Dry Electrode Films With Elastic Binders for Lower Capacity Loss
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Solution Overview
Problem
Conventional energy storage devices using polytetrafluoroethylene (PTFE) binders exhibit increased irreversible capacity loss during redox processes, and the drying procedures in wet processes are time-consuming and costly.
Innovation Solution
Development of dry electrode films using PTFE-free or insubstantial PTFE binders composed of elastic polymers like PE, PEO, and PVDF, which are processed through nondestructive mixing and calendering to form free-standing electrode films.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If PTFE binder is used in dry electrode processes, then electrode film formation is achieved, but irreversible capacity loss increases during redox processes
Solution Approach 1:
The patent changes the chemical composition parameters of the binder from PTFE to elastic polymers (PE, PEO, PVDF), which fundamentally alters the electrochemical behavior and reduces irreversible capacity loss during redox processes
Solution Approach 2:
The patent uses composite binder systems combining multiple elastic polymers (PE, PEO, and PVDF in various ratios) to achieve optimal balance between mechanical properties and electrochemical performance, reducing capacity loss while maintaining film integrity
2Ease of manufacture
If wet coating method is used to form electrode films, then active electrode materials are combined with binder materials, but substantial drying time and cost are required
Solution Approach 1:
The patent extracts and eliminates the solvent component from the traditional wet coating process, transitioning to a dry mixing process where binder and active materials are combined without liquid solvents, thereby eliminating the drying step entirely
Solution Approach 2:
The patent replaces the thermal drying process with a mechanical calendering process that forms the electrode film through pressure and heat applied to the dry mixed materials, eliminating the need for evaporative drying
3Strength
If PTFE-free elastic polymer binders are used, then capacity loss is reduced and mechanical properties improve, but film formation complexity increases
Solution Approach 1:
The patent optimizes the molecular weight parameters of the elastic polymer binders (e.g., PE with Mw 100,000-1,000,000, PVDF with Mw 100,000-500,000) to achieve the right balance between film-forming capability and mechanical strength without excessive process complexity
Solution Approach 2:
The patent develops composite binder formulations combining PE, PEO, and PVDF in specific ratios (e.g., 2-10 wt% PE, 1-5 wt% PVDF, 0.1-5 wt% PEO) to synergistically improve both film formation and mechanical properties while managing process complexity
Data Source
AI summary
Provided herein are dry process electrode films, and energy storage devices incorporating the same, including an elastic polymer binder. In some embodiments, the dry process electrode films are PTFE-free or comprise an insubstantial amount of PTFE. The electrode films exhibit improved mechanical and processing characteristics. Also provided are methods for processing such elastic polymer binders, and for incorporating the elastic polymer binders in electrode films.