Patterned Negative Electrode Coating to Prevent End Dragging
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Solution Overview
Problem
The existing methods for preparing negative electrodes for rechargeable lithium batteries face challenges in accurately forming patterned active material layers, leading to issues like dragging of the end portion during coating, which can result in electrode instability and potential fires.
Innovation Solution
A method involving the concurrent coating of a first and second negative active material layer composition on a current collector, with capillary numbers between 0.25 to 1.50 and 0.28 to 1.50 respectively, to create a patterned active material layer, effectively preventing dragging and ensuring uniform coating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a single active material layer composition is coated on the current collector, then the coating process is simple, but the pattern coating accuracy is poor and dragging occurs at the end portion
Solution Approach 1:
The active material layer composition is divided into two separate compositions: a first composition containing a first active material and a second composition containing a second active material. These two compositions are coated in sequence to form a multi-layer structure, which enables precise pattern coating and prevents dragging at the end portion while maintaining a relatively simple overall coating process
Solution Approach 2:
Different regions of the active material layer are assigned different compositions with specific properties. The first composition is coated in a first region and the second composition is coated in a second region, allowing each layer to have optimized local characteristics that prevent dragging and achieve accurate pattern coating
2Manufacturing precision
If the active material layer is coated to ensure uniform distribution, then the coating quality is good, but the end portion dragging occurs leading to electrode instability
Solution Approach 1:
The coating process is segmented into two sequential steps with two different compositions. The first composition is coated and then the second composition is coated on top, which maintains uniform distribution throughout the layer while the layered structure prevents end portion dragging, thereby ensuring electrode stability
Solution Approach 2:
The active material layer is constructed as a composite of two different compositions. The first composition contains a first active material and the second composition contains a second active material, creating a composite layered structure that simultaneously achieves uniform coating quality and prevents dragging-induced instability
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 approach prevents the dragging of the end portion, enhances electrode stability, and reduces the risk of fires by maintaining uniform loading and coating quality of the negative active material layer.
Implementation Method 1
coating a first negative active material layer composition having a capillary number of about 0.25 to about 1.50 on the current collector and coating a second negative active material layer composition having a capillary number of about 0.28 to about 1.50 on the first negative active material layer composition
Data Source
AI summary
A method of preparing a negative electrode for a rechargeable lithium battery and a rechargeable lithium battery including the negative electrode, and the method of preparing the negative electrode may include preparing an active material layer on a current collector so that a coated portion in which the active material layer is formed and an uncoated region in which an active material is not formed are alternatively arranged, the active material, wherein the coated portion is formed by coating a first negative active material layer composition having a capillary number of about 0.25 to about 1.50 on the current collector and coating a second negative active material layer composition having a capillary number of about 0.28 to about 1.50 on the first negative active material layer composition.