Lithium-Ion Battery Electrode Primer Layer Design
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Solution Overview
Problem
Lithium-ion secondary batteries face challenges with rare metal scarcity and safety issues due to oxidation of current collectors and sulfur elution in aqueous solvents, leading to decreased charge and discharge capacity and cycle characteristics.
Innovation Solution
A lithium-ion secondary battery design featuring a sulfur-based active material with a primer layer and crosslinking agent layer between the current collector and active material layer, using a compound capable of crosslinking an aqueous binder, which enhances durability and prevents sulfur elution, regardless of current collector type.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an aluminum current collector is used with an aqueous electrode slurry, then the current collector is oxidized and an insulating film is formed, but this decreases charge and discharge capacity
Solution Approach 1:
A primer layer is introduced as an intermediary between the aluminum current collector and the aqueous electrode slurry. This primer layer prevents direct contact between the aluminum and water, avoiding oxidation while maintaining electrical conductivity and allowing the aqueous slurry to be applied effectively.
Solution Approach 2:
The electrode structure is segmented into multiple functional layers: the aluminum current collector, the primer layer, and the electrode slurry layer. This segmentation allows each layer to perform its specific function without interfering with others, preventing oxidation while maintaining capacity.
2Reliability
If a non-aqueous electrode slurry is used, then the aluminum oxidation problem is solved, but sulfur elutes into the organic solvent, decreasing electrode capacity and binder bonding strength
Solution Approach 1:
The primer layer serves as an intermediary that prevents sulfur from eluting into the non-aqueous solvent. It acts as a barrier that maintains sulfur within the electrode structure while allowing the benefits of non-aqueous slurries to be realized.
Solution Approach 2:
The primer layer is applied in advance to the current collector before applying the electrode slurry. This preliminary action creates a protective barrier that prevents sulfur elution before it can occur during electrode formation and battery operation.
3Reliability
If a primer layer is added to protect the current collector, then oxidation is prevented, but the device complexity increases
Solution Approach 1:
The primer layer is applied locally only where needed - on the current collector surface before slurry application. This localized approach provides protection exactly where oxidation occurs without adding complexity to the entire electrode structure.
Solution Approach 2:
The primer layer application is merged with the existing electrode manufacturing process flow. It is applied as part of the standard slurry coating procedure, integrating the protective function into the existing process without requiring separate complex equipment or steps.
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
The configuration results in a battery with improved charge and discharge capacity, excellent cycle characteristics, and enhanced high-temperature durability, while minimizing environmental impact and maintaining high electric conductivity.
Implementation Method 1
a crosslinking agent layer comprising a compound being capable of crosslinking an aqueous binder contained in the primer layer
Implementation Method 2
when an aluminum foil is used as a current collector of an electrode and an aqueous electrode slurry comprising a sulfur-based active material is applied thereto, there is a problem such that the aluminum foil is oxidized and an insulating film is formed
Data Source
AI summary
An object of the present invention is to provide a lithium-ion secondary battery having a large charge and discharge capacity and excellent cycle characteristics irrespective of kind and shape of a current collector. The lithium-ion secondary battery comprises an electrode comprising a primer layer for protecting a current collector and a crosslinking agent layer comprising a compound being capable of crosslinking an aqueous binder contained in the primer layer, the both layers being disposed between a current collector and an active material layer comprising a sulfur-based active material.