Conductive Adhesive Current Collectors for Solvent-Free Cells
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Solution Overview
Problem
Existing battery technologies, such as thin film, lithium polymer, and semi-printed batteries, face limitations including low storage capacity, sensitivity to environmental conditions, sealing issues, and challenges in integrating multiple layers, hindering their adoption in various applications.
Innovation Solution
The development of solvent-free electrochemical cells utilizing a conductive pressure sensitive adhesive layer to interface the negative active material layer with the negative current collector, providing electronic conductivity and mechanical support, while using ionic liquids for ionic transfer and a packaging layer to protect the cell components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If liquid electrolytes are used in semi-printed batteries, then ionic conductivity is achieved, but sealing issues and potential leaks occur
Solution Approach 1:
The patent transitions the electrolyte from liquid phase to solid phase by using an ionic liquid that is solid at room temperature. This phase transition eliminates the leakage and sealing issues associated with liquid electrolytes while maintaining ionic conductivity through the solid ionic liquid material.
Solution Approach 2:
The patent changes the physical state parameter of the electrolyte from liquid to solid by selecting an ionic liquid with a melting point below operating temperature. This parameter change allows the electrolyte to function as a solid material that provides ionic conductivity without the harmful effects of liquid electrolytes.
2Strength
If conventional adhesives are used to attach current collectors, then mechanical bonding is achieved, but electronic conductivity is lost
Solution Approach 1:
The patent uses a composite adhesive material that combines non-conductive polymer matrix with conductive filler particles. This composite structure provides both mechanical bonding strength from the polymer and electronic conductivity from the metal or carbon filler particles, resolving the contradiction between adhesion and conductivity.
Solution Approach 2:
The conductive adhesive acts as an intermediary layer between the current collector and active material layers. It mediates both mechanical attachment and electrical connection, replacing conventional non-conductive adhesives that could only provide mechanical bonding.
3Ease of manufacture
If solvent-based processes are used for battery manufacturing, then ease of fabrication is improved, but material stability deteriorates due to electrochemical instability in solvent-containing environments
Solution Approach 1:
The patent extracts and removes solvents from the battery system entirely, using solvent-free ionic liquid-based electrolytes and adhesives. This extraction eliminates the stability issues caused by solvents while maintaining ease of manufacturing through direct application and drying processes.
Solution Approach 2:
The ionic liquid creates an inert, non-aqueous environment that is chemically stable and does not react with electrochemically unstable materials. This inert environment allows materials that would otherwise be unstable in solvent-containing environments to function reliably in the battery.
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 solution ensures robust and safe battery performance by maintaining electro-mechanical connections and ionic conductivity without solvents, allowing the use of materials that are electrochemically unstable in solvent-containing environments, and enabling flexible integration in various applications.
Implementation Method 1
provides electronic conductivity between negative active material layer 160 and negative current collector 185
Implementation Method 2
each of the positive electrode, electrolyte layer, and negative electrode comprises an ionic liquid enabling ionic transfer
Implementation Method 3
conductive pressure sensitive adhesive layer 170 directly interfaces, adheres to each of negative active material layer 160 and negative current collector 185
Data Source
AI summary
Provided are electrochemical cells and methods of manufacturing these cells. An electrochemical cell comprises a positive electrode and an electrolyte layer, printed over the positive electrode. In some examples, each of the positive electrode, electrolyte layer, and negative electrode comprises an ionic liquid enabling ionic transfer. The negative electrode comprises a negative active material layer (e.g., comprising zinc), printed over and directly interfacing the electrolyte layer. The negative electrode also comprises a negative current collector (e.g., copper foil) and a conductive pressure sensitive adhesive layer. The conductive pressure sensitive adhesive layer is disposed between and adhered to, directly interfaces, and provides electronic conductivity between the negative active material layer and the negative current collector. In some examples, the conductive pressure sensitive adhesive layer comprises carbon and/or metal particles (e.g., nickel, copper, indium, and/or silver). Furthermore, the conductive pressure sensitive adhesive layer may comprise an acrylic polymer, encapsulating these particles.