Flexible Graphene Electrode-Separator Elements for Li-Ion Batteries
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Solution Overview
Problem
Conventional processes for preparing electrodes in lithium-ion batteries are time-consuming and costly, requiring toxic solvents and heavy aluminum current collectors, which limit energy density and efficiency.
Innovation Solution
A process for manufacturing flexible electrode-separator elements using graphene and electrochemically active materials, eliminating the need for binders and current collectors by applying a suspension of graphene and active materials onto a separator, followed by solvent removal, allowing for a self-standing electrode with improved flexibility and energy density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If conventional processes use aluminum current collectors and PVDF binders, then electrode structural stability is improved, but energy density decreases and manufacturing cost increases
Solution Approach 1:
The invention extracts and eliminates the aluminum current collector and PVDF binder from the electrode structure, retaining only the essential components (active material, conductive additive, and separator). This removal of non-essential components directly increases energy density while maintaining structural stability through the alternative design of applying active material slurry directly onto the separator.
Solution Approach 2:
The separator serves multiple functions: it acts as both the physical separator between electrodes and the substrate for mounting the active material layer, replacing the traditional dual-component structure of current collector plus separator. This multi-functionality reduces overall electrode weight and increases energy density.
2Strength
If conventional processes use PVDF binders and NMP solvents, then electrode coating adhesion is improved, but manufacturing cost increases and environmental harm increases
Solution Approach 1:
The invention converts the traditionally harmful NMP solvent into a beneficial or neutral alternative by replacing it with water or alcohol-based solvents. This substitution eliminates the toxicity and environmental harm associated with NMP while maintaining the necessary coating application and drying processes. The adhesion is maintained through the direct application methodology and formulation adjustments.
Solution Approach 2:
The invention replaces expensive PVDF binder with cheaper alternative binding mechanisms, including the use of water or alcohol solvents that evaporate readily, and reliance on the physical interlocking of particles during the drying process. This substitution reduces both material cost and environmental impact.
3Ease of manufacture
If conventional processes include milling, mixing, coating, and solvent elimination steps, then electrode manufacturing completeness is improved, but manufacturing time increases
Solution Approach 1:
The invention merges multiple conventional steps (milling, mixing, and coating) into a single integrated slurry preparation and application step. By preparing a homogeneous slurry that contains all necessary components (active material, conductive additive, binder, and solvent) and applying it directly onto the separator in one operation, the process eliminates sequential processing steps and significantly reduces manufacturing time while maintaining completeness.
Solution Approach 2:
The invention performs preliminary mixing and formulation of the slurry to ensure all components are pre-combined in optimal proportions before application. This preliminary preparation allows for direct coating without subsequent milling or mixing steps, streamlining the manufacturing process and increasing productivity.
4Strength
If aluminum current collectors are used, then electrode mechanical strength is improved, but electrode weight increases
Solution Approach 1:
The invention extracts and removes the aluminum current collector from the electrode assembly, eliminating its weight contribution (which accounts for nearly 50% of traditional electrode weight). Mechanical strength is maintained through the alternative design where the separator serves as the structural substrate and the active material layer is directly applied, creating a self-supported structure.
Solution Approach 2:
The invention employs thin film separators as the structural base, replacing the thick aluminum current collector. These thin films provide sufficient mechanical strength and flexibility while contributing minimal weight, enabling the electrode to maintain integrity without the heavy metal substrate.
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
This process reduces manufacturing time and costs, increases energy density, and uses greener methods, resulting in improved electrochemical performance and mechanical resistance of electrodes.
Implementation Method 1
steps of filtering the suspension obtained in (a) through the separator to obtain an electrode material layer on a surface of the separator
Implementation Method 2
step of removing the solvent to obtain the electrode-separator element
Data Source
AI summary
This application describes a process for the preparation of flexible electrode-separator elements or assemblies, which includes the application of an electrode material on the separator. The electrode material comprises graphene, for instance produced by graphite exfoliation. The electrode-separator elements obtained by the process as well as their use in electrochemical cells are also described.