Vinylidene Fluoride Binder for Battery Electrode Adhesion
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Solution Overview
Problem
Current binder resins used in batteries lack sufficient adhesiveness, which hinders the performance of lithium ion secondary batteries.
Innovation Solution
A vinylidene fluoride polymer composition is developed, incorporating a first structural unit from vinylidene fluoride and a second structural unit from a specific monomer, represented by Formula (1), with the second structural unit content ranging from 0.05 to 20 mol%, enhancing the adhesiveness of the binder resin.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional binder resins are used, then the battery structure is simple and easy to manufacture, but the adhesiveness is insufficient leading to poor electrode cohesion
Solution Approach 1:
The patent applies composite materials by creating a copolymer that combines vinylidene fluoride units with fluorinated cyclic carbonate units. This composite polymer structure integrates the adhesive properties of vinylidene fluoride with the bonding capabilities of fluorinated cyclic carbonate, achieving both strong adhesion and electrode cohesion without requiring multiple separate binder components.
Solution Approach 2:
The patent utilizes parameter changes by controlling the molar ratio of vinylidene fluoride to fluorinated cyclic carbonate within specific ranges (70:30 to 95:5). By adjusting these compositional parameters, the binder resin achieves optimal balance between adhesiveness, electrode cohesion, and manufacturing feasibility, resolving the contradiction between improved strength and reduced complexity.
2Reliability
If binder resin with higher adhesiveness is used, then electrode cohesion improves, but the likelihood of cracks or peeling during battery assembly and operation increases with conventional resins
Solution Approach 1:
The patent changes the chemical composition parameters of the binder resin by incorporating fluorinated cyclic carbonate units at controlled concentrations (5-30 mol%). This parameter modification enhances electrode cohesion and prevents cracks and peeling during battery assembly and operation, directly addressing the reliability issue.
Solution Approach 2:
The composite polymer structure combines the adhesive strength of vinylidene fluoride with the crack-resistant properties of fluorinated cyclic carbonate. This material composition creates a binder that maintains electrode integrity under mechanical stress and thermal cycling, eliminating the harmful effects of cracking and peeling while ensuring reliable electrode cohesion.
3Strength
If vinylidene fluoride copolymer with fluorinated cyclic carbonate is used, then adhesiveness and electrode cohesion improve, but the energy density of the battery increases
Solution Approach 1:
The patent optimizes the compositional parameters of the binder resin to minimize its volume and mass in the electrode structure. By controlling the fluorinated cyclic carbonate content within 5-30 mol% and the overall binder resin at 1-20 wt% of the electrode mixture, the design achieves high adhesiveness while maintaining high energy density, as the binder occupies minimal space that would otherwise be available for active materials.
Solution Approach 2:
The composite polymer provides high binding efficiency at low concentrations. The synergistic combination of vinylidene fluoride and fluorinated cyclic carbonate units creates a binder with enhanced adhesive properties per unit mass, allowing the use of smaller amounts of binder material. This maintains high energy density while achieving the required adhesiveness and electrode cohesion.
Data Source
AI summary
As a novel vinylidene fluoride polymer and its use, provided are a binder composition, an electrode mixture, an electrode, and a non-aqueous electrolyte secondary battery including the vinylidene fluoride containing the vinylidene fluoride polymer. The vinylidene fluoride polymer includes a first structural unit derived from vinylidene fluoride and a second structural unit derived from a monomer other than vinylidene fluoride. The monomer to be the second structural unit is a primary amine, a secondary amine, or a tertiary amine having at least one of a hydroxyl group and a carboxyl group, and the content of the second structural unit is from 0.05 to 20 mol% when the total of structural units derived from all the monomers constituting the vinylidene fluoride polymer is 100 mol%.