PVdF-HFP Binder for Battery Cell Lamination
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Solution Overview
Problem
Existing battery cell manufacturing processes face challenges in finding binders that can effectively adhere separators to electrodes in both wet and dry lamination processes, leading to inconsistencies in adhesion and potential material and processing complexities.
Innovation Solution
The use of a PVdF-HFP copolymer binder with specific molecular weight and HFP weight percent, and optionally a blended binder, which provides enhanced adhesion and mechanical strength, allowing for both wet and dry lamination processes by manipulating its properties such as molecular weight, HFP content, and acid value.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional binders are used for lamination, then adhesion can be achieved in one process type, but the binder fails to provide consistent adhesion in both wet and dry lamination processes
Solution Approach 1:
The patent applies parameter changes by modifying the molecular weight of the PVdF-HFP copolymer binder to greater than or equal to 1,000,000 u and adjusting the HFP weight percent to specific ranges (5-15% for single binder, or 10-15% for second binder in blended systems). These parameter adjustments enable the binder to provide consistent adhesion performance across both wet and dry lamination processes, resolving the contradiction between adhesion reliability and process adaptability
Solution Approach 2:
The patent employs composite materials by creating a blended binder system that combines a first PVdF-HFP copolymer (with molecular weight ≥1,000,000 u and HFP ≤7%) and a second PVdF-HFP copolymer (with molecular weight 500,000-1,000,000 u and HFP 10-15%). This composite binder system leverages the complementary properties of each component to achieve reliable adhesion in both wet and dry lamination processes simultaneously
2Manufacturing precision
If different binders are used for wet and dry lamination, then adhesion performance can be optimized for each process, but manufacturing complexity and material handling increase
Solution Approach 1:
The patent applies universality by developing a single PVdF-HFP copolymer binder formulation that functions effectively in both wet and dry lamination processes. The specific molecular weight (≥1,000,000 u) and HFP content (5-15%) enable the binder to provide optimized adhesion performance across different process types without requiring separate binder formulations, thereby reducing manufacturing complexity while maintaining high adhesion precision
Solution Approach 2:
The patent uses parameter changes to create a binder with molecular weight ≥1,000,000 u and specific HFP content that universally performs in both wet and dry lamination. This single optimized formulation eliminates the need for multiple binder systems, reducing process complexity while maintaining manufacturing precision through consistent adhesion performance
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 ensures strong adhesion in both wet and dry lamination processes, improving the mechanical strength and resistance to thermal shrinkage of the separator, thereby enhancing the performance and reliability of battery cells.
Implementation Method 1
a binder, which may be deposited as a coating thereon
Implementation Method 2
where the separator is soaked in electrolyte fluid
Implementation Method 3
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.