating unit, and the binder includes the siloxane-based repeating unit in an amount of ≥ 1 wt% to ≤ 49 wt%.