Double-Coated Cathode Structure for Adhesion and Energy Density
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Solution Overview
Problem
Manufacturing dual-chemistry electrodes, particularly dual-chemistry cathodes, faces challenges such as delamination issues due to poor adhesion of certain active materials to current collectors, leading to sub-optimal energy density and performance, requiring different slurry formulations for varying ratios of active materials and limiting active material concentrations to below 94% and porosities to above 30%.
Innovation Solution
A double-coated electrode design is implemented, where two cathode layers with different particle size distributions and/or chemical makeups are formed at the slurry level, with the first layer acting as an interface buffer, allowing higher active material concentrations and porosities by varying layer thicknesses instead of slurry formulations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a single-layer cathode electrode is used with uniform slurry formulation, then the manufacturing process is simple, but the adhesion of certain active materials to current collector is poor leading to delamination
Solution Approach 1:
The cathode electrode is divided into two distinct layers: a first layer with slurry formulation optimized for strong adhesion to the current collector, and a second layer with slurry formulation optimized for high active material concentration. This segmentation allows each layer to perform its specific function independently, resolving the contradiction between adhesion quality and manufacturing simplicity.
Solution Approach 2:
Different regions of the cathode electrode (first layer vs. second layer) are assigned different slurry formulations with specific properties. The first layer uses a formulation with higher binder content for strong adhesion, while the second layer uses a formulation with higher active material concentration for energy density. This local differentiation resolves the contradiction by allowing each region to have optimized properties for its specific function.
2Manufacturing precision
If different slurry formulations are used for varying ratios of active materials, then the adhesion and energy density can be optimized, but the manufacturing complexity increases
Solution Approach 1:
The electrode is segmented into two layers, each with its own optimized slurry formulation. This allows the first layer to be formulated for adhesion and the second layer for energy density, achieving manufacturing precision without requiring complex variable formulation across a single layer. The segmentation simplifies the overall manufacturing approach compared to attempting to optimize a single uniform layer.
Solution Approach 2:
Instead of varying slurry formulation composition across a single layer (compositional dimension), the invention uses layering (spatial dimension) to achieve different formulations in different regions. This dimensional transition allows multiple optimized formulations to coexist in a single electrode without increasing manufacturing process complexity.
3Quantity of substance
If active material concentration is increased above 94%, then the energy density improves, but the porosity must be reduced below 30% compromising performance
Solution Approach 1:
The cathode is segmented into two layers with different active material concentrations. The first layer can have lower concentration with higher porosity for structural integrity and adhesion, while the second layer can have very high active material concentration (above 94%) for maximum energy density. This segmentation allows the system to achieve high overall energy density without compromising porosity in critical regions.
Solution Approach 2:
Different regions of the cathode are assigned different active material concentrations based on their functional requirements. The second layer, which is in contact with the electrolyte and separator, is assigned high active material concentration for energy density, while the first layer, which provides structural support and adhesion, maintains lower concentration with higher porosity. This local optimization resolves the contradiction between energy density and porosity.
Data Source
AI summary
Aspects of the disclosure include a double-coated electrode for dual-chemistry cathode systems and methods of manufacturing the same. An exemplary vehicle includes an electric motor and a battery pack electrically coupled to the electric motor. The battery pack includes a battery cell that includes an anode current collector, an anode active material layer in direct contact with a surface of the anode current collector, a cathode current collector, and a cathode active material layer in direct contact with a surface of the cathode current collector. The cathode active material layer includes a dual-chemistry electrode having a first cathode layer in direct contact with the cathode current collector and a second cathode layer positioned directly on the first cathode layer. The first cathode layer and the second cathode layer are made of materials having at least one of a different particle size distribution and a different chemical makeup.