Li-Ion Positive Electrode Boundary Layer for Thin Insulating Coatings
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Solution Overview
Problem
Existing methods for applying insulating materials to lithium ion secondary battery electrodes face challenges such as increased thickness, cost, and cracking due to the difficulty in applying thin films, especially when coating thick active material layers.
Innovation Solution
A positive electrode design 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 layer is partially covered by the first and positioned at the boundary between formed and unformed areas, with a conductive substance dispersed throughout, allowing for continuous or intermittent application to reduce manufacturing costs and improve performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If insulating material is applied after coating a thick film of active material, then the insulating layer can be applied, but the gap between coating equipment tip and work cannot be narrowed making it difficult to apply thin film, resulting in increased cell thickness and higher cost
Solution Approach 1:
The insulating layer is applied preliminarily before the active material coating process. By forming the insulating layer on the current collector first, the coating equipment can apply a thin film with precise thickness control without the interference of a thick active material layer. This preliminary action resolves the difficulty of narrowing the gap between equipment tip and work surface, enabling thin film application while reducing overall cell thickness.
2Reliability
If insulating material thickness is increased to ensure coverage, then manufacturing becomes easier, but cost increases and cracking risk during drying increases
Solution Approach 1:
The patent changes the physical and chemical parameters of the insulating layer by applying it as a thin film with controlled thickness and specific composition. The insulating layer contains conductive materials dispersed in an insulating matrix, creating a composite structure that maintains electrical insulation while preventing cracking during drying. This parameter optimization ensures sufficient coverage without excessive thickness that would cause drying cracks.
3Quantity of substance
If thin film insulating layer is applied, then cell thickness and cost are reduced, but manufacturing precision requirements increase making application difficult
Solution Approach 1:
The insulating layer is designed as a composite material containing both insulating matrix and dispersed conductive materials. This composite structure provides inherent self-leveling and crack-prevention properties that facilitate thin film application with controlled thickness. The conductive particles within the insulating matrix help maintain film integrity during drying, enabling precise thickness control while reducing overall material quantity and cell thickness.
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.