Electrostatic Electrode Coating for Higher Loading and Metal Filtration
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Solution Overview
Problem
Existing electrode manufacturing methods using electrostatic coating face limitations in achieving high coating weight of active material layers due to the gravitational separation of metal foreign substances and uneven binder distribution, leading to reduced battery performance and energy density.
Innovation Solution
The method involves forming an electric field with opposing polarities between a substrate and a screen, using composite particles with a binder to enhance adhesion and uniform distribution, and adjusting the flight direction of coating powder to 90 degrees to 270 degrees to filter out metal foreign substances, thereby increasing the coating weight and adhesion rate while maintaining uniform binder distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the active material layer is made thicker to increase coating weight, then the coating weight increases, but the electrostatic force acting on the surface of the active material layer decreases due to increased distance from the substrate
Solution Approach 1:
A screen is introduced as an intermediary component between the coating powder supply and the substrate. The screen is charged with a polarity opposite to that of the coating powder, creating an electric field that mediates the attraction of coating powder to the substrate. This intermediary electric field structure allows for stronger and more uniform electrostatic attraction across the coating process, enabling higher coating weights without the electrostatic force diminishing as rapidly with thickness increases.
Solution Approach 2:
The patent applies a voltage to the screen in addition to the substrate, fundamentally changing the electric field parameters. By charging the screen with opposite polarity to the coating powder and maintaining appropriate voltage relationships (where the absolute voltage difference between screen and substrate exceeds a threshold), the system creates a reinforced electric field that can penetrate through thicker active material layers, maintaining sufficient electrostatic force even as coating weight increases.
2Reliability
If the flight direction of coating powder is adjusted to 90 degrees to 270 degrees relative to vertically downward direction to achieve filter action, then metal foreign substances are removed, but the coating weight is limited due to gravity exceeding adhesive force
Solution Approach 1:
The charged screen acts as an intermediary that creates a strong electric field between itself and the substrate. This electric field generates sufficient adhesive force to counteract gravity on the coating powder particles throughout their flight path and even after deposition. The screen's electric field serves as a mediating force that maintains coating powder adhesion despite the gravitational limitation imposed by the horizontal/vertical flight direction configuration needed for filter action.
Solution Approach 2:
The electric field generated by the charged screen provides an upward counteracting force against gravity. By charging the screen with polarity opposite to the coating powder and maintaining adequate voltage, the system creates an electrostatic force that counterbalances the gravitational force on the coating powder particles. This anti-weight effect allows coating powder to adhere to the substrate even when flight direction is horizontal (90 or 270 degrees), where gravity would otherwise cause particles to fall away from the substrate.
3Quantity of substance
If voltage is applied to both substrate and screen with opposite polarities to increase adhesive force, then coating weight increases, but device complexity increases
Solution Approach 1:
The screen serves multiple functions simultaneously: it acts as a physical barrier or support structure for the coating powder, serves as a charging element to generate the electric field, and functions as an electrode to which voltage is applied. This multi-functionality reduces the need for separate components, thereby limiting the increase in device complexity despite the added voltage application requirement.
Solution Approach 2:
The patent combines the screen and substrate into an integrated electric field generation system where both elements are charged with opposite polarities. By merging the screen into the voltage application system rather than treating it as a separate passive component, the design achieves enhanced adhesive force while keeping the overall system structure relatively simple and unified.
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 significantly increases the upper limit value of the coating weight, improves adhesion frequency, and enhances the energy density of batteries by reducing metal foreign substances and ensuring uniform binder distribution, resulting in improved battery performance.
Implementation Method 1
When the coating powder passes through the screen, the coating powder comes into contact with the screen to apply a charge to the coating powder. The coating powder flies in the electric field by an electrostatic force to reach the substrate.
Implementation Method 2
The coating powder adheres to the substrate by the electrostatic force.
Data Source
AI summary
An electric field is formed between a substrate and a screen by applying a first voltage to the substrate and applying a second voltage to the screen. Coating powder is introduced into the electric field through the screen. An electrode is manufactured by causing the coating powder to adhere to the substrate. The first voltage has a polarity opposite to a polarity of the second voltage. When the coating powder passes through the screen, the coating powder comes into contact with the screen to apply a charge to the coating powder. The coating powder flies in the electric field by an electrostatic force to reach the substrate. An angle between a flight direction of the coating powder and a vertically downward direction is 90 degrees to 270 degrees.