Lithium-Ion Cathode Boundary Coating for Thin Insulating Films
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Solution Overview
Problem
The application of an insulating material as a thin film is challenging due to the gap between coating equipment and the work, leading to increased thickness, cost, and cracking risks in lithium ion secondary batteries with high energy density.
Innovation Solution
A positive electrode for lithium ion secondary batteries featuring a first mixture layer with a positive electrode active material and a second mixture layer containing different particles, where the second mixture layer is partially covered by the first and positioned at the boundary between formed and non-formed areas, with a conductive substance dispersed in both layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If an insulating material is applied after coating a thick film, then the insulating layer can be formed, but the gap between coating equipment and work cannot be narrowed, making it difficult to apply a thin film
Solution Approach 1:
The insulating layer is formed on the current collector before the active material layer is applied. This preliminary action allows the coating equipment to apply a thin insulating film directly to the current collector surface without the interference of a thick active material layer, thereby achieving precise thickness control while maintaining ease of manufacture
Solution Approach 2:
The electrode structure is segmented into distinct layers with the insulating layer positioned at the boundary between the active material layer and the current collector. This segmentation allows each layer to be optimized independently, enabling the insulating layer to be applied as a thin film while the active material layer can be coated separately
2Ease of manufacture
If the insulating layer thickness is increased, then application difficulty is reduced, but cell thickness increases and manufacturing cost increases
Solution Approach 1:
By applying the insulating layer preliminarily to the current collector before active material coating, the process allows for thin film application that reduces cell thickness while maintaining manufacturing feasibility through proper sequencing of coating operations
3Ease of manufacture
If the insulating layer thickness is increased, then application difficulty is reduced, but manufacturing cost increases
Solution Approach 1:
The preliminary formation of the insulating layer on the current collector enables the use of thinner insulating material, thereby reducing the quantity of insulating material required and lowering manufacturing costs while maintaining ease of application through proper process sequencing
Solution Approach 2:
The patent optimizes the thickness parameter of the insulating layer by forming it as a thin film through preliminary coating, which changes the material quantity parameter to reduce cost while maintaining the functional requirements of electrical insulation
4Quantity of substance
If a thick active material layer is used to increase capacity, then battery capacity increases, but the risk of cracking during drying increases
Solution Approach 1:
The insulating layer is formed preliminarily on the current collector before the active material layer is applied and dried. This preliminary action provides a stable base layer that can accommodate the thick active material layer without transferring drying stresses to the current collector, thereby reducing cracking risk while maintaining high capacity
Solution Approach 2:
The insulating layer acts as a cushioning layer between the current collector and the thick active material layer. This beforehand cushioning prevents direct stress transmission during the drying process, reducing the risk of cracking in the thick active material layer while preserving battery capacity
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 configuration reduces manufacturing costs and ensures high performance by allowing a thin film application of the insulating material, preventing cracking and maintaining electrical insulation while enhancing conductivity.
Implementation Method 1
the first mixture layer and the second mixture layer contain a dispersed conductive substance
Data Source
AI summary
Provided is a positive electrode for a lithium ion secondary battery including a metal foil (9) (current collector), a first mixture layer (11) which is provided on one surface of the metal foil (9) and contains a positive electrode active material, and a second mixture layer (12) which is partially covered by the first mixture layer (11) and includes, as a main component, particles different from the active material, in which the second mixture layer (12) is provided on one end (11a) side of the first mixture layer (11) in a boundary portion between a formed area of the first mixture layer (11) and a non-formed area of the first mixture layer (11), one end (12a) of the second mixture layer (12) is positioned between the one surface of the metal foil (9) and a lower surface of the first mixture layer (11) in the formed area of the first mixture layer (11), and the other end (12b) is positioned in the non-formed area, and the first mixture layer (11) and the second mixture layer (12) contain a dispersed conductive substance.