PVdF-HFP Binder for Wet and Dry Lamination Adhesion
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Solution Overview
Problem
Existing battery cell manufacturing processes face challenges in finding binders that can effectively facilitate adhesion of separators to electrodes in both wet and dry lamination processes, leading to complexities in material and processing requirements.
Innovation Solution
The use of a PVdF-HFP copolymer binder with specific molecular weight and HFP weight percent, and optionally a blended binder with varying molecular weights and acid values, which can enhance adhesion and mechanical strength for both wet and dry lamination processes by manipulating its properties to suit different lamination conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If different binders are used for wet and dry lamination processes, then adhesion performance is improved for each specific process, but material complexity and processing requirements increase
Solution Approach 1:
The patent applies universality by developing a single binder composition that functions effectively in both wet and dry lamination processes. The binder system includes a first binder component that provides adhesion in wet conditions and a second binder component that enables adhesion in dry conditions, allowing one material to serve multiple functions across different manufacturing processes, thereby reducing material complexity while maintaining reliable adhesion performance
Solution Approach 2:
The patent employs composite materials by formulating a binder system comprising multiple binder components in specific weight ratios. The composite includes a first binder (30-70 wt%) optimized for wet lamination and a second binder (20-50 wt%) optimized for dry lamination, along with optional third and fourth binder components. This composite approach combines the advantages of different binder types to achieve universal adhesion performance across both wet and dry processes
2Device complexity
If a single binder is used for both wet and dry lamination, then material complexity is reduced, but adhesion performance may deteriorate in one or both processes
Solution Approach 1:
The patent applies parameter changes by carefully controlling the molecular weights, weight percentages, and compositional ratios of multiple binder components. The first binder has a specific molecular weight range (50,000-500,000 g/mol) and the second binder has a different molecular weight range (10,000-100,000 g/mol), with their weight ratios optimized to ensure adequate adhesion performance in both wet and dry lamination processes while maintaining a single unified binder material
3Reliability
If multiple binder components are combined, then adhesion performance for both wet and dry processes is improved, but formulation complexity increases
Solution Approach 1:
The patent simplifies formulation complexity by establishing specific parameter ranges for the binder components: the first binder comprises 30-70 wt% with molecular weight 50,000-500,000 g/mol, the second binder comprises 20-50 wt% with molecular weight 10,000-100,000 g/mol, and optional third and fourth binders are present in 5-20 wt% and 1-10 wt% respectively. These defined parameters provide clear formulation guidelines that balance improved adhesion performance with manageable formulation 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 PVdF-HFP copolymer binder achieves improved adhesion and mechanical strength, allowing for efficient lamination in both wet and dry processes, reducing material and processing complexities, and enhancing the performance and reliability of battery cells.
Implementation Method 1
the separator includes a binder, which may be deposited as a coating thereon. Binders suitable for both 'wet' lamination processes and 'dry' lamination 'processes' are desirable in battery manufacturing
Implementation Method 2
the separator includes a binder, which may be deposited as a coating thereon
Implementation Method 3
The methods also include the step of heating the first cell stack to laminate the separator to the first electrode
Data Source
AI summary
Cell stacks are presented that include binders for wet and dry lamination processes. The cell stacks, when laminated, produce battery cells (or portions thereof). The cell stacks include a cathode having a cathode active material disposed on a cathode current collector. The cell stacks also include an anode having an anode active material disposed on an anode current collector. The anode is oriented towards the cathode such that the anode active material faces the cathode active material. A separator is disposed between the cathode active material and the anode active material and comprising a binder comprising a PVdF-HFP copolymer. In certain instances, an electrolyte fluid is in contact with the separator. Methods of laminating the cell stacks are also presented.