Porous Electrode Production via Solvent-Free Pore Former Removal
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Solution Overview
Problem
Existing electrode production methods for electrochemical cells, such as lithium-ion batteries, face challenges in achieving a homogeneous distribution of active materials and binders, leading to reduced porosity and accessibility for charge carriers, especially when using solvent-free processes like calendering, which can agglomerate polymer constituents and decrease charge carrier accessibility.
Innovation Solution
A process involving a homogeneous mixture of particulate active materials, binders, and pore formers, which are formed into a compact electrode and then heated or contacted with a liquid electrolyte to create a porous structure, allowing for increased porosity and improved charge carrier diffusion without the need for solvents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a solvent-free process like calendering is used to produce electrodes, then the manufacturing process is simplified and productivity is improved, but the porosity of the electrode decreases and charge carrier accessibility is reduced
Solution Approach 1:
Pore formers are incorporated into the electrode composition before the calendering process. The compact electrode is formed first, and then the pore formers are dissolved or melted out in a subsequent step, creating porosity after the structural formation is complete
Solution Approach 2:
The pore formers undergo phase transitions (dissolution or melting) after electrode formation. Heating the compact electrode to a temperature of at least 60°C causes the pore formers to melt and be removed, creating the desired porous structure without affecting the earlier calendering process
2Stability of the object's composition
If calendering processes at elevated temperatures are used to form compact electrodes, then the electrode structure is stabilized, but the homogeneous distribution of active material particles and binder is impaired and polymer constituents agglomerate on the surface
Solution Approach 1:
Pore formers are introduced as intermediary substances that prevent direct contact and agglomeration between binder particles during calendering. These pore formers act as spacers that maintain homogeneous distribution of constituents while allowing the electrode structure to be stabilized
Solution Approach 2:
The processing temperature is controlled to be below the melting point of the pore formers during the calendering step. This parameter control prevents binder agglomeration during formation, and temperature is only increased later to melt the pore formers for porosity creation
3Manufacturing precision
If the porosity of the electrode is increased to improve charge carrier diffusion, then the accessibility for charge carriers is enhanced, but the mechanical strength and structural stability of the electrode may be reduced
Solution Approach 1:
The electrode is designed with a controlled porous structure created by removing pore formers. This porous structure enhances charge carrier diffusion pathways while the remaining binder network and active material matrix maintain the necessary mechanical strength
Solution Approach 2:
The electrode consists of a composite structure combining active material particles, binder, and porous framework. This composite architecture provides both the porosity needed for charge carrier access and the mechanical integrity required for structural stability
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 method enables the production of electrodes with high porosity and improved charge carrier accessibility, enhancing the performance of electrochemical cells by maintaining a stable and porous structure while eliminating the need for solvent-based drying steps.
Implementation Method 1
heating of the at least one compact electrode in order to liquefy the at least one particulate pore former
Implementation Method 2
contacting the compact electrode with at least one liquid electrolyte composition or at least one liquid constituent of an electrolyte composition for an electrochemical cell, which is able to at least partially dissolve the at least one particulate pore former
Implementation Method 3
contacting the compact electrode with at least one liquid electrolyte composition or at least one liquid constituent of an electrolyte composition for an electrochemical cell, which is able to at least partially dissolve the at least one particulate pore former
Data Source
AI summary
The invention relates to a method for producing an electrochemical cell comprising at least one porous electrode (2′), the method comprising at least the following method steps: (a) providing an electrode composition in the form of a homogeneous mixture comprising (i) at least one particulate active material (3); (ii) at least one particulate binder (5); (iii) at least one particulate pore-forming agent (4); and (iv) optionally at least one conducting additive (6); (b) forming a mouldable mass from the electrode composition; (c) applying the electrode composition to at least one surface of a substrate (1) to obtain a compact electrode (2); (d) producing an electrochemical cell comprising at least one compact electrode (2) which comprises the electrode composition according to method step (a); and (e) heating the at least one compact electrode (2) to liquefy the at least one particulate pore-forming agent (4); and/or (f) bringing the compact electrode (2) into contact with at least one liquid electrolyte composition or at least one liquid constituent of an electrolyte composition for an electrochemical cell which is capable of at least partially dissolving the at least one particulate pore-forming agent (4) to obtain a porous electrode (2), wherein method steps (a), (b), (c), (d) and (e) are carried out substantially without solvents.