Cell Stack Bonding via Electromagnetic Heating of Conductive Layers
Solution Overview
Problem
The existing methods for producing electrochemical storage devices, such as lithium-ion batteries, face challenges in achieving uniform and rapid bonding of anode, separator, and cathode layers due to inhomogeneous temperature distributions caused by external heating, which can lead to delayed bonding and adverse effects on material properties.
Innovation Solution
The method involves generating heat directly within the electrically conductive layers of the cell stack using electromagnetic or electrical heating, thereby uniformly activating the thermally activated adhesive, ensuring quick and uniform bonding without excessive thermal stress on the layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If external heating plates are used to heat the cell stack layers, then the bonding process can be initiated, but the temperature distribution becomes inhomogeneous and bonding uniformity deteriorates
Solution Approach 1:
The patent replaces the mechanical contact heating system (heating plates pressing against the cell stack) with an electromagnetic induction heating system. The induction heating device generates an alternating magnetic field that induces eddy currents in the conductive layers, converting electromagnetic energy directly into heat within the layers themselves. This eliminates the thermal conduction bottleneck and achieves homogeneous temperature distribution throughout the cell stack, resolving the contradiction between initiating bonding and maintaining bonding uniformity.
Solution Approach 2:
The patent transitions from external surface heating (two-dimensional contact at the boundaries) to volumetric internal heating (three-dimensional heat generation throughout the bulk). By inducing eddy currents within the conductive layers, heat is generated throughout the volume of each layer simultaneously, creating a homogeneous temperature field that ensures uniform adhesive activation and bonding across the entire cell stack.
2Manufacturing precision
If heating time is extended to achieve uniform bonding, then bonding quality improves, but production productivity decreases
Solution Approach 1:
The induction heating system converts electromagnetic energy directly into thermal energy within the conductive layers through eddy current generation. This direct energy conversion is highly efficient and rapid, heating the layers uniformly throughout their volume simultaneously. The process achieves complete adhesive activation in a fraction of the time required by conventional conduction heating, thereby improving both bonding quality and production productivity by eliminating the time penalty associated with slow thermal diffusion.
Solution Approach 2:
The patent changes the fundamental heating parameter from slow thermal conduction to rapid electromagnetic induction heating. By adjusting the frequency and power of the alternating magnetic field, the system can precisely control the rate and distribution of heat generation, achieving optimal bonding quality in significantly reduced time. This parameter change enables rapid heating while maintaining uniform temperature distribution, resolving the contradiction between bonding quality and production speed.
3Productivity
If higher temperature or greater pressing force is applied to accelerate bonding, then bonding speed increases, but material properties deteriorate
Solution Approach 1:
The induction heating system provides localized and uniform heat generation within each conductive layer through controlled eddy current distribution. The alternating magnetic field penetrates the layers and induces currents that generate heat precisely where needed - within the adhesive layers and substrate - without creating hot spots or excessive temperature gradients. This localized quality control ensures rapid bonding speed while maintaining material integrity by avoiding thermal stress and degradation.
4Device complexity
If conventional external heating is used, then the heating process is simple to implement, but heat conduction is time-consuming and temperature distribution becomes inhomogeneous
Solution Approach 1:
The patent replaces the simple but inefficient thermal conduction heating system with an electromagnetic induction heating system. While the induction system involves electromagnetic field generation and control, it eliminates the time-consuming thermal diffusion process. The alternating magnetic field directly induces eddy currents in the conductive layers, converting electromagnetic energy to thermal energy instantaneously throughout the material volume, thereby dramatically reducing heating time while achieving homogeneous temperature distribution.
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 approach reduces the time required for the adhesive to develop its bonding properties, achieves a homogeneous temperature profile, and minimizes thermal stress on the outer layers, preventing adverse material changes and ensuring a more efficient production process.
Implementation Method 1
electrically conductive layers, in particular the copper foils and aluminum foils of the anode electrodes and/or the cathode electrodes and/or additional layers or grids, are heated electromagnetically and/or electrically
Implementation Method 2
electrically conductive layers, in particular the copper foils and aluminum foils of the anode electrodes and/or the cathode electrodes and/or additional layers or grids, are heated electromagnetically and/or electrically
Data Source
Figure 1~2
Figure 3~4
Figure 5
AI summary
The invention relates to a method for producing a cell stack, particularly for an electrochemical storage device, wherein at least anode electrodes, separator layers, and cathode electrodes are repeatedly stacked, folded, or wound one over the other, wherein at least one layer is coated or provided with a thermally activatable adhesive on one or both sides, wherein electrically conductive layers, particularly the anode electrodes and/or the cathode electrodes, are heated electromagnetically and/or electrically, wherein the heating of the electrically conductive layers thermally activates the adhesive and, in particular, connects the anode electrodes, separator layers, and cathode electrodes to form a cell stack. The invention further relates to a device for producing cell stacks and an electrochemical storage device with at least one cell stack.