PVDF-g-PAN Polymer for Battery Electrode Binders
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Solution Overview
Problem
Conventional polyvinylidene fluoride (PVDF) binders in lithium battery cells are functionally inert, adding dead weight and volume, and lack electrochemical functionality, which limits energy and power density, and are brittle, prone to fracture, and have limited oxidative stability.
Innovation Solution
A new polymer material is developed by grafting acrylonitrile onto PVDF, creating an ionically conductive polymer that acts as both a binder and electrolyte, enhancing ionic conductivity and flexibility, synthesized using controlled radical polymerization methods without expensive pretreatments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If PVDF is used as a binder, then binding function is provided, but electrochemical functionality is lost and dead weight is added
Solution Approach 1:
The PVDF-g-PAN polymer serves multiple functions simultaneously: it acts as a binder to hold electrode particles together, provides ionic conductivity to facilitate ion transport, and contributes to the electrochemical performance of the electrode. This multi-functionality eliminates the need for separate binder and electrolyte components, reducing dead weight while maintaining binding reliability.
2Stability of the object's composition
If PVDF is used as a binder, then binding stability is achieved, but flexibility and fracture resistance are reduced
Solution Approach 1:
The invention creates a composite polymer structure by grafting PAN chains onto the PVDF backbone. This composite structure combines the stability and binding properties of PVDF with the flexibility and ionic conductivity of PAN. The grafted PAN segments introduce molecular flexibility that prevents brittle fracture while maintaining the overall structural stability needed for binding.
3Reliability
If PVDF is used as a binder, then oxidative stability up to 5.0V is achieved, but ionic conductivity is limited
Solution Approach 1:
The PVDF-g-PAN polymer exhibits local quality differentiation where different segments of the polymer chain provide different functions. The PVDF backbone segments provide oxidative stability and binding functionality, while the grafted PAN segments provide ionic conductivity. This local differentiation of properties within the same polymer structure allows simultaneous achievement of oxidative stability and enhanced ionic conductivity.
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-g-PAN polymer increases energy and power density by providing electrochemical functionality, improving flexibility and oxidative stability, and maintaining binder properties, while allowing for enhanced ionic conductivity and reduced brittleness.
Implementation Method 1
A new polymer material in which acrylonitrile is grafted to PVDF is disclosed
Implementation Method 2
synthesized using controlled radical polymerization methods
Implementation Method 3
The material can also be used as an electrolyte to facilitate ionic conduction between the electrodes in an electrochemical cell
Data Source
AI summary
PVDF-g-PAN has been synthesized by grafting polyacrylonitrile onto polyvinylidene fluoride using an ATRP/AGET method. The novel polymer is ionically conducive and has much more flexibility than PVDF alone, making it especially useful either as a binder in battery cell electrodes or as a polymer electrolyte in a battery cell.