Layered Dry Cathode Film for Solvent-Free Low-Resistivity Cells
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Solution Overview
Problem
The challenge is to develop a dry cathode film and battery technology that achieves high energy density, improved mechanical properties, and reduced resistivity, while eliminating the use of organic solvents in electrode preparation.
Innovation Solution
A dry cathode film is created using a composite of Li2S, a lithium salt, a carbon-based material, and a dry binder, with multiple cathode active material layers having different compositions, which are applied to a cathode current collector to enhance mechanical properties and reduce resistivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a slurry including a solvent is used to prepare the electrode, then the electrode can be manufactured with conventional methods, but an excessive amount of organic solvent is utilized which is harmful to the environment and requires additional drying steps
Solution Approach 1:
The patent extracts and eliminates the organic solvent component from the electrode preparation process by using a dry mixing method instead of a slurry method. The active materials, conductive agents, and binders are directly mixed in their dry powder forms without requiring dissolution in organic solvents, thereby removing the harmful factor while maintaining manufacturability
Solution Approach 2:
The patent changes the physical state parameter of the electrode preparation process from liquid slurry to dry powder mixture. By altering the aggregation state of materials from dissolved/ suspended in solvent to dry particulate form, the process eliminates organic solvent usage while enabling direct deposition onto current collectors
2Device complexity
If a single-layer cathode structure is used, then the manufacturing process is simple, but the mechanical properties and resistivity are not optimized
Solution Approach 1:
The patent segments the cathode into multiple functional layers with distinct compositions and purposes. Different layers contain different ratios of active materials, conductive agents, and binders to optimize specific functions such as electron conduction, ion transport, and mechanical integrity at different locations within the cathode structure
Solution Approach 2:
The patent applies local quality by giving different regions of the cathode different material compositions tailored to their specific functional requirements. For example, certain layers may have higher conductive agent content for electron transport, while others have higher binder content for mechanical strength, optimizing performance locally rather than uniformly throughout
3Quantity of substance
If the cathode active material content is increased to achieve high energy density, then the battery capacity improves, but the mechanical strength and electrical conductivity may deteriorate
Solution Approach 1:
The patent applies local quality by giving different regions of the cathode different material compositions tailored to their specific functional requirements. For example, certain layers may have higher conductive agent content for electron transport, while others have higher binder content for mechanical strength, optimizing performance locally rather than uniformly throughout
Solution Approach 2:
The patent uses composite materials by combining active materials with conductive agents and binders in specific ratios within each layer. This creates a composite structure where the conductive agents form conductive networks and binders provide mechanical integrity, allowing high active material content while maintaining overall cathode performance
Data Source
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AI summary
A dry cathode film includes a first dry cathode active material layer adjacent to a cathode current collector, and a second dry cathode active material layer on the first dry cathode active material layer. The first dry cathode active material layer and the second dry cathode active material layer each independently include a dry cathode active material including a composite of Li2S, a lithium salt, and a carbon-based material; a dry sulfide-based solid electrolyte; and a dry binder. A content of the dry cathode active material in the first dry cathode active material layer is greater than a content of the dry cathode active material in the second dry cathode active material layer, and a content of the dry sulfide-based solid electrolyte in the first dry cathode active material layer is less than a content of the dry sulfide-based solid electrolyte in the second dry cathode active material layer.