Two-Step Coating Process for 3D Lithium-Ion Battery Electrodes
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Solution Overview
Problem
Conventional methods for manufacturing thick electrodes for lithium-ion batteries face issues such as air trapped inside the three-dimensional electrode substrate (3DF) leading to unstable material filling and Li ion movement disturbances, and the risk of micro short circuits due to metallic powder dust and Li dendrites.
Innovation Solution
A two-step coating process is employed, where the first step involves filling and drying the active material paste within the 3DF while removing air, followed by a second step of coating a new paste on both sides of the electrode to ensure uniform coverage and prevent air pockets, thereby preventing Li dendrite formation and micro short circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a single-step coating process is used to fill active material paste into the three-dimensional electrode substrate, then the manufacturing process is simple, but air becomes trapped inside the 3DF causing unstable material filling and Li ion movement disturbances
Solution Approach 1:
The coating process is divided into multiple sequential steps: first applying paste to one surface, drying, then applying paste to the opposite surface, and drying again. This segmentation allows air to be gradually expelled and prevents trapping, ensuring stable material filling while maintaining manufacturing simplicity through a systematic multi-step approach.
2Ease of manufacture
If a single-step coating process is used, then the manufacturing process is simple, but air pockets remain causing Li dendrite formation and micro short circuits
Solution Approach 1:
The first coating step applies paste to one surface and dries it completely before the second coating step. This preliminary action ensures that air is expelled during the first drying phase, preventing air pockets that would lead to Li dendrite formation and micro short circuits, thereby improving battery reliability.
3Quantity of substance
If thick electrodes are manufactured using conventional methods, then the battery capacity increases, but air trapped inside disturbs Li ion movement reducing battery performance
Solution Approach 1:
The multi-step coating and drying process enables thick electrodes to be manufactured with uniform material distribution and no trapped air. By sequentially coating and drying each surface, the method ensures efficient Li ion movement pathways are maintained throughout the thick electrode structure, preserving battery performance while increasing 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
The two-step coating process ensures stable filling of the active material, prevents micro short circuits, and allows for efficient Li ion movement, enhancing the reliability and capacity of lithium-ion batteries while reducing manufacturing complexity and costs.
Implementation Method 1
a liquid flow of the paste is formed in the paste tank of the active material and the paste is filled while removing air inside of the 3DF by applying the paste flow from one side of the 3DF to pass through
Implementation Method 2
it is dried
Implementation Method 3
a new paste onto both sides of the electrode obtained by the first step
Data Source
AI summary
Using the generally used coating method of an active material paste to a metal foil on a 3DF made the electrode properties instable due to residual air inside of the 3DF, and had the risk of causing micro short circuit of the battery due to metal fine powder and the like adhered to the 3DF and the 3DF exposed to the electrode surface. To solve the above-mentioned, the coating of the active material paste to the 3DF was made into a two-step coating process as shown below. Step one removes the air and fills the paste at the same time by applying the paste flow from one side of the 3DF (the first step coating process). Step two coats a new paste onto the surface of the electrode obtained by step one (the second step coating process). This electrode obtained by the two-step coating process hardly has remaining air amount, can uniformly confine metallic power dust or the 3DF itself inside the electrode (the first step coating process), and in addition to this, has the capability of Li ions freely moving between the electrode surface and the depth portion of the electrode through the opening portion formed on the tip portion of the innumerable protrusions of the 3DF, the micro short circuit of the battery due to Li dendrite was prevented even in repeated charge and discharge.